In vitro antibacterial activities of pomegranate extract against standard microorganisms of bovine mastitis

Bovine mastitis is characterized by inflammation of the mammary gland, usually due to bacterial infection, compromising quantity and quality of milk production. This study aimed to determine the antibacterial activity, in vitro, of the hydroalcoholic extract of the pomegranate peel at 10% against standard strains of bovine mastitis. The colonies were adjusted to the concentration of 10⁷ ml^-1 using UV-visible spectrophotometry, and the extracts were evaluated in quintuplicate in concentrations of 1000, 500, 250, 75, 50 and 25 μg ml^-1. The sensitivity of the strains was determined using the minimum inhibitory concentration and disk diffusion test. Additionally, antioxidant activity and total phenolic content was evaluated. The extract, at concentrations of 500 and 1000 μg ml^-1, inhibited Staphylococcus aureus (ATCC 25923), S. Saprophyticus (ATCC 15305), S. Epidermidis (ATCC 12228), Escherichia coli (ATCC 11229), Enterobacter cloacae (ATCC 23355 ) and Bacillus cereus (ATCC 33018), but it was not effective for Pseudomonas aeruginosa (ATCC 27853) and Salmonella enterica subspecie, enterica serovar Typhi (ATCC 19214). Antioxidant activity was observed from 50 μg ml^-1 reaching a plateau at 500 mg ml^-1 with 64.90%, and the concentration that causes 50% of the inhibition (IC₅₀) corresponded to 378.80 μg l^-1. Perhaps the presence of other substances in the extract may have been responsible for the antioxidant activity detected. That way, the antioxidant and antibacterial activities of EHPG 10% may represent an important therapeutic potential, particularly for animal health in organic and agroecological production systems.