Phytochemical, Antiplasmodial, Cytotoxic and Antimicrobial Evaluation of a Southeast Brazilian Brown Propolis Produced by Apis mellifera Bees

Seven phenolic compounds (ferulic acid, caffeic acid, 4-methoxycinnamic acid, 3,4-dimethoxycinnamic acid, 3-hydroxy-4-methoxybenzaldehyde, 3-methoxy-4-hydroxypropiophenone and 1-O,2-O-digalloyl-6-O-trans-p-coumaroyl-beta-D-glucopyranoside), a flavanonol (7-O-methylaromadendrin), two lignans (pinoresinol and matairesinol) and six diterpenic acids/alcohol (19-acetoxy-13-hydroxyabda-8(17),14-diene, totarol, 7-oxodehydroabietic acid, dehydroabietic acid, communic acid and isopimaric acid) were isolated from the hydroalcoholic extract of a Brazilian Brown Propolis and characterized by NMR spectral data analysis. The volatile fraction of brown propolis was characterized by CG-MS, composed mainly of monoterpenes and sesquiterpenes, being the major alpha-pinene (18.4 %) and beta-pinene (10.3 %). This propolis chemical profile indicates that Pinus spp., Eucalyptus spp. and Araucaria angustifolia might be its primary plants source. The brown propolis displayed significant activity against Plasmodium falciparum D6 and W2 strains with IC50 of 5.3 and 9.7 mu g/mL, respectively. The volatile fraction was also active with IC50 of 22.5 and 41.8 mu g/mL, respectively. Among the compounds, 1-O,2-O-digalloyl-6-O-trans-p-coumaroyl-beta-D-glucopyranoside showed IC50 of 3.1 and 1.0 mu g/mL against D6 and W2 strains, respectively, while communic acid showed an IC50 of 4.0 mu g/mL against W2 strain. Cytotoxicity was determined on four tumor cell lines (SK-MEL, KB, BT-549, and SK-OV-3) and two normal renal cell lines (LLC-PK1 and VERO). Matairesinol, 7-O-methylaromadendrin, and isopimaric acid showed an IC50 range of 1.8-0.78 mu g/mL, 7.3-100 mu g/mL, and 17-18 mu g/mL, respectively, against the tumor cell lines but they were not cytotoxic against normal cell lines. The crude extract of brown propolis displayed antimicrobial activity against C. neoformans, methicillin-resistant Staphylococcus aureus, and P. aeruginosa at 29.9 mu g/mL, 178.9 mu g/mL, and 160.7 mu g/mL, respectively. The volatile fraction inhibited the growth of C. neoformans at 53.0 mu g/mL. The compounds 3-hydroxy-4-methoxybenzaldehyde, 3-methoxy-4-hydroxypropiophenone and 7-oxodehydroabietic acid were active against C. neoformans, and caffeic and communic acids were active against methicillin-resistant Staphylococcus aureus.

Automated summary

Brown propolis contains various phenolic compounds, flavanonol, lignans, and diterpenic acids/alcohol. Its chemical profile suggests that it may originate from Pinus spp., Eucalyptus spp., and Araucaria angustifolia. The propolis has significant antimicrobial activity against Plasmodium falciparum and drug-resistant bacteria, as well as cytotoxic effects on tumor cells but not on normal cells.