Bioassay-guided isolation of antibacterial and anti-biofilm compounds from Peltophorum africanum Sond. Stem and mechanisms of active fractions against nosocomial pathogens

ETHNOPHARMACOLOGICAL RELEVANCE: Peltophorum africanum is widely used in indigenous medicine to treat infections, wounds, and inflammatory conditions. This study employs a bioassay-guided approach to isolate antibacterial compounds elucidating their pharmacological mechanisms and supporting their potential as sources of anti-infective agents.

AIM OF THE STUDY: The study aimed to investigate P. africanum stem as a potential source of novel compounds for drug discovery, emphasizing its antibacterial, antibiofilm, and antioxidant properties.

MATERIALS AND METHODS: Chromatographic techniques were used to fractionate and isolate antibacterial compounds. Structural elucidation was performed using NMR and LC-MS. Antioxidant activity was assessed using the DPPH radical scavenging assay. Antibacterial activity was determined using the microbroth dilution method against Pseudomonas aeruginosa and Staphylococcus aureus. Anti-biofilm activity was evaluated using the crystal violet staining method. The antibacterial mechanism of action of the most active fraction was examined by assessing changes in INT-dehydrogenase activity and monitoring the leakage of intracellular proteins and DNA.

RESULTS: Betulinic acid-3-3,4-dihydroxybenzoate and 3-octadecanoyl stigmasterol were isolated from the hexane crude extract. LC-MS identified 13 compounds. The plant samples MIC varied from 0.31 to 1.25 mg/mL. Isolated compounds had noteworthy activity across all biofilm phases. The fraction exhibited the lowest number of viable cells when assessing INT-dehydrogenase activity. Additionally, it was more effective in causing the release of intracellular proteins and DNA, while also displaying superior antioxidant activity.

CONCLUSION: The ability of antioxidant and antibacterial compounds of the P. africanum stem to inhibit biofilm formation and eradication of mature biofilms holds promise for the treatment of biofilm-associated nosocomial infections.