Unravelling the metabolomic pool of Ocimum microgreens under diverse growing conditions through targeted compound analysis and non-targeted UHPLC-QToF-IMS based approach

Abstract

Ocimum Sanctum L. (Basil) is a perennial herb belonging to the Lamiaceae family. The composition of microgreens is influenced by environmental conditions. Consequently, Ocimum microgreens were cultivated under varying growing conditions, assessing average height, total chlorophyll content, targeted compounds, and non-targeted UHPLC-QToF-IMS-based metabolomic profile. Under T3 growing condition (longer photoperiod of 22 h with 26 °C in light and 20 °C in the dark), Ocimum microgreens exhibited approximately 43% and 26% increases in average height and chlorophyll content, respectively. The targeted phenolic profile analysis identified gallic acid, caffeic acid, and resveratrol in microgreens. The growing conditions significantly influenced the phenolic profile. Also, sugar profiling indicated elevated levels of myo-inositol, glucose, fructose, sucrose, and d-raffinose under longer photoperiods with T3 conditions. Furthermore, microgreens exhibited a high abundance of amino acids such as aspartic acid, glutamic acid, proline, arginine, and phenylalanine. Notably, proline concentration increased from 13.40 mg/g to 25.15 mg/g in response to T3 growth condition. The comprehensive non-targeted UHPLC-QToF-IMS analysis revealed various metabolite classes, including organic compounds, phenolic and flavonoid derivatives, alkaloids, terpenoids, amino acids, sugars, polyalcohol and a few nucleic acid derivatives. Also, some organic acids, specifically rosmarinic acid, salvianolic acid D, and chicoric acid, showed highest expression level under T3 condition.