Ziziphus spina-christi (L.) Willd. Leaves Extract Affecting agr Quorum Sensing System in Staphylococcus aureus

Ziziphus spina-christi L. (Sider) is a longstanding Arabian medicinal herb. The present study aimed to explore whether Ziziphus spina-christi leaves extract (ZSCLE) affects agr quorum sensing (QS) system and the phenotypic blood hemolytic activity regulated by this system in Staphylococcus aureus. The luciferase is encoded by plasmid pSB2035 in the reporter strain 8325–4, which is promoted by the agr P3 promoter. The result indicated that the total extract of (ZSCL) is effective against agr QS system in the reporter strain, where it reduces the lux gene expression up to 80.41% at a concentration of 0.25 mg/mL of total extract. Also, the hemolytic activity was reduced up to 98.9% by comparing with positive control by total extract. Successive extracts: hexane, diethyl ether, chloroform, ethyl acetate, and methanol were performed. The result revealed that the diethyl ether fraction was the greatest one that inhibited the production of both agr locus and the phenotypic hemolysin protein of S. aureus. Accordingly, phytochemical analysis in this total extract was performed and showed a high number of flavonoids and other compounds. FT-IR analysis of the most active fraction showed Monoelaidin as the main component of this fraction.