Isoflavone formononetin from red propolis acts as a fungicide against Candida sp

Abstract A bioassay-guided fractionation of two samples of Brazilian red propolis (from Igarassu, PE, Brazil, hereinafter propolis 1 and 2) was conducted in order to determine the components responsible for its antimicrobial activity, especially against Candida spp. Samples of both the crude powdered resin and the crude ethanolic extract of propolis from both locations inhibited the growth of all 12 tested Candida strains, with a minimum inhibitory concentration of 256 µg/mL. The hexane, acetate and methanol fractions of propolis 1 also inhibited all strains with minimum inhibitory concentration values ranging from 128 to 512 µg/mL for the six bacteria tested and from 32 to 1024 µg/mL for the yeasts. Similarly, hexane and acetate fractions of propolis sample 2 inhibited all microorganisms tested, with minimum inhibitory concentration values of 512 µg/mL for bacteria and 32 µg/mL for yeasts. The extracts were analyzed by HPLC and their phenolic profile allowed us to identify and quantitate one phenolic acid and seven flavonoids in the crude ethanolic extract. Formononetin and pinocembrin were the major constituents amongst the identified compounds. Formononetin was detected in all extracts and fractions tested, except for the methanolic fraction of sample 2. The isolated isoflavone formononetin inhibited the growth of all the microorganisms tested, with a minimum inhibitory concentration of 200 µg/mL for the six bacteria strains tested and 25 µg/mL for the six yeasts. Formononetin also exhibited fungicidal activity against five of the six yeasts tested. Taken together our results demonstrate that the isoflavone formononetin is implicated in the reported antimicrobial activity of red propolis.

Development and validation of a new method for the quantification of norfloxacin by HPLC-UV and its application to a comparative pharmacokinetic study in human volunteers

The development and validation of a simple and accurate method based on HPLC with ultraviolet detection for the quantification of norfloxacin (NFX) in human plasma and its application to a bioequivalence study between two norfloxacin formulations is described. NFX and the internal standard (cyprofloxacin) were extracted from plasma using liquid-liquid extraction. Chromatographic separation of norfloxacin, cyprofloxacin and plasma interferents was achieved with a C-18 column and a mobile phase consisting of 20 mM sodium hydrogen phosphate buffer pH 3.0 and acetonitrile (88:12, v/v) and quantitation was done at 280 nm. The method was linear from 25 to 3000 ng mL-1 (r² > 0.997578), and norfloxacin and cyprofloxacin had an average recovery from plasma of 93.9 percent and 91.2 percent respectively. The RSD of inter-day quality control samples at the lower limit of quantification was less than 15 percent. After a single oral dose (400 mg) of norfloxacin administered to healthy human volunteers using a randomized 2x2 crossover design, pharmacokinetic parameters (AUC0-t, AUC0-00, Cmax, t1/2) were derived from the plasma concentration curves for both formulations. Pharmacokinetic analysis of the data showed that the two formulations were bioequivalent, while no adverse reactions to the drug were observed.

O desenvolvimento e validação de um método simples e preciso por CLAE-UV para quantificação de norfloxacino (NFX) em plasma humano e a sua aplicação a um estudo de bioequivalência entre duas formulações são descritos. NFX e o padrão interno (ciprofloxacino, PI) foram extraídos do plasma através de extração líquido-líquido. A separação cromatográfica do NFX, do PI e dos interferentes do plasma foi realizada com uma coluna C-18 e fase móvel composta de tampão fosfato de sódio 20 mM pH 3,0 e acetonitrila (88/12, v/v) e quantificado em 280 nm. A resposta do detector aos analitos mostrou-se linear entre 25 a 3000 ng mL-1 (r² > 0,997578) e a recuperação média de NFX e PI foi de 93,9 por cento e 91,2 por cento respectivamente. O desvio padrão relativo de amostras analisadas ao nível do limite inferior de quantificação foi menor que 15 por cento. Foi administrada uma dose de NFX (400 mg) por via oral a voluntários humanos em um estudo aberto, aleatório e cruzado 2x2 entre duas formulações. Os parâmetros farmacocinéticos (AUC0-t, AUC0-00, Cmáx, T1/2) foram observados a partir da curva de concentração versus tempo. A análise farmacocinética mostrou que as duas formulações são bioequivalentes entre si. Nenhum efeito adverso foi observado.