Osama B. Abdel-Halim

Cytotoxic Hydroazulene Diterpenes from the Brown Alga Cystoseira myrica

Cytotoxicity-guided fractionation of the alcohol extract of the brown alga, Cystoseira myrica, afforded four new cytotoxic hydroazulene diterpenes, dictyone acetate (2), dictyol F monoacetate (4), isodictytriol monoacetate (6), and cystoseirol monoacetate (8), together with two known cytotoxic hydroazulene diterpenes, pachydictyol A (1) and dictyone (3). The constitution of each isolated compound has been determined on the basis of spectroscopic and chemical evidence

Cytotoxic triterpenes from Cleome africana

Eighteen dammarane-type triterpenes were obtained from the whole plant of Cleome africana by means of cytotoxic bioassay-directed fractionation. Twelve of them were novel compounds whose structures were elucidated by various spectroscopic methods.

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

(−)-6α-Hydroxylupanine, a lupin alkaloid from Lygos raetam var. sarcocarpa

Abstract A new lupin alkaloid, (−)-6α-hydroxylupanine, was isolated from aerial parts of Lygos raetam var. sarcocarpa . Its structure, including absolute configuration, was determined by different spectroscopic methods and by chemical transformation into (+)-5,6-dehydrolupanine.

Glycosidic alkaloids from Lupinus varius

Abstract A new glycosidic alkaloid, (−)-( trans -3′-methoxy-4′- α - l -rhamnosyloxy cinnamoyl)epilupinine, was isolated from the aerial parts of Lupinus varius , together with the eight knownalkaloids, (−)-( trans -4′- α - l -rhamnosyloxycinnamoyl) epilupinine, (+)-( trans -4′-hydroxy-3′-methoxy-cinnamoyl) epilupinine, (+)-epilupinine, (+)-epilupinine- N -oxide,(−)-multiflorine, (−)- δ 5 -dehydromultiflorine, (+)-ammodendrine and (−)-sparteine. Benzoylepilupinine was identified by GC–mass spectral analysis. The structure of the new glycosidicalkaloid was determined by chemical and spectroscopic methods.

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