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.

Evidence-based medicinal value of Rudbeckia hirta L. flowers.

A phytochemical investigation on the 5-lipoxygenase (5-LOX) inhibitory methanolic extract of Rudbeckia hirta L. flowers yielded 10 phenolic metabolites, including three phenolic acids, two phenolic acid esters, four flavonol glycosides and a trimethylated flavonol. The structures of the isolated metabolites were determined on the basis of spectroscopic analyses and by comparison with the literature data. Seven of these metabolites were isolated for the first time from the genus Rudbeckia. The in vitro 5-LOX inhibitory, immunomodulatory and antioxidant (oxygen radical absorbance capacity) activities of the isolated compounds were evaluated, and the results provided a new scientific evidence for the ethnopharmacological use of the herb in inflammatory conditions.

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.

Diterpenoids from Fagonia mollis.

A new acyclic diterpenoid (1) and a new erythroxan diterpenoid (2), together with 4 erythroxan diterpenoids and 3 triterpenoids, have been isolated from the aerial parts of Fagonia mollis. Their structures were elucidated on the basis of 1D and 2D NMR data. The cytotoxic activity of the isolated compounds was investigated against HL-60 cancer cells.

A new highly oxygenated pseudoguaianolide with 5-LOX inhibitory activity from Rudbeckia hirta L. flowers.

A new highly oxygenated pseudoguaianolide, rudbeckolide (1), was isolated from Rudbeckia hirta L. flowers. The structure of this terpenoid lactone was established on the basis of extensive 1D and 2D NMR spectroscopic analyses. The compound exhibited strong 5-lipoxygenase inhibitory activity (84.9% inhibition at 10 µg/mL) in vitro and the result provided partial evidence for the usage of the plant as traditional medicine.

New erythroxane-type diterpenoids from Fagonia boveana (Hadidi) Hadidi & Graf.

The aerial parts of Fagonia boveana afforded two new erythroxane-type diterpenes, 3beta,15,16-trihydroxy-erythrox-4(18)-ene (2) and 15,16-dihydroxy-cis-ent-erythrox-3-ene (fagonene) (3) together with two known ones; 16-O-acetylfagonone (1) and 7beta-hydroxy fagonene (8). Also a new guaiane sesquiterpene alcohol, 6,10-epoxy-4alpha-hydroxy guaiane type sesquiterpene (4) has been isolated. In addition three 8-methoxy flavonols, 8-methoxy-quercetin-3,7,3'-trimethyl ether (ternatin) (5), gossypetin, 3,8,3',4' tetramethyl ether (6) and herbacetin-3,8-dimethyl ether (7) were also isolated. The structures of the isolated compounds have been determined on the basis of spectroscopic evidences as well as physical and chemical correlation with known compounds. On performing different assays for biological activities, 6 displayed significant cytotoxic activity against KA3IT and NIH3T3 cell lines, 8 was the most active antiviral against Herpes simplex type 1 while 7 was the most active cancer-preventive agent using protein-tyrosine kinase inhibitory method.

Cytotoxic hydroazulene diterpenes from the brown alga Dictyota dichotoma.

Two new hydroazulenoid (prenyl guaiane) diterpenes, dictyone acetate (2) and 3,4-epoxy 13-hydroxy pachydictyol A (4) were isolated from the petroleum ether fraction of the alcoholic extract of the brown alga, Dictyota dichotoma (Hudson) Lamouroux, which was collected from the Red Sea coasts at Hurgada, Egypt, together with three known ones, pachydictyol A (1), dictyone (3) and 11-hydroxypachydictyol A (dictyol E) (5). In addition, the steroidal compound, stigmasta-5,(E)-24(28)-dien-3-beta-ol (fucosterol) (6) was also isolated. The structures of the isolated compounds have been determined on the basis of spectroscopic evidences as well as physical and chemical correlation with known compounds. Compounds 1, 2, 3 and 5 showed moderate cytotoxic activity.