Phytochemical analysis, evaluation of antioxidant activity, and investigation of antibacterial activity in euphorbia candelabrum root extracts

• Euphorbia candelabrum is plant rich in many secondary metabolites which could be attributed to be its traditional medicinal uses. • The methanol crude extract contained the highest quantities of phenolics, flavonoids and alkaloids. • The methanol root extract of Euphorbia candelabrum exhibited larger inhibition zones against gram positive bacteria. • Euphorbia candelabrum root may serve as a valuable source of natural antibacterial agents. Euphorbia candelabrum is a medicinal plant traditionally used for treating coughs, tuberculosis, malaria, wound healing, and various skin conditions. This study aimed to analyze the secondary metabolites present in its root extract and evaluate its antioxidant and antibacterial properties. Samples were collected from Sika Kebele in the Gedeo Zone of Southern Ethiopia, air-dried, and then extracted using hexane, dichloromethane, a methanol:dichloromethane mixture (1:1 v/v), and methanol. Phytochemical analysis revealed the presence of alkaloids, flavonoids, phenolics, glycosides, terpenoids, tannins, and saponins in the dichloromethane, methanol:dichloromethane 1:1 mixture, and methanol extracts. In contrast, the hexane extract contained only alkaloids, terpenoids, and steroids. Notably, the methanol:dichloromethane extract yielded flavonoids (10.47 mg QE/g), phenolics (13.4 mg GAE/g), alkaloids (1.426 mg AE/g), and steroids (2.91 mg DME/g). The methanol extract demonstrated higher levels of flavonoids (11 mg QE/g) and phenolics (19 mg GAE/g). Antibacterial activity was assessed against E. coli, P. aeruginosa, S. aureus, and S. pyogenes using the disc diffusion method. The isolated compounds exhibited greater antibacterial activity than crude extracts, with compound KJ-3 showing greater activity against all tested strains, slightly less tetracycline. These findings suggest that the root of Euphorbia candelabrum may serve as a promising source for the development of new antibacterial agents.