The immunotoxicity of dibutyl phthalate on the macrophages in mice.

OBJECTIVE: Dibutyl phthalate (DBP), a widely used phthalate chemical, is commonly used as plasticizer. It is well known that DBP causes reproductive and developmental diseases, but the effect of DBP on the immune system remains to be determined. We assessed the effect of DBP on immune functions of murine macrophages, which constitute a key component in the immune response. MATERIALS AND METHODS: Murine peritoneal exudate macrophages (PEMs) were treated with 0, 1, 5, 10, 50 or 100 µM DBP in vitro for 24 h and then the viability of PEMs were measured by flow cytometry (FCM) and trypan blue count. To investigate the effect of DBP on the functions of PEMs, we treated the PEMs with moderate dose of DBP (0, 1, 5 or 10 µM) in vitro for 24 h. The phenotypes, phagocytosis and cytokine production of PEMs were measured by FCM or real-time PCR. The immunogenicity and antigen presenting capacity of PEMs treated with DBP in vitro were assessed both by the mixed lymphocytereaction (MLR) in vitro assay and through the injection of exposed cells in mice by the delayed-type hypersensitivity (DTH) assay. RESULTS: High dose of DBP (50-100 µM) showed cytotoxicity on PEMs, whereas after the treatment with moderate dose of DBP (1-10 µM) in vitro, PEMs expressed low level of CD36, CD80 and MHC-II molecules, and showed significantly decreased phagocytosis on apoptotic cells and Escherichia coli. In addition, DBP treatment exhibited a decrease in the cytokine production, immunogenicity and antigen-presenting capacity of PEMs. CONCLUSIONS: The present study shows the effects of DBP on macrophages, demonstrating immunogenicity and decreased antigen presentation in vitro.

Intestinal permeability of metformin using single-pass intestinal perfusion in rats.

AIM: To characterize the intestinal transport and mechanism of metformin in rats and to investigate whether or not metformin is a substrate for P-glycoprotein (P-gp). METHODS: The effective intestinal permeability of metformin was investigated using single-pass intestinal perfusion (SPIP) technique in male Waster rats. SPIP was performed in three isolated intestinal segments (duodenum, jejunum and ileum) at the same concentration of metformin (50 microg/mL) to test if the intestinal transport of metformin exhibited site-dependent changes, and in a same isolated intestinal segment (duodenal segment) at three different concentrations of metformin (10, 50, 200 microg/mL) to test if the intestinal transport of metformin exhibited concentration-dependent changes. Besides, P-gp inhibitor verapamil (400 microg/mL) was co-perfused with metformin (50 microg/mL) in the duodenum segment to find out if the intestinal absorption of metformin was affected by P-gp exiting along the gastrointestinal track. Stability studies were conducted to ensure that the loss of metformin could be attributed to intestinal absorption. RESULTS: The effective permeability values (P(eff)) of metformin in the jejunum and ileum at 50 microg/mL were significantly lower than those in the duodenum at the same concentration. Besides, P(eff) values in the duodenum at high concentration (200 microg/mL) were found to be significantly lower than those at low and medium concentrations (10 and 50 microg/mL). Moreover the co-perfusion with verapamil did not increase the P(eff) value of metformin at 50 microg/mL in the duodenum. CONCLUSION: Metformin could be absorbed from the whole intestine, with the main absorption site at duodenum. This concentration-dependent permeability behavior in the duodenum indicates that metformin is transported by both passive and active carrier-mediated saturable mechanism. The P(eff) value can not be increased by co-perfusion with verapamil, indicating that absorption of metformin is not efficiently transported by P-gp in the gut wall. Furthermore metformin is neither a substrate nor an inducer of P-gp. Based on the P(eff) values obtained in the present study and using established relationships, the human fraction dose absorbed for metformin is estimated to be 74%-90% along human intestine.

[Advances on biological activities of coumarins].

This paper reviewed the advances on effective constituents and biological activities of coumarins in recent ten years. Coumarins are a group of important natural compounds, and have been found to have multi-biological activities such as anti-HIV, anti-tumor, anti-hypertension, anti-arrhythmia, anti-osteoporosis, assuaging pain, preventing asthma and antisepsis. Therefore, further investigation should emphasize on improving techniques for extraction and separation, searching the effective precursory compound, and synthesizing and screening out courmarin derivatives with high activity and low toxicity.