Bioactive agents from Parkia biglobosa (Jacq.) R.Br. ex G. Don bark extracts for health promotion and nutraceutical...

Parkia biglobosa stem bark extracts were prepared using methanol, methanol 80%, water and ethyl acetate to investigate their phytochemical contents, as well as antioxidant and enzyme inhibitory properties.

Liquid chromatography (LC) quadrupole time-of-flight mass spectrometry (MS) and LC-MSⁿ revealed the presence of flavonoids, hydroxycinnamic acid derivatives and gallotannins. Particularly, the water extract contained rutin (480 μg per 100 mg) and 3-caffeoylquinic acid (1109 μg per 100 mg) in higher amounts, whereas the 80% methanol extract contains methoxyluteolin-7-O-rutinoside and catechin derivatives as major compounds. Total phenolic and flavonoid contents of the extracts were yielded in the range of 32.26-119.88 mg gallic acid equivalents g^-1 and 0.60-2.39 mg rutin equivalents g^-1 , respectively. Total antioxidant capacity was also displayed in the range of 0.53-6.34 mmol Trolox equivalents (TE) g^-1 . Both the methanolic extracts showed higher total antioxidant capacity that could be related to the total phenolic contents. Radical scavenging capacity in DPPH (2,2-diphenyl-2-picryl-hydrazyl) (37.21-508.30 mg TE g^-1 ) and ABTS [2,2-azinobis(3-ethylbenzothiazoline- 6-sulfonic acid)] (60.95-1068.06 mg TE g^-1 ) assays, reducing power in cupric ion reducing antioxidant capacity (54.23-1002.78 mg TE g^-1 ) and ferric ion reducing antioxidant power (33.18-558.68 mg TE g^-1 ) assays, as well as metal chelating activity (2.45-11.28 mg EDTA equivalents g^-1 ), were exhibited by all extracts. All extracts were found to inhibit acetylcholinesterase [0.23-2.47 mg galanthamine equivalents (GALAE) g^-1 ], tyrosinase [27.20-83.33 mg kojic acid equivalents g^-1 ], amylase [mmol acarbose equivalents (ACAE) g^-1 ]. On the other hand, all extracts, except the water extract, inhibited butyrylcholinesterase (5.38-6.56 mg GALAE g^-1 ), whereas only the water and ethyl acetate extract showed glucosidase inhibitory potential (1.96 and 1.82 mmol ACAE g^-1 ). In general, the water extract was found to be a weaker enzyme inhibitor suggesting that water is not the preferrable extraction solvent to obtain active products.

The present study demonstrated that the stem bark extracts of P. biglobosa contains good amount of phytochemical and extracts present significant antioxidant, as well as reasonable enzyme inhibitory effects. Hence, these findings suggest that further studies can be performed on more specific biological targets and models of bioactivity to determine their safe usage as a nutraceutical or for the preparation functional foods. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.