RESUMEN
The construction and application of a novel electrochemical detection system with an in situ plated lead film electrode for high-performance liquid chromatography (HPLC) is described. The working electrode of interest was tested as a potential sensor for the adsorptive stripping voltammetric determination of betulinic acid (BA). The high sensitivity of the proposed electrochemical detection results from the accumulation by adsorption of BA on the lead film surface before the proper electrode process. In a solution of sodium hydroxide, used as a supporting electrolyte for the proposed voltammetric method, the oxidation signal for BA was found to be proportional to the BA concentration in the range from 0.02 to 0.5 µg L(-1) with a limit of detection equal to 0.009 µg L(-1) (with preconcentration for 15 s). The voltammetric detection was successfully applied to the determination of BA in the birch bark (Betula verrucosa) extracts after HPLC separation. The content of BA obtained by the proposed method was in close agreement with that obtained by HPLC coupled with photodiode array detector (HPLC-PAD). This appears to be the first application of electrochemical detection to the determination of pentacyclic triterpene.
Asunto(s)
Betula/química , Electroquímica/métodos , Triterpenos/análisis , Calibración , Cromatografía Líquida de Alta Presión/métodos , Electroquímica/instrumentación , Electrodos , Electrólitos/química , Plomo , Límite de Detección , Oxidación-Reducción , Triterpenos Pentacíclicos , Extractos Vegetales/análisis , Extractos Vegetales/química , Plantas/química , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Ácido BetulínicoRESUMEN
Three extracts of Calendulae officinalis flos (Asteraceae): heptane, ethyl acetate and methanol were introduced to a human skin fibroblast (HSF) cells culture and a culture of human breast cancer cells (T47D), cell culture collection ECACC number 85102201. The ethyl acetate but not the heptane and methanol extracts in concentrations above 25 microg/mL, can stimulate cell proliferation and cellular metabolism by increase of mitochondrial dehydrogenase activity. However, concentrations exceeding 75 microg/mL are toxic for cells. The second part of the study concerned elaborating of optimal chromatographic systems for quantitative analysis of these extracts by the use of HPTLC with densitometry. Oleanolic acid, beta-amyrin, beta-amyrin acetate, rutin, narcissin, 3-glucoside of isorhamnetin, quercetin, isoquercitrin, vanillic acid, caffeic acid, chlorogenic acid, protokatechuic acid, p-coumaric acid and syringic acid were all identified.