used as anti-viral, anti-oxidant, anti-inflammatory, anti-microbial, anti-aging,
stomachic, cardio-tonic, diuretics, laxatives, anti-hyperglycemic, anti-cancer,
anti-coagulant etc. (Smeriglio et al. 2017). Despite of all these beneficial effects on
body, tannins also cause side effects like loss of appetite, sickness, nausea, stomach
irritation, over urination, or sometimes more serious side effects like hepatotoxicity,
sore and throat cancer, and heart failure (Kumar and Singh 1984).
21.2 Tannin Occurrence: Plants Containing Tannins
Tannin, being a secondary metabolite, can be found in almost all higher plants.
Tannins are found commonly in angiosperms and gymnosperms. Among the plants,
tannins are distributed through the different parts of plants like, fruits, roots, barks,
woods, leaves, seeds and plant galls. In major cases, tannins are found normally in
the plants belonging to different families like combretaceae, fagaceae, euphorbiaceae, leguminosae, rubiaceae, anacardiaceae, aceraceae, actinidiaceae, bixaceae,
burseraceae, dipterocarpaceae, ericaceae, myricaceae among dicot plants and
najadaceae, typhaceae among monocot plants. Condensed tannins are most abundant polyphenols and it is found in almost all families of plants. Tannins are often
found in the xylem and secondary phloem or in the layer between the epidermis and
cortex (Ashok and Upadhyaya 2012). The production of condensed tannins
occurred inside tannosome, a chlorophyllus organelle, enclosed within tannoplast,
attached on the cytosolic face of the endoplasmic reticulum (Brillouet et al. 2013).
After synthesis, tannins are stored in vacuoles or in the surface wax of the plants
giving protection to the plants from the outer environmental predators. While
staying in the vacuoles, tannins present in the active form but it does not show any
of its activeness i.e., it does not interfere with plant metabolism or proteins until cell
breakdown or cell death occurs and it is released (Cannas 2008). Tannin can also be
accumulated in the vacuole of tannin cells, which are the idioblasts of parenchyma
cells (Kanzaki et al. 2001). The presence of tannin can be seen generally in the outer
part of the bud and in case of leaf tissues, the most common part where tannin is
obtained is in the upper epidermis. They protect the leaf tissues against predators as
it is distributed in leaf tissues also. In root tissues the most common region is the
hypodermis, where they act as a chemical barrier of pathogens to penetration and
colonization in roots. In seeds, they are located in between outer integument and
aleuronic layer, where they exhibit allopathic and bactericidal properties (Ashok
and Upadhyaya 2012). The different tannins obtained from different plant sources
with their pharmacological indications are given in Table 21.1.
21 Tannins and Polyphenols Extracted from Natural Plants …
717
stomachic, cardio-tonic, diuretics, laxatives, anti-hyperglycemic, anti-cancer,
anti-coagulant etc. (Smeriglio et al. 2017). Despite of all these beneficial effects on
body, tannins also cause side effects like loss of appetite, sickness, nausea, stomach
irritation, over urination, or sometimes more serious side effects like hepatotoxicity,
sore and throat cancer, and heart failure (Kumar and Singh 1984).
21.2 Tannin Occurrence: Plants Containing Tannins
Tannin, being a secondary metabolite, can be found in almost all higher plants.
Tannins are found commonly in angiosperms and gymnosperms. Among the plants,
tannins are distributed through the different parts of plants like, fruits, roots, barks,
woods, leaves, seeds and plant galls. In major cases, tannins are found normally in
the plants belonging to different families like combretaceae, fagaceae, euphorbiaceae, leguminosae, rubiaceae, anacardiaceae, aceraceae, actinidiaceae, bixaceae,
burseraceae, dipterocarpaceae, ericaceae, myricaceae among dicot plants and
najadaceae, typhaceae among monocot plants. Condensed tannins are most abundant polyphenols and it is found in almost all families of plants. Tannins are often
found in the xylem and secondary phloem or in the layer between the epidermis and
cortex (Ashok and Upadhyaya 2012). The production of condensed tannins
occurred inside tannosome, a chlorophyllus organelle, enclosed within tannoplast,
attached on the cytosolic face of the endoplasmic reticulum (Brillouet et al. 2013).
After synthesis, tannins are stored in vacuoles or in the surface wax of the plants
giving protection to the plants from the outer environmental predators. While
staying in the vacuoles, tannins present in the active form but it does not show any
of its activeness i.e., it does not interfere with plant metabolism or proteins until cell
breakdown or cell death occurs and it is released (Cannas 2008). Tannin can also be
accumulated in the vacuole of tannin cells, which are the idioblasts of parenchyma
cells (Kanzaki et al. 2001). The presence of tannin can be seen generally in the outer
part of the bud and in case of leaf tissues, the most common part where tannin is
obtained is in the upper epidermis. They protect the leaf tissues against predators as
it is distributed in leaf tissues also. In root tissues the most common region is the
hypodermis, where they act as a chemical barrier of pathogens to penetration and
colonization in roots. In seeds, they are located in between outer integument and
aleuronic layer, where they exhibit allopathic and bactericidal properties (Ashok
and Upadhyaya 2012). The different tannins obtained from different plant sources
with their pharmacological indications are given in Table 21.1.
21 Tannins and Polyphenols Extracted from Natural Plants …
717