Antibacterial activity of plant extracts and phytochemicals on antibiotic-resistant bacteria

Abstract

The antimicrobial activity of plant extracts and phytochemicals was evaluated with antibiotic susceptible and resistant microorganisms. In addition, the possible synergistic effects when associated with antibiotics were studied. Extracts from the following plants were utilized: Achillea millifolium (yarrow), Caryophyllus aromaticus (clove), Melissa offficinalis (lemon-balm), Ocimun basilucum (basil), Psidium guajava (guava), Punica granatum (pomegranate), Rosmarinus officinalis (rosemary), Salvia officinalis (sage), Syzygyum joabolanum (jambolan) and Thymus vulgaris (thyme). The phytochemicals benzoic acid, cinnamic acid, eugenol and farnesol were also utilized. The highest antimicrobial potentials were observed for the extracts of Caryophyllus aromaticus and Syzygyum joabolanum, which inhibited 64.2 and 57.1% of the tested microorganisms, respectively, with higher activity against antibiotic-resistant bacteria (83.3%). Sage and yarrow extracts did not present any antimicrobial activity. Association of antibiotics and plant extracts showed synergistic antibacterial activity against antibiotic-resistant bacteria. The results obtained with Pseudomonas aeruginosa was particularly interesting, since it was inhibited by clove, jambolan, pomegranate and thyme extracts. This inhibition was observed with the individual extracts and when they were used in lower concentrations with ineffective antibiotics.

Antibacterial effect (in vitro) of Moringa oleifera and Annona muricata against Gram positive and Gram negative bacteria

“…As shown by GONÇALVES et al 18 and NASCIMENTO et al 31 , S. aureus has been inhibited by extracts prepared from a variety of phanerogams. Likewise, VIEIRA et al 42 found S. aureus to be sensitive to guava leaf extracts in a study testing medicinal plants against bacteria causing diarrhea in children.…”

Composition of the essential oil from the leaves of tree domestic varieties and one wild variety of the guava plant (Psidium guajava L., Myrtaceae)

“…They also possess antioxidant activity as a result of the presence of vitamins, carotenoids, polyphenols and, principally, ascorbic acid (Nogueira et al, 1978;Nascimento et al, 2000;Qian & Nihorimbere, 2004).…”

Avaliação da atividade antibacteriana de extratos etanólico e de ciclohexano a partir das flores de camomila (Matricaria chamomilla L.)

“…Na sua maioria, os constituintes químicos responsáveis pela atividade farmacológica não são conhecidos, mas acredita-se que envolva a interação de inúmeras moléculas presentes no extrato (Yunes & Calixto, 2001). Dados sobre a atividade antibacteriana de extratos vegetais frente a variados microrganismos permitem evidenciar que as plantas apresentam potencial para o tratamento terapêutico, apesar de muitos destes extratos não terem sido completamente investigados cientificamente (Nascimento et al, 2000).…”

“…Segundo a Organização Mundial de Saúde (OMS), as plantas medicinais são a melhor fonte para a obtenção de uma variedade de moléculas biologicamente ativas, e cerca de 80% da população mundial usa a medicina tradicional na busca de alívio de alguma sintomatologia dolorosa ou desagradável (Nascimento et al, 2000).…”