Phytochemical composition, in vitro antioxidant and antibacterial activities of Dorstenia barnimiana Schweinf leaf extracts

Abstract

BACKGROUND: Dortinia barnimiana is an indigenous plant celebrated for its traditional medicinal uses, especially in treating infectious diseases. Rich in bioactive compounds like phenolics and flavonoids, it exhibits notable antioxidant and antibacterial properties. As interest in indigenous plants grows, D. barnimiana stands out as a promising candidate for addressing modern health challenges, including antibiotic resistance and the pursuit of sustainable healthcare solutions. This study examines how different solvents (ethanol, ethyl acetate, and petroleum ether) impact the extraction of phenolics, flavonoids, and the antioxidant and antibacterial properties of D. barnimiana. METHODS: Crude plant extracts were prepared using the maceration technique. Total phenolic content was assessed using the Folin-Ciocalteu method, while total flavonoid content was measured through the aluminum chloride complex formation assay. The antioxidant activity was evaluated using the DPPH free radical scavenging method and ferric reducing power assay. Antibacterial efficacy was tested against both Gram-positive and Gram-negative strains using the agar well diffusion method, with minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) determined via broth microdilution. Data were analyzed using Analysis of Variance (ANOVA). RESULTS: Ethanol extracts exhibited the highest phenolic content (185.16 ± 0.65 mg GAE/g dry weight) and flavonoid content (141.1 ± 0.75 mg CE/g dry weight). The highest DPPH radical scavenging activity was also found in the ethanol extract (78.46 ± 0.41 µg/mL). Notably, the highest antibacterial activity was against Staphylococcus aureus (20.66 ± 0.57 mm) at 50 mg/mL, while Pseudomonas aeruginosa showed the lowest inhibition zone (0.33 ± 0.57 mm) at 6.25 mg/mL. The extracts demonstrated significant inhibitory effects, particularly against S. aureus, with an MIC of 6.25 mg/mL. CONCLUSION: Ethanol emerged as the most effective solvent for extracting D. barnimiana leaves, showcasing impressive antioxidant and antibacterial properties that suggest potential applications in pharmaceuticals. Further research is essential to isolate and characterize the active compounds for the development of new therapeutic agents.