Isolation of diverse bioactive compounds from Euphorbia balsamifera: Cytotoxicity and antibacterial activity studies

Salha M Aljubiri; Samir A Mahgoub; Abdulrahman I Almansour; Mohamed Shaaban; Kamel H Shaker

doi:10.1016/j.sjbs.2020.10.025

Isolation of diverse bioactive compounds from Euphorbia balsamifera: Cytotoxicity and antibacterial activity studies

Saudi J Biol Sci. 2021 Jan;28(1):417-426. doi: 10.1016/j.sjbs.2020.10.025. Epub 2020 Oct 27.

Authors

Salha M Aljubiri^{1

2}, Samir A Mahgoub³, Abdulrahman I Almansour¹, Mohamed Shaaban⁴, Kamel H Shaker⁴

Affiliations

¹ Department of Chemistry, College of Science, King Saud University, Riyadh, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
² Department of Chemistry, College of Science, University of Bisha, Bisha 61922, P.O. Box 551, Saudi Arabia.
³ Agricultural Microbiology Department, Faculty of Agriculture, Zagazig University, Zagazig 44511, Egypt.
⁴ Chemistry of Natural Compounds Department, Pharmaceutical and Drug Industries Research Division, National Research Center, El-Behoos st., Dokki-Cairo 12622, Egypt.

Abstract

Antibacterial and cytotoxic activities of Euphorbia balsamifera, fractions and pure compounds were evaluated. The cytotoxic assays for HCT116, HePG2 and MCF7 showed a significant IC₅₀: 54.7 and 76.2 µg/mL of non-polar fraction "n-hexane" against HCT116 and HePG2, respectively. Antibacterial results revealed that plant fractions exhibited significant potential against the tested pathogens than the total extract where n-butanol and ethyl acetate fractions showed significant antibacterial activity (P < 0.05) against tested bacterial strains. Isolation and structure determination of compounds from n-hexane and n-butanol fractions were performed. From n-hexane fraction, 29-nor-cycloartanol (1), lanost-8-en-3-ol (2a), cycloartanol (2b) and kampferol-3,4'-dimethyl ether (3) were isolated and structurally identified, along with 24 compounds were tentatively identified by GC-MS. From the polar n-butanol fraction, 4-O-β-D-glucopyranosyl-2-hydroxy-6-methoxyacetophenone (4), 4-O-α-L-rhamnosyl-(1 → 6)-β-D-glucopyranosyl-2-hydroxy-6methoxy-acetophenone (5), quercetin-3-O-glucopyranoside (6) and isoorientin (7) were assigned. Structures of the obtained compounds were determined by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. Except compounds 1 and 5, all reported compounds announced antibacterial efficiency. Compound 2 showed selectively the highest activity against Enterococcus faecalis (22 ± 0.13 mm), meanwhile 4-O-β-D-glucopyranosyl-2-hydroxy-6-methoxyacetophenone (4) showed broadly the highest antibacterial activity with MIC of 1.15-1.88 mg/mL against the test Gram-positive and Gram-negative bacteria. Cytotoxic assays indicated that kampferol-3,4'-dimethyl ether (3) exhibited the highest activity with matching IC₅₀ values to doxorubicin; 111.46, 42.67 and 44.90 µM against HCT116, HePG2 and MCF7, respectively, however, it is toxic on retina normal cell line RPE1.

Keywords: 1H–1H COSY, Proton Correlation Spectrometry; Antibacterial; Asir region; Cytotoxicity; DEPT, Distortionless enhancement by polarization transfer; E. balsamifera, Euphorbia balsamifera; ESIMS, Electrospray Ionization Mass Spectrometry; Euphorbia balsamifera; GC–MS; GC–MS, Gas Chromatogrphy/ Mass Spectrometry; HCT116, Colon cell line; HMBC, Hetero-nuclear multiple bond correlation spectroscopy; HMQC, Hetero-nuclear multiple quantum correlation spectroscopy; HSQC, Heteronuclear single quantum coherence spectroscopy; HePG2, Human hepatocellular carcinoma cell line; Isolation; J, Coupling Constant; MCF7, Human Caucasian breast adenocarcinoma; MTT, Colorimetric assay for measuring cell metabolic activity as an indicator of cell viability, proliferation, and cytotoxicity; Spectroscopy; TLC, Thin-layer Chromatography; d, Doublet; dd, Doublet of doublet; δ, Chemical shift (in ppm).