PHYTOCHEMICAL INVESTIGATION AND ANTIBACTERIAL ACTIVITY TESTS ON ROOT EXTRACT OF EUPHORBIA CANDELABRUM

Abstract

Euphorbia candelabrum is a medicinal plant that is known to be used for the treatment of various diseases such as coughs, tuberculosis, malaria, and wound healing and for treating various skin disorders in different communities. This study aimed to investigate the chemical constituents and characterize the compounds isolated from the root extract of Euphorbia candelabrum using UV-Vis and FT-IR spectroscopy as well as to test its antibacterial activity. Due to its medicinal importance, the plant material was collected from, the Sika kebele, Bule woreda, Gedeo zone, Southern Ethiopian region. The plant material was air dried and sequentially extracted with n-hexane, dichloromethane, dichloromethane/methanol (1:1 v/v) and methanol. Phytochemical screening of the dichloromethane, dichloromethane/methanol (1:1 v/v) and methanol crude extracts revealed the presence of alkaloids, flavonoids, phenols, glycosides, terpenoids, tannins, saponins and steroids, whereas the n-hexane crude extracts contained alkaloids, glycosides, terpenoids, steroids and saponins. The total contents of flavonoids, phenolics, alkaloids, and steroids in the dichloromethane/methanol (1:1 v/v) crude extract were 10.47 mg QE/g, 13.4 mg GAE/g, 1.426 mg AE/g, and 2.91 mg DE/g , respectively. The methanol extract contained 11 mg QE/g, 19 mg GAE/g, and 2.1 mg AE/g of extract for the total of flavonoid, phenolic, and alkaloid contents, respectively. Column chromatographic separation of dichloromethane/methanol (1:1 v/v) resulted in the isolation of three compounds (KJ-1, KJ-2 and KJ-3) and structure of the isolated compounds were not fully characterized due to lack of NMR instrument. The crude extracts and isolated compounds were tested against four bacterial strains in vitro (E. coli, P. aeruginosa, S. aureus and S. pyogen) using the disc diffusion method. The antibacterial activity tests revealed that the isolated compounds had greater activity than did the crude extracts. Notably, compound KJ-3 demonstrated the highest antibacterial activity against all tested bacterial strains than crude extracts and isolated compounds but slightly lower than that of the reference drug tetracycline. The present study indicated that the root of Euphorbia candelabrum could be a good source of compounds for the discovery of antibacterial agents because in vitro tests were carried out on several bacterial strains.