Comparative analysis of the antibacterial efficacy and bioactive components of Thuja occidentalis obtained from four different geographical sites

Abstract

The purpose of this study was to determine whether or not there were significant differences in the antibacterial potential of Thuja occidentalis collected from four distinct geographical sites, namely Chamba (Himachal Pradesh, India), Jalandhar (Punjab, India), Aurangabad (Bihar, India) and Kakching (Manipur, India). The plant extracts were prepared in three different solvents: ethanol, methanol, and acetone. The antibacterial potential of the plant extracts was tested against five different bacterial species using well diffusion test. The minimum inhibitory and bactericidal concentrations of the plant sample exhibiting maximum zone of inhibition against different bacterial strains were calculated. Further, the total phenols, flavonoids, and antioxidant efficacy (using DPPH assay) were also analysed biochemically. The activity of different antioxidant enzymes including SOD, CAT and APX were also recorded as these enzymes protect the cells from free radical damage. GC-MS analysis was also performed on all plant extracts to identify the bioactive components. The results showed that the T. occidentalis collected from the Kakching, Manipur, East side of India showed the highest zone of inhibition against all the bacterial strains, followed by Chamba, Jalandhar, and lastly Aurangabad. To analyse the impact of phytochemicals on the antibacterial efficacy, a correlation was drawn between the biochemical parameters and zone of inhibition using Karl Pearson's method. Most bacterial species demonstrated a positive correlation between antibacterial effectiveness (zone of inhibition) and biochemical markers. The GC-MS study revealed positive correlation between zone of inhibition and peak area percentages of α-Pinene, β-caryophyllene, Germacrene-D, and Humulene in all bacterial species indicating that these chemicals may play a key role in the bactericidal potential of T. occidentalis. Based on the results of this investigation, it is evident that the antibacterial effectiveness of T. occidentalis varies with its geographical location which may be attributed to the differences in the phytochemical makeup.

Keywords: Antibacterial; Antioxidant; DPPH; GC–MS; Phenols; Thuja occidentalis.