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The antioxidant activities of three parts (peel, juice, and seed) and extracts of three pomegranate varieties in China were investigated by using a chemiluminescence (CL) method in vitro. The scavenging ability of pomegranate extracts (PEs) on superoxide anion, hydroxide radical, and hydrogen peroxide was determined by the pyrogallol-luminol system, the CuSO4-Phen-Vc-H2O2 system, and the luminol-H2O2 system, respectively. DNA damage preventing the effect of PE was determined by the CuSO4-Phen-Vc-H2O2-DNA CL system. The results showed that the peel extract of red pomegranate had the best effect on the scavenging ability of superoxide anion because its IC50 value (4.01 +/- 0.09 microg/mL) was the lowest in all PEs. The seed extract of white pomegranate could scavenge hydroxide radical most effectively of the nine extracts (the IC50 value was 1.69 +/- 0.03 microg/mL). The peel extract of white pomegranate had the best scavenging ability on hydrogen peroxide, which had the lowest IC50 value (0.032 +/- 0.003 microg/mL) in the nine extracts. The seed extract of white pomegranate (the IC50 value was 3.67 +/- 0.03 microg/mL) was the most powerful on the DNA damage-preventing effect in all of the PEs. Also, the statistical analysis indicated that there were significant differences (at P< 0.05) among the extracts of the different varieties and parts in each system.

The present work is undertaken to characterize a Granny Smith apple procyanidin extract (AE) and investigate the beneficial effect of the AE in the intestine in vitro. Each AE was characterized via LC-ESI-MS. Caco-2 cells were used to study the preventive actions of the AE against the downregulation of tight junction protein expression, oxidative stress and inflammation induced by lipopolysaccharides (LPS). Phenolic compounds present in the AE, including chlorogenic acid, catechin, epicatechin, proanthocyanidin dimers, and proanthocyanidin trimers, were characterized. The expression of the tight junction protein, including occludin and zona occludens (ZO)-1, increased significantly in LPS + AE treated Caco-2 cells, compared to LPS induced Caco-2 cells. Proanthocyanidin dimers had the most potent effect on increasing tight junction protein expression. The addition of LPS to Caco-2 cells induced oxidative stress and inflammation. However, incubation with proanthocyanidin dimers prevented LPS-mediated oxidative stress, including the increase of SOD, HO-1, CAT, and GSH-Px mRNA expression, and counteracted LPS-mediated inflammation as evidenced by the down-regulation of inflammatory markers (NF-κβ, IL-6, and TNF-α mRNA expression). Our findings provide evidence that AE could upregulate tight junction protein expression, probably acting via the reduction of oxidative stress and inflammation.