In vitro antioxidant and in silico enzyme inhibition studies of <i>Carissa carandas</i> Linn.: potential ingredient for nutraceutical development

Carissa carandas L. is a wild food plant, however, is cultivated for its fruits to be utilized to make pickles, jams, and other similar products. Fruit of this plant has been intensively investigated for its bioactive potential; however, a scanty study is reported on the leaf, which is usually wasted. In the present study, ethanolic extract of the leaf of C. carandas was analyzed for its total bioactive contents and found rich in phenolics and flavonoids (26.67 ± 0.33 mg GAE/g extract and 18.42 ± 0.05 mg RE/g extract, respectively). These findings were substantiated due to UHPLCMS/MS analysis, which disclosed the presence of about 110 secondary metabolites, mostly lignans, flavonoids, and terpenoids. In DPPH and ABTS free radical inhibition assays, the extract showed inhibitory values as 47.51 ± 0.09 and 93.09 ± 2.8 mg TE/g extract, respectively. Its further antioxidant potential was observed in CUPRAC and FRAP assays, wherein the metal reducing power was recorded as 102.05 ± 1.03 and 67.24 ± 0.9 mg TE/g extract, respectively, while in phosphomolybdenum and metal chelating assays, the extract also disclosed potential activity (0.92 ± 0.02 mmol TE/g extract and 21.42 ± 0.34 mg EDTAE/g extract). The extract was also significantly active against tyrosinase (45.69 ± 0.7 mg KAE/g extract) and showed mild activities against AChE (3.61 ± 0.16 mg GALAE/g extract), BChE (1.43 ± 0.2 mg GALAE/g extract), α-amylase (0.46 ± 0.01 mmol ACAE/g extract) and α-glucosidase (1.05 ± 0.02 mmol ACAE/g extract). In computational studies, binding affinities for AChE and BChE enzymes were from −4.21 to −12.70 and −7.58 to −12.53 kcal/mol, respectively, confirming the results of the invitro tests and ADME studies. The current finding suggested that C. carandas may be considered as a source for several nutraceutical formulations.