**2.3 Medicine and pharmaceuticals**

After the industrial revolution, large numbers of synthetic chemicals were used as drug molecules to treat numerous diseases but they left several adverse effects on the human and environment. Therefore, attention has been shifted to identify new alternative natural compounds that are to be clinically effective and create minimum adverse effects. A large number of natural compounds such as polyphenolicbased secondary metabolites, for example, tannins, are isolated and characterized as preventive therapeutic agents, which can be isolated from fruits, vegetables, or plants or expressed in the microorganism by metabolic engineering. Many studies have clearly shown that tannins are natural antioxidants linked with the prevention of degenerative diseases such as atherosclerosis, cardiovascular diseases, neurodegenerative diseases, and certain types of cancers by acting as antioxidants and antibacterial.

#### *2.3.1 Tannins as preventive medicine*

Reactive oxygen species such as, hydroxyl radical (HO•), superoxide anion (O2• <sup>−</sup>), and peroxyl radical (ROO•) and the non-radicals like, hydrogen peroxide (H2O2) and hypochlorous acid (HOCl) are produced in biological systems. They adversely affect cellular protective systems which are responsible for many degenerative diseases in human. In order to overcome toxic effects of reactive oxygen

**125**

*Applications of Tannins in Industry*

*DOI: http://dx.doi.org/10.5772/intechopen.85984*

species (ROS), tannins can be used as ROS scavenging agents. Actually, tannins have the ability to donate electron to a free radical or ROS and make them more stable compounds therefore, render less harmful effects on cellular environment [22, 30, 31]. Tannins also help by supporting antioxidant enzymes involved in the ROS scavenging activities, simultaneously inactivating the metal ions produced by free radicals. Many tannin-based products such as gallic acid (GA) (3,4,5-trihydroxybenzoic acid), proanthocyanidins, epigallocatechin gallate (EGCG), and ellagic acid-4-O-α-D-xylopyranoside have been tested and found highly effective as antioxidants. Gallic acid, isolated from many plant extracts, shows strong antioxidant properties responsible for the antioxidant and anticancer activities. Moreover, gallic acid derivatives (GADs) are present in large number of herbal medicines and formulations used for variety of diseases. Tannin derivatives like mucic acid gallate, mucic acid lactone gallate, monogalloylglucose, gallic acid, digalloylglucose, putranjivain A, galloyl-HHDP-glucose, elaeocarpusin, and chebulagic acid isolated from fruits of *Phyllanthus emblica* exhibit antioxidant activities that are already proved by the study of animals models. Currently, researchers have shifted their focus on the role of individual tannin molecules rather than group of compounds in the biological system for example, gallic acid, and epigallocatechin gallate (EGCG)

from fruits and teas, respectively, are widely studied [22, 32].

Synthetic antibiotics are being used as antibacterial agents for a long time in medical and animal sciences. But prolonged application of antibiotics lead to the development of resistance against the antimicrobial agents among the bacterial species attributed to selective evolutionary processes, a problem being faced by researcher world over. Nowadays, methicillin-resistant *Staphylococcus aureus* (MRSA), and multidrug-resistant pathogenic microorganisms are great health problems responsible for large number of morbidity and mortality in human population. Moreover, development of resistance to virtually all currently available antibiotics make situation more worsen. Therefore, it is of urgent need to discover new natural antimicrobial agents or antibiotics to cope with the development of

However, many antibiotic resistance mechanisms are prevailed in the resilient microbial strains, but the mechanisms studied in *Staphylococcus aureus* RN4220 and IS-58 strains show that these particular strains have the capability to drain out the antibiotics from cytoplasm through proteinous membrane pumps. In a highly significant study, sub-concentration of pump inhibitors and tannins was used which significantly inhibited pump functions in both RN4220 and IS-58 strains [33]. Tannins have been used against the ATCC 43300 and MRSA clinical strains as membrane pump inhibitors and their mode of action was studied by using nextgeneration sequencing (NGS) in order to get deep understanding of antibacterial mechanisms at genome, transcriptome, and protein synthesis level. This investigation indicates that tannins mainly disrupt protein synthesis mechanisms by bringing major changes in ribosome pathways, which further caused a change in the translation processes in MRSA cells eventually leading to reduction in bacterial growth. Hence, tannins can be used as potential tools against the anti-MRSA agents in clinical application particularly, in antiseptic body solutions and antibacterial cream [31]. More recently, three ellagitannin-based tannins and isorugosin-A extracted in acetone from the fresh leaves of *Liquidambar formosana* showed high level of antibacterial activity against methicillin-resistant *Staphylococcus aureus* (MRSA) and *Pseudomonas aeruginosa* that attributed to tannins binding with mem-

