Anti-inflammatory effects of trans-2,3,5,4′-tetrahydroxystilbene 2-O-β-glucopyranoside (THSG) from Polygonum multiflorum (PM) and hypoglycemic effect of cis-THSG enriched PM extract

- Active compound in PM extract, trans-THSG has significant anti-inflammatory effects.
- Raw PM extract (cis-/trans-THSG = 1:20) has no hypoglycemic effect in diabetic mice.
- Processed PM extract (cis-/trans-THSG = 2:3) has significant hypoglycemic effect.
- There is no hypoglycemic effects of trans-THSG in diet induced diabetic mouse model.

Polygonum multiflorum (PM) has been used as a tonic edible plant and is a popular anti-ageing dietary supplement. Trans-2,3,5,4′-tetrahydroxystilbene 2-O-β-glucopyranoside (trans-THSG) is the major active compound in PM. It was found to have potent anti-inflammatory effects in RAW 264.7 macrophage cells and in TPA-induced mouse ear edema model. Research in the significance and rational of traditional process of post-harvested PM has been neglected. With the aid of modern analytical technology, we studied the major phytochemical transformation of PM solution from trans- to cis-THSG under UV light, reminiscent of traditional process, and further evaluated the hypoglycemic effects of the processed PM extract. In a high fat diet-induced type 2 diabetic mice model, processed PM extract containing cis- and trans-THSG (ratio = 2:3) exhibited significant hypoglycemic capacity, while pure trans-THSG and unprocessed PM extract (cis-/trans-THSG ratio = 1:20) did not, suggesting the importance of anti-diabetic effect of cis-THSG and PM natural process.