Essential Oil Variation in Matricaria chamomilla L.: The Impact of Harvest Timing and Flower Development

This study investigates the impact of flower harvesting times on the essential oil (EO) yield and composition of Matricaria chamomilla L. Flowers were collected at various developmental stages, including early flower opening, full flowering (at ۶:۰۰ AM, ۹:۰۰ AM, ۱۲:۰۰ PM, ۳:۰۰ PM, and ۶:۰۰ PM), the end of flowering, and fruit set. EO extraction was performed via hydro-distillation, and volatile components were analyzed using GC and GC/MS. The highest EO yield (۰.۲۸% w/w) was obtained at full flowering at ۱۲:۰۰ PM. This peak may be attributed to increased enzymatic activity, light intensity, and diurnal accumulation of volatile compounds. A total of ۲۲ compounds were identified, making up as much as ۹۶.۴% of the EO profile. Oxygenated sesquiterpenes, particularly α-Bisabolol oxide A (up to ۶۶.۷%), α-Bisabolone oxide A (۱۰.۵%), and α-Bisabolol oxide B (۶.۸%), were predominant at noon and late afternoon. In contrast, trans-β-Farnesene peaked in early morning samples, and chamazulene showed no significant variation across times. Comparison with ISO ۱۹۳۳۲:۲۰۲۰ standards revealed that α-Bisabolol oxide A and α-Bisabolone oxide A exceeded reference values, while chamazulene and trans-β-Farnesene remained below typical ranges. The highest proportion of oxygenated sesquiterpenes was observed at ۱۲:۰۰ PM (۸۰.۲%), suggesting strong pharmacological potential at this time. Minor compounds such as cis-Spiroether and linalool varied slightly by harvest stage. These results demonstrate that both harvest timing and flower developmental stage are critical for optimizing EO yield and therapeutic quality in M. chamomilla.

کلیدواژه ها:

Chamomile ، Essential oil ، Flowering stage ، Harvest timing ، α-Bisabolol oxide A