Next Article in Journal
Marine-Derived Defenses Against HIV: Emerging Bioactive Molecules from the Seas
Previous Article in Journal
Taxonomic Diversity and Metabolic and Pharmacological Profiles of Marine-Derived Actinomycetes from the Lisbon and Setúbal Coast, Portugal
Previous Article in Special Issue
Natural Products from Marine Microorganisms with Agricultural Applications
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Marine Drugs
Volume 24
Issue 2
10.3390/md24020069
marinedrugs-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Anti-Inflammatory Effects of Marine-Derived Resorcylic Acid Lactone Derivatives in Ulcerative Colitis via the MAPK/ERK Pathway

by
Xuan Zhang
1,2,3,†,
Tuxiang Mo
1,2,3,†,
Yuyue Qin
1,2,3,
Meiling Le
1,2,3,
Li Tang
1,2,3,
Zhao Zhang
1,2,3,
Jiling Yi
1,2,3,
Fuling Cen
1,2,3,
Wanshan Li
1,2,3,* and
Guangying Chen
1,2,3,*
1
Key Laboratory of Tropical Medicinal Resource Chemistry of Ministry of Education, Hainan Normal University, Haikou 571158, China
2
Key Laboratory of Tropical Medicinal Plant Chemistry of Hainan Province, School of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158, China
3
Hainan Provincial International Joint Research Center for Comprehensive Utilization and Efficient Conversion of Tropical Medicinal Resources, Haikou 571158, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Mar. Drugs 2026, 24(2), 69; https://doi.org/10.3390/md24020069
Submission received: 7 January 2026 / Revised: 29 January 2026 / Accepted: 3 February 2026 / Published: 5 February 2026
(This article belongs to the Special Issue Pharmacological Potential of Marine Natural Products, 3rd Edition)
Browse Figures
Review Reports Versions Notes

Abstract

Ulcerative colitis (UC) is an inflammatory bowel disease characterized by recurrent inflammation of the colonic mucosa, and there is currently a lack of safe and effective treatment drugs. Resorcylic acid lactones (RALs) are a natural product that have been reported to have anti-inflammatory effects. However, the mechanism of whether RALs can treat UC and their anti-inflammatory effects remains underexplored. In this study, three new RAL derivatives, Penicillactones A–C (1–3), along with seven known analogs (4–10), were isolated from the marine fungus Penicillium sp. HN20. The structures of compounds 1–3 were elucidated by spectroscopic methods, 13C NMR theoretical calculations, and ECD analysis. Among these, compound 4 exhibited potent anti-inflammatory activity in LPS-stimulated RAW 264.7 macrophages. In a dextran sulfate sodium (DSS)-induced UC model, compound 4 alleviated body weight loss, disease activity, colon shortening, and spleen enlargement, and protected intestinal epithelial integrity. Mechanistic studies revealed that compound 4 primarily exerts its effects by downregulating the Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase (MAPK/ERK) signaling pathway, inhibiting pro-inflammatory cytokine production. Collectively, these findings provide the first evidence that marine-derived RAL derivatives exert anti-inflammatory effects by inhibiting the MAPK/ERK pathway, highlighting compound 4 as a promising therapeutic candidate for inflammation and UC.

1. Introduction

Ulcerative colitis (UC), a subtype of inflammatory bowel disease, is characterized by recurrent inflammation of the colonic mucosa, leading to symptoms like bloody diarrhea, abdominal pain, and urgent defecation, which significantly impair patients’ quality of life [1,2]. The pathogenesis of UC is driven primarily by immune dysregulation, where an inappropriate immune response to the gut microbiota leads to sustained inflammation and mucosal damage [3,4]. Currently, ranging from 5-aminosalicylic acid (5-ASA) to corticosteroids, immunosuppressants, and biological agents, often fail due to inadequate response, secondary treatment failure, or serious side effects [5,6]. The high relapse rates further complicate management, underscoring the need for novel, more effective, and safer drugs to address the complex pathophysiology of UC.
Resorcylic acid lactones (RALs), a class of fungal polyketides characterized by a β-resorcylic acid moiety embedded within a macrocyclic lactone, exhibit diverse biological activities, including anticancer, antifungal, antiparasitic, antiviral, and anti-inflammatory effects [7,8,9,10]. Notably, several RALs have been shown to suppress key inflammatory mediators, such as nitric oxide (NO), prostaglandin E2 (PGE2), and pro-inflammatory cytokines in activated macrophages, which are critically involved in the pathogenesis of UC. For example, 14-membered RALs from Aspergillus sp. ZJ-65 and penicimenolides from Penicillium sp. SYP-F-7919 significantly inhibits LPS-induced NO production [11,12]. More recently, β-RALs isolated from Colletotrichum gloeosporioides were reported to reduce NO, PGE2, and pro-inflammatory cytokine levels through suppression of iNOS, COX-2, and inflammatory signaling pathways [13].
Given the central role of macrophage-derived cytokines in epithelial barrier disruption and mucosal injury in UC [14], these findings suggest that RALs may be relevant to intestinal inflammatory disorders beyond their anti-inflammatory effects observed in simplified cell models. Nevertheless, current evidence is largely restricted to in vitro macrophage systems, and the in vivo efficacy of RALs in colitis models and the underlying signaling pathways remain unexplored. We therefore proposed that selected marine-derived RAL derivatives may overcome the limitations of macrophage-based assays by modulating inflammatory signaling pathways involved in both immune activation and epithelial injury. In particular, the macrocyclic lactone scaffold and characteristic oxygenation patterns of marine RALs may promote interactions with inflammation-related signaling pathways [15], such as MAPK, which links macrophage activation to intestinal epithelial dysfunction in UC [16]. On this basis, the present study was designed to evaluate whether the anti-inflammatory activity of marine-derived RALs can be translated into therapeutic efficacy in an experimental colitis model and to elucidate the underlying molecular mechanisms.
In this study, three new RAL derivatives, penicillolides A–C (1–3), together with seven known analogs (4–10), were isolated from the marine fungus Penicillium sp. HN20 (Figure 1). Compounds 4–7 exhibited inhibitory effects on lipopolysaccharide-induced inflammatory responses, with compound 4 demonstrating the most potent activity and pronounced anti-colitis effects. We further investigated the therapeutic mechanism of compound 4 and found that it attenuates inflammation primarily through suppression of the ERK-dependent inflammatory axis. This work highlights marine-derived RALs as promising anti-inflammatory candidates and provides mechanistic insight into the protective effects of compound 4 in UC.

