The application of elicitors in plant tissue culture technique is one of the most widely used methods to increase secondary-medicinal metabolites. Chitosan, as a biopolymer, induces defense responses, increases the activity of antioxidant enzymes and the phenylpropanoid pathway, and accumulates phenolic compounds. In the present study, to optimize the production of secondary metabolites and increase the antioxidant capacity, the effect of Chitosan bio-elicitor was studied on some phenolic compounds of Teucrium polium. Leaf explants were placed on an MS culture medium containing BAP (1 and 1.5 mg L-1) and NAA (0.5 mg L-1), and Chitosan (0, 50, 100, and 150 mg L-1). After eight weeks of calli growth, the amounts of phenolic derivatives and antioxidant activity (DPPH free radical scavenging activity and FRAP reducing power assay) were measured. The results showed that MS medium supplemented with BAP1.5 + NAA0.5 mg L-1 and 100 mg L-1 Chitosan caused the maximum contents of phenolic derivatives (1884.95 mg 100 g-1 for Phenol, 936.65 mg 100 g-1 for o-diphenol, 1462.28 mg 100 g-1 for flavonoid, 631.07 mg 100 g-1 for flavon, and 662.41 mg 100 g-1 for phenolic acids). In the same treatment, the antioxidant capacities measured based on DPPH and FRAP tests increased by 68.34 and 71.92%, respectively, compared to the control sample. The activity of phenyl-alanine-ammonialyase (PAL) enzyme also increased significantly in calluses induced by Chitosan (65.81% increase compared to the control sample). Therefore Chitosan, as a successful elicitor, is able to promote the synthesis of phenolic secondary metabolites and, as a result, increase the antioxidant power of T. polium callus.

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