ANALYTICAL PROCEDURE ELABORATION OF TOTAL FLAVONOID CONTENT DETERMINATION AND ANTIMICROBIAL ACTIVITY OF BEE BREAD EXTRACTS

Sixteen ethanolic extracts were obtained from seven different bee bread samples. The total flavonoid content in the extracts was determined by aluminium-chloride method and was in the range of 8.3 mg/L +/- 6.24% to 195.3 mg/L +/- 1.35% and 28.8 mg/L +/- 19.33% to 603.3 mg/L +/- 4.64% with reference to quercetin and rutin, respectively. The relative standard deviations (RSD) for parallel measurements for the calibration curves of quercetin dehydrate and rutin trihydrate were in the range of 0.51% to 9.39% and 5.02% to 19.91%, respectively. The RSD for parallel measurements for the extracts with reference to quercetin dihydrate and rutin trihydrate were in the range of 0.23% to 11.64% and 4.64% to 19.33%, respectively. The total flavonoid content mainly depended on a ratio of bee bread to 50% ethanol and technology of obtaining bee bread (presence or absence of drying operation). The increase of bee bread in the solvent in 2 times yield an elevation of the total flavonoid content in approximately 1.5 times at similar maceration time (7 days). The significant differences between results were statistically confirmed. Antimicrobial activity was evaluated with disc diffusion method. The best antibacterial activity of the bee bread extracts was found against Bacillus cereus CCM 2010, Clostridium perfringens CCM 4435, and Staphylococcus aureus subsp. aureus CCM 4223. The activity of the bee bread extracts against Gram-negative bacteria, Aspergillus and Penicillium genera was lower with moderate anticandidal activity. The obtained results indicated that it was very important to employ extracts with a high content of bee bread in 50% ethanol (1 : 5, 1 : 10) during the development of bee bread extracts with the purpose of their potential usage in medical practice. According to the results of this study, bee bread is a product which is rich in flavonoids and with good antibacterial activity against Gram-positive bacteria and can be considered as a raw material for the development of diet supplements and antimicrobial medicinal products.