Relationship between podophyllotoxin accumulation and soil nutrients and the influence of Fe2+ and Mn2+ on podophyllotoxin biosynthesis in Podophyllum hexandrum tissue culture

Podophyllotoxin (PDT) and its derivatives, which are isolated from the Podophyllum species, are widely used in the clinical setting. The present study was designed to analyze the correlation between PDT levels in the rhizomes of Podophyllum hexandrum (P. hexandrum) and Dysosma versipellis (D. versipellis) and the nutrients in soil. We also aimed to investigate the influence of Fe2+ and Mn2+ on the enzyme activity of phenylalanine ammonia lyase (PAL), cinnamyl alcohol-dehydrogenase (CAD), and deoxypodophyllotoxin 6-hydroylase (DOP6H) and PDT accumulation via P. hexandrum tissue culture. The results showed that PDT accumulation was positively correlated with the NO3−, PO43−, Na+, Fe, and Mn levels and was negatively correlated with the SO42− and K+ levels, while the correlation with the Mg2+, Ca2+, Cu and Zn levels was not significant. The Fe2+ and Mn2+ levels were associated with the increased activity of PAL and CAD at 3-18 days; Fe2+ enhanced the activity levels by 2.66- and 1.76-fold, respectively, and Mn2+ was associated with a 1.68- and 1.10-fold increase in activity levels, respectively, compared with the control (CK) at 18 days. DOP6H activity was enhanced by Mn2+, but it was not significantly affected by Fe2+. Finally, PDT production was enhanced approximately 60% and 34% by Fe2+ and Mn2+, respectively, compared with CK at 16 days. These observations may be useful for the generation of PDT and related lignans via commercial cultivation as well as cell and tissue culture of P. hexandrum and other related plant resources.