*2.3.2 Antibacterial properties of tannins*

antibiotics resistance [31].

brane proteins, by polyphenolic acyl groups [30].

#### *Applications of Tannins in Industry DOI: http://dx.doi.org/10.5772/intechopen.85984*

*Tannins - Structural Properties, Biological Properties and Current Knowledge*

In recent years, a lot of attempts have been made to improve the bio-durability and commercial properties of wood and wood-based furniture by using tanninbased preservatives. Although both condensed and hydrolysable tannins are used as adhesive, but mimosa tannin is proved to be the most effective wood glue, which attributed to good cross-linking, auto-condensation, poly condensations reactions, and hyper activity. Tannin-based adhesive is proved to be harder than pure synthetic adhesive due to great level of bonding with other aldehydes or different non aldehyde hardeners (glyoxal, furfuryl alcohol, hexamine, etc.) and lignocellulosic materials. Several industries in South Africa and America are using the mimosa and quebracho-based tannins that could reduce the formaldehyde-based emission from the industries. A similar technology has been used to produce the interior and exterior grade particle board largely used in the furniture industry [28]. Apart from this, catechin and gallic acid-based epoxide adhesives and starch-based adhesives from tannins were also produced. Epoxy adhesives are produced by reactions between catechin and epichloridrin via alkylation in the presence of unsaturated halogenated compound that leads to the oxidation. Tannin-based adhesives have been used for grinding wheels, angle grinder disks, and automotive brake pads

Coating material is extremely useful to prevent wood surface from biotic and abiotic adversities like, rain, winter, and summer, and insects and microorganisms. Generally, coating material comprises of polyurethane and isocyanates. The urethane-based coating material is prepared by using the lignin and lignosulfonate/hydroxypropylate. Recently, Pinus tannins and di-isocyanates were used to prepare more effective coating material by exploiting hydroxypropylation and hydroxybutylation reactions which enhanced the bonding patterns between hydroxyl groups provided by tannins (flavonoids) and isocyanates [29]. However, tannins and isocyanate-based adhesives are good and environmental friendly, but these should be replaced with more bio-based material like tannins because they are naturally designed to protect wood against fungal attacks and natural decaying

After the industrial revolution, large numbers of synthetic chemicals were used as drug molecules to treat numerous diseases but they left several adverse effects on the human and environment. Therefore, attention has been shifted to identify new alternative natural compounds that are to be clinically effective and create minimum adverse effects. A large number of natural compounds such as polyphenolicbased secondary metabolites, for example, tannins, are isolated and characterized as preventive therapeutic agents, which can be isolated from fruits, vegetables, or plants or expressed in the microorganism by metabolic engineering. Many studies have clearly shown that tannins are natural antioxidants linked with the prevention of degenerative diseases such as atherosclerosis, cardiovascular diseases, neurodegenerative diseases, and certain types of cancers by acting as antioxidants and

Reactive oxygen species such as, hydroxyl radical (HO•), superoxide anion

<sup>−</sup>), and peroxyl radical (ROO•) and the non-radicals like, hydrogen peroxide (H2O2) and hypochlorous acid (HOCl) are produced in biological systems. They adversely affect cellular protective systems which are responsible for many degenerative diseases in human. In order to overcome toxic effects of reactive oxygen

**124**

(O2•

matrices also.

process of wood.

antibacterial.

