Impact of circadian rhythm and seasonal variability on the essential oil of Allium stracheyi Baker from Uttarakhand, Himalaya

This study presents the first report on the volatile composition of Allium stracheyi Baker, evaluating the impact of seasonal variability and circadian rhythm on the yield and chemical composition of its essential oil. Seasonal analysis involved leaf collection during three distinct seasons (dry, transition, and rainy), while the circadian study examined oil composition at three-hour intervals from 6 AM to 6 PM. Essential oils were extracted via hydrodistillation and analyzed using GC–MS. The highest essential oil yield (1.02 %, v/w) was recorded in the dry season (May), while the lowest yield (0.15 %) was observed in the rainy season. Circadian analysis revealed yield variations from 0.02 % (6 AM) to 1.02 % (12 PM), with peak production at 12 PM and 3 PM. A total of 78 compounds were identified and classified into seven major groups: organosulfur compounds, fatty acids, esters, phenols, terpenoids, amines, and ketones. The abundance of organosulfur compounds has significant potential for its application in natural preservatives, flavor enhancers, antimicrobial agents, and therapeutic products. Ethylthioacetone (21.96 %), identified exclusively in the dry season, is reported for the first time in the Allium genus. However, no significant correlation (p > 0.05) was observed between essential oil yield or composition and climatic variables. Although this study highlights the commercial relevance of the species in the food, pharmaceutical, and cosmetic industries by identifying key bioactive compounds, it promotes the integration of sustainable harvesting with traditional knowledge and modern product development. Furthermore, this study provides an in-depth analysis of A. stracheyi, highlighting its potential to contribute to the economic growth of local communities residing in the high-altitude regions of Uttarakhand, where agriculture is a primary livelihood, thereby paving the way for further research and commercial utilization.