Rhodomyrtone from Rhodomyrtus tomentosa (Aiton) Hassk. as a Natural Antibiotic for Staphylococcal Cutaneous Infections

Abstract

The ethanol extract of Rhodomyrtus tomentosa (Aiton) Hassk. (R. tomentosa) was determined for its antibacterial activity on staphylococci isolated from acne lesions. Antibiotic susceptibility patterns of the isolates were performed. Preliminary screening of the antibacterial property of the extract using disk diffusion method demonstrated pronounced antibacterial activity of the extract on all tested isolates. The average inhibition zones of 64 coagulase-positive and 85 coagulase-negative isolates were 12 mm and 14 mm, respectively. Minimal inhibitory concentration (MIC) was determined by broth microdilution method. The MIC 50 and MIC 90 ranged from 64-512 µg/ml. Time-kill curves were assessed at 0.5 MIC, MIC, 2 MIC, and 4 MIC by counting viable bacterial cells after time intervals. At 4 MIC, the level of treated staphylococci declined by at least 3 log fold within 6-8 hr. Rhodomyrtone, a pure compound in acylphloroglucinol class, isolated from this plant species was very effective against Staphylococcus aureus (S. aureus) ATCC 25923 with the MIC value at 0.5 µg/ml which is very closed to that of vancomycin. This finding challenges the use of rhodomyrtone as an alternative agent for staphylococcal cutaneous infections.

Rhodomyrtus Tomentosa: A Phytochemical and Pharmacological Review

“…However, the study challenges the use of rhodomyrtone as an alternative in treating cutaneous staphylococcal 12 infections [33]. The same study assessed the antibacterial activity of the crude ethanolic extract of R. tomentosa on staphylococci isolated from acne lesions, and the authors reported antibacterial activity against all isolated coagulase-positive and coagulase-negative staphylococci.…”

“…[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] …”

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

“…The ethanol was evaporated using a rotary evaporator and the extract was resuspended in 10 % DMSO (Merck) before use. Rhodomyrtone was isolated according to a method described previously and dissolved in 10 % DMSO (Saising et al, 2008). Vancomycin (Fluka) and DMSO were included as controls.…”

“…An ethanol extract of Rhodomyrtus tomentosa leaves as well as rhodomyrtone, a pure compound in the acylphloroglucinol class isolated from the leaves of this medicinal plant species, have shown profound antibacterial activity against a wide range of Gram-positive pathogenic bacteria with low MIC values, comparable to available antibiotics including vancomycin (Saising et al, 2008;Limsuwan et al, 2009;Voravuthikunchai et al, 2010). Natural compounds from certain plants such as carvacrol, thymol and salvipisone have also been demonstrated to exert effects on staphylococcal biofilm (Kuźma et al, 2007;Nostro et al, 2007;Wang et al, 2009).…”

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).…”