Search Results (15)

Canthin-6-one alkaloids have consistently attracted the interest of medicinal chemists due to their wide range of promising bioactivities, including antitumor, antifungal, antibacterial, and antiviral properties. However, their low natural abundance in plants has constrained the further exploration of their potential bioactivities. This study reports a comprehensive synthesis of canthin-6-one alkaloids, utilizing key Suzuki coupling and Cu-catalyzed amidation reactions to construct their core scaffold. Derivatives were synthesized with Koenig–Knorr glycosylation for the further modification of synthetic canthin-6-ones. The antimicrobial activities of the synthesized compounds were evaluated against C. albicans, C. neoformans, S. aureus and E. coli using the micro-dilution method. In total, 17 compounds were synthesized, including nine canthin-6-ones. Notably, alkaloids 4, 5, 7 and 12-13 were prepared for the first time, along with 8 new derivatives. Their structures were confirmed by NMR and MS analyses. At 50 µg/mL, the alkaloids 1-4 and 9 exhibited antimicrobial properties against C. albicans, C. neoformans and S. aureus. The antimicrobial activity of alkaloids 2, 4-5 and 12-13 against these four microbial human pathogens is reported here for the first time. Overall, this research not only advances our understanding of canthin-6-one alkaloid synthesis, but also provides a foundation for developing novel compounds with pharmaceutical properties. Full article

This publication reports the controlled cultivation of Zanthoxylum chiloperone var. angustifolium Engl. (Rutaceae) in several growth substrates under controlled greenhouse conditions. This plant is well-known for its anti-Chagas (trypanocidal) activity, related to the presence of several β-carboline alkaloids. The metabolomic study of Z. chiloperone seedlings over two years of growth (2018–2020) was performed using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS). The canthin-6-one alkaloids, canthin-6-one and 5-methoxy-canthin-6-one, were putatively identified in Z. chiloperone extracts. Finally, in vitro and in silico studies of trypanocidal activity were performed, suggesting that canthin-6-one alkaloids could interact with the main pharmacological targets against Trypanosoma cruzi, cruzain protease, dihydroorotate dehydrogenase, lanosterol 14-alpha-demethylase, farnesyl diphosphate, and squalene synthases. Full article

Rheumatoid arthritis (RA) is an autoimmune disorder that leads to severe cartilage deterioration and synovial impairment in the joints. Previous studies have indicated that the aberrant activation of the NLRP3 inflammasome in synovial macrophages plays a significant role in the pathogenesis of RA and has been regarded as a therapeutic target for the disease. In this study, we synthesized a novel canthin-6-one alkaloid, namely methyl canthin-6-one-2-carboxylate (Cant), and assessed its effects on NLRP3 inflammasome activation in macrophages. Our data reveal that exposure to Cant significantly suppressed the transcription and secretion of multiple pro-inflammatory mediators, including IL-1β, IL-6, IL-18, TNF-α, NO, and COX2, in a dose-dependent manner. These alterations were associated with changes in the activation of various signaling pathways, including NF-kB, MAPK, and PI3K-AKT pathways. Notably, pretreatment with Cant significantly reduced LPS/ATP-induced activation of the NLRP3 inflammasome, as evidenced by the decline in the cleaved forms of IL-1β and caspase-1 in cell culture supernatants of BMDMs. Regarding the mechanisms, our data show that Cant could enhance the expression of Nrf2 in macrophages, which play an inhibitory role in ROS production. Collectively, our data demonstrate that Cant might suppress the activation of the NLRP3 inflammasome by upregulating the production of Nrf2, suggesting that Cant could serve as a candidate for the further development of anti-RA drugs. Full article

Flash column chromatographic fractionation of tree of heaven (Ailanthus altissima) stem and trunk bark extracts, guided by thin-layer chromatography (TLC)–Bacillus subtilis assay and TLC–heated electrospray high-resolution tandem mass spectrometry (HESI-HRMS/MS), lead to the isolation of six known compounds: (9Z,11E)-13-hydroxy-9,11-octadecadienoic acid (13-HODE, A1), (10E,12Z)-9-hydroxy-10,12-octadecadienoic acid (9-HODE, A2), hexadecanedioic acid (thapsic acid, A3), 16-hydroxyhexadecanoic acid (juniperic acid, A4), 16-feruloyloxypalmitic acid (alpinagalanate, A5), and canthin-6-one (A6). Their structures were elucidated by HESI-HRMS/MS and one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy. This is the first study identifying A1–A5 in A. altissima tree. Except for A5, all isolated compounds exhibited antibacterial activity against B. subtilis in microdilution assays. A6 showed the strongest effect with a minimum inhibitory concentration (MIC) value of 8.3 µg/mL. The antibacterial activity of A3 and A4 is newly described. Full article

