Elsevier

South African Journal of Botany

Volume 141, September 2021, Pages 357-366
South African Journal of Botany

Bioactive compounds from Euphorbia schimperiana with cytotoxic and antibacterial activities

https://doi.org/10.1016/j.sajb.2021.05.021Get rights and content
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Highlights

  • Euphorbia schimperiana is a rich natural source for bioactive secondary metabolites.

  • Ethyl acetate and n-hexane fractions are highly recommended to be used for further vivo study against PC3 cell line with no/low cytotoxicity against normal cell line.

  • 4-O-ethylgallic acid (7) is reported from Euphorbia genus for the first time.

  • 3,3′-di-O-methylellagic acid (5) has a selective cytotoxicity against PC3 as a pure compound with low cytotoxicity against the normal cell.

  • Antibacterial efficiency of 4-O-ethylgallic acid (7) has a significant against Gram-positive and Gram-negative bacteria.

Abstract

Cytotoxicity and antibacterial activities of Euphorbia schimperiana total extract, fractions, and isolated secondary metabolites were investigated. The cytotoxicity assays were assessed against four human cancer cell lines HCT116, MCF7, HePG2, and PC3 as well as against normal cell line RPE1. The plant total extract, fractions, and pure compounds were more effective against PC3 and HepG2 cell lines than HCT116 and MCF7. Significant results were observed for ethyl acetate and n-hexane fractions against PC3 with IC50 of 4.7 μg/ml for ethyl acetate, however, n-hexane exhibited 100% cytotoxicity up to 6.25 μg/ml. The antibacterial potential activity was achieved on four pathogenic Gram-positive and four Gram-negative bacteria. The results showed that ethyl acetate and n-butanol fractions had more valuable results (p < 0.05) against the tested pathogenic bacteria than total extract and n-hexane fraction. The major components of n-hexane were determined by GCMS analysis and 14 compounds were tentatively identified. Chromatographic isolation of ethyl acetate and n-butanol afforded 7 secondary metabolites: Quercetin (1), quercetin-3-O-α-glucuronide (2), quercetin-3-O-β-D-glucuronide-methyl ester (3), quercetin-3-O- α-L-rhamnoside (4), 3,3′-di-O-methylellagic acid (5), 3,3′-di-O-methyl-ellagic acid-4-β-D-xylopyrnoside (6) and 4-O-ethylgallic acid (7). Structures of the obtained compounds were elucidated by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. The inhibition zones of pure compounds revealed that compounds 4,6 and 7 exhibited antibacterial efficiency against all tested strains. A significant inhibition for 4-O-ethylgallic acid (7) was recorded against Listeria monocytogenes (LM) and Staphylococcus aureus (SA). Promising cytotoxicity of pure compounds was observed for 3,3′-di-O-methylellagic acid (5) against PC3 with IC50 of 5.5 μg/ml.

Keywords

Pathogenic bacteria
Cytotoxicity
Spectroscopy
Euphorbia schimperiana
Chromatography
GCMS

Abbreviation

CC
Column chromatography
d
Doublet
dd
Doublet of doublet
E. schimperiana
Euphorbia schimperiana
EIMS
Electron Ionization Mass Spectrometry
ESMS
Electron Spray Ionization Mass Spectrometry
GCMS
Gas Chromatography/ Mass spectrometry
1H-1H COSY
Proton Correlation Spectrometry
HMBC
Hetero-nuclear multiple bond correlation spectroscopy
HSQC
Heteronuclear single quantum coherence spectroscopy
HCT116
Colon cell line
HePG 2
Human hepatocellular carcinoma cell line
HPLC- RP
High-performance liquid chromatography- Reversed-phase
IC50
The half-maximal inhibitory concentration
J
Coupling Constant
NMR
Nuclear Magnetic Resonance
MCF7
Human Caucasian breast adenocarcinoma
MTT
colorimetric assay for measuring cell metabolic activity as an indicator of cell viability, proliferation, and cytotoxicity
PC3
Prostate cell line
RPE1
normal retina cell line
TLC
Thin-layer Chromatography
UV
Ultraviolet
δ
Chemical shift (in ppm)

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