Nutrient evaluation, minerals quantification and antibacterial potential of <i>Mentha longifolia</i> (L.) flower, leaves and stem against foodborne bacterial pathogens

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This study was conducted for the assessment of the nutrition, minerals and antibacterial activities of leaves, stem and flower of Mentha longifolia (wild mint). Proximate compositions were carried out using standards methods, mineral analysis were determined using Atomic Absorption Spectrophotometer and Flame Photometer, antibacterial activities were assessed using Zone of Inhibition Assay. Broth dilution method was used to determine the Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The proximate composition of Mentha longifolia observed that moisture was found in the range of 2.3-2.8%, ash was 2.5-7.5%, crude fat was 0.5-2.1%, crude fiber was 8.5-22.5%, protein was 2.1-4.5%, carbohydrate was 69.6-78.7% and energy was 291.3-347.7 Kcal/100 g dw. Sodium concentration was found in the range of 1250-1590 mg/kg, Potassium was 3240-4820 mg/kg, Calcium was 12400-24000 mg/kg, Magnesium was 4800-9600 mg/kg, Zinc was 32-64 mg/kg, Iron was 140-498 mg/kg, Manganese was 32-107 mg/kg and Chromium was 3-6 mg/kg in Mentha longifolia leaves, flower and stem. The highest zone of inhibition (23±0.2) of Mentha longifolia leaves extract (tincture) was calculated against Bacillus cereus. Similarly the highest zone of inhibition of Mentha longifolia flower and stem was noted against Bacillus cereus in tincture extract were 17±01 mm and 16±01 mm respectively. The Mentha longifolia leaves MIC range was 40–120 mg/mL and MBC 60–200 mg/mL. The flower extracts MIC range 70–220 mg/mL and MBC 110–300 mg/mL. Generally the antibacterial activities of wild mint leaves extracts were higher as compared to flower and stem extracts (p<0.05). The results commonly observed Gram-negative bacteria are typically high opposed to the Mentha longifolia extracts as compared to Gram-positive bacteria. The proximate and minerals analysis concludes that this herb is used to formulate nutraceutical products and their extracts can be used against multi drug resistance bacteria accomplished of causing foodborne diseases.