Usha Rawat

The genus Stephania (Menispermaceae): Chemical and pharmacological perspectives

The plants of the genus Stephania (Menispermaceae) are widely distributed, and have long been used in folk medicine for the treatment of various ailments such as asthma, tuberculosis, dysentery, hyperglycemia, malaria, cancer and fever. Over 150 alkaloids together with flavonoids, lignans, steroids, terpenoids and coumarins have been identified in the genus, and many of these have been evaluated for biological activity. This review presents comprehensive information on the chemistry and pharmacology of the genus together with the traditional uses of many of its plants. In addition, this review discusses the structure-activity relationship of different compounds as well as recent developments and the scope for future research in this aspect.

Anti-hyperglycemic effect of 11-hydroxypalmatine, a palmatine derivative from Stephania glabra tubers.

A palmatine derivative, named 11-hydroxypalmatine (4), has been isolated from the tubers of Stephania glabra, together with three known alkaloids, palmatine (1), dehydrocorydalmine (2), and stepharanine (3). The structures of the compounds were elucidated by means of spectroscopic analysis including 2D NMR experiments. The hypoglycemic activity of 4 was evaluated against alloxan-induced diabetic mice. The test compound was administered at doses of 25, 50, and 100 mg/kg, p.o., 36 h after alloxan injection (60 mg/kg, i.v.). The alloxan-induced diabetic mice showed significant reduction in blood glucose after treatment with the test compound by 52% as compared to the positive control glibenclamide (54%) and the diabetic control (27%).

Chemical constituents and biological applications of the genus Symplocos

The genus Symplocos has been reviewed for its chemical constituents and biological activities including traditional importance of some common species. The plants of this genus contain terpenoids, flavonoids, lignans, phenols, steroids, alkaloids, and iridoids. Terpenoids are the major constituents within the genus Symplocos and most of them exhibit antiproliferative effects. Some phenolic glycoside derivatives showed inhibitory activity against snake-venom phosphodiesterase I and human nucleotide pyrophosphatase phosphodiesterase I. The members of genus Symplocos are well known for their traditional uses in the treatment of various diseases like leprosy, gynecological disorders, ulcers, leucorrhea, menorrhagia, malaria, and tumefaction. The aim of the present paper is to review the comprehensive knowledge of the plants of this genus including the traditional uses, chemistry, and pharmacology.

Chemical constituents from the leaves of Boehmeria rugulosa with antidiabetic and antimicrobial activities.

Three new flavonoid glycosides, named chalcone-6′-hydroxy-2′,3,4-trimethoxy-4′-O-β-d-glucopyranoside (1), isoflavone-3′,4′,5,6-tetrahydroxy-7-O-{β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside} (2), and isoflavone-3′,4′,5,6-tetrahydroxy-7-O-{β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranoside} (3), were isolated from the leaves of Boehmeria rugulosa, together with five known compounds, β-sitosterol, quercetin, 3,4-dimethoxy-ω-(2′-piperidyl)-acetophenone (4), boehmeriasin A (5), and quercetin-7-O-β-d-glucopyranoside. The structures of the isolated compounds were determined by means of chemical and spectral data including 2D NMR experiments. The ethanolic extract of leaves showed significant hypoglycemic activity on alloxan-induced diabetic mice. Glibenclamide, an oral hypoglycemic agent (5 mg/kg, p.o.), was used as a positive control. The ethanolic extract of the plant as well as the isolated compounds 1–3 (25 μg/ml) showed potent antimicrobial activity against two bacterial species (Staphylococcus aureus and Streptococcus mutans) and three fungus pathogens (Microsporum gypseum, Microsporum canis, and Trichophyton rubrum). The activities of the isolated compounds 1–3 have been compared with positive controls, novobiocin, and erythromycin (15 μg/ml).

Antimicrobial hasubanalactam alkaloid from Stephania glabra.

A novel hasubanalactam alkaloid, named glabradine, has been isolated from the tubers of Stephania glabra, together with three known quaternary protoberberine alkaloids, palmatine, dehydrocorydalmine and stepharanine. The structure of glabradine was assigned as 7-O-demethyl-N,O-dimethyloxostephinine, by means of rigorous spectroscopic analysis including 2 D NMR measurements. It was evaluated for antimicrobial activity against Staphylococcus aureus, S. mutans, Microsporum gypseum, M. canis and Trichophyton rubrum and displayed potent antimicrobial activity superior to those of novobiocin and erythromycin used as positive controls.

Celtisanin, a novel sulphonated phenolic from Celtis australis L. fruits

A novel sulphonated phenolic named celtisanin (1), elucidated as 3-[8′-hydroxy-prop-6′-ene-6′-yl]-5-hydroxymethyl-4-methoxy-2-[penta-1′,4′-diene-1′-yl-5′-sulphonic acid]-5,6-dihydrobenzofuran, has been isolated from the fruits of Celtis australis (Ulmaceae), together with three known compounds: apigenin, quercetin and its glucoside. Their structures were characterised by means of chemical and spectral methods, including advanced 2-D nuclear magnetic resonance (NMR) studies.

Further Aporphine Alkaloids from Phoebe lanceolata

Stem bark of Phoebe lanceolata was extracted with ethanol and fractionated with ethyl acetate yielded soluble and insoluble fractions. Ethyl acetate insoluble fraction was subjected to column chromatography afforded two oxalyl-fused didehydroaporphine alkaloids, N-6/C-7 oxalyl-fused 2,9-dihydroxy-1,10-dimethoxy 6a,7-didehydroaporphine and N-6/C-7 oxalyl-fused 1,2,9,10-tetramethoxy 6a,7-didehydroaporphine along with well known β-sitosterol and β-sitosterol glucoside. The structures of isolated compounds were elucidated by chemical and spectral analysis.

A New Flavonoid Glycoside from Salix denticulata Aerial Parts

Abstract: A new flavonoid glycoside (1) has been isolated from the aerial parts of Salix denticulata (Salicaceae) together with five known compounds, β-sitosterol, 2,6-dihydroxy- 4-methoxy acetophenone, eugenol-1-O-β-D-glucopyranoside, 1-O-β-D-(3’-benzoyl) salicyl alcohol and luteolin-7-O-β-D-glucopyranosyl-(1-6)-glucopyranoside. The structure of 1 was elucidated as 2’,5-dihydroxy-3’-methoxyflavone-7-O-β-D-glucopyranoside by means of chemical and spectral data including 2D NMR studies.