Potassium humate inhibits carrageenan-induced paw oedema and a graft-versus-host reaction in rats.

It has been shown in a previous study that brown coal-derived potassium humate is safe and effective in suppressing contact hypersensitivity in rats. In this study the efficacy of potassium humate on other types of inflammation was determined. Preparative TLC followed by mass spectroscopy was used in an attempt to fingerprint the product. The effects of potassium humate, at an oral dose of 60 mg/kg bodyweight, on a delayed type hypersensitivity reaction, a carrageenan-induced inflammation model and an allogeneic graft-versus-host reaction (GVHR) in rats were investigated. Paw oedema was used as a measure of inflammation. It was found that potassium humate had no effect on the delayed type hypersensitivity reaction but significantly inhibited the increase in paw volume of the carrageenan-induced oedema in rats which compared favourably with indomethacin treatment. Furthermore, potassium humate inhibited the GVHR induced in normal and cyclophosphamide-treated immune-incompetent rats. The identification of a naturally occurring compound that is safe and effective in reducing different types of inflammation merits further evaluation in clinical trials.