ABSTRACT
Objective: To determine the best time of harvest for Melissa officinalis (M. officinalis) L. to gain highest amounts essential oil.Methods: M. officinalis leaves were harvested in three different stages (before flowering stage, flowering stage and after of flowering stage) and were dried. The essential oils were isolated by hydro- distillation and analyzed by GC/MS.Results: It showed that most essential oils of plants were in before flowering stage. In before flowering stage 37 compounds were identified in leaves oil of M.officinalis. The major components before flowering stage were decadienal (29.38%), geraniol (25.3%), caryophyllene oxide (8.75%), geranyl acetate (5.41%). In the flowering stage 36 compounds were identified as the major components of plant essential oils: decadienal (28.04%), geraniol (24.97%), caryophyllene oxide (7.55%), caryophyllene E (4.65%) and 16 components in the after flowering stage of plant were identified as the major components carvacrol (37.62%), methyl citronellate (32.34%), geranyl acetate (5.82%), caryophyllene (5.50%).Conclusions: The essential oils yields vary considerably from month-to-month and is also influenced by the micro-environment (sun or shade) in which the plant is growing. We found that the essential oil content of M. officinalis L. of leaves is significantly affected by harvesting stages.