Phytochemical Screening and Biological Activities of <i>Diospyros villosa</i> (L.) De Winter Leaf and Stem-Bark Extracts

Abstract

This study aimed to evaluate the phytochemical components, antioxidant capacity, and antimicrobial effects of Diospyros villosa (L.) De Winter leaves and stem bark. The extracts were obtained using different media (methanol, chloroform, and hexane). The DPPH and FRAP methods were used to assess the antioxidant activity and the Folin–Ciocalteu method was used to determine the total phenolic contents of the crude extracts. The antimicrobial effects of the extracts against five pathogenic bacteria were determined using the MIC, MBC, and agar-well diffusion methods. Flavonoids, alkaloids, and phenols were identified in the D. villosa extracts. The mean concentrations of the methanolic leaf and stem-bark extracts against DPPH providing 50% inhibition were 9.53 ± 0.25 μg·mL−1 and 9.52 ± 0.30 μg·mL−1, respectively. In addition, the total phenolic content within the test range of concentrations was found to be 28.45 ± 0.50 mg of gallic acid equivalent per g of sample extract [mg·g−1 (GAE)] (methanolic leaf extract) and 4.88 ± 0.36 mg·g−1 (GAE) (methanolic stem-bark extract). The methanolic leaf extracts further showed promising antimicrobial activity against Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus with inhibition zones of 18.0 ± 0.58, 23.5 ± 0.58, 20.0 ± 0.88, and 17.0 ± 2.0 mm, respectively which were comparable to the control (gentamicin and streptomycin). The results suggest that bioactive compounds are abundant in D. villosa leaves and stem bark and could serve as a potential source of natural antioxidants as well as an antibacterial agent for the treatment of pathogenic bacterial infections.

Keywords

• DPPH
• free radicals
• minimum inhibitory concentration
• phenol content