Artemisia annua cell cultures as tools for investigating the production of bioactive compounds

Plant cell cultures are valuable tools for the production of bioactive compounds. Recently, many efforts have been made in order to develop and optimize strategies for increasing the yields of the desired plant metabolites by eliciting their biosynthesis or improving the efficiency of product recovery. We established Artemisia annua L. (Asteraceae) cell suspension cultures to investigate the biosynthesis of the antimalarial artemisinin (AN) [1] and other healthful phytochemicals such as carotenoids and quinones. The use of culture supplementation with cyclic oligomers ?-cyclodextrins was successful to significantly increase intracellular and extracellular levels of AN, lutein, Q9 and Q10 [2, 3]. In order to investigate the mechanism underlying these effects, other oligosaccharides having a linear structure were explored as putative elicitors in A. annua cell suspension cultures. For this purpose, oligogalacturonides (OGA) were obtained by hydrolysis of polygalacturonic acid with pectolyase from Aspergillus japonicus. Various OGA fractions were used for culture medium supplementation at different concentrations. The results showed that the 4-5 OGA fraction induced significant increases of AN and the intermediate dihydroartemisinic acid. These results suggest that the ability of ?-CDs to elicit the production of bioactive compounds in A. annua cell cultures could be due to their chemical similarity to pectic oligosaccharides often occurring in plants after fungal infection.