Tumour-associated angiogenesis play key roles in tumour growth and cancer metastasis. Consequently, several anti-angiogenic drugs such as sunitinib and axitinib have been approved for use as anti-cancer therapies. However, the majority of these drugs target the vascular endothelial growth factor A (VEGFA)/VEGF receptor 2 (VEGFR2) pathway and have shown mixed outcome, largely due to development of resistances and increased tumour aggressiveness. In this study, we used the zebrafish model to screen for novel anti-angiogenic molecules from a library of compounds derived from natural products. From this, we identified canthin-6-one, an indole alkaloid, which inhibited zebrafish intersegmental vessel (ISV) and sub-intestinal vessel development. Further characterisation revealed that treatment of canthin-6-one reduced ISV endothelial cell number and inhibited proliferation of human umbilical vein endothelial cells (HUVECs), suggesting that canthin-6-one inhibits endothelial cell proliferation. Of note, canthin-6-one did not inhibit VEGFA-induced phosphorylation of VEGFR2 in HUVECs and downstream phosphorylation of extracellular signal-regulated kinase (Erk) in leading ISV endothelial cells in zebrafish, suggesting that canthin-6-one inhibits angiogenesis independent of the VEGFA/VEGFR2 pathway. Importantly, we found that canthin-6-one impairs tumour-associated angiogenesis in a zebrafish B16F10 melanoma cell xenograft model and synergises with VEGFR inhibitor sunitinib malate to inhibit developmental angiogenesis. In summary, we showed that canthin-6-one exhibits anti-angiogenic properties in both developmental and pathological contexts in zebrafish, independent of the VEGFA/VEGFR2 pathway and demonstrate that canthin-6-one may hold value for further development as a novel anti-angiogenic drug. Full article

Rheumatoid arthritis (RA) is an inflammatory condition that causes severe cartilage degradation and synovial damage in the joints with multiple systemic implications. Previous studies have revealed that fibroblast-like synoviocytes (FLSs) play a pivotal role in the pathogenesis of RA. The appropriate regulation of FLS function is an efficient approach for the treatment of this disease. In the present study, we explored the effects of methyl canthin-6-one-2-carboxylate (Cant), a novel canthin-6-one alkaloid, on the function of FLSs. Our data showed that exposure to Cant significantly suppressed RA-FLS migration and invasion properties in a dose-dependent manner. Meanwhile, pre-treatment with Cant also had an inhibitory effect on the release of several pro-inflammatory cytokines, including IL-6 and IL-1β, as well as the production of MMP1 and MMP3, which are important mediators of FLS invasion. In further mechanistic studies, we found that Cant had an inhibitory effect on the Hippo/YAP signaling pathway. Treatment with Cant suppressed YAP expression and phosphorylation on serine 127 and serine 397 while enhancing LATS1 and MST1 levels, both being important upstream regulators of YAP. Moreover, YAP-specific siRNA or YAP inhibition significantly inhibited wound healing as well as the migration and invasion rate of FLS cells, an impact similar to Cant treatment. Meanwhile, the over-expression of YAP significantly reversed the Cant-induced decline in RA-FLS cell migration and invasion, indicating that YAP was required in the inhibitory effect of Cant on the migration and invasion of RA-FLS cells. Additionally, supplementation of MMP1, but not MMP3, in culture supernatants significantly reversed the inhibitory effect of Cant on RA-FLS cell invasion. Our data collectively demonstrated that Cant may suppress RA-FLS migration and invasion by inhibiting the production of MMP1 via inhibiting the YAP signaling pathway, suggesting a potential of Cant for the further development of anti-RA drugs. Full article

Chronic inflammatory disease (CID) is a category of medical conditions that causes recurrent inflammatory attacks in multiple tissues. The occurrence of CID is related to inappropriate immune responses to normal tissue substances and invading microbes due to many factors, such as defects in the immune system and imbalanced regulation of commensal microbes. Thus, effectively keeping the immune-associated cells and their products in check and inhibiting aberrant activation of the immune system is a key strategy for the management of CID. Canthin-6-ones are a subclass of β-carboline alkaloids isolated from a wide range of species. Several emerging studies based on in vitro and in vivo experiments reveal that canthin-6-ones may have potential therapeutic effects on many inflammatory diseases. However, no study has yet summarized the anti-inflammatory functions and the underlying mechanisms of this class of compounds. This review provides an overview of these studies, focusing on the disease entities and the inflammatory mediators that have been shown to be affected by canthin-6-ones. In particular, the major signaling pathways affected by canthin-6-ones, such as the NLR family pyrin domain containing 3 (NLRP3) inflammasome and the NF-κB signaling pathway, and their roles in several CIDs are discussed. Moreover, we discuss the limitations in studies of canthin-6-ones and provide possible solutions. In addition, a perspective that may suggest possible future research directions is provided. This work may be helpful for further mechanistic studies and possible therapeutic applications of canthin-6-ones in the treatment of CID. Full article

