Abstract: This study aimed to compare the phytochemical constituents, antioxidant activity, anti-diabetes activity and anti-gout potential of the leaf, stem, aril, seed shell and seed kernel of Torreya grandis cv. Merrillii by analyzing the contents of phenolics, flavonoids and condensed tannins, as well as radical scavenging ability and inhibitory activities against α-glucosidase and xanthine oxidase. The results indicated that the main bioactive constituents, antioxidant activity and α-glucosidase inhibitory activity of different plant parts varied significantly (P < 0.05). The kernel and leaf extracts had the highest total phenolic content (25.28 mg GAE/g) and condensed tannins content (1.10 mg CE/g), respectively. The highest content of flavonoids was found in the stem and aril extracts (P > 0.05). Bioactivity analysis revealed that the kernel extract showed the strongest 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability, 2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS+·) scavenging ability, inhibitory activities against α-glucosidase and xanthine oxidase, and its α-glucosidase inhibitory activity (IC50 = 0.14 mg/mL) was much higher than that of the positive control acarbose (IC50 = 1.29 mg/mL). Thus, it can be concluded that the seed kernel of Torreya grandis cv. Merrillii is a better resource of natural antioxidants and inhibitors of both α-glucosidase and xanthine oxidase than its leaf, stem, aril and seed shell.

Key words: Torreya grandis cv. Merrillii, bioactive constituents, antioxidant activity, α-glucosidase, xanthine oxidase