Search Results (6)

Investigation of the roots of Tripterygium wilfordii Hook. f. resulted in the isolation of nine sesquiterpene pyridine alkaloids (SPAs), including four previously undescribed compounds 1–4. The structures of all compounds were elucidated by extensive spectroscopic analysis, including NMR and HRESIMS. In particular, compound 1 was found to possess an unprecedented cage-like ether moiety, representing the first report of such a structural feature within this class of alkaloids. All isolated compounds were evaluated for their anti-inflammatory activity using a lipopolysaccharide (LPS)-induced RAW264.7 macrophage model. Compounds 1, 2, and 4 exhibited significant inhibition of nitric oxide (NO) production, with IC₅₀ values of 7.14 ± 1.89, 8.55 ± 0.37, and 14.76 ± 0.39 μM. Furthermore, compounds 1 and 2 suppressed the secretion of key pro-inflammatory cytokines, including TNF-α, IL-6, and IL-1β, in the same cellular model. These results not only enhanced the structural diversity of SPAs identified from T. wilfordii, but also highlight their potential as promising anti-inflammatory lead compounds. Full article

Sesquiterpene pyridine alkaloids (SPAs), as a main class of components in Tripterygium wilfordii Hook. f., possess a variety of bioactivities, such as immunosuppressive, insecticidal, and anti-tumor activities. SPAs can be structurally classed into four subtypes: wilfordate-, evoninate-, iso-wilfordate-, and iso-evoninate types. Our previous study unveiled ten new wilfordate-type SPAs, named wilfordatine A–J, isolated from the roots of Tripterygium wilfordii Hook. f., several of which exhibited significant immunosuppressive activities. As an extension and augmentation of the previous findings, we have now isolated one new iso-wilfordate-type SPA, wilfordatine K (1), alongside three new iso-evoninate-type SPAs, wilfordatines L–N (3–5), and six known analogs. Their structures were characterized by the extensive use of 1D and 2D NMR spectroscopic analysis, as well as HRMS data. Interestingly, compounds 4 and 6 were found to exhibit potent inhibitory effects on the nuclear factor-kappa B (NF-κB) pathway in lipopolysaccharide (LPS)-induced HEK293/NF-κB-Luc cells, with IC₅₀ values of 1.64 μM and 9.05 μM, respectively. Notably, these two compounds had no influence on the cell viability at a concentration of 100 μM. Consequently, they hold significant promise as potential anti-inflammatory candidates for further exploration and development. Full article

Maytenus dhofarensis Sebsebe (Celestraceae) is a naturally growing shrub in Oman. It is not a reputed medicinal plant in Oman, but it is regionally endemic and causes shivering attacks on goats that graze on it. The chemical investigation of the hexane and chloroform extracts of the fruits and stems of M. dhofarensis afforded dihydro-β-agarofuran-type sesquiterpene pyridine alkaloid (1), lupanyl myristoate (2) and lignanolactone (3). Compounds (1–3) are new isolates from M. dhofarensis. The structures of these compounds were assigned through comprehensive IR, NMR, and ESI-MS analyses, and the relative configurations of compounds 1 and 3 were deduced from density function theory (DFT) calculations and NMR experiments. Compound 1 was assayed against the kinase enzyme and showed no inhibition activity for p38 alpha and delta at a 10 µM test concentration. Compound 3 inhibited the 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH) by 69.5%, compared to 70.9% and 78.0% for gallic acid and butylated hydroxyanisole, respectively, which were used as positive controls. Full article

Tripterygium wilfordii Hook. f. is a well-known traditional Chinese medicine used to treat autoimmune diseases. Sesquiterpene pyridine alkaloids (SPAs) are a major class of components found in this herb that have piqued the interest of researchers due to their complex and diverse structures as well as significant biological activities. In this study, ten new SPAs, wilfordatine A–J (1–10), were isolated from the roots of T. wilfordii, along with ten known analogues (11–20). Their structures were primarily elucidated by extensive 1D and 2D NMR spectroscopic analysis. To search for more immunosuppressive ingredients related to the clinical efficacy of T. wilfordii, the total alkaloids (TA) and compounds 4, 5, and 9–16 were tested for their inhibitory effects on nuclear factor-kappa B (NF-κB) pathway in Lipopolysaccharide (LPS) induced HEK293/NF-κB-Luc cells. Among them, TA, compounds 5, 11, and 16 showed potent immunosuppressive activity, with IC₅₀ values of 7.25 μg/mL, 8.75 μM, 0.74 μM, and 15.66 μM, respectively, and no influence on the cell viability at a concentration of 100 μg/mL (TA) or 100 μM (5, 11, and 16). Accordingly, TA, 5, 11, and 16, especially 11, were identified as promising candidates for further investigation into their potential use as immunosuppressive agents. Full article

Biodiversity is key for maintenance of life and source of richness. Nevertheless, concepts such as phenotype expression are also pivotal to understand how chemical diversity varies in a living organism. Sesquiterpene pyridine alkaloids (SPAs) and quinonemethide triterpenes (QMTs) accumulate in root bark of Celastraceae plants. However, despite their known bioactive traits, there is still a lack of evidence regarding their ecological functions. Our present contribution combines analytical tools to study clones and individuals of Maytenus ilicifolia (Celastraceae) kept alive in an ex situ collection and determine whether or not these two major biosynthetic pathways could be switched on simultaneously. The relative concentration of the QMTs maytenin (1) and pristimerin (2), and the SPA aquifoliunin E1 (3) were tracked in raw extracts by HPLC-DAD and ¹H-NMR. Hierarchical Clustering Analysis (HCA) was used to group individuals according their ability to accumulate these metabolites. Semi-quantitative analysis showed an extensive occurrence of QMT in most individuals, whereas SPA was only detected in minor abundance in five samples. Contrary to QMTs, SPAs did not accumulate extensively, contradicting the hypothesis of two different biosynthetic pathways operating simultaneously. Moreover, the production of QMT varied significantly among samples of the same ex situ collection, suggesting that the terpene contents in root bark extracts were not dependent on abiotic effects. HCA results showed that QMT occurrence was high regardless of the plant age. This data disproves the hypothesis that QMT biosynthesis was age-dependent. Furthermore, clustering analysis did not group clones nor same-age samples together, which might reinforce the hypothesis over gene regulation of the biosynthesis pathways. Indeed, plants from the ex situ collection produced bioactive compounds in a singular manner, which postulates that rhizosphere environment could offer ecological triggers for phenotypical plasticity. Full article

Two new dimacrolide sesquiterpene pyridine alkaloids (DMSPAs), dimacroregelines A (1) and B (2), were isolated from the stems of Tripterygium regelii. The structures of both compounds were characterized by extensive 1D and 2D NMR spectroscopic analyses, as well as HRESIMS data. Compounds 1 and 2 are two rare DMSPAs possessing unique 2-(3′-carboxybutyl)-3-furanoic acid units forming the second macrocyclic ring, representing the first example of DMSPAs bearing an extra furan ring in their second macrocyclic ring system. Compound 2 showed inhibitory effects on the proliferation of human rheumatoid arthritis synovial fibroblast cell (MH7A) at a concentration of 20 μM. Full article