Flowering phenophases influence the antibacterial and anti-biofilm effects of Thymus vulgaris L. essential oil

Abstract

Background Essential oils are becoming increasingly popular in medicinal applications because of their antimicrobial effect. Thymus vulgaris L. (Lamiaceae) is a well-known and widely cultivated medicinal plant, which is used as a remedy for cold, cough and gastrointestinal symptoms. Essential oil content of thyme is responsible for its antimicrobial activity, however, it has been reported that the chemical composition of essential oils influences its biological activity. In order to explore flowering phenophases influence on the chemical composition of thyme essential oil and its antibacterial and anti-biofilm activity, plant materials were collected at the beginning of flowering, in full bloom and at the end of flowering periods in 2019. Methods Essential oils from fresh and dried plant materials were distilled and analyzed with gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The antibacterial activity was performed by broth microdilution and thin layer chromatography-direct bioautography (TLC-DB) assays and the anti-biofilm effect by crystal violet assay, respectively. Scanning electron microscopy was applied to illustrate the cellular changes of bacterial cells after essential oil treatment. Results Thymol (52.33–62.46%) was the main component in the thyme essential oils. Thyme oil distilled from fresh plant material and collected at the beginning of flowering period exerted the highest antibacterial and anti-biofilm activity against Haemophilus influenzae, H. parainfluenzae and Pseudomonas aeruginosa. Conclusion The different flowering periods of Thymus vulgaris influence the antibacterial and anti-biofilm activity of its essential oils, therefore, the collection time has to be taken into consideration and not only the full bloom, but the beginning of flowering period may provide biological active thyme essential oil.

Antibacterial mechanism of ultrasound combined with thymol against Shewanella putrefaciens: implications for cell integrity and biofilm control

“…Thy possesses both antioxidant and antibacterial activities and is one of the main components in essential oils such as oregano, thyme, and winter peppermint. Thymus vulgar is essential oil, for instance, has been found to exhibit antibacterial activity against various Gram-negative and Gram-positive bacteria by inducing intracellular glycans and protein molecule leakage, altering membrane permeability, and disrupting phospholipid bilayers, ultimately leading to microbial death (Galovicova et al, 2021;Bako et al, 2023).…”

Inhibitory effect of natural compounds on quorum sensing system in Pseudomonas aeruginosa: a helpful promise for managing biofilm community

“…The strongest antibacterial and anti-biofilm activity was shown in thyme oil obtained through distillation of fresh plant material gathered at the onset of the flowering period. This oil demonstrated efficacy against many microorganisms, including P. aeruginosa ( Bakó et al, 2023 ). Finally, a further study on the anti-biofilm properties of thymol found that this powerful plant compound is mostly present in log (30.28%) and stationary phase (20.89%) extracts.…”

New Antimicrobial Strategies to Treat Multi-Drug Resistant Infections Caused by Gram-Negatives in Cystic Fibrosis

“…Among the plant essential oils, immortelle (Helichrysum italicum), Origanum majorana, thyme and citrus showed valuable biofilm inhibition activity against P. aeruginosa and H. influenzae [51][52][53][54].…”

“…Dioon spinulosum extract P. aeruginosa [49] Plant-derived triterpenes (analogs of oleanolic acid) P. aeruginosa, B. cenocepacia [50] Plant essential oils P. aeruginosa, H. influenzae [51][52][53][54] Ceragenins (CSAs) A. xylosoxidans [55] Metalloproteases from stony coral S. maltophilia [56] Vitamin C S. maltophilia [57] Allium stipitatum extract S. maltophilia [58] Glycosyl hydrolases PslG from P. fluorescens Pseudomonas strains…”