Callogenesis optimization and cell suspension culture establishment of Dracocephalum polychaetum Bornm. and Dracocephalum kotschyi Boiss.: An in vitro approach for secondary metabolite production

Dracocephalum kotschyi Boiss. and D. polychaetum Bornm. (Lamiaceae family) are wild medicinal herbs native to Iran and a source of potential bioactive compounds for pharmaceutical and food industries. For their bulk production, the present work aimed to investigate the effects of explants, different plant growth regulators (PGRs), and photoperiod conditions on the callus induction and cell suspension of two Dracocephalum species. A factorial experiment method based on a completely randomized design with three replications was chosen. The best conditions for callus growth obtained on the 45th day from hypocotyl, stem, and leaf explants in Murashige and Skoog (MS) medium supplemented by 1.0 mg. L−1 1-naphthalene acetic acid (NAA) and 4.5 mg. L−1 6-benzylaminopurine (BAP) in both D. polychaetum and D. kotschyi, while the best condition for callus growth from root explant was MS medium supplemented by 1.0 mg. L−1 NAA and 6.0 mg. L−1 BAP in both species. The cell suspension cultures of two species showed the highest growth rate in B5 media supplemented by 1.0 mg L−1 NAA and 2.5 mg L−1 BAP, with friable callus. The methanolic extracts of D. kotschyi and D. polychaetum cells were then determined by high performance liquid chromatography and recognized as a valuable source of such phenolics as rosmarinic acid, naringin, epicatechin, thymol, carvacrol, rutin, p-coumaric acid, gallic acid, benzoic acid, cinnamic acid, apigenin, quercetin, chlorogenic acid, and 4-hydroxybenzoic acid.