Screening and Isolation of β-Glucosidases from Selected Medicinal and Aromatic Plants

Glucosidase catalyzes the hydrolysis of a wide range of β-glucosides and complex β-1, 4 linked gluco-conjugates. The enzyme is involved in various cellular metabolic processes and other biochemical and biotechnological processes. We screened a wide variety of medicinal and aromatic plants (MAPs) for β-glucosidase activity and comparatively reviewed the kinetic attributes of the enzyme. The enzyme was isolated from young leaves of the plants and subjected to enzyme assay using p-nitrophenyl-D-glucopyranoside (PNPG) as substrate. The isozyme profiling of enzyme was performed on native-PAGE and band scoring was analyzed. Results demonstrate that Rauvolfia serpentina showed highest enzyme activity (348 IU/gm f.w.t.) as compared to other MAPs screened in the study. Other five plants with high activity were Lycopersicum esculentum, Withania somnifera, Physalis alkekengi, Mentha arvensis and Andrographis paniculata with 192, 174, 142, 138 and 136 IU/gm f.w.t., respectively. Ocimum basium showed no enzyme activity. Zea mays showed highest specific activity (51.91) with 107 IU enzyme activity. The in situ localization of enzyme demonstrated a diverse distribution of β-glucosidase isozymes in MAPs. Total eight isozymes of β-glucosidase (GS-iso-I through VIII) were observed. GS-iso-I and VII were exclusively present one plant each. GS-iso-IV was diversely present in five MAPs, GS-iso-II and V present in four MAPs, GS-iso-VI was present in three aromatic plants, and GS-iso-III and VIII were present only in two plants each. Results of the study are highly important for biochemical and enzymatic studies in plant secondary metabolism. β-Glucosidases identified were found to be novel members of the family in terms of enzyme kinetics.