2. Results

2.1. Structural Characterization

Penicillactone A (1), obtained as a yellowish oil, possessed a molecular formula C18H22O6 determined by the HR-ESI-MS ion at m/z 357.1294 [M + Na]+ (calcd 357.1314) and at m/z 333.1344 [M − H]− (calcd 333.1338), which indicated 8 degrees of unsaturation. The 1H NMR spectrum (Table 1) showed the presence of two secondary methyl groups (δH 1.33, H-17 and δH 2.07, H-19), four methylenes (δH 1.64–3.20, H-4 to H-6 and H-10), two oxygenated methines (δH 5.06, H-3 and δH 5.12, H-9), two hydrogen protons of the alkene (δH 5.33, H-7 and δH 5.52, H-8), and two aromatic protons (δH 6.28, H-12 and δH 6.22, H-14) that are meta-coupled (J = 2.3 Hz), indicating a 1,2,3,5-tetrasubstituted phenyl ring. The 13C NMR data (Table 1) and DEPT 135 experiment revealed 18 carbon resonances distinguished as two methyls, four methylenes, four methines (two aromatic and two oxygenated), four quaternary aromatic carbons, two olefinic carbons, and two ester carbonyls. The 1D-NMR data of 1 (Table 1) were similar to those of Penicimenolide E (9) [12], except for the hydroxyl group at C-9 being replaced by the acetoxy group. This deduction was confirmed by the 1H−1H COSY correlations of H-8 with H-9 and H-8 with H2-10, as well as the HMBC correlations from H3-19 to C-18 and from H-9 to C-18 (Figure 2). Detailed analysis of 1H–1H COSY, HSQC, and HMBC spectral data established the planar structure of 1 (Figure 2). Since compound 1 failed to form single crystals in multiple solvent systems, and given that compounds 1 and 9 share the same chiral carbon atoms, single crystal cultivation was performed on compound 9. X-ray crystallographic analysis (Cu Kα) of compound 9 unambiguously assigned its absolute configuration as (3R,9S) (Figure 3). Since compound 1 possesses the same chiral centers, its configuration was deduced to be identical to that of 9 by the perfect match of the ECD curve of 1 with that of 9 (Figure 4) and named as Penicillactone A.
Penicillactone B (2), a yellowish oil with a molecular formula of C16H20O5, as deduced from the HRESIMS at m/z [M + Na]+ 315.1191 (calcd 315.1209) and at m/z [M − H]− 291.1240 (calcd 291.1232), indicating seven degrees of unsaturation. The 1D-NMR data of 2 (Table 1) showed much similarity with those of (3R,7S)-7-hydroxyresorcylide (10) [17], except for the loss of a ketocarbonyl group and the appearance of a pair of olefinic signals [δC 135.4, 131.3; δH 5.30 (ddd, 15.2, 8.1, 1.2), 5.38 (ddd, 15.2, 9.5, 3.5)] at C-8/C-9 in 2, which was further proven by the 1H−1H COSY correlations between H-7/H-8, H-8/H-9, and H-9/H2-10, as well as HMBC correlations from H-7 to C-9 and from H-8 to C-10 (Figure 2). Detailed analysis of its 1H–1H COSY, HSQC, and HMBC spectra further confirmed that compound 2 was a 12-membered RAL (Figure 2). The coupling constant (J8,9 = 15.2 Hz) indicated an E configuration for the double bond.
Owing to their common biosynthetic pathway, the absolute configuration of C-3 in compound 2 was determined to be R via. Thus, there were two possible absolute configurations of 2. The 13C NMR theoretical calculations of two possible diastereomers, (3R*,7S*)-2c and (3R*,7R*)-2d, were performed to confirm the relative configuration of C-7 in 2. Due to the highly matched linear dependence of 2c (R2 = 0.9952) between the experimental and calculated 13C NMR chemical shifts (Figure 5), with a DP4+ probability of 100% (Table S8). The absolute configuration of 2 was determined by ECD calculations. The experimental ECD spectrum for 2 matched well with the calculated spectrum for (3R,7S)-2a, which showed a positive cotton effect at approximately 220 and a negative cotton effect at 250 nm (Figure 4). Thus, the absolute configuration of 2 was assigned as 3R,7S and named Penicillactone B.
Penicillactone C (3), obtained as a yellowish oil, possessed a molecular formula of C16H20O5, determined by the HR-ESI-MS ion at m/z 291.1236 [M − H]− (calcd 291.1232), which indicated 7 degrees of unsaturation. A comparison of the 1H and 13C NMR data (Table 1) revealed that compound 3 closely resembled 5, except for the absence of the carbonyl signal and the presence of an additional oxygenated carbon resonance in 3. The deduction was corroborated by the HMBC correlations between H-6/C-4, H-6/C-8, H-7/C-9, and H-9/C-11 and the 1H−1H COSY correlations between H2-5/H-6, H-6/H-7, H-7/H2-8, H2-8/H-9, and H-9/H2-10 (Figure 2). According to the biosynthetic pathway, the configuration of C-3 in compound 3 is R. The 13C NMR theoretical calculations of two possible diastereomers, (3R*,9S*)-3c and (3R*,9R*)-3d, were performed to confirm the relative configuration of C-9 in 3. Due to the highly matched linear dependence of 3d (R2 = 0.9986) between the experimental and calculated 13C NMR chemical shifts (Figure 5) with a DP4+ probability of 100% (Table S9) [18,19]. Therefore, the absolute configuration of 3 was established as 3R,9R. Finally, compound 3 was confirmed and named as Penicillactone C.
By detailed comparison of its spectroscopic data with those reported in the literature, the structures of the known compounds were identified as cis-resorcylide (4) [12], penicimenolides A-B (5–6) [12], (3R,7S)-7-methoxyresorcylide (7) [12], (3R,7R)-7-methoxyresorcylide (8) [12], penicimenolide E (9) [12], and (3R,7S)-7-hydroxyresorcylide (10) [17], respectively (Figure 1).

2.2. Anti-Inflammatory Effects

Marine natural products remain relatively unexplored as sources of anti-inflammatory lead compounds. In continuation of our research for novel inflammation inhibitors from marine microorganisms, the isolated compounds were evaluated for their inhibitory effects on inflammatory mediators. Firstly, the anti-inflammatory activity of the isolated compounds was evaluated by measuring LPS-induced NO production in RAW 264.7 cells. Among these, compounds 4–7 showed markedly stronger inhibition of NO production, with IC50 values of 2.53, 11.28, 17.48, and 42.61 μM, respectively, whereas the other compounds were considered inactive (IC50 > 50 μM) (Table 2).
We further examined the anti-inflammatory effects of the compounds 4–7, which significantly inhibited the production of the inflammatory mediator PGE2 and the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β in LPS-stimulated RAW 264.7 cells. Notably, compound 4 exhibited the most potent inhibition of PGE2, TNF-α, IL-6, and IL-1β production, with IC50 values of 6.10, 2.94, 2.07, and 6.04 μM (low micromolar range), respectively, and its inhibitory effects were significantly stronger than those of the positive control dexamethasone (Table 2). To assess the in vitro safety profile, the cytotoxicity of compounds 4–7 toward RAW 264.7 cells was evaluated using a CCK-8 assay. As summarized in Table 3, the CC50 values of the active compounds 4, 5, and 7 indicate low cytotoxicity toward RAW 264.7 cells and are substantially higher than their effective anti-inflammatory concentrations. In contrast, compound 6 exhibited relatively higher cytotoxicity (Table 3 and Figure S38). Taken together, these results indicate that compound 4 possesses significant anti-inflammatory activity in LPS-stimulated RAW 264.7 cells. Hence, compound 4 was selected for further in vivo anti-inflammatory evaluation.

2.3. Compound 4 Exhibits Potent In Vivo Anti-Inflammatory Activity in DSS-Induced Colitis

To further evaluate the in vivo anti-inflammatory activity of compound 4, we established a DSS-induced experimental colitis model in mice (Figure 6A). DSS treatment markedly shortened colon length, reduced body weight, increased DAI scores, and induced splenomegaly compared with normal controls, whereas compound 4 prevented colon shortening, ameliorated body weight loss, lowered DAI scores, and reduced spleen weight, with efficacy comparable to 5-ASA (Figure 6B–E). Histologically, DSS caused severe epithelial injury characterized by crypt destruction, dense inflammatory cell infiltration, and marked goblet cell loss, while compound 4 markedly restored epithelial architecture, limited inflammatory infiltration, and preserved goblet cells (Figure 6F), indicating protection of the intestinal barrier [20]. Consistently, DSS-induced downregulation of the tight junction proteins ZO-1, Occludin, and Claudin-1 was partially reversed by compound 4 (Figure 6G). Notably, the ZO-1/β-actin and claudin-1/β-actin ratios in the compound 4 group were higher than in the control group, suggesting compensatory upregulation and accelerated tight-junction reassembly during mucosal repair after DSS injury, rather than an abnormal response, further supporting its barrier-protective effect. Given the tight interplay between barrier dysfunction and innate immune activation in UC, we next measured the serum levels of LPS and inflammatory cytokines [21,22]. Barrier restoration by compound 4 was accompanied by a significant reduction in serum LPS levels (Figure 6H), as well as decreased systemic levels of pro-inflammatory cytokines TNF-α, IL-6, and IL-1β (Figure 6I–K). Together, these data demonstrate that compound 4 displayed significant anti-inflammatory activity in DSS-induced colitis, highlighting its therapeutic potential for UC.

