Production of Podophyllotoxin.

Podophyllotoxin (PPT) is a lignan, which is used as precursor for the semisynthesis of i.a. Etoposide®, Teniposide®, and Etopophos®. These compounds are currently used in combination therapy to treat many different cancers.

For the production of PPT three different routes are known:

• extraction and isolation from Podophyllum hexandrum and Linum species,
• production in plant cell cultures
• and organic synthesis.

Extraction and isolation of PPT from Indian Podophyllum hexandrum is not economic and characterized by a high price for the final product. Another problem is that the cultivation of the plant is not easy because of the limited growth rate. Mostly PPT is extracted from wild collected species. As a consequence from wild collection P. hexandrum is actually endangered in India, especially in the Himalaya region. Working with plant cell cultures as described in the past or obtaining the drug by organic synthesis is difficult, the yield is limited and the price cannot compete with wild collection.

Anthriscus sylvestris (L.) Hoffm. (Apiaceae) is a common wild plant in Northwest Europe that accumulates considerable amounts of lignans. Deoxypodophyllotoxin (DPT) as the main attractive constituent can be used as a precursor for the production of podophyllotoxin but this is not yet applied on an industrial scale.

The aim of the PhD project is to produce PPT. One angle will be the identification of the enzymes responsible for the conversation of DPT to PPT in plants. The other will be the optimization of the conversion by the human liver enzyme cytochrome P450 3A4, which was shown to convert DPT to PPT.

Techniques: Molecular biology (PCR, cloning, etc.) and analytical chemistry (HPLC / GC, etc.)

For more information, contact Christel Seegers MSc., Dept. of Pharmaceutical Biology, GRIP, building 3215-room 9.65, Antonius Deusinglaan 1, 9713 AV GRONINGEN or prof.dr. Wim J. Quax .

Interesting references:

1. Canel, C.; Moraes, R.M.; Dayan, F.E.; Ferreira, D. Podophyllotoxin. Phytochemistry (2000), 54, 115-120.

2. Vasilev, N.P.; Julsing, M.K.; Koulman, A.; Clarkson, C.; Woerdenbag, H.J.; Ionkova, I.; Bos, R.; Jaroszewski, J.W.; Kayser, O.; Quax, W.J. Bioconversion of deoxypodophyllotoxin into epipodophyllotoxin in E. coli using human cytochrome P450 3A4. Journal of Biotechnology (2006), 126, 383-393.