Effect Of Lemon Peel Extracts On A Variety Of Cariogenic Enzymes Activity And Metabolic Products Of Streptococcus Mutans

Objectives Dental Carie is one of the most common infectious dieases,and Streptococcus mutans are one of the major cariogenic bacteria.Seeking caries-preventive natural medcine have become a hot research at home and abroad. Lemon peel extract is a yellow liquid which is extracted from the rutaceae citrus plant lemon. Previous experiments approved the effect of Lemon peel extract on growth,acid production and adhension of Streptococcus mutans. This paper studied the effect of lemon peel extracts on a variety of cariogenic enzymes activity and metabolic products of streptococcus mutans to detect the anti-adhesion and acid-suppression mechanism of lemon peel extracts and analyze the role of metabolic enzyme,providing basis for the future development of a new type of natural anti-caries agents without side effects.Methods1.Effect of Lemon peel extracts on glucosyltransferase and extra-cellular glucan of Streptococcus mutansThe lemon peel extracts was used as the experimental group with concentrations ranging from 12.5μl/10ml to 0.39μl/10ml prepared with TSB medium with contained 2% glucose, and TSB culture medium was used as the control group. Streptococcus mutans was added to each group,after cultured for 6,18,24,48 hours the test tubes, centrifugation was followed. Neson-Somogyi method were used to measure the content of reducing sugar, and the specific activity of enzyme was alculated. Measure the content of water-insoluble glucan and water-soluble glucan by anthrone method, and do correlative analysis between the activity of extract-cell glucan and enzyme activity.2.Effect of Lemon peel extracts on sucrase activity of Streptococcus mutansSucrose was hydrolyzed by sucrase,the product glucouse reacted with 3,5-dinitrosalicylic acid and produce a orange-red compound. The color depth is proportionate to the content of reducing sucrose.The activity of sucrase was detected by way of measuring the quality of glucose producing by hydrolysis of sucrase to sacrose, and the specific activity was alculated. 3.Effect of Lemon peel extracts on Lactate Dehydrogenase activity and acid generation of Streptococcus mutansLactate Dehydrogenase's activity was assayed by the pyruvate-dependent oxidation of NADH. Before and after treatment was measured with a pH meter ofΔpH medium to detect the anti-acid capability of lemon peel extract on Streptococcus mutans, and do correlative analysis between the activity of Lactate Dehydrogenase and the capability of acid generation.Results1.The glucosyltransferase and extra-cellular glucan of Streptococcus mutans decreased gradually with the increase of each concentration of lemon peel extracts. From the group of 0.078μl/ml to 0.313μl/ml lemon peel extracts,there were highly significant differences(P<0.01).There were highly significant differences of extra-cellular glucan between each experimental group and control group (P<0.01);and between glucosyltransferase activity or specific activity of each experimental group and control group as well (P<0.01);There was positive correlation between glucosyltransferase activity and water-insoluble glucan content (V=0.825-0.963 P<0.01),and between glucosyltransferase activity and water-soluble glucan content as well(r=0.814-0.950,P<0.01);and There were highly significant differences of positive correlation between glucosyltransferase activity and water-insoluble glucan content,water-soluble glucan content(t=4.37,P<0.01).There were highly significant differences of glucosyltransferase activity among 6h,18h,24h and 48h (F=19.28 P< 0.01),there were highly significant differences of extra-cellular glucan content between 18h and another hour(F=5.15 F=36.16, P<0.01).2.The sucrase activity of Streptococcus mutans decreased gradually with the increase of each concentration of lemon peel extracts. From the group of 0.078μl/ml to 0.313μl/ml lemon peel extracts,there were highly significant differences(P<0.01). There were significant differences between the overall mean of enzyme's activity at 18h and 6h,24h,48h(F=300.78,P<0.01),there were significant differences between 6h and 24h,48h(P<0.01),there were no significant differences between 24h and 48h(q=1.51,P>0.05).3.The lactate dehydrogenase activity and ApH of Streptococcus mutans decreased gradually with the increase of each concentration of lemon peel extracts.From the group of 0.078μl/ml to 0.313μl/ml lemon peel extracts,there were highly significant differences(P<0.01).There were highly significant differences of lactate dehydrogenase activity between each experimental group and control group (P<0.01); and between ApH of each experimental group and control group as well (P<0.01); There was positive correlation between LDH activity andΔpH (r=0.8596-0.9460 P<0.01).There were no significant differences between four time(P>0.05).Conclusion1.Lemon peel extracts could inhibit the glucosyltransferase and extra-cellular synthesis of water-insoluble glucan,water-soluble glucan of Streptococcus mutans; with increase of concentration from 0.078μl/ml to 0.313μl/ml,the inhibiting effect increase.2. Lemon peel extracts could inhibit the sucrase activity of Streptococcus mutans;with. increase of concentration from 0.078μl/ml to 0.313μl/ml,the inhibiting effect increase.3.Lemon peel extracts could inhibit the lactate dehydrogenase activity and capability of acid generation of Streptococcus mutans; with increase of concentration from 0.078μl/ml to 0.313μl/ml,the inhibiting effect increase.4.The inhibitory effects of Lemon peel extracts on the glucosyltransferase,sucrase activity and extra-cellular glucan of Streptococcus mutans in18h-24h phase is stronger than that on other phases of growth cycle.