Lactuca sativa (lettuce) is an edible plant commonly used by local communities for the management of diabetes and stomach problems. This study focuses on the optimization of hydroponic conditions to investigate the effects of heavy metal stress on the lettuce. In the second part, in vitro pharmacological effects of plant extracts of hydroponically grown lettuce (HyL), in comparison with heavy metals stress induced (HyCd, HyCr and HyPb) were studied. Among three heavy metals, including Cd, Cr and Pb; Pb showed comparatively positive effects on morphological and physiological changes in lettuce, including leaf length, plant height, number of leaves, stem girth, root fresh weight, shoot dry weight, shoot fresh weight, and root dry weight of plants. The highest salt tolerance was estimated at 0.256 mM of Cd, Cr and Pb respectively. So, we selected plants from 0.256 mM salt stress and extracts were prepared in DMSO for in vitro pharmacological studies. Results showed that the highest levels of TPC, TFC, TAC and TRP contents were quantified in HyL, while among the stress induced plants the contents were highest in HyPb. In lipid peroxidation, DPPH and DNA damage assay HyPb showed comparatively better activity than HyCd and HyCr. The results of α-glucosidase inhibition assays represented good inhibition potential by HyL (IC₅₀ 1.09 mg/ml). In stress plants, HyPb showed comparatively better activity than HyCd (IC₅₀ 1.30 mg/ml) and HyCr (IC₅₀ 1.28 mg/ml), having IC₅₀ value 1.25 mg/ml. In α-amylase, acetylcholinesterase and butyrylcholinesterase assays, the lowest IC₅₀ value was shown by HyPb, following HyCd and HyCr. Overall, the study showed that Lactuca sativa is enriched with medicinal effects and these effects can be further enhanced using controlled conditions like hydroponics.

Index Terms- Antioxidant, Enzyme inhibition, Hydroponics, Heavy metal stress,