Isolation and bioactivity of an angiogenesis inhibitor extracted from the cartilage of Dasyatis akajei.

The aim of this study is to isolate, characterize, and identify the bioactivity of an angiogenesis inhibitor derived from the Dasyatis akajei cartilage. By guanidine hydrochloride extract, refrigerated centrifugation, ultrafiltration, 20%-80% acetone precipitation, dialysis and refrigerated desiccation, the DCGE (Dasyatis akajei cartilage guanidine hydrochloride extract) of molecular weights from 3 kDa to approximately 300 kDa was obtained from the Dasyatis akajei cartilage. DCAI (Dasyatis akajei cartilage angiogenesis inhibitor) from 20%-30% acetone precipitation of DCGE was found to have the strongest angiogenesis inhibitory effect. Protein quantification of DCAI shows the main components were proteins with about 73.5% weight of the total DCAI. The bioactivity of the DCAI was investigated by inhibiting the formation of the blood vessels of the chick embryo chorioallantoic membrane (CAM). The ratio between the vascular area and the non-vascular area (VA/ NVA) in sampling point was used for quantitative analysis of the inhibitory effect of DCAI, which can be obtained by computer image analysis system (CIAS). Compared with the control group, the sampling point of the DCAI group had significantly lower VA/NVA. A large area of blood vessels in sampling point was significantly faded and the vascular structure was blurred with broken branches accompanied by the decreased density of vessels. The inhibitory effect with same dosage of DCAI is about ten times higher than that in the positive control group (chondroitin sulphate group) and the effect increases with the concentration of DCAI. The results from the present study indicates that the DCAI from Dasyatis akajei cartilage has an angiogenesis inhibitory effect, and there is also a positive correlation between the concentration and the inhibitory effect.