Study of yeast extract and salicylic acid elicitors effects on percentage of cell survival and the amount of beta-caryophyllene and isopulegone secondary metabolites in Pennyroyal (Mentha pulegium) cell culture

Plant tissue and cell culture is being used as a stable method to investigate plant secondary metabolites widely. Because of the important position of Pennyroyal (Mentha pulegium) in food industries, sanitary and pharmaceutical fields, cell culture is done to investigate effectiveness of different concentrations of yeast extract and salicylic acid on the cell survival and the amount of β-Caryophyllene and Iso-Pulegone secondary metabolites. MS medium with 1 mg/l 2,4-D without agar was used with different concentrations of yeast extract and salicylic acid to investigate amount of secondary metabolites. after ten days, the amount of these two secondary metabolites were investigated by GC-MS and the cell survival was investigated by tetrazolium test. In the cell culture, percentage of cell surviving was decrease by increasing density of two elicitors and amount of β-Caryophyllene secondary metabolite significantly increased compared to the natural plants (maximum amount of this metabolite was obtained in the cell culture containing yeast extract 80 mg/l). Given that increasing the amount of secondary metabolites is the main purpose of the plant cell culture, the use of high concentrations of elicitor to increase β-Caryophyllene is justified despite the decrease in cell viability. Percentage of Iso-Pulegone secondary metabolite was in the natural plant more than the cell culture and also in the cell suspension culture, amount of this metabolite was decrease by increasing density of yeast extract and salicylic acid elicitors, thus cell culture containing these two elicitors is not recommended to increase amount of this secondary metabolite.