2.4. Compound 4 Inhibits the Activation of MAPK/ERK Signaling Pathways in Colon Tissues of Colitis Mice

Compound 4 significantly alleviated DSS-induced colitis; however, the signaling pathways involved in the anti-inflammatory effects of compound 4 remain to be elucidated. Hence, RNA-seq analysis was performed on colon tissues to investigate the anti-inflammatory mechanism of compound 4. Notably, the gene expression profile of the compound 4-treated group showed a significant divergence from the DSS group, with a predominant downregulation trend, and was closer to the control group profile (Figure 7A). KEGG pathway analysis of the downregulated genes revealed significant involvement of inflammatory pathways, including cytokine–cytokine receptor interaction, MAPK, TNF, PI3K/AKT, and NF-κB signaling (Figure 7B). GSEA further confirmed significant downregulation of the MAPK and INFLAMMATORY RESPONSE pathways following compound 4 treatment (Figure 7C). These results suggest that compound 4 may alleviate colitis mainly by reducing the inflammatory response through the MAPK pathway. To validate these findings, we examined their impact on the MAPK pathway, which plays an essential role in regulating inflammation [23]. Notably, compound 4 significantly suppressed MAPK/ERK phosphorylation (Figure 7D), a critical step in the inflammatory cascade. Taken together, these findings suggest that compound 4 may exert a therapeutic effect in DSS-induced colitis by regulating the MAPK/ERK signaling pathway.

2.5. Effect of MAPK/ERK Signaling Pathway on Compound 4 Modulation of Inflammatory Response in RAW 264.7 Cells

The MAPK/ERK pathway is a central regulator of inflammatory responses, controlling cytokine production, cell proliferation, differentiation, and immune cell activation [24,25]. To determine whether compound 4 exerts its anti-inflammatory effects primarily via ERK, we first established an LPS-induced inflammatory model in RAW 264.7 cells. ERK signaling was enhanced by pretreatment with SEW2871, a selective sphingosine-1-phosphate receptor 1 (S1PR1) agonist known to induce downstream ERK phosphorylation, prior to compound 4 administration. SEW2871 markedly increased p-ERK levels, confirming effective indirect activation of ERK signaling, and markedly impaired the inhibitory effect of compound 4 on p-ERK activation (Figure 8A, blue). In parallel, SEW2871-mediated ERK activation attenuated the inhibitory effect of compound 4 on proinflammatory cytokine production (Figure 8B–D, blue), further supporting an ERK-dependent mechanism.
To further verify the specificity of compound 4 toward the ERK pathway, we next inhibited ERK using Ulixertinib. Ulixertinib significantly reduced p-ERK expression, and compound 4 did not further decrease p-ERK when combined, suggesting that both agents act on the same target (Figure 8A, orange). Likewise, Ulixertinib alone reduced inflammatory cytokine levels, while co-treatment with compound 4 failed to produce additional inhibitory effects (Figure 8B–D, orange). Taken together, these data indicate that compound 4 and Ulixertinib share a common ERK-centered mechanism and that compound 4 exerts its anti-inflammatory activity predominantly through ERK inhibition.

3. Discussion

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by immune and barrier dysfunctions, with current therapies demonstrating limited efficacy and safety [1,2]. The need for novel therapeutic agents remains critical, and natural products derived from marine microorganisms present promising candidates [26]. In this study, we systematically assessed the anti-inflammatory properties of resorcylic acid lactones (RALs) isolated from the marine-derived fungus Penicillium sp. HN20. Notably, we identified compound 4 as a potent anti-inflammatory agent, significantly alleviating DSS-induced UC in mice.
In vitro, compound 4 markedly suppressed the production of NO, PGE2, and pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) in LPS-stimulated RAW 264.7 macrophages at low micromolar concentrations, exhibiting greater inhibitory potency than several previously reported resorcylic acid lactones (RALs), while showing no obvious cytotoxicity at effective doses. This combination of strong anti-inflammatory efficacy and a favorable safety profile underscores compound 4 as a promising lead candidate. Structure-activity relationship (SAR) analysis reveals that compound 4 exhibited the lowest IC50 value for NO inhibition (2.53 μM). In contrast, structural modifications at the C-7 position in compounds 5–7 led to higher IC50 values (e.g., 11.28 μM for compound 5, 17.48 μM for compound 6, and 42.61 μM for compound 7), while a reduction in the C-9 carbonyl group likely resulted in loss of activity (e.g., compounds 1, 2, 3, and 9, with IC50 values >50 μM). The potent anti-inflammatory activity of compound 4 may be attributed to the concurrent presence of a C-9 carbonyl group and a C-7-C-8 double bond. These findings suggest that these structural elements may play a critical role in the anti-inflammatory efficacy of RAL derivatives, although further investigation is required to confirm this hypothesis.
In the DSS-induced acute colitis mouse model, compound 4 significantly improved the disease activity index, mitigated weight loss, and alleviated colon shortening and spleen enlargement, demonstrating efficacy comparable to the clinical drug 5-ASA. Histological analysis further revealed that compound 4 markedly reduced DSS-induced epithelial damage and inflammatory cell infiltration while preserving goblet cell numbers and intestinal mucosal integrity. Notably, compound 4 upregulated the expression of tight junction proteins ZO-1, Occludin, and Claudin-1 and reduced serum LPS levels, suggesting that it not only suppresses inflammation but also enhances intestinal barrier function, thereby limiting endotoxin translocation and preventing the amplification of inflammation. This dual “anti-inflammatory-barrier protective” action holds significant therapeutic potential for UC [27]. Compared to previous studies on resorcylic acid lactones (RALs), this research provides substantial advancements in both the depth of investigation and disease relevance [10]. Existing literature primarily focuses on the inhibitory effects of RALs on NO or certain inflammatory mediators in LPS-stimulated macrophage models, often limited to preliminary in vitro anti-inflammatory screening [11,12,13]. This study systematically evaluates the anti-inflammatory activity of marine-derived RALs in the DSS-induced ulcerative colitis model, confirming their in vivo therapeutic potential.
Importantly, this study establishes a comprehensive mechanistic framework through transcriptomic analysis, in vivo signaling pathway validation, and in vitro functional intervention, demonstrating that compound 4 primarily exerts its anti-inflammatory effects by inhibiting the MAPK/ERK signaling axis. ERK plays a central role in regulating pro-inflammatory cytokine transcription, immune cell activation, and intestinal epithelial stress responses [28]. Further validation through ERK agonist and inhibitor contrast experiments confirms that compound 4’s anti-inflammatory effects are ERK-dependent, enhancing the specificity and reliability of the proposed mechanism. However, the precise molecular target(s) responsible for ERK modulation remain undefined. Compound 4 may act at the receptor-proximal level, dampening signal transmission into the RAF–MEK–ERK cascade, or it could directly influence the kinase module, such as by modulating MEK or ERK activity or facilitating ERK dephosphorylation via ERK-directed phosphatases [29]. Given that ERK regulates inflammatory gene expression through downstream transcription factors like AP-1 [30], suppression of ERK signaling provides a consistent mechanism for the reduction in inflammatory mediators observed in both cellular and animal models. Identifying the direct binding partner(s) of compound 4 will require further investigation using techniques such as kinase profiling, target engagement assays, and chemical proteomics to clarify whether its primary site of action is within the kinase cascade or at upstream signaling nodes.
Overall, this study provides strong experimental evidence for marine-derived RALs as potential lead compounds for UC therapy, highlighting compound 4’s protective effects through modulation of the ERK-mediated inflammatory axis and intestinal barrier function. These findings offer new insights and candidate molecules for the development of natural product-based therapies for UC.

