A comprehensive multi-directional exploration of phytochemicals and bioactivities of flower extracts from Delonix regia (Bojer ex Hook.) Raf., Cassia fistula L. and Lagerstroemia speciosa L

Delonix regia (Bojer ex Hook.) Raf., Cassia fistula L. and Lagerstroemia speciosa L. are three ornamental plants that produce colorful flowers. The present study aimed to evaluate the phytochemicals and bioactivities of methanolic extracts of flowers from Delonix regia (DrFME), Cassia fistula (CfFME), and Lagerstroemia speciosa (LsFME). The presence of ten different chemical classes in varying degrees was confirmed while qualitatively screened. During quantitative determination, LsFME possesses the highest amount of total phenolic (418.0 mg/g), flavonoid (50.8 mg/g), and tannin (256.3 mg/g) contents. The extracts showed excellent antioxidant capacity in a concentration-dependent manner with the lowest IC50 value (41.51 μg/mL) displayed by LsFME. LsFME paralyzed the experimental worms at 2.95 min and killed at 3.96 min. DrFME was found to be more effective in thrombolytic (35.5% clot lysis) and anticoagulant activities. Negligible hemolytic activity (IC50 > 200 μg/mL) found for all extracts which suggest their less potential toxicity. The in vivo experiments revealed that the CfFME has the highest analgesic (64.34% pain inhibition) activity while LsFME has the highest antidiarrheal (70.27% inhibition) and antihyperglycemic (46.94% inhibition) activities at 400 mg/kg of body weight doses. This study has shown the presence of phytochemicals and potential bioactivities which indicates the possibility of these flowers to be used as a source of phytochemicals as well as safe and effective natural medicine.

Keywords: Bioefficacy; CE, Catechin equivalent; CfFME, Cassia fistula flower methanolic extract; DPPH, 2,2-diphenyl-1-picrylhydrazyl; DrFME, Delonix regia flower methanolic extract; Flowers; Folk medicine; GAE, Gallic acid equivalent; IC50, Half-maximal inhibitory concentration; LsFME, Lagerstroemia speciosa flower methanolic extract; Mice model; Ornamental plants; PT, Prothrombin time; Phytoconstituents; SEM, Standard error of the mean; TAE, Tannic acid equivalent; TFC, Total flavonoid content; TPC, Total phenolic content; TTC, Total tannin content; UV, Ultra-violet; aPTT, Activated partial thromboplastin time.