Antibacterial Activity of Passion Fruit Purple Variant (Passiflora edulis Sims var. edulis) Seeds Extract Against Propionibacterium acnes

Background: Passion fruit is used commercially for consumption and in beverages. This plant exhibits various pharmacological properties and possesses a complex phytochemistry. In recent years, this plant has been shown to have potential antimicrobial activity. The seeds contain a high amount of piceatannol, which exhibits an inhibitory effect on Propionibacterium acnes. Therefore, the seed extract of purple variant, Passiflora edulis Sims var. edulis, may have potential antibacterial activity against P. acnes. Aim: To evaluate the antibacterial activity of P. edulis Sims var. edulis seeds extract on P. acnes. Methods: Seed extract was prepared by maceration and dissolved in DMSO in multiple concentrations. Propionibacterium acnes was cultured in Brucella blood sheep 5% agar for 24 hours and the agar disc diffusion method was used to evaluate the inhibitory effect of each concentration (1.25%, 2.5%, 5%, 10%, 20%, and 40%), in comparison with clindamycin and erythromycin. Zones of inhibition at 24 hours were measured and documented, then analyzed to obtain the mean inhibition zone (MIZ). The Mann-Whitney test was conducted to compare the antibacterial activity of the extract, clindamycin and erythromycin. A serial dilution assay of five different concentrations (5%, 10%, 15%, 20%, and 25%) in brain-heart infusion broth was performed to determine the minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC). Results: After 24 hours, all concentrations of P. edulis Sims var. edulis showed an inhibitory effect against P. acnes, with MIZs for of each concentration of 1.25% 6 mm, 2.5% 6.83 mm, 5% 8.5 mm, 10% 10.08 mm, 20% 14 mm, and 40% 16 mm. Clindamycin revealed comparable antibacterial effect to 5% seed extract, with an MIZ of 8 mm. However, erythromycin was found to be superior to the seed extract, with a 22.67 mm MIZ (p<0.05). The serial dilution assay revealed an MIC of 20% and MBC of 25%. Conclusion: Seed extract of P. edulis Sims var. edulis had good antibacterial activity against P. acnes, and the effect increased with the concentration.