Investigation on traditional medicines of Guarany Indio and studies on diterpenes from Scoparia dulcis.

In interviews on the traditional herbal medicines of Tupi-Guarany Indians at the herbal market of Asuncion and questionnaire from their users, it was clarified that various useful medicinal plants are available in Paraguay and most of them are generally used without drying. In the search for bioactive substances from those plants, a β-glucuronidase-inhibitory diterpene called scoparic acid A (SA) was isolated from Scoparia dulcis L. together with scoparic acid B, scoparic acid C, and the aphidicolin-like tetracyclic diterpenes scopadulcic acid A (SDA) and scopadulcic acid B (SDB). HPLC analysis of diterpenes in the individual plants of Paraguayan and Asian S. dulcis revealed the presence of three chemotypes based on major component, i.e., SA type, SDB type, and SDX type containing mainly scopadiol and scopadulciol (SDC). SA and SDB were elucidated to be mainly biosynthesized in the leaves via 2-C-methyl-D-erythritol- 4-phosphate pathway, and a leaf organ culture system containing methyl jasmonate 10 µM was found to enhance the production of diterpenes by activation of Ca-signal transduction systems such as calmodulin and protein kinase C. On the other hand, SDB and SDC were found to show multifaceted pharmacological effects such as inhibitory effects on gastric acid excretion, bone resorption, replication of herpes simplex virus type 1 (HSV-1), etc. In addition, SDC was suggested to be applicable to cancer gene therapy using ganciclovir or acyclovir and the HSV-1 thymidine kinase gene called the suicide gene.