Antimicrobial Effects and Resistant Regulation of Magnolol and Honokiol on Methicillin-ResistantStaphylococcus aureus

Abstract

The antimicrobial killing activity toward methicillin-resistant Staphylococcus aureus (MRSA) has been a serious emerging global issue. In a continuing search for compounds with antibacterial activity against several microorganisms including S. aureus and MRSA, an n-hexane extract of Magnolia officinalis was found to contain magnolol. This compound exhibited potent activity against S. aureus, standard methicillin-susceptible S. aureus (MSSA), and MRSA as well as clinical MRSA isolates. When combined with oxacillin, the antibacterial activities of magnolol and honokiol against the MRSA strain were increased compared to single treatment without antibiotics at 10 µg/mL and 25 µg/mL, respectively. These activities of magnolol and honokiol were dose dependent. Also, magnolol showed synergistic effects with oxacillin against 13 clinical isolates of MRSA. It was determined that magnolol and honokiol had a synergistic effect with oxacillin against MRSA strain. Furthermore, the magnolol inhibited the expression of the resistant genes, mecA, mecI, femA, and femB, in mRNA. We concluded that the antibacterial activity of magnolol against MRSA strain is more related to the mecI's pathway and components of the cell wall than mecR1. Therefore, the results obtained in this study suggest that the combination of magnolol and antibiotics could lead to the development of new combination antibiotics against MRSA infection.

Biological activity and toxicity of the Chinese herb Magnolia officinalis Rehder & E. Wilson (Houpo) and its constituents

“…Lignans, mainly honokiol and magnolol, have marked dose-dependent antimicrobial effects (Table 11) (Kim et al, 2015). Previous studies have shown that phenolic compounds can affect microbial growth by altering microbial cell permeability and permitting the loss of macromolecules.…”

Innovative approaches to treat Staphylococcus aureus biofilm-related infections

“…Antibacterial activity of some of these hits had been reported before, e.g. for honokiol [93,94], MK-886 and 5-nonyloxytryptamine [80], but for most of the hits there were no previous indications for potential use as an anti-infective. Also four antipsychotic phenothiazine drugs (fluphenazine, perphenazine, thioridazine and trifluoperazine) and the antidepressant sertraline were hits.…”

Non-microbial Natural Products That Inhibit Drug-Resistant Staphylococcus aureus

“…The bactericidal non-microbial natural products are derived from various sources including, plants, insects, animals, and fungi. These natural compounds have been reported to target and act on multiple bacterial targets such as cell wall [62,63], pyruvate kinase [64], cell division [65], DNA topoisomerase [66], and efflux pump [67,68]. These pharmacological targets are further discussed in Section 4.…”