Antibacterial Evaluation of Saponins Extracted from Fresh Fruit of Luffa acutangula against Multidrug Resistance Staphylococcus aureus and their Mechanism in Ultrastructural Surface

Abstract Background Bacterial resistance leads to the dilemma in the treatment with synthetic antibiotics. A new alternative strategy is to develop some safe and non-toxic natural antibiotics as alternative therapeutic drugs. The aims of this research were to determine the saponins extracted from fresh fruit of Luffa acutangula, to evaluate their antibacterial property by inhibiting the formation of biofilm, and to reveal the mechanism in ultrastructural surface. Methods the saponin components were extracted and isolated from Fresh Fruit of Luffa acutangula by organic solvents extraction; their chemical structures were identified by HPLC-MS/MS. The growth inhibition curves and the 50% inhibitory concentrations (IC50) were used to evaluate the antibacterial activity of the extract. Then, crystal violet staining method was accepted to investigate the capacity of the saponins to inhibit biofilm formation. Anti-biofilm activity was assessed with minimum biofilm inhibitory concentration (MBIC). The interaction of the chemical compounds with saponins and biofilm were observed by SEM in ultrastructural surface. Results the extract by n-butanol was mainly saponins and the total content of saponins in the extract was 322.58 mg/g. nine saponin compounds were identified in n-butanol extract and the saponin compounds were mainly triterpene aglycone and triterpene glucosides. The extracted saponins have great bacteriostasis with IC50 value 3mg/ml, and the saponins can also inhibite the biofilm formation with MBIC value 16mg/ml. Conclusions the saponins extracted from fresh fruit of Luffa acutangula could inhibit multidrug resistance Staphylococcus aureus and substantially eradicate biofilm, it may be a potential to be developed as antibacterial agent.