Abstract:

Objective To discuss the becteriostatic effect of flavonoids in the Carex meyeriana Kunth extract on infection of Staphylococcus aureus （S. aureus） of the rats after skin scalding， and to provide the new ideas，for the research on new-style anti-infection traditional Chinese medicine. Methods The water-alcohol extraction method was used to extract the active ingredients of Carex meyeriana Kunth and the content of flavonoids was determined by UV spectrophotometry， Oxford cup bacteriostatic test was used to detect the bacteriostatic activity of active ingredients of the Carex meyeriana Kunth against bacteria， and its minimal inhibitory concentration（MIC） was determined by tube dilution method. A total of 24 SD rats were used to establish Ⅱ degree scalding models and randomly divided into normal saline control group， penicillin sodium （NaBP） control group and Carex meyeriana Kunth extract CM-70 treatment group， and there were 8 rats in each group. The rats in three groups were inoculated with 20 μL （1.0×10⁸ CFU·mL^－1） S.aureus by multi-point injection in the wound skin；on the next day， the rats in three groups were smeared with sterile normal saline （0.5 g sterile absorbent cotton adsorbed normal saline 0.5 mL·cm^－2）， NaBP （0.5 g sterile absorbent cotton adsorbed NaBP， 5 000 U·kg^－1 body mass） and 10 g·L^－1Carex meyeriana kunth CM-70 extract diluent （0.5 g sterile absorbent cotton adsorbed 0.5 mL·cm^－2Carex meyeriana Kunth extract CM-70 extract diluent）. The wound infection of the rats in various groups were observed； the bacteria number （CFU·g^－1）under scalding wound scab of the rats on the 1st， 2nd， 3rd， 4th， 5th， 6th， and 7th days after scalding was measured by bacteria quantitative test； the serum levels of interleukin-1β （IL-1β）， interleukin-10 （IL-10）， and tumor necrosis factor-α （TNF-α） of the rats in various groups before scalding and on the 1st， 3rd， 7th， and 14th days after scalding were detected by ELISA method. Results The in vitro bacteriostatic activity test results showed that different dilution concentrations of Carex meyeriana Kunth extract CM-70 formed different sizes of inhibition zones against S.aureus， and did not formed the inhibition zones against Escherichia and Candida albicans. The MIC detection results showed that the MIC value of active ingredients of the Carex mgyeriana Kunth extract to S. aureus was 2.5 g·L^－1. The observation results of infection and healing of scalding wounds of the rats in various groups showed that compared with normal saline control group， on the 3rd day after scalding， the exudation of wound serous of the rats in Carex meyeriana Kunth extract CM-70 treatment group was less； on the 7th day after scalding， the wound serous exudation， redness and swelling，and the wound area of the rats were decreased； on the 14th day after scalding， the wounds of the rats were completely dry without serous exudation，the scabs were formed on the surface， and the wounds healed well， which was similar to that in NaBP control group. The number of bacteria under scalding wound scab detection results showed that compared with normal saline control group， the number of bacteria under scalding wound scab of the rats in Carex meyeriana Kunth extract CM-70 treatment group was decreased significantly at the same time （P<0.01）. The ELISA results showed that compared with normal saline control group， the level of serum IL-10 of the rats in Carex meyeriana Kunth extract CM-70 treatment group was increased significantly on the 1st day and 3rd day after scalding（P<0.01）， and it was decreased significantly on the 7th day and 14th day （P<0.05）；the serum levels of IL-1β and TNF-α of the rats in Carex meyeriana Kunth extract CM-70 treatment group were decreased significantly on the 7th day and 14th day（P<0.05）. Conclusion The active ingredients of Carex meyeriana Kunth can significantly inhibit the infection of S. aureus after skin scalding in the rats and exert the anti-inflammatory and bacteriostatic effects by regulating the levels of serum IL-10，IL-1β， and TNF-α.

Key words: Carex meyeriana Kunth, Skin scalding, Infection, Staphylococcus aureus, Inflammatory factor, Bacteriostasis