Investigation of in vitro Biological Activity from Extracts of Ruellia tuberosa

Background and Objective: Ruellia tuberosa is a common plant in the Mekong Delta and is widely used in many Vietnamese folk remedies. This study was conducted to investigate the potential use of roots, stems, leaves of Ruellia tuberosa as antioxidant, antimicrobial, α-amylase and α-glucosidase inhibitors. Materials and Methods: The extracts were tested for their ability to inhibit the enzymes α-amylase and α-glucosidase associated with diabetes. The antioxidant activities of the extracts were evaluated using 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) and 2,2-Azino-Bis-(3-Ethylbenzothiazoline-6-Sulfonic Acid) (ABTS), ferric reducing antioxidant power (FRAP), total antioxidant capacity (TAC) and reducing power (RP) assays. The antibacterial activity of extracts from Ruellia tuberosa was evaluated by the agar well diffusion method. Results: The root extract of Ruellia tuberosa has more polyphenols (32.49±0.72 mg GAE/g extract) and flavonoids (15.48±1.32 mg QE/g extract) than the other parts. Simultaneously, the root extract of Ruellia tuberosa has antioxidant activity (IC₅₀ values range from 117.67±2.82 to 569.20±7.68 μg/mL), inhibiting amylase (IC₅₀ = 266.72±10.58 μg/mL) and glucosidase (IC₅₀ = 147.13±3.58 μg/mL) enzymes more effectively than the other parts. Research results also show that extracts from Ruellia tuberosa are capable of inhibiting Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa bacteria with minimum inhibitory concentrations ranging from 1280 to 10240 mg/mL. Conclusion: These results highlighted the potential using of Ruellia tuberosa extracts as natural antioxidant, antimicrobial, α-amylase and α-glucosidase inhibitors agents.