Keywords: Acorus calamus , Methicillin-resistant Staphylococcus aureus (MRSA), Antibacterial activity, Bacterial invasion, Phytochemical analysis, Mucosal fibroblasts
Acorus calamus is widely used as an Indian medicinal plant and extensively reported for treatments of skin, digestive and nervous disorders. A methanol extract of A. calamus (rhizome) showed maximum extraction yield of 4% (w/w) followed by 3% (w/w) in water. Total 8 Staphylococcus aureus isolates were obtained from nose, groin, wounds, axilla, throat of various patients exhibited strong β-lactamase activity and antibiotic resistance for ampicillin, oxacillin, and methicillin coded for mec A gene. Thus, all isolates belong to methicillin-resistant Staphylococcus aureus (MRSA) class. Methanol extract is the most potent MRSA antibacterial extract followed by water, n-butanol and chloroform. Minimum inhibitory concentration (MIC) of methanol extract varied from 1.25 to 2.50 mg/ml for all MRSA isolates which also exhibited highest MIC values of 512 µg/ml and 128 µg/ml for ampicillin and oxacillin antibiotics, respectively. Interestingly, the synergistic interaction of 128 µg/ml of A. calamus methanol extract with antibiotics (ampicillin, 64 µg/ml and oxacillin, 32 µg/ml) showed lowered MICs. All extracts of A. calamus and β-asarone showed no significant cytotoxic activity against non-cancerous 3T3 fibroblasts cells which was confirmed by MTT assay on MRSA-08 isolate. Antibacterial effect and preventive invasion properties of MRSA of methanol extract of A. calamus were found to be potent when compared with β-asarone, an active component of A. calamus. The present investigation showed a correlation of polyphenolics and flavonoid based major phytochemical constituents with bioactivities on MRSA revealed A. calamus as a potential non-toxic drug candidate for various skin diseases.