Naheed Fatima

Phenolic glycosides from Symplocos racemosa: natural inhibitors of phosphodiesterase I.

One new phenolic glycoside named benzoylsalireposide (1) along with one known phenolic glycoside named salireposide (2) have been isolated from Symplocos racemosa. Four other known compounds i.e. beta-amyrin (3), oleonolic acid (4), beta-sitosterol (5) and beta-sitosterol glycoside (6) were also isolated from this plant. The structure elucidation of the isolated compounds was based primarily on 1D- and 2D-NMR analysis, including COSY, HMQC, and HMBC correlations. The compound 1 and 2 showed inhibitory activity against snake venom phosphodiesterase I.

1,3,4-Oxadiazole-2(3H)-thione and its analogues: a new class of non-competitive nucleotide pyrophosphatases/phosphodiesterases 1 inhibitors.

A series of 1,3,4-oxadiazole-2 (3H)-thiones and 1,3,4-thiadiazole-2 (3H)-thiones were synthesized and evaluated for their inhibitory activities against the two nucleotide pyrophosphatase phosphodiesterase 1 enzymes. Dixon, as well as Lineweaver-Burk plots, and their secondary replots have indicated that the inhibition was of pure non-competitive type, against both snake venom and pure human recombinant enzymes as the V(max) values decreases without affecting the K(m) values. 5-[4-(t-Butyldimethylsilyloxy)-phenyl]-1,3,4-thiadiazole-2 (3H)-thione (17) and [4-(t-butyldimethylsilyloxy)-phenyl]-1,3,4-oxadiazole-2 (3H)-thione (1) were found to be the most active compounds with IC(50) values 66.47 and 368microM, respectively. The K(i) values were 100microM and 360microM against the snake venom and human recombinant NPP1 enzyme, respectively. Most active compounds were found to be non-toxic in neutrophil viability assay.

Quinovic Acid Glycosides From MitraGyna Stipulosa - First Examples of Natural Inhibitors of Snake Venom Phosphodiesterase I

Phytochemical investigations on the non-alkaloidal extracts of Mitragyna stipulosa bark has led to the isolation of a series of triterpenoids mainly consisting of quinovic acid ( 1 ) and its glycoside derivatives 2 and 3 . The other constituents isolated include f -amyrin, 3 g -acetyl ursolic acid and a mixture of oleanolic and ursolic acid and g -sitosterol glucopyranoside. Their structures were identified by spectral and chemical studies and compounds 2 and 3 were, respectively, identified as quinovic acid 3- O -[ g - d -glucopyranoside] (quinovin glycoside C) and quinovic acid 3- O -[ g - d -quinovopyranoside]-27- O -[ g - d -glucopyranosyl] ester. Compounds 1 and 2 showed significant inhibitory activity against snake venom phosphodiesterase I.

Phosphodiesterase-I inhibitor quinovic acid glycosides from Bridelia ndellensis.

Quinovic acid-3-O-α-l-rhamnopyranoside (1), quinovic acid-3-O-β-d-fucopyranoside (2), quinovic acid-3-O-β-d-glucopyranosyl (1 → 4)-β-d-fucopyranoside (3), methyl gallate (4) and ethyl gallate (5) were isolated from the ethyl acetate extract of Bridelia ndellensis barks by fractionation. Compounds 1–3 showed significant inhibitory activity against snake venom phosphodiesterase-I.

Phenolics from Colchicum decaisnei

Abstract Colchicum decaisnei has yielded three new compounds, namely, dibenzo[ b , f ][1,5]dioxocin, 4,6-dimethoxy-3,7-dimethyl coumarin and 3- O -demethyl- N -desacetyl- N -formyl-β-lumicolchicine, as well as the first report of 2-hydroxy-3-methoxy benzoic acid from a natural source.

Phenolic Glycosides from Symplocos racemosa

The re-investigation of the chemical constituents of the bark of the stem of Symplocos racemosa Roxb. led to the isolation of two new phenolic glycosides, Symconoside A (1) and Symconoside B (2). The structures of the new compounds were determined by 1D and 2D-homonuclear and heteronuclear NMR spectroscopy, chemical evidences, and by comparison with the published data of the closely related compounds. The phenolic glycosides 1 and 2 displayed in vitro inhibitory activity against phosphodiesterase-I with the IC50 values of 158±0.02 and 900±0.08 μM, respectively.