Chemical, physical, and biological evaluation of hydro-distilled essential oil from leaves of Ethiopian thymus species

Abstract

Physicochemical profile, phytochemical constituents, bioactivity, and thermal stability of the hydro-distilled essential oil (EO) for T.schimperi and T.serrulatus were investigated. EO yield for T.schimperi and T.serrulatus was 2.05± 0.09% and 1.2 ± 0.3% (w/w) respectively. The chemical profiles of the EO were analyzed using GC-MS (Gas Chromatography-Mass spectrometry).Twenty one (99.99 %) and Twenty (98.59%) EO components were identified from T. schimperi and T.serrulatus, respectively. The two stage mass losses, the first one (38%) was from 37°C to 164°C and (55%) from 46°C to 178°C for T.schimperi and T.serrulatus EO respectively and the second one was (11%) from 164°C to 220°C for T.schimperi and (8%) from 178°C to 223°C for T.Schimperi and T.serrulatus EO respectively were observed for TGA analysis.The essential oils in this study showed a strong antioxidant effect for different tests. IC50 value of 0.17 μg/mL on DPPH assay for both species; 73 ± 0.50 and 64 ± 3.4% inhibition for ABTS assay 4.6 ± 0.42 and 8.04 ± 0.9 mM Fe+2/mL percent in FRAP assay for T.schimperi and T.serrulatus respectively. Antimicrobial activities for both species EOs were investigated on Escherichia coli, Staphylococcus aureus, Salmonella typhi, and Streptococcus epidermidis. MIC values for E.coli and S.typhi were 0.5 and 1 μL/mL for T.schimperi, 2 and 4 μL/mL of T.serrulatus EO, for S.aureus and Streptococcus epidermidis were 0.2 and 4 μL/mL for T.schimperi, 2 and 0.5 μL/mL for T.serrulatus EO’s. MBC values for both E.coli and S.typhi were 2 μL/mL for T.schimperi and 4 μL/mL for T.serrulatus EO, While for S.aureus and Streptococcus epidermidis were 1 and 4 μl/ml for T.schimperi, 2 and 8 μL/mL for T.serrulatus EO.

Keywords

• Thymus schimperi
• T.serrulatus
• essential oil
• antibacterial activity
• antioxidant activity
• thermogravimetric analysis