| Spearmint(Mentha spicata L.)is Lamiaceae Mentha aromatic herb which has important edible and medicinal value.In this paper,spearmint producted in Nanjing is the research object.Based on the essential oil and phenolic acids,flavonoids and other ingredients,the article evaluated the quality of spearmint of different harvest times,and the bioactivity of the extracts were explored.The aim was to provide new basis for the utilization.Determined the content of essential oil according to the IS06571-2008 standard,and analysed essential oil compositions by GC-MS.The results showed that oil content increased first and then decreased from June to October,and the highest reached 3.95%at the end of August.The main components of oil were carvone(about 60%～70%)and limonene(about 20%～35%).Essential oil content in flower spike was higher than leaves and stems,and carvone content of flower oil was higher.Different drying methods caused oil loss by the order:bake-dried>drying in the sun>drying in the shade.Loss of limonene was more than carvone.Considering the essential oil yield,the best harvest period is from late August to mid September.The essential oil yield of fresh plant is highest,and drying in the shade can avoid the loss of oil in the maximum extent.Determined the content of phenolic acids and flavonoids by absorptiometry.The results showed that,the phenolic acids and flavonoids contents decreased firstly and then increased from June to October.Phenolic acid contents were in the range of 3～8 mg/g,and flavonoid contents were in the range of 7～30 mg/g.Established the HPLC method of determining chlorogenic acid,caffeic acid and rosmarinic acid of Spearmint at the same time.Chlorogenic acid contents were in the range of 0.3-0.8 mg/g at different harvest periods.Rosmarinic acid contents were in the range of 0.4～1.3 mg/g.The contents of caffeic acid were less than 0.08 mg/g.Phenolic acids and flavonoids contents are higher before early July or after late September.So,if used as medicine directly,these two stages are the best harvest periods.Studied on the antioxidant activity of spearmint.The results showed that spearmint essential oil and crude extracts had certain antioxidant capacity which had significant quantity effect.The reducing power of 0.2%(V/V)oil was similar to 5 μg/mL Vc.When the oil concentration was 1%,the scavenging rate of hydroxyl radical was similar to 50 μg/mL Vc,and the superoxide anion radical scavenging rate was similar to 20 g/mL Vc.The reduction ability of 50 g/mL crude extract was slightly lower than the 5 g/mL Vc.When the crude extract concentration was 2 mg/mL,the scavenging rate of hydroxyl radical could reached to 91.3%,and the scavenging rate of superoxide radical was 70.5%.Studied on the antibacterial activity of spearmint essential oil and extractive comparing with oregano oil by filter paper method and tube constant dilution method.The results showed that spearmint essential oil had antibacterial activity on Escherichia coli,Staphylococcus aureus and Bacillus subtilis,and the inhibition had obvious dose-effect relationship.Antibacterial effect of oregano oil was stronger than spearmint oil.The MIC values of spearmint oil on Escherichia coli,Staphylococcus aureus and Bacillus subtilis were 0.08%,0.04%,0.01%.The MBC values were 4-8 times of MIC values.Spearmint extractive had no antibacterial effect.With spearmint oil,peppermint oil and oregano oil as natural essence and antiseptic,stevioside as sweetener,adding with sodium usnic acid which has deodorizing and sterilizing effect,developed a kind of natural ingredient based mouthwash slobber products.The main quality indexes of the mouthwash were in line with QBT 2945-2012 standard,and the germicidal efficacy had reached the requirements of industrial products.Spearmint has antibacterial,antioxidant and other effects which has application prospect in food preservation,cosmetic fragrance,medical sterilization diseases prevention of animal and plant.This paper provides research basis for the development and utilization of spearmint. |
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