Variação sazonal de parâmetros de qualidade da própolis vermelha de Alagoas

Abstract

Propolis is a natural product made by bees of the species Apis mellifera, which produce it by mixing their salivary secretion with the exudate of various plants. It can be present in nature in different chemical compositions, biological activities, colors and organoleptic properties, as the species of origin varies according to the region, and environmental factors influence the phytochemical composition. From this it was possible to identify 12 Brazilian varieties of propolis, later discovering the red propolis from Alagoas state, belonging to group 13, produced through the red exudate of the plant Dalbergia ecastophyllum. The red propolis has antibacterial, antifungal, anticancer and antioxidant activities, as well as a relatively high content of phenolic compounds. The aim of this study was to investigate the influence of seasonal variability on chemical and biological parameters of PVA collected over 12 months. The DPPH● radical scavenging capacity assay showed good results in all analyzed months (April 2017 to March 2018), surpassing the same effect in the red varieties of Maceió (Alagoas), Sergipe, Bahia and Rio Grande do Norte. It also showed high total levels of flavonoids, between 7.48% (March 2018) and 12.79% (January 2018), with a variable performance, in this test, in relation to the content in the other propolis. The broth microdilution test resulted in MICs of 128-1024 μg/mL against S. aureus (ATCC 25923) and 625-1250 μg/mL against E. coli (ATCC 25922). S. aureus was more sensitive to PVA than E. coli. The results against both strains, although high, were lower than those observed in other red propolis varieties from the Brazilian Northeast. The HPLC-DAD fingerprint showed a higher concentration of the markers formononetin, daidzein, liquiritigenin and isoliquiritigenin, compared to biochanin A, pinocembrin and pinobanksin. The analysis of the results with rainfall in the region allowed the distinction of two cycles of better results — (1) from April to June 2017 and (2) between October 2017 and February 2018 —, from a longer cycle of low results, from July to September 2017, and from March 2018, with the worst performance. In general, biological activities and flavonoid content reduced in the rainy season, increasing significantly with low rainfall.