Surface functionalization-specific binding of coagulation factors by zinc oxide nanoparticles delays coagulation time and reduces thrombin generation potential in vitro.

Zinc oxide nanoparticles (ZnO NPs) have many biomedical applications such as chemotherapy agents, vaccine adjuvants, and biosensors but its hemocompatibility is still poorly understood, especially in the event of direct contact of NPs with blood components. Here, we investigated the impact of size and surface functional groups on the platelet homeostasis. ZnO NPs were synthesized in two different sizes (20 and 100 nm) and with three different functional surface groups (pristine, citrate, and L-serine). ZnO NPs were incubated with plasma collected from healthy rats to evaluate the coagulation time, kinetics of thrombin generation, and profile of levels of coagulation factors in the supernatant and coronated onto the ZnO NPs. Measurements of plasma coagulation time showed that all types of ZnO NPs prolonged both active partial thromboplastin time and prothrombin time in a dose-dependent manner but there was no size- or surface functionalization-specific pattern. The kinetics data of thrombin generation showed that ZnO NPs reduced the thrombin generation potential with functionalization-specificity in the order of pristine > citrate > L-serine but there was no size-specificity. The profile of levels of coagulation factors in the supernatant and coronated onto the ZnO NPs after incubation of platelet-poor plasma with ZnO NPs showed that ZnO NPs reduced the levels of coagulation factors in the supernatant with functionalization-specificity. Interestingly, the pattern of coagulation factors in the supernatant was consistent with the levels of coagulation factors adsorbed onto the NPs, which might imply that ZnO NPs simply adsorb coagulation factors rather than stimulating these factors. The reduced levels of coagulation factors in the supernatant were consistent with the delayed coagulation time and reduced potential for thrombin generation, which imply that the adsorbed coagulation factors are not functional.

Toxicity assessment of Leonuri Herba aqueous extract orally administered to rats for 13 consecutive weeks.

ETHNOPHARMACOLOGICAL RELEVANCE: The Leonuri Herba has been traditionally used for women's disease in Asian countries. AIM OF THE STUDY: The objective of the present study was to evaluate the subchronic toxicity of Leonuri Herba aqueous extract in male and female F344 rats. MATERIAL AND METHODS: Leonuri Herba aqueous extract was administered orally once daily at dose levels of 0, 125, 250, 500, 1000 and 2000 mg/kg/day for 13 weeks. Toxicological assessment was performed including mortality, clinical signs, body and organ weights, food consumption, ophthalmology, urinalysis, hematology, serum chemistry, gross findings and histopathologic examination. RESULTS: There were no treatment related differences in clinical signs, urinalysis, hematology and serum chemistry, except for a histopathologic examination. The squamous cell hyperplasia in the forestomach was observed in both sexes of rats given 2000 mg/kg/day of Leonuri Herba aqueous extract. CONCLUSION: In conclusion, the NOAEL (No Observed Adverse Effect Level) for Leonuri Herba aqueous extract was determined as 1000 mg/kg/day in both sexes of rats under the present experimental conditions. And the acceptable daily intake value for Leonuri Herba aqueous extract was calculated to be 10mg/kg body weight per day using a safety factor of 100 to the NOAEL.