Gallic acid (GA) is a naturally occurring polyphenol compound present in fruits, vegetables, and herbal medicines. According to previous studies, GA has many biological properties, including antioxidant, anticancer, anti-inflammatory, and antimicrobial properties. GA and its derivatives have multiple industrial uses, such as food supplements or additives. Additionally, recent studies have shown that GA and its derivatives not only enhance gut microbiome (GM) activities, but also modulate immune responses. Thus, GA has great potential to facilitate natural defense against microbial infections and modulate the immune response. However, the exact mechanisms of GA acts on the GM and immune system remain unclear. In this review, first the physicochemical properties, bioavailability, absorption, and metabolism of GA are introduced, and then we summarize recent findings concerning its roles in gastrointestinal health. Furthermore, the present review attempts to explain how GA influences the GM and modulates the immune response to maintain intestinal health.
Understanding
the wettability of clay mineral surfaces is crucial
for enhancing oil recovery, investigating primary migration of hydrocarbon,
and evaluating the performance of sealing rocks in a petroleum system.
On the basis of molecular dynamics simulations, we investigated the
interactions between four typical clay minerals (i.e., pyrophyllite,
montmorillonite, illite, and kaolinite) and confined pore fluids (i.e.,
water/alkane/salts). The influences of surface group, layer charge,
and salts on the wettability of clay surfaces were revealed. As the
layer charge increases, the hydrophilicity of the montmorillonite
basal surface gradually increases. The basal surface of 2:1-type pyrophyllite
is completely alkane-wet independent of salts. However, for 1:1-type
kaolinite, the presence of salts makes the siloxane surface completely
water-wet, whereas it is partially alkane-wet at the absence of salts.
In general, the salt ions adsorbed onto clay surfaces promote the
surface hydrophilicity. By using nonequilibrium molecular dynamics,
we explored the hydrodynamics of the water/alkane/salts fluid confined
in slit nanopores with pore walls made up of montmorillonite and kaolinite.
Both montmorillonite and kaolinite surfaces remarkably restrain the
movement of the water confined in nanopores. Decane molecules tend
to aggregate together and transport as a cluster. Moreover, the migration
of the decane cluster is faster than that of water molecules. These
findings are helpful for understanding the primary migration of hydrocarbon
in clayey source rocks and the geological sealing of oil by clayey
cap rocks in petroleum systems.
Silymarin, a polyphenolic flavonoid antioxidant, is known to have anti-inflammatory, hepatoprotective, and anticarcinogenic effects. In the present study, we report the inhibitory effect of silymarin on nitric oxide production and inducible nitric-oxide synthase (iNOS) gene expression in macrophages. In vivo administration of silymarin attenuated nitric oxide production by peritoneal macrophages in lipopolysaccharide (LPS)-treated mice. Silymarin also dose dependently suppressed the LPSinduced production of nitric oxide in isolated mouse peritoneal macrophages and RAW 264.7, a murine macrophage-like cell line. Moreover, iNOS mRNA and its protein expression were completely abrogated by silymarin in LPS-stimulated RAW 264.7 cells. To further investigate the mechanism responsible for the inhibition of iNOS gene expression by silymarin, we examined the effect of silymarin on LPS-induced nuclear factor-B (NF-B)/Rel activation, which regulates various genes involved in immune and inflammatory response. In RAW 264.7 cells, the LPS-induced DNA binding activity of NF-B/Rel was significantly inhibited by silymarin, and this effect was mediated through the inhibition of the degradation of inhibitory factor-B. Silymarin also inhibited tumor necrosis factor-␣-induced NF-B/Rel activation, whereas okadaic acid-induced NF-B/Rel activation was not affected. NF-B/Rel-dependent reporter gene expression was also suppressed by silymarin in LPSstimulated RAW 264.7 cells. Further study showed that silymarin suppressed the production of reactive oxygen species generated by H 2 O 2 in RAW 264.7 cells. Collectively, these results suggest that silymarin inhibits nitric oxide production and iNOS gene expression by inhibiting NF-B/Rel activation. Furthermore, the radical-scavenging activity of silymarin may explain its inhibitory effect on NF-B/Rel activation.
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