4. Materials and Methods

4.1. General Experimental Procedures

HR-ESI-MS spectra were obtained on a Bruker Daltonics Apex-Ultra 7.0 T (Bruker Corporation, Billerica, MA, USA). UV spectra were recorded on a Beckman DU 640 spectrophotometer. Semi-preparative HPLC was performed on an Agilent 1260 LC series with a DAD detector using an Agilent Eclipse XDB-C 18 column (250 × 9.4 mm, 7 µm). Silica gel (Qing Dao Hai Yang Chemical Group Co.; 100–200 and 200–300 mesh) and octadecylsilyl silica gel (YMC; 50 µm) were used for column chromatography (CC). ECD spectra were obtained on a circular dichromatic spectrometer (Biologic, MOS-500, Grenoble, France). Optical rotations were obtained on a Modular Circular Polarimeter (Anton Paar, MCP 5100, Graz, Austria). The 1D and 2D NMR spectra were measured on a Bruker AV-400 (Bruker Corporation, Fällanden, Switzerland) spectrometer with tetramethylsilane as the internal standard. X-ray data were collected using a Bruker APEX DUO X-ray single-crystal diffractometer with Cu K α radiation (Bruker AXS Technologies, Karlsruhe, Germany). FACS Verse (Becton, Dickinson and Company, San Jose, CA, USA).

4.2. Fungal Material

The fungal strain Penicillium sp. HN20 (GenBank accession number M20211162) was isolated from the root of mangrove Lumnitzera littorea (Jack) Voigt collected from Sanya, Hainan Island, China, in August 2018. It was identified as Penicillium sp. according to ITS rDNA sequence data. The strain was preserved in the Key Laboratory of Tropical Medicinal Resource Chemistry of the Ministry of Education, Hainan Normal University.

4.3. Fermentation, Extraction, and Isolation

The fungus Penicillium sp. HN20 was cultivated in 800 × 1000 mL Erlenmeyer flasks, each containing rice solid medium (40 g of rice and 0.003 g of sea salt dissolved in 110 mL of H2O) for 45 days at room temperature under static conditions. The fermentations were extracted with EtOAc, and the solutions were evaporated to dryness under reduced pressure to yield an oily residue (324 g).
The extract was subjected to silica gel column chromatography (200−300 mesh silica) with a gradient elution (v/v, petroleum ether/EtOAc, 100:0–0:100) to yield six fractions (Fr.1-Fr.6). Fr. 3 (32 g) was subjected to an ODS column (v/v, CH3OH/H2O, 30:70–0:100) to obtain seventeen fractions (Fr.3.1-Fr.3.17). Fr.3.4 was further purified with semipreparative reversed-phase HPLC (CH3CN/H2O, 58:42) to obtain 1 (3.5 mg) and 9 (23.4 mg), respectively. Fr.3.7 was further purified with semipreparative reversed-phase HPLC (CH3CN/H2O, 63:37) to yield 3 (2.9 mg) and 10 (8.4 mg), respectively. Fr.3.9 was further purified with semipreparative reversed-phase HPLC (CH3CN/H2O, 60:40) to yield 4 (341.4 mg), 5 (7.9 mg), 6 (8.9 mg), 7 (12.5 mg), and 8 (10.2 mg), respectively. Fr.3.13 was purified with semipreparative reversed-phase HPLC (CH3CN/H2O, 55:45) to obtain 2 (3.6 mg).

4.4. X-Ray Crystallographic Data for Compound 9

The crystals of compound 9 were obtained by slow evaporation from a MeOH solution. The crystallographic data for compound 9 have been deposited in the Cambridge Crystallographic Data Centre (CCDC) with the deposition number CCDC 2524940.
Crystal Data for C16H20O5 (M = 292.32 g/mol): trigonal, space group P31 (no. 144), a = 11.04757(6) Å, c = 10.29687(5) Å, V = 1088.351(12) Å3, Z = 3, T = 150.00(10) K, μ(Cu Kα) = 0.819 mm−1, Dcalc = 1.338 g/cm3, 15613 reflections measured (9.244° ≤ 2Θ ≤ 145.89°), 2588 unique (Rint = 0.0196, Rsigma = 0.0078), which were used in all calculations. The final R1 was 0.0235 (I > 2σ(I)), and wR2 was 0.0641 (all data).

4.5. Computational Methods

Merck Molecular Force Field (MMFF) calculation was performed with the Spartan’14 software package (Wavefunction Inc., Irvine, CA, USA), and density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were implemented using the Gaussian16 program package. The MMFF model was used for conformation search, and the conformation with lower relative energy (<10 kcal/mol) was subjected to geometry optimization with the DFT method at the B3LYP/def2-SVP level. Vibrational frequency calculations were done at the same level to evaluate their relative thermal (ΔE) and free energies (ΔG) at 298.15 K. To obtain the energies of these low-energy conformers, the geometry-optimized conformers were further calculated at the B3LYP/6-311G* level, which was taken into consideration by using SMD. ECD spectra of different conformers were simulated using SpecDis with a half-width of 0.26–0.30 eV, and the calculated spectra of compounds were generated from the low-energy conformers according to the Boltzmann weighting of each conformer in MeOH solution. The 13C NMR calculations were calculated with the GIAO method at the B3LYP/6-31+G (d, P) level in methanol with PCM. The calculated chemical shifts were directly subjected to statistical analyses with experimental chemical shifts by using the DP4+ method. The DP4+ probability, linear correlation coefficients (R2), and mean absolute deviation (MAD) were adopted for evaluation of the results.

4.6. Cell Culture and Treatment

RAW 264.7 cells were maintained in Dulbecco’s Modified Eagle Medium (DMEM) (C11995500BT, Gibco, Waltham, MA, USA), supplemented with 10% (v/v) fetal bovine serum (FBS) (10099141C, Gibco, Waltham, MA, USA) and 1% penicillin–streptomycin (PS) (15140122, Gibco, Waltham, MA, USA). Cells were incubated in a humidified incubator with 5% CO2 and 95% air at 37 °C. To evaluate the anti-inflammatory effects of compound 4, RAW 264.7 cells were seeded at a density of 2 × 104 cells per well in a 96-well plate. The cells were treated with 1 μg/mL lipopolysaccharide (LPS) in the presence or absence of compound 4 (20 μM) or SEW2871 (500 nM)/Ulixertinib (1 μM) (MCE, Shanghai, China) for 12 h. Inflammatory mediator production, including nitric oxide (NO), prostaglandin E2 (PGE2), and pro-inflammatory cytokines (TNF-α, IL-6, IL-1β), was measured to evaluate the inhibitory effects of compound 4 on LPS-stimulated inflammatory responses.

4.7. Animal Experiment and Handling

Eight-week-old C57BL/6 mice were provided by the Experimental Animal Center of Spibio (Beijing) Biotechnology Co., Ltd., Beijing, China. They were kept in specific pathogen-free conditions, with the temperature maintained at 24 ± 2 °C and relative humidity at 55 ± 5%. A 12 h light/dark cycle was observed. They were provided with unlimited access to food and water and were acclimatized for a minimum of one week prior to the start of the experiments. All animal care and procedures were conducted in accordance with the Guide for the Care and Use of Laboratory Animals in China and approved by the Animal Ethical Council of Hainan Normal University Health Science Center (permit NO. HNECEE2024-008).

4.8. Establishment and Treatment of DSS-Induced Acute Colitis Model

Male C57BL/6 mice, aged 6 to 8 weeks, were randomly divided into experimental groups (n = 6 mice per group). Mice in all colitis groups were given water containing 3% (w/v) DSS (MW = 40 kDa, Adamas, Basel, Switzerland) for 8 days to induce acute colitis, while the control group received regular water. Starting from the first day of DSS administration, colitis mice were orally gavaged daily with sterile double-distilled water (ddH2O), 5-ASA (100 mg/kg, Solarbio, Beijing, China), 4 (10 mg/kg), or 4 (20 mg/kg). Throughout the experiment, the mice’s body weights were recorded daily, and they were sacrificed on the 8th day. The colon length was measured immediately after dissection. The Disease Activity Index (DAI) was assessed based on the severity of body weight change, diarrhea, and bleeding, as previously described. Specifically, body weight losses of none, 1–5%, 5–10%, 10–15%, or more than 15% were assigned scores of 0, 1, 2, 3, or 4 points, respectively. Diarrhea was scored as 0 for none, 2 for loose stools, or 4 for watery diarrhea. Bleeding was scored as 0 for none, 2 for slight, or 4 for gross bleeding. DAI is the sum of the scores of these three parameters divided by 3.

