Study On Preparation Of Alkaloids Of Berberberine And Inhibition Of Bacteria

Berberis poiretii is a plant in the wild without artificial cultivation,which is abundant in the northern and central of China.The traditional medicine has always used its roots and stems as the medicines,and has significant effects in bacteriostatic,anti-inflammatory,heat-clearing and dampness.The yield of the Berberis poireti of fruit is also very considerable.Because of its unpleasant taste and sourness,it is abandoned on barren hills in the natural status.It is found that the fruit contain alkaloids besides the basic nutrients.In this paper,we studied the process of semi-bionic to extracted total alkaloids from Berberis poiretii and researched its antibacterial in broad-spectrum,effectiveness and basic mechanism.Finally,we carried out a validation test of antibacterial effect in fruits and vegetables.The main findings are as follows:(1)Using the extraction yield of total alkaloids and the diameter of bacteriostatic circle as indicators of investigation,total alkaloids were extracted from Berberis poiretii by the method of semi-bionic.The results showed that the optimum extracting conditions were:27%ethanol concentration,solvent-to-solid ratio of 32 mL/g,52?,ultrasonic power was 300W;the extraction time was 40min when the pH value of the extract was 2.2;the extraction time was 20min when the pH value of the extract was 8.5.Under the above conditions,the extraction amount of total alkaloids in Berberis poiretii was 16.24±0.54 mg/g,and the diameter of its bacteriostatic circle was 91.21 ± 0.47 mm.Compared with the single ultrasonic assisted method,the extraction amount was increased by 1.31 times and the bacteriostatic effect was increased by 1.07 times.(2)We studied that the stability under different processing conditions and the antibacterial activity by three kinds of bacteria of the alkaloids in Berberis poiretii.It was found that acidic pH conditions are beneficial to the residual of alkaloids and played an important role in bacteriostasi;temperature was negatively correlated with residual amount and antibacterial activity,and an important factor influencing the irreversible transformation of alkaloids;natural light and ultraviolet light have no significant effected on the alkaloid residue and activity.The thermal degradation of the alkaloids in Berberis poiretii was consistent with the first-order reaction kinetics model.At a high temperature of 82?,the rate constant under the condition of pH 2 was 0.0244,the regression coefficient was 0.8738;and the rate constant under the condition of pH 11 was 0.0180,the regression coefficient was 0.9816.(3)The minimum inhibitory concentration and growth curve of common bacteria in four kinds of foods were studied in the alkaloids in Berberis poiretii,which confirmed that it has a broad spectrum of antibacterial effects on common bacteria,especially the antibacterial effect against Escherichia coli.The minimum inhibitory concentration was only 2.4 mg/mL for Escherichia coli,and the antibacterial effect against Gram-negative bacteria was better than the Gram-positive bacteria.The determination of the conductivity of the suspension also reflected that the alkaloids have significant inhibitory effects on Escherichia coli.The mechanism of action was that alkaloids in Berberis poiretii would destroied the bacterial cell wall and membrane of the cell,affected the permeability of the cell membrane,disturbed the ion homeostasis in the cell,caused the electrolyte to leak out,and finally caused the cell to die;From the study of bacterial protein synthesis,we conclude that the alkaloids inhibited the expression and synthesis of intracellular proteins,led to a decrease in the amount of protein in the cell,thereby inhibited sodium,potassium,ATP,and enzyme activities.(4)We selected the strawberries and cucumbers which were not resistant to storage as the test subjects for high,medium and low dose soaking treatment,In order to verified the antibacterial effect of the alkaloids in Berberis poiretii in the process of preservation of fruits and vegetables.The results showed that compared with the blank control group,the medium and high doses of alkaloids could maintained the main chemical components of the fruit was decayed slowly;The physical properties such as sensory and hardness of the alkaloid soaking group showed the advantage in the preservation of fruits and vegetables;The rot rate,weight loss rate and respiratory intensity of fruits and vegetables also reflected that alkaloid could provid obvious bacteriostatic effect and improve the quality of fruits and vegetables.