Bioguided Isolation of Antibiofilm and Antibacterial Pregnane Glycosides from : Disarming Multidrug-Resistant Pathogens.

Methicillin-resistant (MRSA) and multidrug-resistant (MDRAB) present a serious challenge because of their capability to cause biofilm resistance to commonly used antibiotics producing chronic infections and hindering the process of wound healing. In the current study, we investigated the antibacterial activity of extracts (MeOH, and its fractions CHCl and -butanol) against multidrug-resistant MRSA USA300 and AB5057. In vitro, the MeOH extract and both fractions of significantly inhibited biofilm formation and disrupted previously established biofilm by MRSA and MDRAB at all the tested concentrations (0.625, 0.313, and 0.156 mg/mL). In vivo, extracts successfully decreased bacterial loads in MRSA-infected skin lesions in mice. Four pregnane glycosides and one flavone glycoside were isolated from the bioactive -butanol fraction. The isolated compounds (-) were tested for their biofilm inhibition and biofilm detachment activities. The results revealed that was the most active compound (IC = 0.139 mmole), while was the least active (IC = 0.818 mmole). These results support the potential use of extracts or their isolated compounds for hindering the biofilm attachment and the virulence of MRSA and MDRAB and their application as a topical antimicrobial preparation for MRSA skin infections.