Biological screening of herbal extracts and essential oil from Plectranthus species: α-amylase and 5-lipoxygenase inhibition and antioxidant and anti-Candida potentials

Abstract The phenolic compound content, the antioxidant and α-amylase inhibition potentials of different extracts of the Plectranthus amboinicus, P. barbatus and P. ornatus were evaluated. We also evaluated the influence of plant growth and harvest time on the chemical composition of the essential oil (EO) of P. amboinicus, its antioxidant and anti-Candida activities and the α-amylase and lipoxygenase inhibitions. The turbo-extract of P. barbatus showed the greatest phenolic compound content and antioxidant activity. No α-amylase inhibition activity was observed in the analyzed extracts, but the turbo-extraction and refluxing extracts possessed high antioxidant activities. Protected cultivation and morning harvest conditions gave the best antioxidant activities, which was associated to the highest carvacrol content. P. amboinicus EO antioxidant activity could contribute to the reduction of oxidative stress in diabetes. Causal Candida strains of diabetic foot ulcers showed sensitivity to P. amboinicus EO. C. albicans and C. dubliniensis were the most sensitive of the selected Candida strains. Turbo-extracts or refluxing of the three species extracts and the EO of P. amboinicus should be considered as a potential candidate for the management the complications of type 2 diabetes.

Seasonal variation in essential oil content and chemical profile of mint in southeast of Brazil / Variação sazonal no teor e perfil químico do óleo essencial de menta no sudeste do Brasil

ABSTRACT: This study evaluated the influence of seasonality in essential oil (EO) chemical composition of Mentha x piperita L. and Mentha viridis L. grown in southeast of Brazil. Leaves were collected from November 2011 until August 2013, in the middle of the following seasons: Spring (November), Summer (February), Autumn (May) and Winter (August). EO extraction was carried out by hydrodistillation in Clevenger apparatus for 1 hour. Chemical composition of EO was analyzed by GC-FID and GC-MS. The EO content and its chemical composition were influenced by seasonality in both species. The highest EO content was obtained for M. x piperita during spring (4.26%) and for M. viridis during spring (3.30%) and summer (3.70%). Mentha x piperita increased menthol (16.31 to 41.26%), neomenthol (3.02 to 6.39%) and menthone (5.56 to 41.58%) contents during spring and summer, respectively. Whereas, M. viridis EO content did not show a quality response pattern in relation to seasonality. Therefore, harvest time for M. x piperita is recommended during spring, and for M. viridis is recommended during spring and summer.

RESUMO: O estudo teve como objetivo avaliar a influência da sazonalidade na composição química do óleo essencial (OE) de Mentha x piperita L. e Mentha viridis L. cultivadas no sudeste do Brasil. As folhas foram coletadas de novembro de 2011 até agosto de 2013, em meados das seguintes estações: primavera (novembro), verão (fevereiro), outono (maio) e inverno (agosto). A extração do OE foi realizada por hidrodestilação em aparelho de Clevenger por uma hora. A composição química do EO foi analisada por GC-FID and GC-MS. O teor de OE e sua composição química foram influenciados pela sazonalidade em ambas as espécies. O maior teor de OE foi obtido para M. x piperita na primavera (4,26%) e para M. viridis na primavera (3,30%) e verão (3,70%). Mentha x piperita aumentou o conteúdo de mentol (16,31 a 41,26%), neomentol (3,02 a 6,39%) e mentona (5,56 a 41,58%) durante a primavera e o verão, respectivamente. Já o conteúdo de OE de M. viridis não apresentou padrão de resposta de qualidade em relação à sazonalidade. Portanto, a colheita para M. x piperita é recomendada durante a primavera, e para M. viridis é recomendada durante a primavera e verão.