Thrombotic diseases are major cause of cardiovascular diseases. This study was designed to investigate the effect of tachyplesin I on platelet aggregation and thrombosis. Platelet aggregation was analysed with a whole blood aggregometer. The mice were employed to investigate the effect of tachyplesin I on thrombosis in vivo. Tachyplesin I inhibited thrombin-induced platelet aggregation in a dose-dependent manner. Furthermore, tachyplesin I significantly reduced thrombosis in carrageenan-induced tail thrombosis model by intraperitoneal injection (0.1, 0.2 or 0.4 mg/kg) or intragastric administration (15, 30 or 60 mg/kg). Tachyplesin I also prolonged the bleeding time (BT) and clotting time (CT). The results revealed that tachyplesin I inhibited platelet aggregation and thrombosis by interfering the PI3K/AKT pathway. Tachyplesin I did not show significantly toxicity to mice under 300 mg/kg via intravenous injection. The results show that tachyplesin I inhibits thrombosis and has low toxicity. It is suggested that tachyplesin I has the potential to develop a new anti-thrombotic drug.

For the first time, a new 16-amino-acid peptide was isolated from Eucheuma, an edible seaweed, and named EZY-1. EZY-1 was used to interfere with bleomycin-induced mice pulmonary fibrosis. The target proteins of EZY-1 were screened by an in vitro pull-down method combined with LC-MS/MS. The results showed that EZY-1 can inhibit the idiopathic pulmonary fibrosis (IPF) induced by bleomycin. The potency and safety of EZY-1 are superior to those of the drug used for clinical treatment, pirfenidone. The results showed that EZY-1 suppresses the TGF-β/Smad, PI3K-Akt-mTOR, Rac1-PAK2-cAb1 and MAPK signal transduction pathways. Proteins such as ERK, Akt, PDGF receptor β, vitronectin, raptor and SHP2 exhibited binding to EZY-1 in an in vitro pull-down assay combined with LC-MS/MS analysis. EZY-1 was confirmed to be an effective component of Eucheuma in the inhibition of IPF. The signalling pathways and target proteins of EZY-1 were preliminarily predicted. This study lays the foundation for the development of new drugs from Eucheuma for the treatment of IPF.