The effect of fulvic acid (FA) on homocysteine-induced COX-2 mRNA expression and PGE
secretion in human monocytes. Human primary monocytes and U937 cells were pre-treated with FA (0–10 μg/mL) for 4 h, and then stimulated with homocysteine (200 μg/mL) for 4 h (A, B) and 8 h (C, D). Monocytes that were not stimulated with homocysteine were used as controls (CL). (A, B) RNA samples were isolated and subjected to real-time PCR analysis. Data are presented as fold changes in fluorescent density from CL monocytes normalized to 18S rRNA level of three individual experiments. (C, D) The PGE2 secretion in conditioned media was determined by ELISA analyses. Data are shown as mean ± standard error of the mean (SEM) of three individual experiments. *P < 0.05 versus CL monocytes. #P < 0.05 versus homocysteine-stimulated cells without pretreatment of FA.