Polysaccharide elicitors enhance phenylpropanoid and naphtodianthrone production in cell suspension cultures of Hypericum perforatum

Hypericum perforatum cell suspensions were evaluated for their growth, phenylpropanoid and naphtodianthrone productions, and antioxidant activity after treatments with polysaccharide elicitors chitin (CHI), pectin (PEC) and dextran (DEX). Polysaccharide elicitation of cell cultures showed a considerable improving effect on phenylpropanoid production (phenolics, flavonoids, flavanols and anthocyanins) during the post-elicitation period. Even that enhanced phenylpropanoid production was related to growth suppression of CHI elicited cells, PEC and DEX were presented as effective elicitors without loss of cell biomass. Phenylpropanoid accumulation in elicited cells was correlated to markedly higher enzyme activities of phenylalanine ammonia lyase and chalcone-flavanone isomerase. Cell cultures were found to respond rapidly towards the applied elicitors through an early stimulation of both naphtodiantrones, hypericin (HYP) and pseudohypericin (PHYP). The CHI was proposed as a much more prominent elicitor in stimulation of HYP and PHYP levels in cell suspensions. All tested polysaccharide elicitors stimulated non-enzymatic antioxidant properties in cell extracts indicating the potential role of phenolic compounds as effective antioxidants. With regards to the antioxidant enzymes, an up-regulation of peroxidase and catalase activities was observed in PEC and DEX elicited cells, whereas CHI did not give any stimulatory effect on enzymatic activities. These findings suggest the involvement of an efficient antioxidant defense system in the adaptive response of cells to polysaccharide elicitation. Altogether, these results indicated that H. perforatum cells elicited with polysaccharides represent a promising experimental system for enhanced production of phenylpropanoids and naphtodianthrones.