New naturally occurring spirostane saponin (25S)-5β-spirostan-3β-yl-3-O-β-D-xylopyranosyl(1 → 3)-O-β-D-xylopyranosyl(1 → 4)-β-D-galactopyranoside (6) and biflavonoid glycoside myricetin-3-O-rhamnoside (C7-O-C7) myricetin-3-O-rhamnoside (4) along with a series of known compounds erythrodiol (1), 3β-O-trans-p-coumaroyl-erythrodiol (2), quercetin-3-O-α-L-rhamnoside (3) and myricetin-3-O-α-L-rhamnoside (5) were separated from the leaves of Acacia saligna (Labill.), H.L. Wendl. Compounds 1 and 2 were separated for the first time from genus Acacia. The structures of compounds 1-6 were established on the basis of extensive 1D and 2D NMR spectroscopic techniques in combination with EI-MS and HR-ESI-MS. These compounds were screened for their antioxidant and cytotoxic activities against HEPG2 (liver cancer) cell line and significant results were obtained.

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The biotransformation of vulgarin (1), an eudesmanolides-type sesquiterpene lactone obtained from Artemisia judaica, by the microorganism, Aspergillus niger, was carried out to give three more polar metabolites; 1-epi-tetrahydrovulgarin (1α,4α-dihydroxy-5αH,6,11βH-eudesman-6,12-olide (2), 20% yield, 1α,4α-dihydroxyeudesm-2-en-5αH,6,11βH-6,12-olide (3a), 10% yield, and C-1 epimeric mixture (3a, b), 4% yield, in a ratio of 4:1, 3a/3b. The structures of vulgarin and its metabolites were elucidated by 1 and 2D NMR spectroscopy in conjunction with HRESIMS. Metabolites (3a) and (3b) are epimers, and they are reported here for the first time as new metabolites obtained by biotransformation by selective reduction at C-1. Vulgarin and its metabolites were evaluated as anti-inflammatory agents using the human cyclooxygenase (COX) inhibitory assay. The obtained data showed that (1) exhibited a good preferential inhibitory activity towards COX-2 (IC50 = 07.21 ± 0.10) and had a moderate effect on COX-1 (IC50 = 11.32 ± 0.24). Meanwhile, its metabolite (3a) retained a selective inhibitory activity against COX-1 (IC50 = 15.70 ± 0.51). In conclusion, the results of this study revealed the necessity of the presence α, β unsaturated carbonyl group in (1) for better COX-2 inhibitory activity. On the other hand, the selectivity of (1) as COX-1 inhibitor may be enhanced via the reduction of C-1 carbonyl group.

Chemical transformation study is considered as an important tool for new drugs discovery. It was conducted on the natural compound eugenol for semi‐synthesizing new structural scaffolds. Three new eugenol 1,2,3‐triazole derivatives as well as a known one were synthesized via click chemistry using the Cu(I)‐catalyzed azide–alkyne 1,3‐dipolar cycloaddition method. All derivatives were characterized by NMR analysis in combination with ESIMS. Molecular docking and in vitro inhibition potency of eugenol and its derivatives towards hyaluronidase enzyme were examined. The synthesized derivative 4‐((4‐allyl‐2‐methoxyphenoxy)methyl)‐1‐benzyl‐1H‐1,2,3‐triazole showed an enhanced hyaluronidase inhibitory effect, 1.5 times, higher than its parent compound eugenol.

A new cytochalasan alkaloid, westalsan (1), along with two known cytochalasan compounds, phomacin B (2) and 19‐hydroxy‐19,20‐dihydrophomacin C (3), were isolated from the solid rice culture of Westerdykella nigra, a marine‐derived endophytic fungus, isolated from the roots of mangrove Avicennia marina (Forssk.) Vierh. The structures of compounds 1–3 were established on the basis of extensive 1D and 2D NMR spectroscopic techniques in combination with HR‐ESI‐MS. The ability of the isolated compounds to inhibit acetylcholine esterase activity was evaluated. Compound 3 showed the highest acetylcholine esterase inhibitory activity (IC50 0.056±0.003 μM), followed by compound 1 (IC50 0.088±0.005 μM) and compound 2 (IC50 0.140±0.007 μM) compared to donepezil (IC50 0.035±0.002 μM). This was further confirmed by molecular docking experiment.