Marine and terrestrial environments are rich sources of various bioactive substances, which have been used by humans since prehistoric times. Nowadays, due to advances in chemical sciences, new substances are still discovered, and their chemical structures and biological properties are constantly explored. Drugs obtained from natural sources are used commonly in medicine, particularly in cancer and infectious diseases treatment. Naphthyridines, isolated mainly from marine organisms and terrestrial plants, represent prominent examples of naturally derived agents. They are a class of heterocyclic compounds containing a fused system of two pyridine rings, possessing six isomers depending on the nitrogen atom’s location. In this review, biological activity of naphthyridines obtained from various natural sources was summarized. According to previous studies, the naphthyridine alkaloids displayed multiple activities, i.a., antiinfectious, anticancer, neurological, psychotropic, affecting cardiovascular system, and immune response. Their wide range of activity makes them a fascinating object of research with prospects for use in therapeutic purposes. Full article

Zanthoxylum paracanthum Kokwaro (Rutaceae) is an endemic Kenyan and Tanzanian plant used in folk medicine by local populations. Although other Zanthoxylum species have been studied, only Z. paracantum stem extracts have been profiled, even though the roots are also used as herbal remedies. As root extracts may be another source of pharmaceutical compounds, the CH₂Cl₂/MeOH (1:1) root bark extract was studied in this report. Eight root bark compounds were isolated and their structural identities were confirmed by mass spectrometry (MS) and nuclear magnetic resonance (NMR) (using COSY, HSQC, NOESY and HMBC) analyses. The structural identities were determined as follows: the fatty acid—myristic acid (1); the sterol—stigmasterol (2); the lignan—sesamin (3); two β-carboline alkaloids—10-methoxycanthin-6-one (6) and canthin-6-one (7); and three phenanthridine alkaloids—8-acetonyldihydrochelerythrine (4), arnottianamide (5) and 8-oxochelerythrine (8). Some of these compounds were identified in the species for the first time. These compounds and the extract were then tested in vitro against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 29213) and Candida albicans (ATCC 10231) before tests for antiproliferative activity against the human breast cancer (HCC 1395), human prostate cancer (DU 145) and normal (Vero E6) cell lines were conducted. Minimum inhibition concentration values of 3.91, 1.95, 0.98 and 7.81 µg/mL against MRSA, S. aureus, E. coli and C. albicans, respectively, were recorded. Among the isolates, canthin-6-one was the most active, followed by 10-methoxycanthin-6-one. The root extract and some of the compounds also had antiproliferative activity against the HCC 1395 cell line. Stigmasterol and canthin-6-one had IC₅₀ values of 7.2 and 0.42. The root bark extract also showed activity, at 8.12 µg/mL, against the HCC 1395 cells. Out of the chemical isolates, 10-methoxycanthin-6-one and canthin-6-one showed the strongest inhibition of the DU 145 cells. The root extract had significant antimicrobial and antiproliferative activities, supporting the traditional use of this plant in treating microbial infections and cancer-related ailments. Full article

A phytochemical study of the root and bark of Brucea antidysenterica J. F. Mill. (Simaroubaceae) afforded three new compounds, including a stilbene glycoside bruceanoside A (1), and two canthinone alkaloids bruceacanthinones A (3) and B (4), along with ten known secondary metabolites, rhaponticin (2), 1,11-dimethoxycanthin-6-one (5), canthin-6-one (6), 1-methoxycanthin-6-one (7), 2-methoxycanthin-6-one (8), 2-hydroxy-1,11-dimethoxycanthin-6-one (9), β-carboline-1-propionic acid (10), cleomiscosin C (11), cleomiscosin A (12), and hydnocarpin (13). The structures of all the compounds were determined using spectrometric and spectroscopic methods including 1D and 2D NMR, and HRSEIMS. The identities of the known compounds were further confirmed by comparison of their data with those reported in the literature. The root and bark methanolic extracts, the dichloromethane and ethyl acetate soluble fractions, and the isolated compounds (3–13), were assessed for their cytotoxicity against the cancer cell lines A-549, MCF-7, and PC-3. The results suggested that compounds in the extracts might possess a synergic action in their cytotoxicity. Full article

