Nutritional evaluation, antioxidant studies and quantification of poly phenolics, in Roscoea purpurea tubers

Roscoea purpurea (Zingiberaceae) is commonly known as "kakoli". Traditionally, various parts like leaves, roots and flower etc. are used for the treatment of diabetic, hypertension, diarrhea, fever, inflammation etc. In Nepal tubers are boiled for edible purpose and also used in traditional veterinary medicine. The study aims for nutritional characterization, chemical profiling of R. purpurea (tubers) methanol extract (RPE) along with evaluation of its anti-oxidant activity. Physicochemical and nutritional content were estimated as per standard protocols. Chemical profiling of markers includes method optimization, identification & quantification of bioactive poly phenolics through HPTLC. Anti oxidant potential RPE was analyzed via. Total phenolics (TPC), total flavonoids (TFC), reducing power assay, DPPH and β-carotene bleaching model.

Physicochemical and nutritional standards were established. Kaempferol (0.30%), vanillic acid (0.27%), protocatechuic (0.14%), syringic (0.80%) and ferulic acid (0.05%) were identified and then quantified. TPC and TFC content were found to be 7.10 ± 0.115 and 6.10 ± 0.055%, reducing power of extract also increases linearly (r(2) = 0.946) with concentration, similar to standards. IC50 value of extract in DPPH and β-carotene bleaching model was observed at 810.66 ± 1.154 and 600.66 ± 1.154 µg/ml, which is significantly different from standards (p < 0.05). Although there is a positive, significant correlation between the phenolic and flavonoid content with anti oxidant activity of extract.

Thus, study will authenticates the identity, utility of herb as nutrient supplement and an important medicinal plant having promising pharmacological activities for further elaborated/extended investigation work.