Chemical profiling, phytotoxicity, cytotoxicity, and antibacterial activity of the essential oil of a high-altitude plant, Allardia tridactylites, from the Trans-Himalayan Region, Ladakh.

The era of ongoing research is clearly progressing in the direction of chemical profiling and the evaluation of pharmacological and toxicological potential of plant extracts. The trend of sourcing essential oils (EOs) from various aromatic plants continues to hold great promise, providing anti-inflammatory, antimicrobial, and anticancer compounds as leads. Given this enormous potential, the EO of Allardia tridactylites (Kar. & Kir.) Sch. Bip., a highly unexplored plant from Ladakh widely known for its therapeutic uses, was explored for its phytotoxic and pharmacological potential in the present study, with a special mention of its antigerminative, antibacterial, and cytotoxic activities. The oil was analysed for its chemical constitution using the GC–MS technique and found to contain an almost equal proportion of monoterpenes (44.74%) and sesquiterpenes (45.08%), with α-pinene (15.85%), α-thujone (15.78%), valeranone (17.44%), and α-bisabolol (9.47%) identified as the major compounds. EO was found to be phytotoxic against the weed Bidens pilosa L., as it reduced the germination and seedling length of the weed with increasing concentrations of EO (0.01–0.1 mg mL^–1). The antibacterial effect of EO (at 25–400 µg mL^–1) was evaluated against six bacterial strains: Bacillus cereus, Streptomyces scabiei, Bacillus pumilus, Rhodococcus fascians, Erwinia herbicola, and Pseudomonas syringae. Except for B. pumilus, a strong dose-dependent inhibition was observed in the growth of all the bacteria with EO treatments. R. fascians was found to be the most susceptible to EO (at 400 µg mL^–1). The cytotoxic effect of EO was confirmed by a reduced mitotic index and an increased percentage of chromosomal aberrations (CAs), especially at treatments of ≥ 0.05 mg mL^–1, in Allium cepa L. The type and frequency of CAs also increased at the highest EO concentration. The study concludes that the EO of A. tridactylites possesses strong phytotoxic, antibacterial, and cytotoxic activities and, thus, can be a potential candidate for weed management, alongside its use in the food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]