Development of Antimicrobial Nanoemulsions Containing Nelumbo nucifera Extract

Abstract

Nelumbo nucifera is a medicinal herb widely distributed in Thailand which possesses its antioxidant and antimicrobial activities. The aims of this study were to investigate the antimicrobial effects and to develop the formulations containing Nelumbo nucifera crude extracts. The crude extracts of each part of the plants, petals, pollens, receptacles and stalks were separately obtained using 95% w/w ethyl alcohol and then subjected to the phytochemical studies. The total phenolic content was quantified by using Folin-ciocalteu colorimetric method, and the antibacterial features against Staphylococcus aureus was also evaluated. The nanoemulsions incorporated with Nelumbo nucifera crude extracts were thereafter formulated. The results showed that saponins, terpenoids, flavonoids and coumarins found in petals was 184.30 ± 0.50 mg GAE/g total phenolic content which was 4-fold higher than those found in the other part of the plants. Moreover, the crude extract from petals exhibited the activity against S. aureus as indicated by the minimum bactericidal concentration (MBC) of 100 mg/mL. Moreover, the good stability of nanoemulsions consisting of 0.05% w/w petal extract was observed displaying a particle size of 400 ± 139 nm, a zeta potential of -8.09 ± 1.04 mV, and a pH value of 5.87 ± 0.07. Owing to the antimicrobial test against S.aureus, the inhibition percentage of nanoemulsions was 80.35 ± 0.106. Accordingly, this study provides the increasing of antimicrobial properties of Nelumbo nucifera crude extract when preparing into the nanoemulsions formulation. In addition, this finding could raise the value of Nelumbo nucifera which could be utilized as an alternative active ingredient for the treatment of skin bacterial infection.