**2.3 Medicine and pharmaceuticals**

*2.3.1 Tannins as preventive medicine*

species (ROS), tannins can be used as ROS scavenging agents. Actually, tannins have the ability to donate electron to a free radical or ROS and make them more stable compounds therefore, render less harmful effects on cellular environment [22, 30, 31]. Tannins also help by supporting antioxidant enzymes involved in the ROS scavenging activities, simultaneously inactivating the metal ions produced by free radicals. Many tannin-based products such as gallic acid (GA) (3,4,5-trihydroxybenzoic acid), proanthocyanidins, epigallocatechin gallate (EGCG), and ellagic acid-4-O-α-D-xylopyranoside have been tested and found highly effective as antioxidants. Gallic acid, isolated from many plant extracts, shows strong antioxidant properties responsible for the antioxidant and anticancer activities. Moreover, gallic acid derivatives (GADs) are present in large number of herbal medicines and formulations used for variety of diseases. Tannin derivatives like mucic acid gallate, mucic acid lactone gallate, monogalloylglucose, gallic acid, digalloylglucose, putranjivain A, galloyl-HHDP-glucose, elaeocarpusin, and chebulagic acid isolated from fruits of *Phyllanthus emblica* exhibit antioxidant activities that are already proved by the study of animals models. Currently, researchers have shifted their focus on the role of individual tannin molecules rather than group of compounds in the biological system for example, gallic acid, and epigallocatechin gallate (EGCG) from fruits and teas, respectively, are widely studied [22, 32].

## *2.3.2 Antibacterial properties of tannins*

Synthetic antibiotics are being used as antibacterial agents for a long time in medical and animal sciences. But prolonged application of antibiotics lead to the development of resistance against the antimicrobial agents among the bacterial species attributed to selective evolutionary processes, a problem being faced by researcher world over. Nowadays, methicillin-resistant *Staphylococcus aureus* (MRSA), and multidrug-resistant pathogenic microorganisms are great health problems responsible for large number of morbidity and mortality in human population. Moreover, development of resistance to virtually all currently available antibiotics make situation more worsen. Therefore, it is of urgent need to discover new natural antimicrobial agents or antibiotics to cope with the development of antibiotics resistance [31].

However, many antibiotic resistance mechanisms are prevailed in the resilient microbial strains, but the mechanisms studied in *Staphylococcus aureus* RN4220 and IS-58 strains show that these particular strains have the capability to drain out the antibiotics from cytoplasm through proteinous membrane pumps. In a highly significant study, sub-concentration of pump inhibitors and tannins was used which significantly inhibited pump functions in both RN4220 and IS-58 strains [33].

Tannins have been used against the ATCC 43300 and MRSA clinical strains as membrane pump inhibitors and their mode of action was studied by using nextgeneration sequencing (NGS) in order to get deep understanding of antibacterial mechanisms at genome, transcriptome, and protein synthesis level. This investigation indicates that tannins mainly disrupt protein synthesis mechanisms by bringing major changes in ribosome pathways, which further caused a change in the translation processes in MRSA cells eventually leading to reduction in bacterial growth. Hence, tannins can be used as potential tools against the anti-MRSA agents in clinical application particularly, in antiseptic body solutions and antibacterial cream [31]. More recently, three ellagitannin-based tannins and isorugosin-A extracted in acetone from the fresh leaves of *Liquidambar formosana* showed high level of antibacterial activity against methicillin-resistant *Staphylococcus aureus* (MRSA) and *Pseudomonas aeruginosa* that attributed to tannins binding with membrane proteins, by polyphenolic acyl groups [30].

Tannin and its derivatives show great antibacterial properties which are used against a large number of bacterial species such as *Aeromanas*, *Bacillus*, *Clostridium*, *Enterobacter*, *Helicobacter*, *Klebsiella*, *Proteus*, *Pseudomonas*, *Shigella*, *Escherichia*, *Staphylococcus*, or *Streptococcus* and fungal species like *Aspergillus*, *Coniophora*, or *Penicillium*. Antibacterial activity of tannins particularly, polymeric proanthocyanidins proved highly effective against *Escherichia coli* and *Staphylococcus aureus*. It is attribute to binding of tannins with urinary tract epithelium and intestinal epithelium that prevent binding of disease causing organisms. In view of above findings, tannic acid is used as an inhibitor and immunomodulatory against multidrug resistant bacteria (MDR) [28, 33].

