Impact of phloroglucinol and indoleamines on growth and accumulation of podophyllotoxin in the roots of Hyptis suaveolens (L.) Poit

Hyptis suaveolens (L.) Poit is known for containing podophyllotoxin (PTOX), a natural lignan used as the lead compound in antitumor agent preparations, in its roots. The use of phloroglucinol (PHL) and indoleamines, such as melatonin (MEL) and serotonin (SER), in plant tissue culture is a promising alternative for eliciting rare and high-value secondary metabolites of medical importance. Aimed to evaluate the impact of different concentrations of PHL, either alone or in combination with MEL or SER, on the growth and accumulation of PTOX in H. suaveolens. Apical segments were vertically inoculated in MS medium containing different concentrations of MEL or SER (0; 0.25; 0.50; 1.00; 5.00 and 10.00 µM) and PHL (0 and 50 mg L^-1). After 40 days, growth parameters, chlorophyll content and PTOX content were assessed. Plantlet rooting and root dry weight notably increased with the use of 0.5 µM MEL alongside PHL. Overall, treatments containing PHL showed superior results, except for chlorophyll content. SER supplementation was effective in increasing root growth, root number and leaf area. The combination of 1.0 µM MEL or SER and 50 mg L^-1 PHL increased the production of PTOX in the roots of H. suaveolens by 2.0 and 1.6 times, respectively. In conclusion, the application of PHL and indoleamines demonstrated an eliciting effect on both growth and PTOX production in H. suaveolens roots, presenting a promising avenue for further research and application in eliciting targeted secondary metabolites.