Microbial Transformation of the Sesquiterpene Lactone, Vulgarin, by Aspergillus niger.

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,6,11ßH-eudesman-6,12-olide (2), 20% yield, 1α,4α-dihydroxyeudesm-2-en-5αH,6,11ßH-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, ß 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.

Westalsan: A New Acetylcholine Esterase Inhibitor from the Endophytic Fungus Westerdykella nigra.

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.

Evaluation of antimicrobial, antiquorum sensing, and cytotoxic activities of new vanillin 1,2,3-triazole derivatives.

Vanillin (1), the main constituent of vanilla species, was used as a starting natural scaffold for the synthesis of five new (2-6) and one known (7) triazole derivatives via click chemistry using the copper (I)-catalyzed azide-alkyne cycloaddition method. Vanillin and its new derivatives; 4-{1-[2-Hydroxymethyl-5-(5 methyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-tetrahydro-furan-3-yl]-1H[1,2,3]triazol-4-ylmethoxy}-3-methoxy-benzaldehyde (2); [4-(4-Formyl-2methoxy-phenoxymethyl)-[1,2,3]triazol-1-yl]-acetic acid methyl ester (3); 4-[1-(4-Acetyl-phenyl)-1H-[1,2,3]triazol-4-ylmethoxy]-3-methoxy-benzaldehyde (4); 4-[4-(1-Benzyl-1H-[1,2,3]triazol-4-ylmethoxy)-3-methoxy-phenyl]-but-3-en-2-one (5); and 4-[4-(1-Benzyl-1H-[1,2,3]triazol-4-ylmethoxy)-3-methoxy-phenyl]-4-hydroxy-butan-2-one (6), as well as the previously known derivative (7) were subjected to antimicrobial, antiquorum-sensing and cytotoxic evaluation. Compounds 4-7 possessed the most notable enhancement in the anti-bacterial activity against Bacillus cereus, Pseudomonas aeruginosa and antifungal activity against Candida albicans. However, compounds 1 and 2 exhibited high antiquorum-sensing activity against Chromobacterium violaceum using catechin as a positive control. Compounds 4-7 demonstrated selective cytotoxicity against MCF-7 and HepG2 cancer cells compared to normal lung fibroblast cells (WI-38). These findings proved the usefulness of synthesis bioactive derivatives from vanillin through chemical modifications.

New prenylated flavonoid and neuroprotective compounds from Tephrosia purpurea subsp. dunensis.

Continuation of the phytochemical investigation of the aerial parts of Tephrosia purpurea subsp. dunensis resulted in the isolation and structural elucidation of a new prenylated flavonoid demeapollinin (1), glabratephrinol (2) and a mixture (3) of tephroapollin G (3a) and epi-tephroapollin G (3b). The neuroprotective activity of compounds (1-3) besides the previously isolated compounds; dunensin (4), pseudosemiglabrin (6), glabratephrin (7), apollinin (5), kampferol 3, 7-O-α-L-dirhamnoside (8) and quercetin 3, 7-O-α-L-dirhamnoside (9) was examined. Molecular docking, acetylcholine esterase inhibitory assay and protection against both H2O2 and induced neurotoxicity were used to evaluate their neuroprotective effect. Compound 2 showed the highest acetylcholine esterase inhibitory activity (IC50 4.31 ± 0.75 µM) compared to galantamine (IC50 1.64 ± 0.32 µM), compounds 4 and 3 exhibited potent protective effect against induced neurotoxicity (IC50 7.70 ± 5.23 and 10.91 ± 6.27 µM, respectively) compared to standard epigallocatechin gallate (IC50 18.36 ± 6.22 µM).

New ent-kaurane diterpenoid dimer from Pulicaria inuloides.

A new naturally occurring ent-kaurane diterpenoid dimer, 15ß, 15'ß-oxybis (ent-kaur-16-en-19-oic acid) (1) along with six known compounds, 15ß-hydroxy-ent-kaur-16-en-19-oic acid (2), 15ß-hydroxy-ent-kaur-16-en-19-oate-ß-d-glucopyranoside (3), 6-hydroxykaempferol-3, 7-dimethyl ether (4), quercetagetin 3, 7, 3'-trimethyl ether (5), ß-sitosterol (6) and ß-sitosterol glucoside (daucosterol) (7) were isolated from the aerial parts of Pulicaria inuloides DC. Compounds 2-5 were isolated for the first time from genus Pulicaria. The structures of compounds 1-7 were established on the basis of extensive 1D and 2D NMR spectroscopic techniques in combination with ESI-MS. The antimicrobial activity of the isolated compounds was evaluated against Staphylococcus aureus, Escherichia coli and Candida albicans. Sulphorhodamine B cytotoxic assay against HepG2 (liver cancer) cell line and ABTS antioxidant assay were carried out.

New cytotoxic spirostane saponin and biflavonoid glycoside from the leaves of Acacia saligna (Labill.) H.L. Wendl.

New naturally occurring spirostane saponin (25S)-5ß-spirostan-3ß-yl-3-O-ß-D-xylopyranosyl(1 → 3)-O-ß-D-xylopyranosyl(1 → 4)-ß-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), 3ß-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.