Salvianolic acid B inhibits thrombosis and directly blocks the thrombin catalytic site.

Background: Salvianolic acid B (SAB) is a major component of Salvia miltiorrhiza root (Danshen), widely used in East/Southeast Asia for centuries to treat cardiovascular diseases. Danshen depside salt, 85% of which is made up of SAB, is approved in China to treat chronic angina. Although clinical observations suggest that Danshen extracts inhibited arterial and venous thrombosis, the exact mechanism has not been adequately elucidated. Objective: To delineate the antithrombotic mechanisms of SAB. Methods: We applied platelet aggregation and coagulation assays, perfusion chambers, and intravital microscopy models. The inhibition kinetics and binding affinity of SAB to thrombin are measured by thrombin enzymatic assays, intrinsic fluorescence spectrophotometry, and isothermal titration calorimetry. We used molecular in silico docking models to predict the interactions of SAB with thrombin. Results: SAB dose-dependently inhibited platelet activation and aggregation induced by thrombin. SAB also reduced platelet aggregation induced by adenosine diphosphate and collagen. SAB attenuated blood coagulation by modifying fibrin network structures and significantly decreased thrombus formation in mouse cremaster arterioles and perfusion chambers. The direct SAB-thrombin interaction was confirmed by enzymatic assays, intrinsic fluorescence spectrophotometry, and isothermal titration calorimetry. Interestingly, SAB shares key structural similarities with the trisubstituted benzimidazole class of thrombin inhibitors, such as dabigatran. Molecular docking models predicted the binding of SAB to the thrombin active site. Conclusion: Our data established SAB as the first herb-derived direct thrombin catalytic site inhibitor, suppressing thrombosis through both thrombin-dependent and thrombin-independent pathways. Purified SAB may be a cost-effective agent for treating arterial and deep vein thrombosis.

Salvianolic Acid B Significantly Suppresses the Migration of Melanoma Cells via Direct Interaction with ß-Actin.

Melanoma is the most aggressive and difficult to treat of all skin cancers. Despite advances in the treatment of melanoma, the prognosis for melanoma patients remains poor, and the recurrence rate remains high. There is substantial evidence that Chinese herbals effectively prevent and treat melanoma. The bioactive ingredient Salvianolic acid B (SAB) found in Salvia miltiorrhiza, a well-known Chinese herbal with various biological functions, exhibits inhibitory activity against various cancers. A375 and mouse B16 cell lines were used to evaluate the main targets and mechanisms of SAB in inhibiting melanoma migration. Online bioinformatics analysis, Western blotting, immunofluorescence, molecular fishing, dot blot, and molecular docking assays were carried out to clarify the potential molecular mechanism. We found that SAB prevents the migration and invasion of melanoma cells by inhibiting the epithelial-mesenchymal transition (EMT) process of melanoma cells. As well as interacting directly with the N-terminal domain of ß-actin, SAB enhanced its compactness and stability, thereby inhibiting the migration of cells. Taken together, SAB could significantly suppress the migration of melanoma cells via direct binding with ß-actin, suggesting that SAB could be a helpful supplement that may enhance chemotherapeutic outcomes and benefit melanoma patients.

Chemopreventive efficacy of salvianolic acid B phospholipid complex loaded nanoparticles against experimental oral carcinogenesis: implication of sustained drug release.

Background: Although we have previously demonstrated that phospholipid complex loaded nanoparticles (PLC-NPs) encapsulating salvianolic acid B (SAB) can enhance anticancer activity in head and neck cancer and precancerous cells in vitro, the chemopreventive efficacy of SAB-PLC-NPs (nano-SAB) in vivo remains unclear. Here, we aimed to investigate the in vivo efficacy of nano-SAB against experimental oral carcinogenesis. Methods: Oral tongue carcinogenesis was induced in C57BL/6 mice through the administration of 4-nitroquinoline-N-oxide (4NQO, 100 µg/mL) in drinking water for 22 weeks. To preliminarily evaluate the effect of sustained drug release against oral carcinogenesis, free- or nano-SAB (16.6 mg/kg/d) was administered orally for 18 weeks, and the treatment was discontinued for the remaining 4 weeks. Results: Histological evaluation revealed a significant (P<0.05) decrease in the incidence of carcinoma in free-SAB-treated (16.7%) and nano-SAB-treated (10.0%) mice compared to mice exposed to 4NQO alone (34.3%). A decrease in carcinoma growth rate was also observed in free-SAB-treated (12.2%) and nano-SAB-treated (5.5%) mice compared to the 4NQO-exposed group (18.3%), even after drug withdrawal for 4 weeks. Immunohistochemical analysis revealed that nano-SAB treatment effectively suppressed Ki-67, proliferative cell nuclear antigen (PCNA), and cyclin D1 expression in high-risk dysplastic lesions compared to free-SAB-treated and 4NQO-exposed groups (all P<0.05). Importantly, nano-SAB maintained low levels of Ki-67, PCNA, and cyclin D1 expression even after drug withdrawal for 4 weeks. Conclusions: Together with our previous in vitro data, this in vivo study confirms that nano-SAB has superior chemopreventive efficacy by promoting more potent anti-proliferation and cell cycle arrest responses. These findings demonstrate the potential of SAB-PLC-NPs as promising chemopreventive agents for treating oral carcinogenesis.