Tannic acid

Parasite Immunol. 2014 Feb;36(2):100-6.

Effects of tannic acid on Haemonchus contortus larvae viability and immune responses of sheep white blood cells in vitro.[Pubmed: 24558656]

METHODS AND RESULTS:
Direct inhibitory effects of Tannic acid on Haemonchus contortus viability were studied in vitro using the larval migration inhibition (LMI) assay. Sheep white blood cells (WBC) were preincubated with 5 and 50 lg/mL Tannic acid or not followed by whole H. contortus antigen (WHA). Cells were harvested at 24 h post-incubation to test host immune responses. Concentrations of 50, 100, 500, 1000, 3000 and 5000 lg/mL Tannic acid inhibited larvae migration by 19.8, 42.4, 46.3, 92.0, 93.7 and 100%, respectively, within 96 h post-incubation (P < 0.001). The relative mRNA levels of interferon (IFN)-c, interleukin (IL)-2, IL-4 and IL-10 were increased by WHA stimulation without Tannic acid. However, the increased effects on IFN-c and IL-2 were inhibited by Tannic acid preincubation (P < 0.001), while the increases in IL-4 and IL-10 were greatly enhanced by Tannic acid preincubation (P < 0.001). Changes in protein levels of all cytokines essentially paralleled the changes in their corresponding mRNA levels.
CONCLUSIONS:
In conclusion, Tannic acid is directly harmful to larvae in a dose- and time-dependent manner and modulates immune responses of sheep WBC stimulated by H. contortus antigen by inhibiting Th1 cytokines and increasing Th2 cytokine expression in vitro.

Biol Trace Elem Res. 2014 Apr;158(1):122-7.

Effect of calcium, tannic acid, phytic acid and pectin over iron uptake in an in vitro Caco-2 cell model.[Pubmed: 24531910]

Calcium, phytic acid, polyphenols and fiber are major inhibitors of iron absorption and they could be found in excess in some diets, thereby altering or modifying the iron nutrition status. The purpose of this study is to evaluate the effect of calcium, Tannic acid, phytic acid, and pectin over iron uptake, using an in vitro model of epithelial cells (Caco-2 cell line).
METHODS AND RESULTS:
Caco-2 cells were incubated with iron (10-30 μM) with or without CaCl2 (500 and 1,000 μM) for 24 h. Then, cells were challenged with phytic acid (50-150 μM); pectin (50-150 nM) or Tannic acid (100-500 μM) for another 24 h. Finally, (55)Fe (10 μM) uptake was determined. Iron dialyzability was studied using an in vitro digestion method. Iron uptake in cells pre-incubated with 20 and 30 μM Fe was inhibited by CaCl2 (500 μM). Iron uptake decreased in cells cultured with Tannic acid (300 μM) and CaCl2 (500-1,000 μM) (two-way ANOVA, p = 0.002). Phytic acid also decreased iron uptake mainly when cells were treated with CaCl2 (1,000 μM) (two-way ANOVA; p < 0.05). Pectin slightly decreased iron uptake (p = NS). Iron dialyzability decreased when iron was mixed with CaCl2 and phytic or Tannic acid (T test p < 0.0001, for both) but not when mixed with pectin.
CONCLUSIONS:
Phytic acid combined with calcium is a strong iron uptake inhibitor. Pectin slightly decreased iron uptake with or without calcium. Tannic acid showed an unexpected behavior, inducing an increase on iron uptake, despite its low Fe dialyzability.

PLoS One. 2014 Aug 12;9(8):e104113.

Tannic acid modified silver nanoparticles show antiviral activity in herpes simplex virus type 2 infection.[Pubmed: 25117537]

The interaction between silver nanoparticles and herpesviruses is attracting great interest due to their antiviral activity and possibility to use as microbicides for oral and anogenital herpes.
METHODS AND RESULTS:
In this work, we demonstrate that Tannic acid modified silver nanoparticles sized 13 nm, 33 nm and 46 nm are capable of reducing HSV-2 infectivity both in vitro and in vivo. The antiviral activity of Tannic acid modified silver nanoparticles was size-related, required direct interaction and blocked virus attachment, penetration and further spread. All tested Tannic acid modified silver nanoparticles reduced both infection and inflammatory reaction in the mouse model of HSV-2 infection when used at infection or for a post-infection treatment. Smaller-sized nanoparticles induced production of cytokines and chemokines important for anti-viral response. The corresponding control buffers with Tannic acid showed inferior antiviral effects in vitro and were ineffective in blocking in vivo infection.
CONCLUSIONS:
Our results show that Tannic acid modified silver nanoparticles are good candidates for microbicides used in treatment of herpesvirus infections.

Biochim Biophys Acta. 2013 Jul;1831(7):1260-6.

Inhibitory effects of tannic acid on fatty acid synthase and 3T3-L1 preadipocyte.[Pubmed: 24046866]

Tannic acid is a hydrolyzable tannin that exists in many widespread edible plants with a variety of biological activities.
METHODS AND RESULTS:
In this study, we found that Tannic acid potently inhibited the activity of fatty acid synthase (FAS) in a concentration-dependent manner with a half-inhibitory concentration value (IC50) of 0.14 microM. The inhibition kinetic results showed that the inhibition of FAS by Tannic acid was mixed competitive and noncompetitive manner with respect to acetyl-CoA and malonyl-CoA, but uncompetitive to NADPH. Tannic acid prevented the differentiation of 3T3-L1 pre-adipocytes, and thus repressed intracellular lipid accumulation. In the meantime, Tannic acid decreased the expression of FAS and down-regulated the mRNA level of FAS and PPARgamma during adipocyte differentiation. Further studies showed that the inhibitory effect of Tannic acid did not relate to FAS non-specific sedimentation.
CONCLUSIONS:
Since FAS was believed to be a therapeutic target of obesity, these findings suggested that Tannic acid was considered having potential in the prevention of obesity.

Toxicol In Vitro. 2013 Sep;27(6):1798-808.

Assessment of in vitro cellular responses of monocytes and keratinocytes to tannic acid modified silver nanoparticles.[Pubmed: 23727252]

Hydrolyzable tannins are known to exhibit diverse biological effects, which can be used in combination with silver nanoparticles (AgNPs).
METHODS AND RESULTS:
In this study, we tested toxic and inflammatory properties of tannic-acid modified 13, 33, 46 nm and unmodified 10-65 nm AgNPs using murine 291.03C keratinocyte and RAW 264.7 monocyte cell lines. Both cell lines exposed for 24h to 1-10 μg/ml of 13 nm, 33 nm, 46 nm and unmodified AgNPs showed dose-dependent toxicity and decreased cell proliferation. Only small-sized AgNPs induced production of ROS by monocytes, but not keratinocytes. Monocytes internalized large aggregates of 33, 46 nm and 10-65 nm AgNPs in cytoplasmic vacuoles, whereas keratinocytes accumulated less particles. AgNPs of 13 nm were localized ubiquitously within both cell types. The tested AgNPs strongly down-regulated production of tumor necrosis factor-α (TNF-α) by monocytes, whereas keratinocytes exposed to AgNPs showed an opposite effect. Unmodified but not Tannic acid-modified AgNPs increased production of the pro-inflammatory MCP-1 by monocytes and keratinocytes.
CONCLUSIONS:
In summary, low inflammatory potential and lack of ROS production by tannic-acid modified AgNPs sized above 30 nm suggests that Tannic acid modification of large silver nanoparticles may help to increase AgNPs biosafety.