Assessment of calcium oxalate crystal inhibition potential, antioxidant activity and amino acid profiling in horse gram (Macrotyloma uniflorum): high altitude farmer’s varieties

Abstract

Seeds of Macrotyloma uniflorum collected from different Himalayan regions of Himachal Pradesh, India were screened for inhibition potential of calcium oxalate crystals along with their antioxidant and amino acid profiling. Aqueous, ethanol, 50% ethanol extracts were tested using agar-gel overlay, nucleation, and artificial urine methods in comparison to marketed products. The aqueous extract of Sundernagar and Rampur seeds showed highest inhibition potential (9.0 ± 0.81mm) than alcohol and hydroalcohol. Sundernagar seeds (aqueous extract) also showed maximum inhibition (45 ± 1.2 and 24 ± 0.88%) in nucleation and artificial urine assay, respectively. The Tris-buffer (pH. 8.0) extract of dry seeds showed more inhibition with low protein than high protein germinated seeds. The findings revealed that horse gram protein is not alone responsible for CaOx-crystals inhibition but its secondary metabolites may also contribute. Among all samples, buffer and aqueous extracts showed maximum activity, followed by hydroalcohol and alcohol. Further, TLC and UPLC method were used to monitor the presence of amino acids in aqueous and Cystone extracts. Sundernagar seeds contain 11 amino acids with additional arginine, aspargine, and methionine. Moreover, higher antioxidant potential was observed in seeds of high altitude, which relates the factors of altitudinal variation in secondary metabolism of plants. Therefore, this study will help in the development of economical and more reliable plant based nutraceuticals for kidney stone problems and related health issues.