Study On The Free Radical Scavenging Abilities,Antiangiogenic Activities Of Cinnamic Acid Amides Of Dopamine And Anthraquinones

It was reported that angiogenesis plays critical roles in many diseases such as cancer and cardiovascular disease.The ROS in vivo could initiate angiogenesis and act as second messengers in angiogenic signal transduction pathways.Many reports revealed that DA(dopamine)and emodin can inhibit angiogenesis in vitro and in vivo.However,the clinical applications of DA are limited by its short half-life about 2 min.For that,our laboratory designed and synthesised the conjugates(2a-2e)of DA with cinnamic acid aiming at the improvement of the stability and pharmacological activities of DA.Here we evaluated the absorption spectrum,free radical scavenging abilities and antiangiogenic activities of the cinnamic acid amides of dopamine(2a-2e)and emodin as well as its derivatives,we also demonstrated on the relationship between their antiangiogenic activities and ROS.We studied on the absorption spectrum of the compounds 2a-2e by UV spectroscopy.The compounds 2a-2e showed broad absorption bands in the ranges of 215nm-230nm and 275nm-320nm.That bands of the compounds were significantly red or blue shifted when the solvent was shifted from polar ethanol to nonpolar hexane.And we conducted the chemical and enzymatic stabilities of 2a-2e by HPLC,they were more stable than DA.The most stable compound was 2a,with half-lives of 12.25±0.81 h and 3.88±0.17 h respectively in pH 7.4 buffer and human plasma,more than 216h in buffers of pH 1.3 and 5.0,while the least stable compound was 2c with half-lives of 3.81±0.14 h and 1.21h±0.04 h respectively in pH 7.4 buffer and human plasma.We tested the free radical(superoxide anion radicals,hydroxyl radicals and ABTS)scavenging capacities of the compounds by UV spectroscopy.The results showed that the cinnamic acid amides of dopamine possessed higher free radical scavenging activities than the cinnamic acid but lower than DA for most of them.We analyzed the cytotoxicity of 2a-2e and DA on HUVEC by MTT(the capacity to inhibit the proliferation of the HUVEC).With the concentration below 40?M 2b-2e showed no toxic effects on HUVECs for 48 h.While The 40 ?M 2a could significantly inhibit the proliferation of HUVEC by(16.2±1.6)%.We demonstrated the inductions of the proliferation and migration of HUVEC by VEGF and ROS to evaluated the antiangiogenic activities of 2a-2e.The experiment results of the anthraquinones showed that the absorption maximums of them significantly red shifted as the pH of the buffer changed from 3.5 to 11.5,especially for chrysophanol(from 403 nm to 502 nm)which reflected the presence of free phenolic hydroxyl groups.The anthraquinones had poor performances in ABTS+ and O2-scavenging tests.For the ABTS+ scavenging assay,the TEAC of emodin and alion were respectively 1.56±0.005 and 0.18±0.007 in pH 7.5 phosphate buffer.Our work revealed that 2a-2e significantly prolonged the half-life of DA while showed lower toxicity towards HUVECs,which laid foundation for the developments of derivatives of DA.And the anthraquinone compounds from rhubarb demonstrated that they were not ideal antioxidants.