Phytochemical investigations, antioxidant, cytotoxic, antidiabetic and antibiofilm activities of Kalanchoe laxiflora flowers

Kalanchoe laxiflora (Family Crassulaceae) contains different bioactive phytochemicals, which possess several biological activities. The present study aimed at assessing the antioxidant, cytotoxic, antidiabetic, and antibiofilm activities of Kalanchoe laxiflora flower extracts, as well as identification of their phytochemicals. The total phenolic and flavonoid contents of the tested extracts were investigated using Folin-Ciocalteu's and aluminum trichloride methods, while the antioxidant, cytotoxic, antidiabetic and antibiofilm activities were evaluated using different biomedical assays. The phytoconstituents of K. laxiflora flower extracts were profiled using LC-ESI(-ve)-MS analysis. The phytochemical investigations showed that the n-BuOH fraction had the highest total phenolic content (397.25 ± 1.18 mg GAE / g ext.) and flavonoid content (99.71 ± 0.24 mg RE / g ext.). The n-BuOH fraction also possessed the most potent antioxidant activities (DPPH; SC50=18.72 ± 1.81 µg/mL, RPA; 78.26 ± 0.49 mg AAE /g ext.), and TAC; 446.37±0.23 mg AAE /g ext.) and cytotoxic potential in HepG2 cells with IC50= 9.15±0.33 μg/mL. Furthermore, it exhibited the strongest α-amylase and α-glucosidase inhibitory activities (IC50= 54.72±0.96 µg/mL and 89.02±0.99 µg/mL, respectively). Whereas, the 85% methanolic extract exhibited the highest antibiofilm activity against Escherichia coli (MBIC100= 15.63 µg/ml). Additionally, the LC-ESI(-ve)-MS analysis of K. laxiflora extracts led to the characterization of a total of 35 compounds classified as flavonoid glycosides, gallotannins, alkaloids and fatty acids, which were considered to be the major components. K. laxiflora extracts reduce ROS, improve antidiabetic responses and inhibit bacterial growth. The identification of K. laxiflora specific phytoconstituents will provide a starting point to carry out further in vivo studies on these extracts.