Quantification of Bioactive Constituent D-Pinitol in Ethiopian Soybean

Vegetable soybean (Glycine max) is well established legume in the human diet in all over the world. D-Pinitol is a natural product belonging to groups of Cyclitols. D-pinitol plays tremendous medicinal roles. The aim of this work is to quantify the bioactive constituent D-Pinitol from seeds, seed pods and leaves of soybean. D-Pinitol extraction of soybean was processed with methanolic extraction followed by quantification using a UV spectrophotometer in comparisons with the Caro pinitol®. The maximum wavelength and absorbance of the standard dissolved in laboratory reagent water were 193 nm and 0.904 respectively. The best-fit line, R2, was found to be greater than 0.9983, indicating the D-pinitol’s concentration has significant effect on D-pinitol’s absorbance over a concentration range of 31.25-1000.0 μg/mL. The mean recovery of the method was 94.3 ± 8.06%. The absorbance of the serially diluted standard of 31.25 μg/nL, 62.5 μg/mL, 125 μg/mL, 250 μg/mL, 500 μg/L and 1000 μg/mL at 193 nm is 0.032, 0.042, 0.096, 0.205, 0.375, and 0.714, respectively. The absorbance of the samples Nyala seed (so), Nyala seed (mz), Nova seed (so), Nova seed (mz), Nyala seed pod (so), Nova seed pod (so), Nyala leaf (so) and Nova leaf (so) at 193 nm were 0.237, 0.267, 0.307, 0.204, 0.213, 0.276, 0.24 and 0.263, respectively. The quantity (gm) of D-pinitol within 25 gm crude extract of Nyala seed (so), nyala seed (mz), nova seed (so), nova seed (mz), nyala seed pod (so), nova seed pod (so), nyala leaf (so) and nova leaf (so) were 16.2, 18.4, 21.3, 13.9, 14.5, 19, 16.5 and 18.1, respectively. The quantitative values of all varieties are closer to each other and this may be attributed to the similarity between the sampling areas, South Omo and Metekel zone. Generally, the Ethiopian soybean has high Dpinitol content. The pairwise comparison using the Student’s t-test shows no significant difference, p>0.05, between the content of D-pinitol in seed, seed pod and leaf.