The antibacterial properties of tannins are not only studied in animals but in plants too. Several microorganisms cause the substantial loss in the fruit, vegetable, and plant species resulting in great economic loss. After the green revolution, huge amount of pesticides were used to prevent the bacterial and insect attacks in crops which lead to the environmental pollution and soil contamination. But bio-based pesticides or natural products can be the best option of chemical-based antibacterial agents. Recently, crude methanol extract of *Sapium baccatum* was used against the *Ralstonia solanacearum*, a causal agent of bacterial wilt of tomato. The extract mainly contains gallic acid, methyl gallate, corilagin, tercatain, chebulagic acid, chebulinic acid, and quercetin 3-O-α-L-arabinopyranoside which all show strong antibacterial activity except one tannin-based product, that is, quercetin 3-O-α-Larabinopyranoside. In in vivo studies, the concentration of 2000 and 1000 μg/mL of crude extract reduced the development of tomato bacterial wilt by 83 and 63%, respectively [34].

#### *2.3.3 Antifungal properties of tannins*

The growth of fungi such as *Fusarium semitectum*, *F. fusiformis*, and *Alternaria altternata* can be hindered by gallic acid [22, 35]. The ethyl acetate extract and its sub-fraction from red raspberry (*Rubus idaeus*) fruit have high level of antifungal activities against the *Candida albicans*, *C. glabrata*, and *C. parapsilosis* strains of fungi due to their antimicrobial activities of tannins. These fungal strains form drug-resistant biofilms inside the oral cavity responsible for dental caries, periodontal disease, and denture stomatitis. However, the activity of extract was dose dependent, and 25 and 12.5 μg/mL of 80% ripe fruit extract was more effective as antiadherence or antibacterial agents against the microbial films formations [35].

#### *2.3.4 Immunomodulatory activities of tannins*

Immune system plays a very significant role to cope up with infectious agents like bacteria, virus, fungus, pollens, and parasites. Some experiments show that tannins modulate human immune system in a highly positive manner, thus tannins act as immunomodulatory agents in the battle against infectious diseases. Leishmaniosis, a disease that caused by parasitic protozoan's complex, comprise of more than 20 different species of *Leishmania* genus. Its conventional treatments are highly expensive, and lead to many side effects; moreover, protozoan resistance to treatments has been reported. Two most important tannins, gallic acid (GA) and ellagic acid (EA), were tested for antileishmania, cytotoxic, and immunomodulatory activities. Both GA and EA significantly reduced the infection and infectivity of macrophages infected by *L. major*. Moreover, both GA and EA induced high immunomodulatory activity of macrophage cells that proved by enhanced phagocytic capability, lysosomal volume, nitrite release, and

**127**

fermentation [42].

**3. Nanotechnology and tannin**

*Applications of Tannins in Industry*

*DOI: http://dx.doi.org/10.5772/intechopen.85984*

**2.4 Role of tannins in animal husbandry**

therapeutic agents against the leishmaniosis [36].

intracellular calcium in macrophages. Therefore, tannins can be used as potential

