Determination of Afzelin and Astragalin from Lespedeza cuneata on Aldose Reductase Inhibition.

The bioactive chemicals in L. cuneata were investigated by repeated column chromatography and their effect on aldose reductase (AR), obtained from rat lenses, was examined. Results showed that the ethyl acetate and n-butanol fractions of L. cuneata exhibited potential inhibitory effect against AR with IC50 values of 0.57 and 0.49 µg/mL, respectively. Phytochemical analysis of these two fractions resulted in the isolation of five flavonoids namely, acacetin (1), afzelin (2), astragalin (3), kaempferol (4) and scutellarein 7-O-glucoside (5). The AR inhibitory effect of compounds 1-5 was explored; compounds 2, 3 and 5 showed potential AR-inhibitory effects with IC50 values of 2.20, 1.91 and 12.87 µM, respectively. Quantitative analysis of afzelin (2) and astragalin (3) in L. cuneata by high performance liquid chromatography with ultraviolet detection revealed its content to be 0.722-11.828 and 2.054-7.006 mg/g, respectively. Overall, this study showed that L. cuneata is rich in flavonoids with promising AR-inhibitory activities, which can be utilized for the development of natural therapies for treating and managing diabetic complications.

Optimization of Extraction Conditions of Continentalic and Kaurenoic Acids from Aralia continentalis by HPLC/UV and Their Validation.

Aralia continentalis (AC) is a perennial herb that has long been used as a traditional medicine for many diseases. Continentalic acid (CA) and kaurenoic acid (KA) are major diterpenoids in AC, which are known to exert various pharmacological activities. This study focuses on the optimization of the extraction of CA and KA from dried AC roots by evaluating the influence of different extraction conditions on their yield. Five extraction variables were examined: sample weight, solvent concentration, extraction time, solid matrix and the number of repeated extractions. The analytical method used in this study was also validated in terms of linearity, limit of detection, limit of quantification, precision and accuracy. The CA and KA yields were measured by high-performance liquid chromatography analysis. The results show that CA and KA were the highest when unpulverized samples (3.75 g) were subjected to a single extraction for 5 h using 50% ethanol (300 mL) as the solvent. These conditions are proposed for the optimization of the extraction of CA and KA from AC.