Brazilian red propolis: unreported substances, antioxidant and antimicrobial activities

Abstract

BACKGROUND: Chloroform, ethyl acetate and methanol extracts of a sample of red propolis from the state of Alagoas (northeast Brazil) were analyzed by gas chromatography–mass spectrometry and high‐performance liquid chromatography–diode array detection–electrospray ionization‐mass spectrometry. Antimicrobial and antioxidant activities were also obtained. RESULTS: The propolis sample contained low content of narigenin‐8‐C‐hexoside, this being the first report of a C‐glycoside in propolis. The main constituent found was characterized as 3,4,2′,3′‐tetrahydroxychalcone. Other important constituents were the chalcone isoliquiritigenin, the isoflavans (3S)‐vestitol, (3S)‐7‐O‐methylvestitol, the pterocarpan medicarpin, the phenylpropenes trans‐anethol, methyl eugenol, elimicin, methoxyeugenol and cis‐asarone, and the triterpenic alcohols lupeol and α‐ and β‐ amyrins. The methanol extract exhibited high antioxidant activities by 2,2‐diphenyl‐1‐picrylhydrazyl and β‐carotene/linoleic acid assay methods, and antimicrobial activity toward Gram‐positive and Gram‐negative bacteria. CONCLUSION: Structures are suggested for new substances never before seen in any kind of propolis. This is the first report of 3,4,2′,3′‐tetrahydroxychalcone and a flavone C‐glycoside in a propolis sample. Copyright © 2011 Society of Chemical Industry