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One new flavonoid named 5,7-dihydroxy-3,6,3`-trimethoxyflavone (1), together with eight known phenolic compounds; 3,4-dihydroxy methyl benzoate (2), 3,4-dihydroxybenzoic acid (3), isorhamnetin (4), quercetin (5), myricetin (6), isorhamnetin-4`-O--D-glucopyranoside (7), quercetin-4`-O--D-glucopyranoside (8) and quercetin-3,4`-O--D-diglucopyranoside (9) were isolated from the flowers of Cucurbita pepo L. for the first time except 3 which was previously isolated from the plant. Their structures have been established on the basis of physical, chemical and spectroscopic methods in addition to comparison with literature data and/or authentic samples. The methanolic and ethyl acetate extracts were evaluated for their antimicrobial activity.

One new flavonoid named 5,7-dihydroxy-3,6,3`-trimethoxyflavone (1), together with eight known phenolic compounds; 3,4-dihydroxy methyl benzoate (2), 3,4-dihydroxybenzoic acid (3), isorhamnetin (4), quercetin (5), myricetin (6), isorhamnetin-4`-O--D-glucopyranoside (7), quercetin-4`-O--D-glucopyranoside (8) and quercetin-3,4`-O--D-diglucopyranoside (9) were isolated from the flowers of Cucurbita pepo L. for the first time except 3 which was previously isolated from the plant. Their structures have been established on the basis of physical, chemical and spectroscopic methods in addition to comparison with literature data and/or authentic samples. The methanolic and ethyl acetate extracts were evaluated for their antimicrobial activity.

Chemical investigation of the n-hexane extract of the sponge Diacarnus megaspinorhabdosa has provided a series of norterpenes, including three new norditerpene cyclic peroxides and five new norsesterterpene peroxides together with four known norterpene peroxides: nuapapuin A methyl ester, epimuqubilin B, methyl-2-epinuapapuinoate and methyl diacarnoate A. The structures of the new compounds were established on the basis of one and two dimensional NMR spectroscopic studies ( H, C, COSY, HMQC, HMBC and ROESY) as well as on mass spectral analysis. The isolated compounds exhibited moderate (2–5µg) to strong toxicity (0.01–0.10µg) toward L5178Y (mouse lymphoma) and HeLa (human cervix carcinoma) while the same congeners showed weaker activity on the PC-12 (rat pheochromocytoma) cell line. Capon's empirical rules1 were extensively used in this study to derive the relative stereochemistry at C-2, C-3 and C-6.Following Horeau's procedure, the peroxide ring was cleaved to yield its diol congener onto which the advanced Mosher method was utilized to confirm the stereochemistry obtained from Capon's empirical rules.

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