M. Naveed

Isolation of natural compounds from Phlomis stewartii showing α-glucosidase inhibitory activity.

Stewartiiside (1), a phenylethanoid glycoside and three 28-nortriterpenoids: stewertiisins A-C [(17R)-19(18→17)-abeo-3α,18β,23,24-tetrahydroxy-28-norolean-12-ene, 2; (17R)-19(18→17)-abeo-2α,16β,18β,23,24-pentahydroxy-28-norolean-12-en-3-one, 3; (17R)-19(18→17)-abeo-2α,3α,23,24-tetrahydroxy-28-noroleane-11,13-diene, 4] together with eight known compounds: lunariifolioside (5), notohamosin A (6), phlomispentanol (7), isorhamnetin 3-(6-p-coumaroyl)-β-D-glucopyranoside (8), tiliroside (9), caffeic acid (10), p-hydrxybenzoic acid (11) and oleanolic acid (12) were isolated from the ethyl acetate soluble fraction of the methanolic extract of whole plant of Phlomis stewartii. The structures of these isolates (1-12) were elucidated by the combination of 1D ((1)H and (13)C NMR), 2D (HMQC, HMBC COSY, NOESY) NMR spectroscopy and mass spectrometry (EIMS, HREIMS, FABMS, HRFABMS) and in comparison with literature data of related compounds. All the isolates (1-12) showed α-glucosidase inhibitory activity with IC50 values ranging between 14.5 and 355.4 μM, whereas, compounds 1, 5, 9 and 10 showed promising α-glucosidase inhibitory activity with IC50 values below 30 μM.

Longipetalosides A-C, new steroidal saponins from Tribulus longipetalus

Longipetalosides A-C (1-3); three new furostane steroidal saponins together with (25S)-5α-furastan-3β,22,26-triol (4) and gitogenin (5) were isolated from the methanolic extract of the whole plant of Tribulus longipetalus. The structures of these compounds (1-5) were established by using 1D ((1)H, (13)C) and 2D NMR (HMQC, HMBC, COSY, NOESY) spectroscopy, and mass spectrometry (ESIMS, HRESIMS), and in comparison with literature data reported for related compounds. Compounds 1-5 were evaluated for their inhibitory activities against enzymes α-glucosidase, lipoxygenase, acetylcholinesterase, and butyrylcholinesterase. Only the compounds 4 and 5 were found as the inhibitors of enzyme α-glucosidase with IC50 values of 33.5±0.22 and 37.2±0.18μM, respectively.

Cholinesterase inhibitory constituents from Ficus bengalensis

Bengalensinone (22β-hydroxylup-12,20-dien-3-one; 1), a new lupane triterpene, and benganoic acid (2), a new apocarotenoid, together with lupanyl acetate, 3-acetoxy-9(11),12-ursandiene, stigmasterol, alpinumisoflavone, 4-hydroxyacetophenone, 4-hydroxybenzoic acid, 4-hydroxymellein, and p-coumeric acid were isolated from the methanolic extract of the aerial roots of Ficus bengalensis. The structures of these compounds were established by the combination of 1D NMR (1H and 13C NMR) and 2D NMR (HMQC, HMBC, and COSY) analyses, and mass spectrometry (EI-MS and HR-EI-MS), and in comparison with literature data of the related compounds. Compounds 1 and 2 displayed inhibitory potential against enzyme cholinesterase in a concentration-dependent manner with IC50 values 194.5 and 154.5 μM for acetylcholinesterase and 224.9 and 120.0 μM for butyrycholinesterase, respectively.