Extraction of α glucosidase inhibitory glycoside from the roots of Clerodendrum phlomidis L.

Abstract

Background: Medicinal plants have therapeutic legacy from herbal ancestry as medicine since ancient times for various ailments. Clerodendrum phlomidis L. (Family Lamiaceae) is a sage glory bower, worthy shrub of south-east Asian countries with great ethno-therapeutic ponderosity in diverse indigenous cultures and for medication of numerous ailments including hyperglycemia. Having many traditional values isolation of active constituents has been aimed with in vitro α glucosidase inhibitory activity from roots of this plant. Methods: A concentrated methanolic extract of the dried roots of plant with active fractions on subjection to silica gel loaded glass column A & B, packed with chloroform and methanol respectively, gradient flow of solvents leads isolation of phytoconstituents. A volume of 50 µL of each sample solutions and 50 µL of phosphate buffer having 0.1 U/ml, α-glucosidase solution was incubated and 50 µL and 2.5 mM solution of PNPG solution in phosphate buffer was added to each well for re-incubation at 37 °C. Reaction was completed by adding 100 µL of Na2CO3 (0.2 M) into each well and absorbance were recorded at 405 nm and compared with the control and standard for enzymatic α-glucosidase activity. Results: Isolation of six new phytoconstituents characterized as stigmata-5-en-3β-olyl salicylate 2ʹ- octadeca-9 ʹʹ,12 ʹʹ,15 ʹʹ-trienoate (β-sitosterol 3-O-salicylate 2ʹ-linolenate, 1), n-octadec-9-enoyl O-β-D-galacturanopyranoside (2), (Z)-n-dotratriacont-24-enoic acid (3), methoxy arabinopyranosyl- (2→1')-arabinopyranosyl-(2'→1'')-arabinopyranosyl-(2''→1''')- arabinopyranosyl-(2'''→1'''')- glucopyranoside (4), n-docosanyl 6ʹ-methoxy-α-D-glucopyraranosyl-(2ʹ→1ʹʹ)-α-D-6ʹʹ-methoxy-glucopyranosyl-(2ʹʹ→1ʹʹʹ)-α-D-glucopyraranosyl-(6ʹʹʹ→1ʹʹʹʹ)- α- D-glucopyraranoside (5) and 6-methoxy-α-D-glucopyranosyl-(2→1ʹ)-α-D- glucopyranosyl-(6ʹ→1ʹʹ) - α-D- glucopyranosyl- (6ʹʹ→1ʹʹʹ)- α-D- glucopyranoside (6). Conclusion: The compounds 5 and 6 exhibited significant α-glucosidase enzymatic inhibitory potential showing IC50 values (mg/ml) 1.52±0.14 and 0.78±0.02, respectively, against standard acarbose IC50 0.55±0.03.