Abstract

Eight undescribed flavonoids including three dimers (1-3) and five monomers (4-8), together with ten known compounds (9-18) were isolated from the resins of Dracaena cochinchinensis (Chinese dragon's blood). Structurally, compounds 1-3 are novel dimers of flavane and dihydrochalcone with a unique dibenzopyran ring. Their structures were determined using a combination of spectroscopic analyses and quantum chemical ECD calculations. The biological evaluation of these isolated compounds for anti-renal fibrosis activity demonstrated that compounds 4-6 effectively downregulated the protein expression levels of fibronectin, collagen I, and α-smooth muscle actin (α-SMA) in transforming growth factor-β1 (TGF-β1)-induced rat renal proximal tubular cells (NRK-52e) and normal rat kidney interstitial fibroblasts (NRK-49f). Moreover, compound 4 could significantly reduce the expression of all the above proteins in a dose-dependent manner in both cell lines.