Table 2.

Effect of protocatechuic acid on nitric oxide inhibition in RAW 264.7 macrophages using two different experimental conditions

Protocatechuic (μM)	Inhibition of NO production (%)
	LPS 1 μg/mL	LPS 1 μg/mL + IFN-γ 1,000 U/mL
Pre-treated	2.4 ± 16.9	3.7 ± 3.3
Co-treated	19.7 ± 7.5*	29.3 ± 4.1*

Cells pre-treated with 10 μM protocatechuic acid for 3 h and then stimulated for 24 h with LPS (1 μg/mL) or LPS (1 μg/mL) + INF-γ (1,000 U/mL) and cells co-incubated with protocatechuic acid and LPS (1 μg/mL) or LPS (1 μg/mL) + INF-γ (1,000 U/mL) for 24 h. Data were compared to activated control. Experiments performed in triplicate, and data are expressed as means ± SD

* Statistical significance: P < 0.05 comparing the value with control