Natural products are one of the important sources for the discovery of new drugs.Betulinic acid(BA),a pentacyclic triterpenoid widely distributed in the plant kingdom,exhibits powerful biological effects,including antitumor activity against various types of cancer cells.A considerable number of BA derivatives have been designed and prepared to remove their disadvantages,such as poor water solubility and low bioavailability.This review summarizes the current studies of the structural diversity of antitumor BA derivatives within the last five years,which provides prospects for further research on the structural modification of betulinic acid.
The study aims to investigate the effects of(-)-Linarinic acid(LA) and one of its derivatives(LAd) on brain injury induced by ischemia. Malonaldehyde(MDA) is determined as an index for lipid peroxidation both in vitro and vivo. Mice were pre-treated with LA and LAd for 3 d.Thereafter, they were induced to have incomplete cerebral ischemia with both bilateral carotid artery occlusion and hypotension(BCAOH). In the first part of the in vivo experiment, mice were divided into four groups: sham(control), ischemia, ischemia + LA(200 mg/kg, i.g.) and ischemia + LAd(200 mg/kg, i.g.). In the second part, the dose-response of LAd was investigated at 100, 200 and 400 mg/kg i.g., respectively. A modified neurological severity score was developed for evaluating behavioral deficits of the mice with ischemia. Brains of the mice were excised in order to determinate MDA after ischemia for 6 h. Survival time, survival rate, neurological injury score and MDA level in brains were observed. Results were: 1) The data in vitro showed that both LA and LAd could inhibit the generation of MDA. IC50 values obtained by Probit analysis were 2.9 mM for LAd and 4.88 mM for LA;2) BCAOH could significantly shorten the survival span, reduce the survival rate and cause neurological deficits,which were associated with high level of lipid hydroperoxide production in cerebral tissues;3) LAd decreased lipid peroxidation and improved the neurological outcome more than LA.It is concluded that LAd offers a better neuroprotection than LA against brain damage caused by cerebral ischemia.