4.9. Histological Analysis

The colonic tissues were fixed in 4% paraformaldehyde solution, embedded in paraffin, and then cut into 5 μm thick sections. The sections were stained with hematoxylin and eosin (H&E) staining. Light microscopy and a panoramic viewer camera system (CX31, Olympus Optical Co., Ltd., Tokyo, Japan) were used to examine, scan, and analyze the histopathology of the colon.

4.10. RNA-Sequencing

During sample collection, colonic tissues were immediately frozen in liquid nitrogen. Total RNA was extracted using TRIzol reagent according to the manufacturer’s instructions. RNA quality was assessed prior to library construction. RNA-seq libraries were prepared through mRNA enrichment, fragmentation, reverse transcription, cDNA synthesis, PCR amplification, and library quantification, followed by paired-end sequencing on an Illumina platform.
RNA-seq analysis was performed using three independent biological replicates per group, with colonic tissues obtained from three individual mice. Raw sequencing reads were quality-filtered using fastp with default parameters to remove adapter sequences and low-quality reads. Clean reads were then aligned to the Mus musculus reference genome using HISAT2 with default settings. Gene expression levels were quantified using RSEM, and gene-level read counts were used for downstream analysis. Differentially expressed genes were identified using the DESeq2 package, with genes showing |log2 fold change| ≥ 1 and a false discovery rate (FDR) < 0.05 considered statistically significant. All RNA sequencing and bioinformatics analyses were conducted by Majorbio (Shanghai, China).

4.11. Pathway Enrichment Analysis

Gene Set Enrichment Analysis (GSEA) was conducted to identify the enriched signaling pathways in the 4-treated group. The gene expression data were analyzed using Metascape (www.metascape.org/, accessed on 3 September 2025) to identify significant Gene Ontology Biological Process (GO BP) terms. The enriched pathways were then visualized using Cytoscape software (version 3.9.1) with the EnrichmentMap app. Default visualization parameters were used, unless otherwise specified.

4.12. Western Blotting Analysis

Cells or colon tissue samples were lysed in RIPA buffer (Beyotime, Shanghai, China) with added protease inhibitors for 30 min on ice. The resulting homogenates were then centrifuged at 12,000 rpm for 10 min at 4 °C. Total protein concentrations in the supernatants were measured using the BCA assay. Protein samples, adjusted to equal concentrations, were separated on SDS-PAGE gels and subsequently transferred to PVDF membranes (Millipore, Burlington, MA, USA). After blocking with 5% BSA for 2 h, the membranes were incubated at 4 °C overnight with primary antibodies against the following target proteins: β-Actin (CST, #4970), P-ERK (CST, #5726), ERK (CST, #4695), ZO-1 (Affinity, #AF5145), Occludin (Proteintech, #27260-1-AP), and Claudin-1 (Proteintech, #28674-1-AP). After washing, the membranes were incubated with the corresponding secondary antibodies for 2 h at room temperature (RT). The immune complexes were detected with an ECL reagent (Millipore, Burlington, MA, USA). Following incubation with horseradish peroxidase (HRP)-conjugated secondary antibodies at room temperature. Immunoblots were analyzed using analytikjena. (Analytik Jena, Burlington, MA, USA).

4.13. ELISA Assay

To evaluate the concentration of serum cytokines, the whole peripheral blood obtained from mice was placed to clot overnight at 4 °C and then centrifuged at 1000× g for 20 min, and the supernatant was serum. The concentration of LPS (Elabscience, Wuhan, China, #E-EL-0180), TNF-α (RayBiotech, Peachtree Corners, GA, USA, #ELM-TNFα), IL-1β (RayBiotech, Peachtree Corners, GA, USA, #ELM-IL-1b), and IL-6 (RayBiotech, Peachtree Corners, GA, USA, #ELM-IL6) in serum was detected using ELISA kits according to manufacturers’ instructions. Briefly, the assay was based on a double-antibody sandwich method, and the absorbance of samples was measured at 450 nm using a microplate reader.
ELISA kits were used for quantification of cytokine levels in line with the manufacturers’ protocols. RAW 264.7 cells (1 × 105) were plated in a 96-well plate. After 1 h of pre-protection of PBS or compound 4 (SEW2871/Ulixertinib), LPS was added to stimulate the cells for 12 h, followed by cell supernatant collection. Expression levels of IL-1β, IL-6, and TNF-α in the cell supernatants were assessed by measuring absorbance using a microplate reader at 450 nm.

4.14. Statistical Analysis

Data were analyzed using GraphPad Prism 10.4. The figures and/or legends contained statistical tests, n values, replicate experiments, and p values. A two-tailed Student’s t-test was used to assess significance between the two groups, while one-way ANOVA with Tukey’s post hoc test was employed to evaluate significance among multiple groups. Statistical significance was defined as a p value < 0.05. Error bars indicate mean ± SD. A difference at * p < 0.05 was considered significant, and that at ** p < 0.01 was considered highly significant. Ns: not significant.

5. Conclusions

This study identified three new RAL derivatives and seven known analogs from the marine fungus Penicillium sp. HN20, among which compound 4 exhibited the strongest anti-inflammatory activity. Compound 4 significantly alleviated DSS-induced colitis and suppressed pro-inflammatory cytokine production by inhibiting the MAPK/ERK signaling pathway. These findings highlight compound 4 as a promising marine-derived lead compound for the treatment of ulcerative colitis.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/md24020069/s1, Table S1: Crystal data and structure refinement for compound 9; Table S2: Fractional atomic coordinates (×104) and equivalent isotropic displacement parameters (Å2 ×103) for compound 9; Table S3: Anisotropic displacement parameters (Å2 ×103) for compound 9; Table S4: Bond lengths for compound 9; Table S5: Bond angles for compound 9; Table S6: Torsion angles for compound 9; Table S7: Hydrogen atom coordinates (Å ×104) and isotropic displacement parameters (Å2 ×103) for compound 9; Table S8: DP4+ analysis result table of model compounds 2c and 2d (experimental for 2, isomer 1 for 2c, isomer 2 for 2d); Table S9: DP4+ analysis result table of model compounds 3c and 3d (experimental for 3, isomer 1 for 3c, isomer 2 for 3d); Figure S1: ^1H NMR spectrum of compound 1 in CD3OD; Figure S2: ^13C NMR spectrum of compound 1 in CD3OD; Figure S3: DEPT135° NMR spectrum of compound 1 in CD3OD; Figure S4: HSQC spectrum of compound 1 in CD3OD; Figure S5: HMBC spectrum of compound 1 in CD3OD; Figure S6: ^1H–^1H COSY spectrum of compound 1 in CD3OD; Figure S7: NOESY spectrum of compound 1 in CD3OD; Figure S8: (−)-HR-ESI-MS spectrum of compound 1; Figure S9: ^1H NMR spectrum of compound 2 in CD3OD; Figure S10: ^13C NMR spectrum of compound 2 in CD3OD; Figure S11: HSQC spectrum of compound 2 in CD3OD; Figure S12: HMBC spectrum of compound 2 in CD3OD; Figure S13: ^1H–^1H COSY spectrum of compound 2 in CD3OD; Figure S14: NOESY spectrum of compound 2 in CD3OD; Figure S15: (+)-HR-ESI-MS spectrum of compound 2; Figure S16: ^1H NMR spectrum of compound 3 in CD3OD; Figure S17: ^13C NMR spectrum of compound 3 in CD3OD; Figure S18: HSQC spectrum of compound 3 in CD3OD; Figure S19: HMBC spectrum of compound 3 in CD3OD; Figure S20: ^1H–^1H COSY spectrum of compound 3 in CD3OD; Figure S21: NOESY spectrum of compound 3 in CD3OD; Figure S22: (−)-HR-ESI-MS spectrum of compound 3; Figure S23: ^1H NMR spectrum of compound 9 in CD3OD; Figure S24: ^13C NMR spectrum of compound 9 in CD3OD; Figure S25: UV spectra of compounds 1–3; Figure S26: Macroscopic morphology of Penicillium sp. HN-20; Figure S27: Microscopic morphology of Penicillium sp. HN-20; Figure S28: Chiral HPLC-UV chromatogram of compound 1; Figure S29: Chiral HPLC-UV chromatogram of compound 2; Figure S30: Chiral HPLC-UV chromatogram of compound 3; Figure S31: Chiral HPLC-UV chromatogram of compound 4; Figure S32: Chiral HPLC-UV chromatogram of compound 5; Figure S33: Chiral HPLC-UV chromatogram of compound 6; Figure S34: Chiral HPLC-UV chromatogram of compound 7; Figure S35: Chiral HPLC-UV chromatogram of compound 8; Figure S36: Chiral HPLC-UV chromatogram of compound 9; Figure S37: Chiral HPLC-UV chromatogram of compound 10; Figure S38: Cytotoxic effects of compounds 4–7 on RAW 264.7 macrophages.