A new alkaloid, Canthin-6-one, Huberine (1), together with three known compounds including 1-Hydroxy-canthin-6-one (2), Canthin-6-one (3) and stigma sterol (4), were isolated from the stem bark of Picrolemma huberi. The isolation was achieved by chromatographic techniques and the purification was performed on a C18 column using acetonitrile/water (90:10, v/v) with 0.1% formic acid as the mobile phase. The structural elucidation was performed via spectroscopic methods, notably 1D- and 2D-NMR, UV, IR, MS and HRMS. The antiplasmodial activity of the compounds was studied. Full article

The present investigation of the chemical constituents of the stem barks of Ailanthus altissima has resulted in the isolation of six canthinone-type alkaloids, including a new compound, (R)-5-(1-hydroxyethyl)-canthine-6-one (1), and five known compounds (2–6). Moreover, four phenyl propanoids (7–10), two lignans (11 and 12), two triterpenoids (13 and 14) and a fatty acid (15) having previously known chemical structures were isolated during the same course of this study. The structure of the new compound was elucidated by physical (m.p., [α]_D) and spectroscopic data (¹H-NMR, ¹³C-NMR, 2D NMR, and HR-DART-MS) interpretation and its absolute configuration was determined by electronic circular dichroism (ECD) data and quantum chemical calculations. The inflammatory activities of the isolates were screened on lipopolysaccharide (LPS)-induced nitric oxide (NO), a proinflammatory mediator, in RAW 264.7 cells. Among these isolated compounds, six compounds exhibited significant inhibition of NO production, with IC₅₀ values in the range of 5.92 ± 0.9 to 15.09 ± 1.8 μM. Full article

In this review, more than 60 natural canthin-6-one alkaloids and their structures are considered. The biosynthesis, efficient and classic synthetic approaches, and biological activities of canthin-6-one alkaloids, from 1952 to 2015, are discussed. From an analysis of their structural properties and an investigation of the literature, possible future trends for canthin-6-one alkaloids are proposed. The information reported will be helpful in future research on canthin-6-one alkaloids. Full article

Eurycoma longifolia Jack (known as tongkat ali), a popular traditional herbal medicine, is a flowering plant of the family Simaroubaceae, native to Indonesia, Malaysia, Vietnam and also Cambodia, Myanmar, Laos and Thailand. E. longifolia, is one of the well-known folk medicines for aphrodisiac effects as well as intermittent fever (malaria) in Asia. Decoctions of E. longifolia leaves are used for washing itches, while its fruits are used in curing dysentery. Its bark is mostly used as a vermifuge, while the taproots are used to treat high blood pressure, and the root bark is used for the treatment of diarrhea and fever. Mostly, the roots extract of E. longifolia are used as folk medicine for sexual dysfunction, aging, malaria, cancer, diabetes, anxiety, aches, constipation, exercise recovery, fever, increased energy, increased strength, leukemia, osteoporosis, stress, syphilis and glandular swelling. The roots are also used as an aphrodisiac, antibiotic, appetite stimulant and health supplement. The plant is reported to be rich in various classes of bioactive compounds such as quassinoids, canthin-6-one alkaloids, β-carboline alkaloids, triterpene tirucallane type, squalene derivatives and biphenyl neolignan, eurycolactone, laurycolactone, and eurycomalactone, and bioactive steroids. Among these phytoconstituents, quassinoids account for a major portion of the E. longifolia root phytochemicals. An acute toxicity study has found that the oral Lethal Dose 50 (LD₅₀) of the alcoholic extract of E. longifolia in mice is between 1500–2000 mg/kg, while the oral LD₅₀ of the aqueous extract form is more than 3000 mg/kg. Liver and renal function tests showed no adverse changes at normal daily dose and chronic use of E. longifolia. Based on established literature on health benefits of E. longifolia, it is important to focus attention on its more active constituents and the constituents’ identification, determination, further development and most importantly, the standardization. Besides the available data, more evidence is required regarding its therapeutic efficacy and safety, so it can be considered a rich herbal source of new drug candidates. It is very important to conserve this valuable medicinal plant for the health benefit of future generations. Full article

Luotonins are alkaloids from the aerial parts of Peganum nigellastrum Bunge. that display three major skeleton types. Luotonins A, B, and E are pyrroloquinazolino-quinoline alkaloids, luotonins C and D are canthin-6-one alkaloids, and luotonin F is a 4(3H)-quinazolinone alkaloid. All six luotonins have shown promising cytotoxicities towards selected human cancer cell lines, especially against leukemia P-388 cells. Luotonin A is the most active one, with its activity stemming from topoisomerase I-dependent DNA-cleavage. Such intriguing biological activities and unique structures have led not only to the development of synthetic methods for the efficient synthesis of these compounds, but also to interest in structural modifications for improving the biological properties. Recent progress in the study of luotonins is covered. Full article