'Green propolis': unreported constituents and a novel compound from chloroform extracts
Giuseppina Negri, Maria Luiza Faria Salatino and Antonio Salatino
Analyses from chloroform extracts are reported for two samples of 'green propolis' from the south of Minas Gerais State (south-east Brazil), listing a variety of compounds, mostly benzoic or cinnamic acid derivatives. Most compounds were identified by GC/ElMS either as mixtures or in pure form, some of them being analysed as the corresponding methyl esters. Derivatives of benzoic acid, benzaldehyde, prenylated and non-prenylated cinnamic acid, chromane, chromene and some other compounds were found in the more polar fractions of chromatographic columns of both samples. Among the substances analysed, several had not been reported in propolis and one (3-prenylcinnamic acid allyl ester) is a new compound, which appeared in highest amounts in both samples. Its structure was determined by mass, 1R and 1 H NMR spectroscopy. The samples have similar composition, but phenols bearing a straight and long hydrocarbon chain were detected in only one sample. The comparative analysis of extracts from three solvents suggests that the current trend of analysing only alcoholic extracts in studies of propolis composition is bound to overlook or miss important propolis constituents.