Antibacterial activity of acetone extract of Boswellia serrata Resin in combination with selected phytochemicals against bovine mastitis pathogens

Abstract

Mastitis in dairy cattle is a highly prevalent infectious disease, leading to significant economic losses worldwide due to decreased milk quality, reduced yield, and increased production costs. Conventional antibiotic therapy, though effective, is associated with concerns such as drug resistance, milk residues, and high treatment costs. These issues highlight the urgent need for new, natural antibacterial alternatives. Phytochemicals, derived from medicinal plants, are promising candidates due to their antimicrobial properties, lack of side effects, and immunomodulatory potential. This study evaluated the antibacterial and antioxidant activities of Boswellia serrata resin extract against bovine mastitis-causing organisms. The resin extract was assessed for phytochemical constituents, antioxidant potential using the phosphomolybdenum assay, and antibacterial activity via microdilution and biofilm inhibition assays. Its synergistic effects were evaluated in combination with enrofloxacin, amoxicillin, and selected phytochemicals such as thymol, xanthone, and caffeic acid. Phytochemical analysis revealed the presence of carbohydrates, saponins, triterpenes, phenols, and flavonoids. The resin extract exhibited moderate antioxidant activity, equivalent to 44.82±0.85 µg/ml of ascorbic acid. Minimum inhibitory concentrations (MIC) against Escherichia coli and Staphylococcus aureus ranged from 5 mg/ml to 1.25 mg/ml, with the lowest MIC observed for S. aureus. Synergistic antibacterial effects were observed with xanthone against E. coli and additive effects against S. aureus. Biofilm inhibition assays confirmed that the resin extract alone significantly reduced biofilm formation, with enhanced inhibition in combination with antibiotics and xanthone. In conclusion, Boswellia serrata resin extract demonstrated notable efficacy against S. aureus, likely due to differences in gram-positive and gram-negative cell wall structures. Its additive and synergistic effects with antibiotics and phytochemicals, coupled with its lack of antagonism, underscore its potential as a natural adjunct in mastitis treatment.