Author Contributions

X.Z.: Formal analysis, methodology, investigation, data curation, writing—original draft, and visualization. T.M.: Formal analysis, investigation, and data curation. Y.Q.: Resources and supervision. M.L.: Writing—review and editing—and formal analysis. L.T.: Investigation and project administration. Z.Z.: Writing—review and editing—and formal analysis. J.Y.: Writing—review and editing. F.C.: Validation, software, and data curation. W.L. (Corresponding Author): Conceptualization and writing—review and editing. G.C. (Corresponding Author): Conceptualization, supervision, funding acquisition, writing—review and editing, and project administration. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the National Natural Science Foundation of China (Nos. 22477021 and 22177023).

Institutional Review Board Statement

All animal housing and handling procedures complied with the “Guide for the Care and Use of Laboratory Animals” and the “Guide for the Use of Laboratory Animals in China,” and were approved by the Animal Ethical Council of Hainan Normal University (permit NO. HNECEE2024-008, approval date: 12 September 2024).

Data Availability Statement

The RNA-seq data presented in this study are openly available in the NCBI Sequence Read Archive (SRA) under the accession number PRJNA1406744. Other data supporting the conclusions of this article will be made available by the authors on request.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Gros, B.; Kaplan, G.G. Ulcerative Colitis in Adults: A Review. JAMA 2023, 330, 951–965. [Google Scholar] [CrossRef]
  2. Liu, Y.; Sun, Q.; Xu, X.; Li, M.; Gao, W.; Li, Y.; Yang, Y.; Yin, D. Platycodon grandiflorus polysaccharides combined with hesperidin exerted the synergistic effect of relieving ulcerative colitis in mice by modulating PI3K/AKT and JAK2/STAT3 signaling pathways. Chin. J. Nat. Med. 2025, 23, 848–862. [Google Scholar] [CrossRef]
  3. Kałużna, A.; Olczyk, P.; Komosińska-Vassev, K. The Role of Innate and Adaptive Immune Cells in the Pathogenesis and Development of the Inflammatory Response in Ulcerative Colitis. J. Clin. Med. 2022, 11, 400. [Google Scholar] [CrossRef]
  4. Bu, F.; Chen, K.; Chen, S.; Jiang, Y. Gut microbiota and intestinal immunity interaction in ulcerative colitis and its application in treatment. Front. Cell. Infect. Microbiol 2025, 15, 1565082. [Google Scholar] [CrossRef]
  5. Solitano, V.; D’Amico, F.; Zacharopoulou, E.; Peyrin-Biroulet, L.; Danese, S. Early Intervention in Ulcerative Colitis: Ready for Prime Time? J. Clin. Med. 2020, 9, 2646. [Google Scholar] [CrossRef]
  6. Yanofsky, R.; Rubin, D.T. A practical approach to positioning therapies in ulcerative colitis. J. Can. Assoc. Gastroenterol. 2025, 8, S6–S14. [Google Scholar] [CrossRef]
  7. Qiu, Y.; Chen, S.; Yu, M.; Shi, J.; Liu, J.; Li, X.; Chen, J.; Sun, X.; Huang, G.; Zheng, C. Natural Products from Marine-Derived Fungi with Anti-Inflammatory Activity. Mar. Drugs 2024, 22, 433. [Google Scholar] [CrossRef]
  8. Lv, F.; Zeng, Y. Novel Bioactive Natural Products from Marine-Derived Penicillium Fungi: A Review (2021–2023). Mar. Drugs 2024, 22, 191. [Google Scholar] [CrossRef]
  9. Bang, S.; Shim, S.H. Beta resorcylic acid lactones (RALs) from fungi: Chemistry, biology, and biosynthesis. Arch. Pharm. Res. 2020, 43, 1093–1113. [Google Scholar] [CrossRef]
  10. Gao, Y.; Li, W.; Ruan, H. The chemical and biological properties of natural resorcylic acid lactones. Nat. Prod. Rep. 2025, 42, 1387–1410. [Google Scholar] [CrossRef]
  11. Yin, G.P.; Gong, M.; Li, Y.J.; Zhang, X.; Zhu, J.J.; Hu, C.H. 14-Membered resorcylic acid lactone derivatives with their anti-inflammatory from the fungus Aspergillus sp. ZJ-65. Fitoterapia 2021, 151, 104884. [Google Scholar] [CrossRef]
  12. An, Y.N.; Zhang, X.; Zhang, T.Y.; Zhang, M.Y.; Zhang, Q.; Deng, X.Y.; Zhao, F.; Zhu, L.J.; Wang, G.; Zhang, J.; et al. Penicimenolides A-F, Resorcylic Acid Lactones from Penicillium sp., isolated from the Rhizosphere Soil of Panax notoginseng. Sci. Rep. 2016, 6, 27396. [Google Scholar] [CrossRef]
  13. Kim, J.; Baek, J.Y.; Bang, S.; Kim, J.Y.; Jin, Y.; Lee, J.W.; Jang, D.S.; Kang, K.S.; Shim, S.H. New Anti-Inflammatory β-Resorcylic Acid Lactones Derived from an Endophytic Fungus, Colletotrichum sp. ACS Omega 2023, 8, 3530–3538. [Google Scholar] [CrossRef]
  14. Wang, H.; Huang, T.; Ma, Y. Mechanisms and therapeutic strategies of macrophages and neutrophils inducing ulcerative colitis progression. Front. Immunol. 2025, 16, 1615340. [Google Scholar] [CrossRef]
  15. Fukazawa, H.; Ikeda, Y.; Fukuyama, M.; Suzuki, T.; Hori, H.; Okuda, T.; Uehara, Y. The resorcylic acid lactone hypothemycin selectively inhibits the mitogen-activated protein kinase kinase-extracellular signal-regulated kinase pathway in cells. Biol. Pharm. Bull. 2010, 33, 168–173. [Google Scholar] [CrossRef][Green Version]
  16. Peng, S.; Zhao, Y.; Jiang, W.; Long, Y.; Hu, T.; Li, M.; Hu, J.; Shen, Y. MAPK signaling mediated intestinal inflammation induced by endoplasmic reticulum stress and NOD2. Mol. Cell. Biochem. 2025, 480, 3709–3717. [Google Scholar] [CrossRef]
  17. Barrow, C.J. New Macrocyclic Lactones from a Penicillium Species. J. Nat. Prod. 1997, 60, 1023–1025. [Google Scholar] [CrossRef]
  18. Qin, Y.Y.; Li, W.S.; Zhang, X.; Yu, Z.X.; Li, X.B.; Chen, H.Y.; Lv, Y.R.; Han, C.R.; Chen, G.Y. Meroterpenoids Possessing Diverse Rearranged Skeletons with Anti-inflammatory Activity from the Mangrove-Derived Fungus Penicillium sp. HLLG-122. Chin. J. Chem. 2023, 41, 2507–2517. [Google Scholar] [CrossRef]
  19. Chen, X.D.; Yang, S.Q.; Li, X.M.; Wang, B.G.; Li, X. Antibacterial polyketides and ascochlorins from deep-sea cold-seep-derived fungus Furcasterigmium furcatum (syn. Acremonium furcatum). Deep. Sea Res. Part I Oceanogr. Res. Pap. 2023, 199, 104114. [Google Scholar] [CrossRef]
  20. Meng, Q.; Guo, J.; Lv, K.; Liu, Y.; Zhang, J.; Li, M.; Cheng, X.; Chen, S.; Huo, X.; Zhang, Q.; et al. 5S-Heudelotinone alleviates experimental colitis by shaping the immune system and enhancing the intestinal barrier in a gut microbiota-dependent manner. Acta. Pharm. Sin. B 2024, 14, 2153–2176. [Google Scholar] [CrossRef]
  21. Tao, Q.; Liang, Q.; Fu, Y.; Qian, J.; Xu, J.; Zhu, Y.; Gu, C.; Xu, W.; Song, S.; Wu, Y.; et al. Puerarin ameliorates colitis by direct suppression of macrophage M1 polarization in DSS mice. Phytomedicine 2024, 135, 156048. [Google Scholar] [CrossRef]
  22. Tulkens, J.; Vergauwen, G.; Van Deun, J.; Geeurickx, E.; Dhondt, B.; Lippens, L.; De Scheerder, M.A.; Miinalainen, I.; Rappu, P.; De Geest, B.G.; et al. Increased levels of systemic LPS-positive bacterial extracellular vesicles in patients with intestinal barrier dysfunction. Gut 2020, 69, 191–193. [Google Scholar] [CrossRef]
  23. Huang, X.; Pan, Q.; Mao, Z.; Zhang, R.; Ma, X.; Xi, Y.; You, H. Sinapic Acid Inhibits the IL-1β-Induced Inflammation via MAPK Downregulation in Rat Chondrocytes. Inflammation 2018, 41, 562–568. [Google Scholar] [CrossRef]
  24. Zhang, W.; Liu, H.T. MAPK signal pathways in the regulation of cell proliferation in mammalian cells. Cell Res. 2002, 12, 9–18. [Google Scholar] [CrossRef]
  25. Liu, J.Y.; Jiang, Y.Y.; Li, P.J.; Yao, B.; Song, Y.J.; Gao, J.X.; Said, G.; Gao, Y.; Lai, J.Y.; Shao, C.L. Discovery of a potential bladder cancer inhibitor CHNQD-01281 by regulating EGFR and promoting infiltration of cytotoxic T cells. Mar. Life. Sci. Technol. 2024, 6, 502–514. [Google Scholar] [CrossRef]
  26. Xu, J.; Yi, M.; Ding, L.; He, S. A Review of Anti-Inflammatory Compounds from Marine Fungi, 2000-2018. Mar. Drugs. 2019, 17, 636. [Google Scholar] [CrossRef]
  27. Turner, J.R. Intestinal mucosal barrier function in health and disease. Nat. Rev. Immunol. 2009, 9, 799–809. [Google Scholar] [CrossRef]
  28. Song, Z.M.; Liu, F.; Chen, Y.M.; Liu, Y.J.; Wang, X.D.; Du, S.Y. CTGF-mediated ERK signaling pathway influences the inflammatory factors and intestinal flora in ulcerative colitis. Biomed. Pharmacother. 2019, 111, 1429–1437. [Google Scholar] [CrossRef]
  29. Xie, J.; Sun, S.; Li, Q.; Chen, Y.; Huang, L.; Wang, D.; Wang, Y. MAPK/ERK signaling pathway in rheumatoid arthritis: Mechanisms and therapeutic potential. PeerJ 2025, 13, e19708. [Google Scholar] [CrossRef]
  30. Whitmarsh, A.J.; Davis, R.J. Transcription factor AP-1 regulation by mitogen-activated protein kinase signal transduction pathways. J. Mol. Med. 1996, 74, 589–607. [Google Scholar] [CrossRef]
