6. Iodometric method: This method follows simple titration. Due to the phenolic
nature of tannins, they can consume iodine from any alkaline medium. The
titration is done by taking standard sodium thiosulphate solution and using
starch as indicator, and the excess consumed iodine determined which is then
used to determine total phenolic contains in the extract (Al-Alimi et al. 2017).
7. Agglutination method: Erythrocytes have a tendency of agglutination when it
comes in contact with tannins but the RBCs do not take part in haemolysis. The
agglutination occurs because of the formation of sticky membrane on their
surface. The end point is reached when all RBCs present, forms precipitation i.e.
solution remains colourless on shaking. The quantity of precipitated RBC
determines the amount of tannin present in sample (Pirofsky et al. 1962).
21.8 Activities of Tannins
Lots of research provide the knowledge about tannins that they are used biologically or can be used in different therapeutic purposes, in manufacturing purposes
etc. From the discovery of this secondary metabolites, tannins are extensively
studied and the outcome of those research shows tannin’s ability to perform in a
versatile way which can show its different activities like anti-oxidant,
anti-inflammatory, anti-microbial, anti-aging, stomachic, cardio-tonic, diuretics,
laxatives, hypoglycemic, anti-corrosive property etc. or it can be used in photography, food, neutraceuticals or cosmeceuticals and so in different sectors. It is
believed that tannins show its applications by two mechanistic way.
1. As un-absorbable, which is usually the complexes with binding properties which
may exert local actions like antioxidant, radical scavenging, antimicrobial,
antiviral, anti-mutagenic, and anti-nutrient effects, or
2. As absorbable, which is having a benefit of possessing lower molecular weight
so that they are easily absorbed, and produce systemic effects in various organs
(Serrano et al. 2009).
21.8.1 Anti-oxidant Properties
Among all of the in-vitro studies, the most extensively studied property is its
anti-oxidant property. Tannins may show the anti-oxidant property because of its
several hydroxyl (OH) groups present in the phenolic moiety. Tannins do have an
ability of scavenging free radicals and inhibiting lipid peroxidation depending on
their structure and degree of polymerization (Tian et al. 2012). The antioxidant
activities of tannins are generally calculated by DPPH radical scavenging method.
The absorbance values of the compounds which changes the colour from violet to
736
S. Mal and D. Pal
nature of tannins, they can consume iodine from any alkaline medium. The
titration is done by taking standard sodium thiosulphate solution and using
starch as indicator, and the excess consumed iodine determined which is then
used to determine total phenolic contains in the extract (Al-Alimi et al. 2017).
7. Agglutination method: Erythrocytes have a tendency of agglutination when it
comes in contact with tannins but the RBCs do not take part in haemolysis. The
agglutination occurs because of the formation of sticky membrane on their
surface. The end point is reached when all RBCs present, forms precipitation i.e.
solution remains colourless on shaking. The quantity of precipitated RBC
determines the amount of tannin present in sample (Pirofsky et al. 1962).
21.8 Activities of Tannins
Lots of research provide the knowledge about tannins that they are used biologically or can be used in different therapeutic purposes, in manufacturing purposes
etc. From the discovery of this secondary metabolites, tannins are extensively
studied and the outcome of those research shows tannin’s ability to perform in a
versatile way which can show its different activities like anti-oxidant,
anti-inflammatory, anti-microbial, anti-aging, stomachic, cardio-tonic, diuretics,
laxatives, hypoglycemic, anti-corrosive property etc. or it can be used in photography, food, neutraceuticals or cosmeceuticals and so in different sectors. It is
believed that tannins show its applications by two mechanistic way.
1. As un-absorbable, which is usually the complexes with binding properties which
may exert local actions like antioxidant, radical scavenging, antimicrobial,
antiviral, anti-mutagenic, and anti-nutrient effects, or
2. As absorbable, which is having a benefit of possessing lower molecular weight
so that they are easily absorbed, and produce systemic effects in various organs
(Serrano et al. 2009).
21.8.1 Anti-oxidant Properties
Among all of the in-vitro studies, the most extensively studied property is its
anti-oxidant property. Tannins may show the anti-oxidant property because of its
several hydroxyl (OH) groups present in the phenolic moiety. Tannins do have an
ability of scavenging free radicals and inhibiting lipid peroxidation depending on
their structure and degree of polymerization (Tian et al. 2012). The antioxidant
activities of tannins are generally calculated by DPPH radical scavenging method.
The absorbance values of the compounds which changes the colour from violet to
736
S. Mal and D. Pal