Sahar R. Gedara

Alkaloids and Polyketides from Penicillium citrinum, an Endophyte Isolated from the Moroccan Plant Ceratonia siliqua

The endophytic fungus Penicillium citrinum was isolated from a fresh stem of the Moroccan plant Ceratonia siliqua. Extracts of P. citrinum grown on rice and white bean media yielded five new compounds, namely, citriquinochroman (1), tanzawaic acids G and H (2 and 3), 6-methylcurvulinic acid (4), 8-methoxy-3,5-dimethylisoquinolin-6-ol (5), and one new natural product, 1,2,3,11b-tetrahydroquinolactacide (6), which had previously been described as a synthetic compound. In addition, 13 known compounds including seven alkaloids and six polyketides were isolated. The structures of the new compounds were unambiguously determined on the basis of one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. Citriquinochroman (1) features a new skeleton, consisting of quinolactacide and (3S)-6-hydroxy-8-methoxy-3,5-dimethylisochroman linked by a C-C bond. 1,2,3,11b-Tetrahydroquinolactacide (6) may be a biogenetic precursor of quinolactacide. Citriquinochroman (1) showed cytotoxicity against the murine lymphoma L5178Y cell line with an IC50 value of 6.1 μM, while the other compounds were inactive (IC50 >10 μM) in this assay.

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-β-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

Diterpenes and a flavone from Leucas neufliseana

Abstract Three labdane-type diterpenes; 3-oxo-marrubiin and a mixture of two related C-15 epimeric diterpenes based on 9α,13α,15,16-bisepoxy-15-hydroxy-3-oxo-labdan-6β, 19-olide, in addition to the acylated flavone apigenin 7- O -[6″- O -( p -hydroxy- trans -cinnamoyl)glucoside] were isolated and identified from the aerial parts of Leucas neufliseana . Their structures were established through physical and chemical methods in addition to standard spectroscopic techniques. This is the first report of the isolation of the two epimeric diterpenes from a natural source.

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

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.

A diterpene from Nepeta septemcrenata

Abstract A new isopimarane-type diterpene was isolated from the ethanol extract of the aerial parts of Nepeta septemcrenata. Its structure was established as 1α-hydroxy-7α,14α,18-triacetoxy-isopimara-8,15-diene using different spectroscopic techniques (UV, IR, MS and 1 and 2D NMR). In addition, 7-O-methylapigenin was also isolated and identified.

New ent-kaurane diterpenoid dimer from Pulicaria inuloides.

Abstract A new naturally occurring ent-kaurane diterpenoid dimer, 15β, 15′β-oxybis (ent-kaur-16-en-19-oic acid) (1) along with six known compounds, 15β-hydroxy-ent-kaur-16-en-19-oic acid (2), 15β-hydroxy-ent-kaur-16-en-19-oate-β-d-glucopyranoside (3), 6-hydroxykaempferol-3, 7-dimethyl ether (4), quercetagetin 3, 7, 3′-trimethyl ether (5), β-sitosterol (6) and β-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 erythroxane-type diterpenoids from Fagonia boveana (Hadidi) Hadidi & Graf.

The aerial parts of Fagonia boveana afforded two new erythroxane-type diterpenes, 3β, 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 7β-hydroxy fagonene (8). Also a new guaiane sesquiterpene alcohol, 6,10-epoxy-4α-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

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.

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.