Antibacterial Activity of Indian Borage (Plectranthus amboinicus Benth) Leaf Extracts in Food Systems and Against Natural Microflora in Chicken Meat

Sandeep Kumar Gupta and Pradeep Singh Negi*

Fruit and Vegetable Technology Department, CSIR-Central Food Technological Research Institute, Mysore 570020, India

Article history:
Received  November 4, 2014
Accepted October 21, 2015

Key words:
antibacterial activity, cell wall damage, food model system, food safety, Plectranthus amboinicus

Summary:
The ability of acetone and ethyl acetate extracts of the leaves of a traditional Indian medicinal plant, Indian borage (Plectranthus amboinicus Benth) to prevent spoilage of artificially inoculated model food systems (cabbage and papaya) and natural microflora of chicken meat was evaluated. These extracts were able to reduce the bacterial counts in all food systems; however, the effective concentration varied with the complexity of the system (cabbage<papaya<chicken). A probable mode of action of extracts was investigated by analyzing the changes they cause in bacterial cell wall and leakage of nucleic acid from bacterial cells. Both acetone and ethyl acetate extracts at their respective minimum inhibitory concentrations resulted in leakage of cell constituents to an extent of 40 to 80 and 60 to 95 %, respectively, compared to the control, and finally leading to disintegration of cell walls. These findings indicate the potential use of ethyl acetate and acetone extracts of Indian borage leaves in food preservation.

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