Antibacterial activity of anacardic acid and totarol, alone and in combination with methicillin, against methicillinresistant Staphylococcus aureus

Abstract

The inhibitory and bactericidal activities of anacardic acid and totarol, alone and in combination with methicillin, were investigated against methicillin-resistant Staphylococcus aureus (MRSA). The growth of two MRSA strains was inhibited by 6 x 25 microg ml-1 of anacardic acid and 0 x 78 microg ml-1 of totarol. The time-kill curve study showed that these two compounds were bactericidal against MRSA. Anacardic acid killed MRSA cells more rapidly than totarol, and no viable cells were detected after being exposed to 6 x 25 microg ml-1 of anacardic acid for 6 h. Anacardic acid showed bactericidal activity against MRSA at any stage of growth, and also even when cell division was inhibited by chloramphenicol. In the combination studies, the minimal inhibitory concentration (MIC) of methicillin was lowered from 800 to 1 x 56 microg ml-1 for MRSA ATCC 33591, and from 800 to 6 x 25 microg ml-1 for MRSA ATCC 33592, by combining with 1/2 x MIC of anacardic acid. The time-kill curves demonstrated synergistic bactericidal activities for these combinations.

Ehrlichia chaffeensis Exploits Host SUMOylation Pathways To Mediate Effector-Host Interactions and Promote Intracellular Survival

“…Therefore, it was not surprising that inhibition of host SUMOylation with the small molecule AA significantly decreased E. chaffeensis infection and survival. A natural derivative of salicylic acid, AA was previously described as an antimicrobial molecule at low micromolar concentrations (82,83). At higher concentrations (Ͼ20 M), AA is also a histone acetyltransferase inhibitor (84,85), and it is cytotoxic to cancer cell lines at 40 to 100 M (86).…”

Anacardic acid (6-nonadecyl salicylic acid), an inhibitor of histone acetyltransferase, suppresses expression of nuclear factor-κB–regulated gene products involved in cell survival, proliferation, invasion, and inflammation through inhibition of the inhibitory subunit of nuclear factor-κBα kinase, leading to potentiation of apoptosis

“…The active principle has been associated with molluscicidal activity 6 and antimicrobial activity. 7,8 How anacardic acid mediates these effects is not fully understood, but it has been shown to have antioxidant activity 9 and to inhibit the activity of numerous enzymes, including tyrosinase, 4 xanthine oxidase, 10 phosphatidylinositol-specific phospholipase C, 11 histone acetyltransferase (HAT), [12][13][14] tissue factor VIIa, 15 lipoxygenase, and cyclooxygenase (COX). [16][17][18] This compound has also been shown to be a mitochondrial uncoupler of oxidative phosphorylation.…”

Atividade antifúngica e possível mecanismo de ação do óleo essencial de folhas de Ocimum gratissimum (Linn.) sobre espécies de Candida

“…A contagem das células viáveis foi determinada após 4 e 24 horas da adição de OEOg. Os experimentos foram realizados em triplicata e os resultados expressos em UFC/mL (Muroi & Kubo, 1996).…”