{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,27]],"date-time":"2026-04-27T22:38:00Z","timestamp":1777329480310,"version":"3.51.4"},"reference-count":25,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2020,12,18]],"date-time":"2020-12-18T00:00:00Z","timestamp":1608249600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Two new epimeric bibenzylated monoterpenes machaerifurogerol (1a) and 5-epi-machaerifurogerol (1b), and four known isoflavonoids (+)-vestitol (2), 7-O-methylvestitol (3), (+)-medicarpin (4), and 3,8-dihydroxy-9-methoxypterocarpan (5) were isolated from Machaerium Pers. This plant was previously assigned as Machaerium multiflorum Spruce, from which machaeriols A-D (6\u20139) and machaeridiols A-C (10\u201312) were reported, and all were then re-isolated, except the minor compound 9, 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 10 + 11 was the most active with an MIC value of 1.25 \u03bcg\/mL against methicillin-resistant Staphylococcus aureus (MRSA) strains BAA 1696, \u22121708, \u22121717, \u221233591, and vancomycin-resistant Enterococcus faecium (VRE 700221) and E. faecalis (VRE 51299) and vancomycin-sensitive E. faecalis (VSE 29212). Compounds 6\u20138 and 10\u201312 were found to be more potent against MRSA 1708, and 6, 11, and 12 against VRE 700221, than the drug control ciprofloxacin and vancomycin. A combination study using an in vitro Checkerboard method was carried out for machaeriols (7 or 8) and machaeridiols (11 or 12), which exhibited a strong synergistic activity of 12 + 8 (MIC 0.156 and 0.625 \u00b5g\/mL), with &gt;32- and &gt;8-fold reduction of MIC\u2019s, compared to 12, against MRSA 1708 and \u22121717, respectively. In the presence of sub-inhibitory concentrations on polymyxin B nonapeptide (PMBN), compounds 10 + 11, 11, 12, and 8 showed activity in the range of 0.5\u20138 \u00b5g\/mL for two strains of Acinetobacter baumannii, 2\u201316 \u00b5g\/mL against Pseudomonas aeruginosa PAO1, and 2 \u00b5g\/mL against Escherichia coli NCTC 12923, but were inactive (MIC &gt; 64 \u00b5g\/mL) against the two isolates of Klebsiella pneumoniae.<\/jats:p>","DOI":"10.3390\/molecules25246000","type":"journal-article","created":{"date-parts":[[2020,12,21]],"date-time":"2020-12-21T04:12:01Z","timestamp":1608523921000},"page":"6000","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Antimicrobial Constituents from Machaerium Pers.: Inhibitory Activities and Synergism of Machaeriols and Machaeridiols against Methicillin-Resistant Staphylococcus aureus, Vancomycin-Resistant Enterococcus faecium, and Permeabilized Gram-Negative Pathogens"],"prefix":"10.3390","volume":"25","author":[{"given":"Ilias","family":"Muhammad","sequence":"first","affiliation":[{"name":"National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Melissa R.","family":"Jacob","sequence":"additional","affiliation":[{"name":"National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0257-860X","authenticated-orcid":false,"given":"Mohamed A.","family":"Ibrahim","sequence":"additional","affiliation":[{"name":"National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7368-9644","authenticated-orcid":false,"given":"Vijayasankar","family":"Raman","sequence":"additional","affiliation":[{"name":"National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9914-1732","authenticated-orcid":false,"given":"Mallika","family":"Kumarihamy","sequence":"additional","affiliation":[{"name":"National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3686-4292","authenticated-orcid":false,"given":"Mei","family":"Wang","sequence":"additional","affiliation":[{"name":"National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA"},{"name":"Natural Products Utilization Research Unit, Agricultural Research Service, U.S. Department of Agriculture, University of Mississippi, Oxford, MS 38677, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Taha","family":"Al-Adhami","sequence":"additional","affiliation":[{"name":"Institute of Pharmaceutical Science, School of Cancer and Pharmaceutical Sciences, King\u2019s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Charlotte","family":"Hind","sequence":"additional","affiliation":[{"name":"National Infection Service, Public Health England, Manor Farm Road, Salisbury SP4 0JG, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Melanie","family":"Clifford","sequence":"additional","affiliation":[{"name":"National Infection Service, Public Health England, Manor Farm Road, Salisbury SP4 0JG, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3856-697X","authenticated-orcid":false,"given":"Bethany","family":"Martin","sequence":"additional","affiliation":[{"name":"National Infection Service, Public Health England, Manor Farm Road, Salisbury SP4 0JG, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4984-5931","authenticated-orcid":false,"given":"Jianping","family":"Zhao","sequence":"additional","affiliation":[{"name":"National Center for Natural Products Research, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, Oxford, MS 38677, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2288-0446","authenticated-orcid":false,"given":"J. Mark","family":"Sutton","sequence":"additional","affiliation":[{"name":"National Infection Service, Public Health England, Manor Farm Road, Salisbury SP4 0JG, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Khondaker Miraz","family":"Rahman","sequence":"additional","affiliation":[{"name":"Institute of Pharmaceutical Science, School of Cancer and Pharmaceutical Sciences, King\u2019s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Mabberley, D.J. (2017). 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