Rhodomyrtus tomentosa (Aiton) Hassk. ethanol extract and rhodomyrtone: a potential strategy for the treatment of biofilm-forming staphylococci

Abstract

The anti-staphylococcal activity of an ethanol extract of Rhodomyrtus tomentosa and its pure compound, rhodomyrtone, as well as their effects on staphylococcal biofilm formation and biofilm-grown cells were assessed. MIC and minimal bactericidal concentration values of the ethanol extract and rhodomyrtone against planktonic cultures and biofilms of five clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis, and American Type Culture Collection (ATCC) strains of both species, were 32-512 and 0.25-2 mg ml "1 , respectively.Results from time-kill studies indicated that rhodomyrtone at a concentration of 4¾ MIC could reduce the number of Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis ATCC 35984 cells by 99.9 % within 3 and 13 h, respectively. The ability of rhodomyrtone and the ethanol extract to prevent biofilm formation and kill mature biofilms was assessed: both demonstrated better activity than vancomycin at inhibiting staphylococcal biofilm formation. In addition, the viability of 24 h and 5-day staphylococcal biofilm-grown cells decreased after treatment with the ethanol extract and rhodomyrtone. The ability to reduce biofilm formation and kill mature biofilms occurred in a dose-dependent manner. Scanning electron microscopy clearly confirmed that treatment with rhodomyrtone at 16¾ MIC could reduce 24 h biofilm formation and the numbers of staphylococci, whilst at 64¾ MIC this compound destroyed the organisms in the 5-day established biofilm. These results suggest that rhodomyrtone has the potential for further drug development for the treatment of biofilm-forming staphylococcal infections.

Activity of Gallidermin on Staphylococcus aureus and Staphylococcus epidermidis Biofilms

“…Providone iodine also inhibits biofilm formation and decreases transcription of the ica operon (38). The effects of natural antibacterial agents, such as berberine, carvacrol, farnesol, oregano, rhodomyrtone, and thymol, against staphylococcal biofilms have been frequently reported (24,37,47,54). Oregano, carvacrol, and thymol exhibit antistaphylococcal activity in biofilms.…”

Rhodomyrtus Tomentosa: A Phytochemical and Pharmacological Review

“…Saising et al [37] suggested that rhodomyrtone had significant effects on both biofilm formation and the survival of the organisms in the established biofilms. Hence, rhodomyrtone is reported to have the potential for further drug development for the treatment of biofilm-forming staphylococcal infections.…”

“…[22] Taraxerol (32) [29] Trans-triacontyl-4-hydroxycinnamate (33) [26] 3,3',4,4'-tetra-O-methylflavellagic acid (34) [26] 3-O-(E)-coumaroyloleanolic acid (35) [26] (-)-(2R,3R)-1,4-O-diferuloylsecoisolariciresinol (36) [26] Arjunolic acid (37) [26] 4-hydroxy-3-methoxybenzoic acid (38) [26] Stigmast-4-en-3-one (39) [26] Oleanolic acid (40) [26] Methyl gallate (41) [26] 3-O-methylellagic acid 4-O-rhamnopyranoside (42) [26] …”

Inhibition of staphyloxanthin biosynthesis in Staphylococcus aureus by rhodomyrtone, a novel antibiotic candidate

“…The compound was isolated from Rhodomyrtus tomentosa (Aiton) Hassk. leaves and exhibits pronounced antibacterial activity against a wide range of Gram-positive bacteria (Limsuwan & Voravuthikunchai, 2008;Saising et al, 2008;Limsuwan et al, 2009a;Voravuthikunchai et al, 2010;Saising et al, 2011). The MIC and minimum bactericidal concentration values of rhodomyrtone against MRSA range from 0.39 to 0.78 mg ml 21 , which is very close to those of vancomycin (Limsuwan et al, 2009b).…”