Marinedrugs 24 00069 g001
Figure 1. Structures of compounds 1–10.
Figure 1. Structures of compounds 1–10.
Marinedrugs 24 00069 g001
Marinedrugs 24 00069 g002
Figure 2. Key 1H−1H COSY and HMBC correlations of compounds 1–3.
Figure 2. Key 1H−1H COSY and HMBC correlations of compounds 1–3.
Marinedrugs 24 00069 g002
Marinedrugs 24 00069 g003
Figure 3. X-ray crystallographic structure of 9.
Figure 3. X-ray crystallographic structure of 9.
Marinedrugs 24 00069 g003
Marinedrugs 24 00069 g004
Figure 4. Experimental and calculated ECD spectra of 1, 2, and 9.
Figure 4. Experimental and calculated ECD spectra of 1, 2, and 9.
Marinedrugs 24 00069 g004
Marinedrugs 24 00069 g005
Figure 5. Regression analyses of experimental versus calculated 13C NMR chemical shifts in model compounds 2c, 2d, 3c, and 3d.
Figure 5. Regression analyses of experimental versus calculated 13C NMR chemical shifts in model compounds 2c, 2d, 3c, and 3d.
Marinedrugs 24 00069 g005
Marinedrugs 24 00069 g006
Figure 6. Compound 4 exhibits potent in vivo anti-inflammatory activity in DSS-induced colitis. (A) Schematic diagram of colitis. C57BL/6 mice were given 3% DSS water for 8 days. 5-ASA (100 mg/kg) and compound 4 (10, 20 mg/kg) were administered daily by gavage for 9 consecutive days, and the mice were sacrificed on day 9. (B) At the end of the experiment, the representative results of colon length. The weight (C) and DAI score (D) of mice in each group were recorded daily. (E) spleen index of each group. (F) Histopathological images of the colon in each group of mice. Scale bar = 100 µm. (G) Expression levels of ZO-1, Occludin, and Claudin-1 in colon tissues of each group. (H–K) The concentration of LPS, TNF-α, IL-6, and IL-1β in the serum of each group. The samples were derived from the same experiment, and the blots were processed in parallel. Data represent mean ± SD, ns: not significant; ## p < 0.01 vs. control group; ** p < 0.01 vs. DSS group.
Figure 6. Compound 4 exhibits potent in vivo anti-inflammatory activity in DSS-induced colitis. (A) Schematic diagram of colitis. C57BL/6 mice were given 3% DSS water for 8 days. 5-ASA (100 mg/kg) and compound 4 (10, 20 mg/kg) were administered daily by gavage for 9 consecutive days, and the mice were sacrificed on day 9. (B) At the end of the experiment, the representative results of colon length. The weight (C) and DAI score (D) of mice in each group were recorded daily. (E) spleen index of each group. (F) Histopathological images of the colon in each group of mice. Scale bar = 100 µm. (G) Expression levels of ZO-1, Occludin, and Claudin-1 in colon tissues of each group. (H–K) The concentration of LPS, TNF-α, IL-6, and IL-1β in the serum of each group. The samples were derived from the same experiment, and the blots were processed in parallel. Data represent mean ± SD, ns: not significant; ## p < 0.01 vs. control group; ** p < 0.01 vs. DSS group.
Marinedrugs 24 00069 g006
Marinedrugs 24 00069 g007
Figure 7. Compound 4 inhibits the activation of MAPK/ERK signaling pathways in the colon tissues of colitis mice. (A) The hierarchical cluster analysis of all differentially expressed genes. (B) KEGG enrichment analysis of the downregulated genes. (C) The MAPK and inflammatory response pathways were enriched according to the results of the GSEA. (D) Effect of compound 4 on the MAPK pathway in the colitis mouse colon tissues, where total JNK, p38, and ERK are used as respective loading controls. The samples were derived from the same experiment, and the blots were processed in parallel. Data represent mean ± SD, ns: not significant; ## p < 0.01 vs. control group; ** p < 0.01 vs. DSS group.
Figure 7. Compound 4 inhibits the activation of MAPK/ERK signaling pathways in the colon tissues of colitis mice. (A) The hierarchical cluster analysis of all differentially expressed genes. (B) KEGG enrichment analysis of the downregulated genes. (C) The MAPK and inflammatory response pathways were enriched according to the results of the GSEA. (D) Effect of compound 4 on the MAPK pathway in the colitis mouse colon tissues, where total JNK, p38, and ERK are used as respective loading controls. The samples were derived from the same experiment, and the blots were processed in parallel. Data represent mean ± SD, ns: not significant; ## p < 0.01 vs. control group; ** p < 0.01 vs. DSS group.
Marinedrugs 24 00069 g007
Marinedrugs 24 00069 g008
Figure 8. Effect of MAPK/ERK signaling pathway on Compound 4 modulation of inflammatory response in RAW 264.7 cells. (A) Western blot showed that compound 4 affected the protein expression of p-ERK in RAW 264.7 cells under the stimulation of SEW2871 or Ulixertinib. (B–D) ELISA showed that compound 4 affected the secretion of TNF-α, IL-6, and IL-1β in cell supernatant under the stimulation of SEW2871 or Ulixertinib. The samples were derived from the same experiment, and the blots were processed in parallel. Data represent mean ± SD, ns: not significant; ## p < 0.01 vs. PBS group; * p < 0.05 and ** p < 0.01 vs. LPS (SEW2871 + LPS or Ulixertinib + LPS) group.
Figure 8. Effect of MAPK/ERK signaling pathway on Compound 4 modulation of inflammatory response in RAW 264.7 cells. (A) Western blot showed that compound 4 affected the protein expression of p-ERK in RAW 264.7 cells under the stimulation of SEW2871 or Ulixertinib. (B–D) ELISA showed that compound 4 affected the secretion of TNF-α, IL-6, and IL-1β in cell supernatant under the stimulation of SEW2871 or Ulixertinib. The samples were derived from the same experiment, and the blots were processed in parallel. Data represent mean ± SD, ns: not significant; ## p < 0.01 vs. PBS group; * p < 0.05 and ** p < 0.01 vs. LPS (SEW2871 + LPS or Ulixertinib + LPS) group.
Marinedrugs 24 00069 g008
Table 1. 1H NMR and 13C NMR data of compounds 1–3 (J in Hz, δ in ppm) in CD3OD.
Table 1. 1H NMR and 13C NMR data of compounds 1–3 (J in Hz, δ in ppm) in CD3OD.
1 a2 a3 b
No.δH (J in Hz)δC (ppm)δH (J in Hz)δC (ppm)δH (J in Hz)δC (ppm)
1 172.0 170.8 171.8
35.09 (m)73.05.06 (ddd, J = 9.3, 6.3, 2.8)70.55.23 (m)74.4
41.91 (m)33.51.60 (m)37.51.83 (m)35.0
1.72 (m)
51.64 (m)21.21.48 (m)20.32.17 (dd, J = 13.6, 6.6)30.8
1.68 (m) 1.13 (m) 2.36 (m)
62.16 (m)31.31.81 (m)34.85.43 (m)135.7
1.98 (m) 1.24 (m)
75.33 (dd, J = 15.7, 6.1)128.93.75 (m)74.75.48 (m)125.2
85.52 (dt, J = 15.7, 6.1)132.35.30 (ddd, J = 15.2, 8.1, 1.2)135.42.12 (m)39.2
2.05 (m)
95.12 (m)77.05.38 (ddd, J = 15.2, 9.5, 3.5)131.33.78 (m)73.5
103.20 (t, J = 11.1)40.03.63 (dd, J = 14.1, 9.5)38.93.41 (dd, J = 13.5, 6.6)39.0
2.90 (m) 3.12 (d, J = 14.1) 2.48 (dd, J = 13.5, 6.6)
11 139.6 142.1 142.8
126.28 (d, J = 2.3)111.3 *6.18 (d, J = 2.1)110.16.30 (d, J = 2.3)111.1
13 161.5 159.0 161.7
146.22 (d, J = 2.3)102.66.19 (d, J = 2.1)102.06.17 (d, J = 2.3)102.0
15 161.6 161.0 161.8
16 112.3 * 114.2 111.3
171.33 (d, J = 6.5)19.11.30 (d, J = 6.2)18.51.36 (d, J = 6.4)20.0
18 172.0
192.07 (s)21.2
a 400 MHz for 1H NMR, 100 MHz for 13C NMR. b 600 MHz for 1H NMR, 150 MHz for 13C NMR. * This signal is absent in the carbon spectrum but is present in both HMBC and HSQC spectra.
Table 2. In vitro anti-inflammatory activities of compounds 1–10 in LPS-stimulated RAW 264.7 cells.
Table 2. In vitro anti-inflammatory activities of compounds 1–10 in LPS-stimulated RAW 264.7 cells.
CompoundNO
IC50 (µM)		PGE2
IC50 (µM)		TNF-α
IC50 (µM)		IL-6
IC50 (µM)		IL-1β
IC50 (µM)
1>50----
2>50----
3>50----
42.53 ± 0.176.10 ± 0.072.94 ± 0.182.07 ± 0.156.04 ± 0.04
511.28 ± 0.7023.59 ± 1.9615.99 ± 1.019.98 ± 0.4724.70 ± 1.32
617.48 ± 0.5337.41 ± 4.3021.79 ± 2.4319.53 ± 0.6530.71 ± 2.24
742.61 ± 2.08>5025.82 ± 1.0820.97 ± 0.27>50
8>50----
9>50----
10>50----
Dexamethasone35.34 ± 1.6540.07 ± 3.3312.63 ± 1.1116.27 ± 0.1816.26 ± 0.68
IC50: compound concentration required to achieve 50% inhibition of inflammatory mediators production; dexamethasone used as a positive control.
Table 3. Cytotoxicity testing of compounds 4–7.
Table 3. Cytotoxicity testing of compounds 4–7.
CompoundCC50 (µM)
493.71 ± 3.43
581.24 ± 1.77
627.85 ± 1.50
798.55 ± 3.12
CC50: compound concentration required to reduce cell viability by 50%.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Zhang, X.; Mo, T.; Qin, Y.; Le, M.; Tang, L.; Zhang, Z.; Yi, J.; Cen, F.; Li, W.; Chen, G. Anti-Inflammatory Effects of Marine-Derived Resorcylic Acid Lactone Derivatives in Ulcerative Colitis via the MAPK/ERK Pathway. Mar. Drugs 2026, 24, 69. https://doi.org/10.3390/md24020069

