Antimicrobial properties of cashew nut (Anacardium occidentale) shell extract against pathogenic bacteria associated with bovine mastitis

Abstract

The increasing bacterial resistance to available antimicrobials necessitates the exploration of new bioactive compounds, particularly from natural sources. Traditional animal healthcare often relies on medicinal plants, many of which possess potent antimicrobial properties. This study evaluated the acetone extract of Anacardium occidentale (cashew) nut shell for its phytochemical composition, antioxidant activity, and antimicrobial potential, both alone and in combination with antibiotics and other phytochemicals. The extract contained carbohydrates, saponins, triterpenes, phenols, flavonoids, proteins, and amino acids. The antioxidant activity of cashew nut shell extract was showing moderate activity. Antibacterial activity was assessed using microdilution assays, with minimum inhibitory concentrations (MICs) determined against Escherichia coli and Staphylococcus aureus. The extract demonstrated stronger activity against S. aureus (MIC = 0.078 mg/ml) than E. coli (MIC = 2.5 mg/ml). When combined with amoxicillin and enrofloxacin, the extract showed additive effects. Overall, cashew nut shell extract demonstrated significant antimicrobial activity, particularly against S. aureus, and shows promise when combined with existing antibiotics.