PPAR and Activation Effects of New Nor-triterpenoidal Saponins from the Aerial Parts of Anabasis articulata

Anabasis articulata , traditionally used to treat diabetes, is rich in saponin content. This study was performed to investigate the agonistic effect of its saponins on peroxisome proliferator-activated receptor- and peroxisome proliferator-activated receptor- in human hepatoma (HepG2) cells to explore the possibility of the involvement of these nuclear receptors in the mechanism of the antidiabetic effect of the plant. Chemical investigation of the n -butanol fraction resulted in the isolation of three new and one known 30-noroleanane triterpenoid saponins. The structures of the new compounds were elucidated as 3 -hydroxy,23-aldehyde-30-norolean-12,20(29)-dien-28-oic acid-28- O - -D-glucopyranosyl ester ( 1 ), 3 - O -D-galactopyranosyl-23-aldehyde-30-norolean-12,20(29)-dien-28-oic acid-28- O - -D-glucopyranosyl ester ( 2 ), and 3 - O -D-xylopyranosyl-30-norolean-12,20(29)-dien-28-oic acid 28- O - -D-glucopyranosyl ester ( 3 ), while the known 30-nortriterpenoidal saponin was identified as boussingoside E ( 4 ). Although, the isolated saponins ( 1 - 4 ) did not show >1.5-fold activation of peroxisome proliferator-activated receptor- , but two of them ( 1 and 3 ) activated peroxisome proliferator-activated receptor- to the higher extents of 2.25- and 1.86-fold, respectively. These results suggest that the reported antidiabetic action of the isolated saponins may not solely involve the activation of peroxisome proliferator-activated receptor- . However, the agonistic activity of the n -butanol fraction of A. articulata (1.71-fold induction) and two of its saponins ( 1 and 3 ) towards peroxisome proliferator-activated receptor- may be beneficial in the cardiovascular condition that is closely associated with diabetes and other metabolic disorders.