Comparison of total chlorophyll, carotene and phenolic contents between species/varieties of Sri Lankan green leafy vegetables Sesbania grandiflora, Centella asiatica and Ipomea aquatica

Abstract

Green Leafy Vegetables (GLVs) are rich sources of phytochemicals which are beneficial to reduce chronic non-communicable diseases due to their therapeutic properties such as antioxidant activity. Among numerous dietary supplements of phytochemicals, GLVs are under spotlight as they are rich sources of phenolics and natural pigments including chlorophylls and carotenoids. Availability and the amount of these phytochemicals may vary depending on many factors including the variety of GLVs. The aim of this study is to quantitatively analyze the phytochemical contents; total phenol, chlorophyll and carotene among 3 selected GLV species and 2 varieties of each, Sesbania grandiflora, Centella asiatica and Ipomea aquatica. Each home garden grow variety was acquired from same geographical location which have similar growth conditions. Edible parts of each sample were well washed, air dried at room temperature under shade, and oven dried at 45 ºC to obtain a constant weight. Dried samples were ground and tests were carried out using homogenous sample powder. Total chlorophyll and carotene contents were determined by measuring the absorbance (at the wavelengths of 470 nm, 645 nm and 662 nm) of methanolic extracts and using formulas. Total chlorophyll content in leafy vegetables ranged from 13.75 to 35.56 μg/g dry weight of the sample. The highest chlorophyll content was observed in S. grandiflora variety 1 (V1), whereas the lowest chlorophyll content was observed in I. aquatica variety 2 (V2). The carotene content of studied leaf samples was within the range of 1.08 to 3.89 mg/g dry weight of the sample. S. grandiflora V1 had the highest carotene content whereas the lowest carotene content was observed in C. asiatica V1. Total Phenolic Content (TPC) was determined by the Folin-Ciocalteu method by measuring the absorbance at 760 nm using the methanolic extracts of leaf samples. TPC were within the range of 3.62 to 18.19 mg GAE/g dry weight of the sample. S. grandiflora V1, leaves showed the highest TPC as 18.19 mg GAE/g dry weight of the sample and the lowest TPC was observed in C. asiatica V2 as 3.62 mg GAE/g dry weight of the sample. The results were analyzed in one-way analysis of variance ANOVA test, which showed a statistically significant difference between species/varieties (p