Fates of Diterpene Lactones in Storage Andrographis paniculata Extracts

Diterpene lactones in Andrographis paniculata are essential bioactive compounds that contribute to the herb's medicinal properties. The main diterpene lactones in A. paniculata are andrographolide and its derivatives. Spontaneous degradation of the diterpene leads to a short-term stability and casts a significant problem in storage and distribution of A. paniculata raw materials and products.

To determine the stability of diterpene lactones in A. paniculata extracts and their transformation dynamics.

A ¹H NMR-based metabolomics workflow and HPLC-based quantitative determination were used to map the stability profiles in A. paniculata extract stored in the standard storage conditions over a 6-month period.

Qualitatively, NMR-based PCA detected both descending and ascending dynamics in transformation of diterpene lactones in A. paniculata extracts over a 6-month storage period. The contents of five lactone markers, compounds 1-5, in storage A. paniculata extracts were monitored to show that compounds 1 and 5 degraded with decelatory rates and presumably transformed via dehydration into compound 3, which otherwise increased also in a coherently decelatory manner. Lacking of the labile allylic hydroxyl group, compounds 2 and 4 were more stable and remained unchanged throughout the storage period.

The short-term stability of A. paniculata extracts and related products was primarily attributed to the dehydration of 1 and it allylic hydroxy analogs, for example, 5, into a diene as in 3. Compound 3 is hence recommended as a plausible candidate as the stability and age marker of A. paniculata raw materials and products.