Analysis of secondary metabolites in agricultural residues of jicama (Pachyrhizus erosus) under biotic stress by UV spectrophotometry and HPLC

Jicama (Pachyrhizus erosus) is a rustic growing plant, of which the only edible part is its tuberous root. It is native to Mexico and Central America, with a national production of 187,916.54 tons in 2023. Currently, the plant has been affected by the attack of pests such as Phyllophaga spp. (white grub), causing economic losses for agriculturalists and an increase in agro-industrial residues which have not been given any use. In addition, there are no studies that evaluate the presence of secondary metabolites when jicama is under biotic stress (damage by pests) that could generate toxic compounds such as cyanogenic glycosides, or even some with functional properties such as flavonoid glycosides and hydroxycoumarins, which develop during the process of plant direct defense , especially against the attack of insects. For the above, the present work aims to carry out a comparative study of secondary metabolites, as well as compounds of industrial interest present in healthy and plague-damaged jicama (Pachyrhizus erosus). To this end, the following are proposed to determine the presence of secondary metabolites in healthy (CJ) and damaged jicama damaged by Phyllophaga spp. (SJ), and will qualitatively be established; finally, the cyanogenic glycosides, hydroxycoumarins, and flavonoid glycosides will be characterized by HPLC. According to the results, the extracts that presented the highest content of saponins were those of jicama at 100 and 140 days of maturity in jicama with stress, decreasing in control jicama. In tannins, no significant differences were observed between the samples at 100 and 180 days, while at 140, the stressed jicama had the highest tannin content; in the case of flavonoids and phenols, the same behavior was observed at 100 and 140 days. The following were found in phenolic compounds: ascorbic, caffeic, rutin, pelargonidin, and ferulic acid. Finally, these results provide a broad understanding of jicama by providing information about morphometric, nutritional, and secondary metabolite changes during the tuberization process.