AMA Style

Zhang X, Mo T, Qin Y, Le M, Tang L, Zhang Z, Yi J, Cen F, Li W, Chen G. Anti-Inflammatory Effects of Marine-Derived Resorcylic Acid Lactone Derivatives in Ulcerative Colitis via the MAPK/ERK Pathway. Marine Drugs. 2026; 24(2):69. https://doi.org/10.3390/md24020069

Chicago/Turabian Style

Zhang, Xuan, Tuxiang Mo, Yuyue Qin, Meiling Le, Li Tang, Zhao Zhang, Jiling Yi, Fuling Cen, Wanshan Li, and Guangying Chen. 2026. "Anti-Inflammatory Effects of Marine-Derived Resorcylic Acid Lactone Derivatives in Ulcerative Colitis via the MAPK/ERK Pathway" Marine Drugs 24, no. 2: 69. https://doi.org/10.3390/md24020069

APA Style

Zhang, X., Mo, T., Qin, Y., Le, M., Tang, L., Zhang, Z., Yi, J., Cen, F., Li, W., & Chen, G. (2026). Anti-Inflammatory Effects of Marine-Derived Resorcylic Acid Lactone Derivatives in Ulcerative Colitis via the MAPK/ERK Pathway. Marine Drugs, 24(2), 69. https://doi.org/10.3390/md24020069

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop