Research On Extraction And Function Of Phytosterol From Mulberry Root Bark

Mulberry root bark, approved by Ministry of Health of the People’s Republic of China in2002, is one of Chinese herbs, which can be used in functional food. Its main pharmacological effects include diuretic, lowering blood pressure, antitussive, expectorant, antiasthmatic, anti-inflammatory, and hypoglycemic. Phytosterol, based on the framework of steroidal nucleus, is a kind of steroidal compounds. Its chemical structure is similar to cholesterol and effects include lowering cholesterol, reducing blood lipid, inhibiting tumor, and anti-inflammatory. Taking mulberry root bark for object, the extraction process and function properties were experimented.In order to optimize the parameters on microwave-assisted extraction of phytosterol from mulberry root bark, effects of microwave power, microwave time, and liquid to solid ratio on phytosterol extraction yield were investigated. Microwave extraction process was optimized by response surface methodology and regression equation between three factors and phytosterol extraction yield was established. Results showed that optimum extraction conditions were as follows:microwave power of539W, microwave time of41s, and liquid to solid ratio of35:1(mL/g). Under these conditions, phytosterol extraction yield of7.74mg/g was obtained. Phytosterol extraction yield extracted by microwave technology were respectively improved by1.57%,19.07%, compared with solvent or ultrasonic extraction method. Meanwhile microwave extraction time was greatly shorter than other methods.The effects of type of extraction solvent, volume ratio of ethanol crude extract to distilled water, extraction time, volume ratio of ethanol crude extract to extraction solvent on phytosterol extraction yield were investigated respectively, hence impurities among crude extract solution were further removed. Extraction process was optimized by orthogonal test on the basis of single factor of volume ratio of ethanol crude extract to chloroform and volume ratio of ethanol crude extract to distilled water. The results were as follows:the phytosterol extraction yield increased by46.92%using chloroform as extraction solvent instead of n-hexane. The extraction time had no significant effect in5-20min. The optimum extraction conditions were volume ratio of ethanol crude extract to chloroform of1:1, and ethanol crude extract to distilled water of1:1. Under these conditions, the phytosterol extraction yield was5.63mg/g.By comparison of macroporous adsorption resin type, the content of phytosterol was50.48%and the recovery rate reached75.45%after using D-900resin column chromatography twice. The maximum absorption peak of the chloroform solution of purified sample was245nm, while standard solution of P-sitosterol was244nm. Purified sample and P-sitosterol standard sample had thin layer chromatography spots at the same position, after qualitative analysis of purified sample by thin layer chromatography. Lanosterol, sitosterol, β-amyrin and a-amyrin were identified by GC-MS.To explore function properties of phytosterol extracted from mulberry root bark, scavenging ability for nitrite was determined at first. The results showed that nitrite scavenging rate reached72.65%when mass concentration of phytosterol from mulberry root bark was0.80mg/mL. Then antibacterial activity and mechanism of phytosterol from mulberry root bark were preliminarily discussed. The antimicrobial effects against various strains was tested by filter paper method. Effects of phytosterol from mulberry root bark against Escherichia Coli were obtained by bacterial growth curve, bacterial protein and conductivity of bacterial suspension solution. The results were as follows:the phytosterol from mulberry root bark had a strong inhibitory effect against bacteria. The sequence of antibacterial activity ranged as:Escherichia Coli, Bacillus Subtilis, Shigella and Staphylococcus aureus. The minimal inhibitory concentration against Escherichia Coli was10.0mg/mL. The phytosterol from mulberry root bark also had a strong inhibitory effect on mucor. When mass concentration of purified phytosterol from mulberry root bark was10.0mg/mL, it inhibited division of Escherichia Coli body, normal metabolism of bacterial protein, and changed permeability of cell membrane.