The Research Of Extracting Cosmetics Preservative From Rhubarb

The research mainly focused on the best rhubarb antibacterial ingredient extraction conditions,it also researched the stability of the rhubarb extract, analyzed, separated the active ingredient and preliminarily studied the inhibitory mechanism.The extraction technology was optimized with disc diffusion method, used the diameter of bacteriostatic circle as assessing index, S. aureus and E. coli as indicative bacteria. With the orthogonal design test, the results showed that the optimum extracting condition was: extraction temperature 60℃, 70%(volume fraction)ethanol, liquid:solid ratio 20:1(mL:g), ultrasonic extraction time 35 min.The rhubarb extraction had wide Antibacterial spectrum.The MIC of the rhubarb extraction leaves was 6.25mg/mL against S. aureus, which was 3.125 mg/mL against E. coli,which was 6.25 mg/mL against Salmonella.The stability to temperature,ultraviolet , pH and heating time value of rhubarb extraction were also studied. The result showed the extract was very stable to temperature,ultraviolet , pH 6.5-7.5 and 3h heating time.All extracts obtained in different fractions by using different polarities of solvents such as petroleum ether, dichloromethane, ethyl acetate, normal butyl alcohol and water were compared through the testing of their antimicrobial activities.The results showed the extraction of dichloromethane had a strong capacity.The alkalescence reaction, acetate magnesium reaction and under ultraviolet and visible light showes that the main actives of the extraction of ethyl acetate is anthraquinone.The extracts of dichloromethane was seperated by silica gel column chromatography and got a yellow substance,then analyzed it with LC-MS and found that it was emodin.The research preliminarily studied the inhibitory mechanism,the experiments showed that the rhubarb extraction could inhibit the activities of intracellular malate dehydrogenase enzyme. Rhubarb is one of the reasons why the bacteria is inhibited or killed.