Comparison of Volatile Constituents, Antioxidant and Antimicrobial Activities of Thymus leucotrichus (Lamiaceae) Stem and Leaves Essential Oils from Both Natural Resources and In vitro Derived Shoots

Abstract

This study aimed to compare the volatile constituents, antioxidant and antimicrobial potentials of Thymus leucotrichus essential oils (EOs) obtained from natural plants and in vitro derived shoots. MS medium fortified 0.5 mg/L kinetin was preferred for an efficient micropropagation protocol and was produced T. leucotrichus shoots. The most efficient antioxidant activity was up to IC₅₀ 0.823 μg/ml in DPPH, 275.021 mg TE/ml in TEAC, and 25.531 mg GAE/ml in reducing power were found. Total phenolics were determined as 69.249 mg/ml GAE in micropropagated samples while 63.377 mg/ml GAE in natural resources. Thymol was determined as the main volatile compound of both natural plants and in vitro derived shoots. The EOs showed a strong antimicrobial effect on selected seven gram-positive, nine gram-negative bacteria, seven gram-negative aquatic bacteria and a fungus. The highest disc diffusion value was obtained as 44.3 mm for P. damselae subsp. damselae from in vitro derived shoots. In both groups of tested EOs, the most effective MICs were obtained with 12.21 μg/ml against V. parahaemolyticus. The novelty of this report is the first comprehensive and comparative study on volatile constituents, antioxidant, and antimicrobial properties of naturally growing plants and in vitro derived shoots of T. leucotrichus.

Key words:

• Antimicrobial
• biological activity
• essential oil
• micropropagation
• Thymus leucotrichus