Recent advances in tissue culture and secondary metabolite production in Hypericum perforatum L.

Hypericum perforatum L., commonly known as St. John's wort is an important medicinal plant, belonging to family Hypericaceae. Among all species of Hypericum, H. perforatum is most investigated and exploited. It is sold as one of the world's topmost retailing antidepressants. This plant possesses antibacterial, antiviral, anti-inflammatory, and anticancerous properties. These medicinal properties are attributed to the presence of bioactive compounds, such as hypericins and pseudohypericins (naphthodianthrones), hyperforin and adhyperforin (prenylated acylphloroglucinols), quercetin, rutin, isoquercetin, and catechin (flavonoids), chlorogenic acid, caffeic acid, and tannic acid (phenols) and xanthones. The conventional methods of propagation of H. perforatum are time consuming and field grown plants are exposed to biotic and abiotic challenges which affect its phytochemical constituents. Moreover, these methods are also unable to meet the commercial demand of secondary metabolites. Therefore, in order to meet the growing raw material demand of pharmaceutical industries there is a need to develop effecient in vitro plant regeneration protocols for large scale production of H. perforatum plants and other biotechnological methods (cell, tissue and organ culture, cell suspension culture, hairy root culture, elicitation, etc.) for improvement of target bioactive compounds. The present review provides a comprehensive account of the available information on in vitro plant regeneration and biotechnological approaches used to enhance the secondary metabolite(s) content in H. perforatum during the past years. It also deals with the unexplored areas which might be exploited for drug discovery.