Dipeptidyl Peptidase-IV Inhibition and Antioxidant Activity in Leaf, Bark, Fruit and Seed of Diospyros foxworthyi

The present research was designed to explore the antioxidant activity and DPP-IV inhibition of secondary metabolites from Diospyros foxworthyi (foxworthyi ebony) leaf, bark, fruit and seed as well as antidiabetic and antioxidant agents. The sample was extracted in methanol using ultrasound-assisted extraction. It was used to study the extraction yield, Total Phenolic Content (TPC), Total Flavonoid Content (TFC), antioxidant activity and Dipeptidyl Peptidase-IV (DPP-IV) inhibition assay by microplate reader. The % yields of the leaf, bark, fruit and seed were 11%, 15.24%, 22.08% and 50.92%, respectively. Phytochemical screening results showed that the stem bark contained all test compounds (phenolic, alkaloid, tannin, saponin, terpenoid and anthraquinone). These showed TPC of the leaf, bark, fruit and seed were 41.01 mg/g extract, 54.38 mg/g extract, 51.99 mg/g and 64.83 mg/g of the extracts, respectively. TFC was 8.40 mg/g, 3.77 mg/g, 4.70 mg/g and 2.38 mg/g extract, respectively. The IC50 values for antioxidant activity using the α, α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging method were 12.10 µg/mL, 5.32 µg/mL, 7.81 µg/mL and 5.86 µg/mL, respectively. The Ferric Reduction Antioxidant Power (FRAP) method was 1.74 FeSO4/g, 4.09 FeSO4/g, 1.91 FeSO4/g and 2.56 g FeSO4/g extract. The % inhibition values of the DPP-IV enzyme for the leaf, bark, fruit, and seed samples were 29.70%, 29.39%, 32.71% and 32.46%, respectively. The test results suggest that the bark and seed of D. foxworthyi hold potential for development as a treatment for diabetes mellitus, due to its antioxidant activities and DPP-IV inhibitory.