Nasim Sultana

A new depsidone and antibacterial activities of compounds from Usnea undulata Stirton

Usnea undulata Stirton (Usneaaceae) is a fruticose lichen used locally in ethnoveterinary medicine to treat mammary infections in cattle while human beings use it for the treatment of wounds in Eastern Cape, South Africa. Bioactivity-guided fractionation of its extracts led to the isolation and characterization of a new depsidone, 2′-O-methylhypostictic acid (8), together with seven known compounds, i.e. methyl β-orsellinate (1), norstictic acid (2), menegazziaic acid (3), (+) usnic acid (4), hypoconstictic acid (5), salazinic acid (6), and galbinic acid (7). The structures of the compounds were elucidated on the basis of their spectral analysis including homo- and hetero-nuclear correlation NMR experiments (COSY, NOESY, HMQC, and HMBC) and mass spectra as well as by comparison with available data in the literature. The minimum inhibitory concentrations (MICs) values of the compounds against six bacteria were determined. Compound 8 showed inhibitory activity against Bacillus cereus, Bacillus subtilis, and Staphylococcus epidermidis with MICs of 31, 62.5, 62.5 μg/ml, respectively. (+) Usnic acid was most active against B. subtilis, B. cereus, Staphylococcus aureus, and Escherichia coli with MICs of 8, 8, 31, and 31 μg/ml, respectively, while other compounds exhibited moderate activity.

A novel daucosterol derivative and antibacterial activity of compounds from Arctotis arctotoides.

Arctotis arctotoides is a perennial herb used medicinally for the treatment of various ailments in the Eastern Cape, South Africa. Different extracts of the plant were investigated for their antimicrobial constituents. This led to the isolation and identification of a new daucosterol derivative 3-O-[β-D-(6′-nonadeanoate)glucopyranosyl]-β-sitosterol and seven known compounds namely: serratagenic acid, stigmasterol, daucosterol, zaluzanin D, dehydrocostuslactone, nepetin, and pedalitin. The structures of the compounds were elucidated on the basis of spectral analysis, including homo and hetero nuclear correlation NMR experiments (COSY, NOESY, HMQC, HMBC) and mass spectra as well as by comparison with available data in the literature. The compounds exhibited antibacterial activity except stigmasterol, daucosterol and dehydrocostuslactone. Nepetin was the most active against Bacillus subtilis and Staphylococcus aureus with the minimum inhibitory concentrations of 4 µg mL - 1 and 31 µg mL - 1, respectively, while others exhibited moderate activity.

A new triterpenoid from roots of Laportea crenulata and its antifungal activity

A new triterpenoid 2α,3β,21β,23,28-penta hydroxyl 12-oleanene and two known compounds were isolated from the roots of Laportea crenulata Gaud. The structures of all compounds were elucidated on the basis of various spectroscopic data. The two known compounds β-sitosterol and β-sitosterol 3-β-D-glucopyranoside are also the first report of isolation from this plant. The antifungal activity of new triterpenoid was studied against Aspergillus flavus, Aspergillus niger, Candida albicans, and Rhizopus aurizae, and compared with the activity of nystatin (30 µg disc−1). This compound has shown moderate activity against tested fungi.

Novel flavonoid glycosides from the bulbs of Urginea indica Kunth.

Three novel flavonoid glycosides, 5,6-dimethyoxy-3′,4′′-dioxymethylene-7-O-(6′′-β-D-glucopyranosyl-β-D-glucopyranosyl) flavanone (1), 5,4′-dihydroxy-3-O-α-L-rhamnopyranosyl-6-C-glucopyranosyl-7-O-(6′′-para-coumaroyl-β-D-glucopyranosyl) flavone (2) and 5,4′-dihydroxy-3-O-(2′′′′′-β-glucopyranosyl-α-L-rhamnopyranosyl)-6-C-glucopyranosyl-7-O-(6′′-para-coumaroyl-β-D-glucopyranosyl) flavone (3) were isolated from the 1-butanol soluble fraction of the bulbs of the plant Urginea indica (Indian squill). The structures of the compounds were elucidated on the basis of spectral analysis, including homo- and heteronuclear correlation NMR experiments (COSY, NOESY, HSQC and HMBC) and mass spectra.

A new phenylpropanoid glycoside from Leucas indica Linn

A new phenylpropanoid glycoside, α-l-rhamnopyranosyl-(1 → 3)-O-α-l-rhamnopyranosyl-(1 → 6)-1-O-caffeoyl-β-d-glucopyranoside (1) along with two known phenylethanoid glycosides (2–3) has been isolated from the aerial parts of Leucas indica Linn. Their structures were deduced from the spectroscopic studies and compared with the literature values.