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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. [ABSTRACT FROM AUTHOR]

Highlights: [•] Chemically well characterized green tea extracts and black tea extracts were used. [•] GTE and BTE both lowered blood glucose and improved glucose intolerance. [•] Anti-diabetic effect of GTE is through insulin resistance, for BTE is insulin secretion. [Copyright &y& Elsevier]

Abstract: Hexahydro-β-acids (HBA), reduced derivatives of β-acids (BA) from hop plant Humulus lupulus, are shown to be more stable than BA with stronger activities. Here, we investigated the inhibitory effects of HBA on the induction of NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in murine RAW 264.7 cells activated with lipopolysaccharide (LPS). Western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) analyses demonstrated that HBA significantly blocked protein and mRNA expression of iNOS and COX-2 in LPS-induced macrophages. Treatment with HBA resulted in the reduction of LPS-induced nuclear translocation of nuclear factor-κB (NFκB) subunit and the dependent transcriptional activity of NFκB by blocking phosphorylation of inhibitor κB (IκB) α and p65 and subsequent degradation of IκBα. Transient transfection experiments using NFκB reporter constructs indicated that HBA inhibits the transcriptional activity of NFκB in LPS-stimulated murine macrophages. HBA also inhibited LPS induced activation of PI3K/Akt, extracellular signal-regulated kinase (ERK) 1/2 and p38 MAPK. Taken together, these results show that HBA down regulates inflammatory iNOS and COX-2 gene expression in macrophages by inhibiting the activation of NFκB through interfering with the activation PI3K/Akt/IKK and MAPK. [Copyright &y& Elsevier]