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  • Antimicrobial Constituents ...
    Muhammad, Ilias; Jacob, Melissa R; Ibrahim, Mohamed A; Raman, Vijayasankar; Kumarihamy, Mallika; Wang, Mei; Al-Adhami, Taha; Hind, Charlotte; Clifford, Melanie; Martin, Bethany; Zhao, Jianping; Sutton, J Mark; Rahman, Khondaker Miraz

    Molecules (Basel, Switzerland), 12/2020, Letnik: 25, Številka: 24
    Journal Article

    Two new epimeric bibenzylated monoterpenes machaerifurogerol ( ) and 5- -machaerifurogerol ( ), and four known isoflavonoids (+)-vestitol ( ), 7- -methylvestitol ( ), (+)-medicarpin ( ), and 3,8-dihydroxy-9-methoxypterocarpan ( ) were isolated from Pers. This plant was previously assigned as Spruce, from which machaeriols A-D ( - ) and machaeridiols A-C ( - ) were reported, and all were then re-isolated, except the minor compound , for a comprehensive antimicrobial activity evaluation. Structures of the isolated compounds were determined by full NMR and mass spectroscopic data. Among the isolated compounds, the mixture + was the most active with an MIC value of 1.25 μg/mL against methicillin-resistant (MRSA) strains BAA 1696, -1708, -1717, -33591, and vancomycin-resistant (VRE 700221) and . (VRE 51299) and vancomycin-sensitive (VSE 29212). Compounds - and - were found to be more potent against MRSA 1708, and , , and against VRE 700221, than the drug control ciprofloxacin and vancomycin. A combination study using an in vitro Checkerboard method was carried out for machaeriols ( or ) and machaeridiols ( or ), which exhibited a strong synergistic activity of + (MIC 0.156 and 0.625 µg/mL), with >32- and >8-fold reduction of MIC's, compared to , against MRSA 1708 and -1717, respectively. In the presence of sub-inhibitory concentrations on polymyxin B nonapeptide (PMBN), compounds + , , , and showed activity in the range of 0.5-8 µg/mL for two strains of , 2-16 µg/mL against PAO1, and 2 µg/mL against NCTC 12923, but were inactive (MIC > 64 µg/mL) against the two isolates of .