[The suppressive effect of melilotus extract on the thermal edema of rats]

The effect of melilotus extract (ME) and Esberiven (ES) which contain coumarin on the thermal edema, which is one of high protein edema, was evaluated by both quantitative and qualitative assays. The intraperitoneal injection of ME immediately after burn greatly reduced the amount of swelling and effectively inhibited the occurrence of necrosis and induration in the injured leg-skin as compared with the saline controls in which a 3rd degree of thermal injury was observed. Administration of ES also induced a similar suppressive effect. Furthermore, either intraperitoneal or subcutaneous local injection of ME 4 hr before burn was effective in reducing the edema and thermal injury. No increase of the lymph flow and output of lymphocytes and protein from the thoracic duct lymph was observed in thermally injured rats given an injection of ME. The massive infiltration of neutrophils and macrophages 6 to 24 hr after the subcutaneous injection of ME was histologically observed in the dermal lesion of normal rats. Twenty-four hr later, macrophages, fibroblasts, and lymphocytes became predominant. The present data taken together suggest that ME exerts the suppressive effect on thermal injury by either prior or post administration, and these effects might be induced in an indirect manner, through the action of phagocytic cells accumulated in the injured lesion, not via lymphatic drainages of excess fluid and protein.