Valorization of Unconventional Traditional Leafy Vegetable Diversity for Minerals, Health-Promoting Phytochemicals, and Antioxidants

Traditional leafy vegetables (TLVs) are rich in beneficial bioactive compounds and mineral elements. The rural areas of Kerala, India, have a diversity of unconventional TLVs, and only limited research is available on their nutritional and biochemical composition. Therefore, this study was designed to evaluate the mineral elements, metabolites, antioxidants, antioxidant activity, and proximate composition of 14 TLVs. The results show that among the selected TLVs, Talinum triangulare exhibited the highest Zn (1214 mg/kg DW) content, whereas the highest amount of Ca (13,532 mg/kg DW) was found in Centella asiatica. GC-MS analysis of these 14 plants unveiled a total of 193 metabolites. The metabolic pathways with high impact were associated with alanine, aspartate, glutamate, galactose, and glyoxylate-dicarboxylate metabolism and aminoacyl tRNA synthesis. Several metabolites showed differential expression across the samples. Celosia argentia, Ipomoea batatas (sweetheart cultivar), and Ipomoea aquatica showed the highest expression of metabolites such as caffeic acid and xylitol. I. batatas cv. sidekick black (0.49 mg/mL) and Cnidoscolus aconitifolius (0.135 mg/mL) demonstrated the highest antioxidant activities. The 14 plants had varying levels of fiber (2.01-7.31%), fat (2.68-9.36%), protein (4.55-22.32%), and carbohydrate (34.62-69.3%). Overall, these TLVs have high nutritional potential and health-protecting properties, which can boost the well-being of consumers.