Antioxidant, Antibacterial, Antidiabetic Potential, and In silico Analysis of Rhus chinensis from Western Nepal

Rhus chinensis Mill, indigenous wild fruit primarily found in the hilly region of Nepal. The ripe fruit is very sour and considered medicinal as a remedy for colic pain. In addition, their astringent and styptic qualities are used internally to treat illnesses such as diarrhea and hemorrhage. Also, they are used as a common component of polyherbal medications for diabetic mellitus.This work aimed to determine the total phenolic and flavonoid content, antioxidant, antibacterial, α-glucosidase, and α-amylase inhibition activity of the crude extract and fractions of Rhus chinensis Mill. Additionally, molecular docking of compounds from Rhus chinensis was performed.Folin Ciocalteu's (FC) reagent was used to estimate total phenolic content. Likewise, the aluminium trichloride method was applied to determine total flavonoid content. A 2,2-diphenyl-1- picrylhydrazyl (DPPH) free radical scavenging assay was performed for the antioxidant activity. Furthermore, the substrate-based enzyme inhibition assay was carried out for α-glucosidase and α- amylase inhibition activity of R. chinensis. P-nitrophenyl-α-D-glucopyranoside (PNPG) and 2- Chloro-4-Nitrophenyl-α-D-Maltotrioside (CNPG3) were used as substrates for α-glucosidase and α- amylase inhibition assay, respectively. Similarly, the well-diffusion method was used for the antibacterial activity. Autodock vina was used to perform molecular docking.The total phenolic and flavonoid content of R. chinensis fruit were 117.092±1.1 mg GAE/g and 62.41±1.23 mg QE/g, respectively. The IC50 value for antioxidant activity of the crude extract and its fractions ranged from 3.12±1.15μg/mL to 50.85±2.10μg/mL. Similarly, the IC50 for α- glucosidase inhibition ranged from2.33±1.01μg/mL to 28.34±2.79μg/mL. Likewise, The IC50 of R. chinensis crude methanolic extract against α-amylase was 120.3±1.382μg/mL. The antibacterial activity of R. chinensis was effective against gram-positive bacteria; Staphylococcus aureus (ZOI=11.0) and Bacillus subtilis (ZOI=9.0). Quercetin-3-O-rhamnoside and Myricetin-3-Orhamnoside showed excellent binding to the active site of protein with binding energy -9.4kcal/mol and -9.6kcal/mol, respectively.Rhus chinensis Mill is a potent antioxidant and inhibits enzymes; α-glucosidase and α- amylase. In addition, the methanolic extract of this plant shows antibacterial activity. However, further research is required to determine the inhibiting compounds.