Effects of harvest time and plant part on essential oils, phenolics, and antioxidant activity in Lippia citriodora

This study investigates the effects of harvest time and plant parts on the concentrations of essential oils, phenolic content, flavonoids, and antioxidant activities (ABTS and DPPH) in the Lippia citriodora plant to determine the best outcome. The experiment consists of four different harvest times during flowering period and two plant parts (upper and lower). Harvest times were scheduled at weekly intervals.Significant variations were observed during experiment, Essential oil (EO) content reached peak value at the first harvest in upper parts of plants (L1U: 1.18%) and lowest value in lower parts by the fourth harvest (L4L: 0.25%). The highest phenolic content determined at the first harvest (L1: 44.04 mg GAE/g DW), while flavonoid levels reached peak value at the fourth harvest (L4: 314.07 mg rutin/g DW). Antioxidant activities, measured by ABTS and DPPH assays, were significantly greater in lower plant parts. Partial Least Squares Discriminant Analysis (PLS-DA) and Principal Component Analysis Discriminant Analysis (PCA-DA) confirmed clear distinctions between the upper and lower parts of the plant regarding bioactive compounds concentrations. The findings shows the importance of targeted harvest timing and plant parts in optimizing bioactive compound in Lippia citriodora, with implications for getting better benefits from plant.