| Mogrosides are made up of cucubitane triterpene glycosides, so far, 12 kinds of cucubitane triterpenes have been isolated from different parts of Momordica grosvenori Swingle. Because Mogrosides contain many glycosyl groups, they are difficult to be absorbed and their bioavailability is as lower as that of the other polar saponins. However, enzymatic hydrolysis these polar glycosides can decrease their polar and increase their bioavailability. This article studied the microbial transformation of cucubitane triterpene glycosides from Momordica grosvenori.In this paper, we found a penicillium sp J-9 which can produceβ-glucosidase with higher activity and it is able to partial hydrolysis the mogrosides. The method of TLC was discussed for finding a suitable condition to analyze transformation products. As a result, the optimal developing solvent of TLC is chloroform-methanol-water (10:4:0.3). Three high purity compounds were separated from enzymatic hydrolysate by Silica Gel Column Chromatography and C18 Reversed-phase Column Chromatography.Three products were identified as mogrol-24-O-β-D-glucopyranosyl-(1â†'2)–β-D-glucopyranoside(A); mogrol-3-O-β-glucopyranosyl-24-O-β-D-glucopyranosyl- (1â†'2)-β-D-glucopyranoside(B); 11-oxo-mogrol-3-O-β-D-glucopyranosyl-24-O-β-D- glucopyranosyl-(1â†'2)-β-D-glucopyranoside(C) by melting point, MS, IR, NMR. The compounds A,B and C have not been reported .The method of HPLC for the assay of the content of transformation products A and B was developed. ZW&A C18(250×4.60mm,5μm) column was used as the stationry phase. The mobile phase was acetonitrile: water, (0~15min, 25%Aâ†'40%A; 15~23min, 40%A); the flow rate (0~15min, 1.0ml/minâ†'0.5 ml/min; 15~23min, 0.5ml/min); The column temperature was 30℃, the injection volume was 5μL, the UV detection wavelength was 203nm. The linear equation of compounds A and B were Y=459.9X+0.2252, r=1.0000; Y=642.5X+25.17, r=1.0000; the linear range were 0.992~9.92μg and 0.229~2.29μg; the sample recovery of compounds A and B were (99.3±1.12%) and(97.8±1.68)%.By using single factor experiment, the conditions of medium and fermentation were studied for improving the yield of these kind mogrosides. The results showed that the suitable composition of fermentation medium was as follows: potato 20%; Corn flour 1.5%, bran 1.5%, KH2PO4 0.2%. And the optimum conditions of transformation by flasking culture were that initial pH of medium was 6, substrate concentration was 5mg/ml, temperature was 28℃, flack speed was 220r/min. Under the suitable conditions, the highest conversion rate of product B or A was in the fourth ,and seventh day respectively.By analyzing the structure of mogrosides and transformation products A, B and C, it is inferred that mogroside V and 11-oxo-mogroside V are converted to the transformation products B and C respectively by (1â†'6)-β-D-glucosidase which came from J-9 fungi, then, B is transformed to A byβ-D-glucosidase. |
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