Hyperglycemia is a strong risk factor for chronic complications of diabetes. Hyperglycemic conditions foster not only the production of
reactive oxygen species (ROS), but also the consumption of
antioxidants, leading to oxidative stress and promoting the occurrence and progression of complications. During our continuous search for
antioxidant constituents from the pericarp of Toona sinensis (A. Juss.) Roem, we isolated two previously unreported
apotirucallane-type
triterpenoids, toonasinensin A (1) and toonasinensin
B (2), together with five known
apotirucallane-type
triterpenoids (3-7) and two known
cycloartane-type
triterpenoids (8-9) from the pericarp. Compounds 8-9 were obtained from T. sinensis for the first time. Their structures were characterized based on interpretation of spectroscopic data (1D, 2D NMR, high-resolution electrospray ionization mass spectra, HR-ESI-MS) and comparison to previous reports. Compounds (2, 4, 6, 7, and 9) were able to inhibit proliferation against rat glomerular mesangial cells (GMCs) cultured under high-
glucose conditions within a concentration of 80 μM. Compounds (2, 6, and 7) were tested for
antioxidant activity attributable to
superoxide dismutase (SOD),
malondialdehyde (MDA), and ROS in vitro, and the results showed that compounds (2, 6, and 7) could significantly increase the levels of SOD and reduce the levels of MDA and ROS. The current studies showed that
apotirucallane-type
triterpenoids (2, 6, and 7) might have the
antioxidant effects against
diabetic nephropathy.