Bacterial and fungal infection is also a threat to the poultry, livestock, and animal husbandry which is responsible for high level of mortality. To overcome this problem, several antibiotics have been used for decades that proved to be very effective; consequently, it improves animal and poultry production in the world. But it is well known that extreme application of antibiotics promotes the antibioticresistant among the microorganisms in cattle [37–39]. Therefore, in-feed antibiotics and plant-based antibacterial agents, such as phytogenic compounds (e.g., tannin), have been discovered and promoted, which have great promises in future. In recent past, great attention has been given to antibacterial activities of tannins and their effects as dietary source in animal [37]. It has been concluded that tannins with saponins and essential oils can be used as in-feed antibiotics against bacteria, fungi, and yeasts. Because, tannins are toxic to bacteria and potentially inhibit growth of *Salmonella*, *Shigella*, *Staphylococcus*, *Pseudomonas*, and *Helicobacter pylori*, but it would be noteworthy that they show species specific antibacterial activity. Moreover, tannin-containing forage in cattle diets helps to control animal pasture bloating, intestinal parasite, and disease causing bacteria in ruins of animals. Tannins can hinder microbial growth by using several mechanisms including lack of nutrient to bacterial cell, inactivate vital extracellular enzymes, inhibition of oxidative phosphorylation, chelation of metal ions, and complex formation with membrane and proteins [38]. It has been seen that condensed type of tannins are mainly present in forage legumes, trees, shrubs, tree leaves, and browse shrubs, but their concentration vary from species to species that influenced by environmental conditions also [40]. Tannins from mimosa (HT), chestnut (HT), and quebracho (CT) have been used as in-feed antibiotics in animals [41]. But the major challenge for tannins as antibiotics is the lack of systematic and comprehensive studies on the various aspects such as doses, side effects on digestions simultaneously prolong use can develop resistance against the in-feed antibiotics as in case of normal antibiotics [40]. Moreover, tan-

nins are antinutrient factors for monogastric animals and poultry.

Tannins can also act as the antinutrients in rumens of livestock due to their binding to vital biomolecules in biological systems. Several adverse effects such as availability of nutrients, metal ions chelation, binding with proteins and hinder the growth of beneficial microflora have been observed in the cattle gut. To test the adverse effect of tannin as diet component on lamb gut microflora and fermentation was studied. Both types of tannins, that is, hydrolysable and condensed with 4% extract of chestnut (*Castanea sativa*, *Caesalpinia spinosa*), *mimosa* (*Acacia negra*), and *gambier* (*Uncaria gambir*) feed to lamb. The results show that tannins meagerly affect gut microflora including fungi in the lamb gut for 45 days. Simultaneously, it also shows that high level of tannin inclusion in diet proved as antimicrobial agent against the harmful methanogens and protozoa without affecting ruminal

Cancer is a fatal disease and its occurrence in the human population is the major cause of concern. However, the role of tannins as chemopreservants in the cure of cancer has been widely discussed by many researchers [42]. The chemoprevention

*Tannins - Structural Properties, Biological Properties and Current Knowledge*

resistant bacteria (MDR) [28, 33].

*2.3.3 Antifungal properties of tannins*

*2.3.4 Immunomodulatory activities of tannins*

respectively [34].

Tannin and its derivatives show great antibacterial properties which are used against a large number of bacterial species such as *Aeromanas*, *Bacillus*, *Clostridium*, *Enterobacter*, *Helicobacter*, *Klebsiella*, *Proteus*, *Pseudomonas*, *Shigella*, *Escherichia*, *Staphylococcus*, or *Streptococcus* and fungal species like *Aspergillus*, *Coniophora*, or *Penicillium*. Antibacterial activity of tannins particularly, polymeric proanthocyanidins proved highly effective against *Escherichia coli* and *Staphylococcus aureus*. It is attribute to binding of tannins with urinary tract epithelium and intestinal epithelium that prevent binding of disease causing organisms. In view of above findings, tannic acid is used as an inhibitor and immunomodulatory against multidrug

The antibacterial properties of tannins are not only studied in animals but in plants too. Several microorganisms cause the substantial loss in the fruit, vegetable, and plant species resulting in great economic loss. After the green revolution, huge amount of pesticides were used to prevent the bacterial and insect attacks in crops which lead to the environmental pollution and soil contamination. But bio-based pesticides or natural products can be the best option of chemical-based antibacterial agents. Recently, crude methanol extract of *Sapium baccatum* was used against the *Ralstonia solanacearum*, a causal agent of bacterial wilt of tomato. The extract mainly contains gallic acid, methyl gallate, corilagin, tercatain, chebulagic acid, chebulinic acid, and quercetin 3-O-α-L-arabinopyranoside which all show strong antibacterial activity except one tannin-based product, that is, quercetin 3-O-α-Larabinopyranoside. In in vivo studies, the concentration of 2000 and 1000 μg/mL of crude extract reduced the development of tomato bacterial wilt by 83 and 63%,

The growth of fungi such as *Fusarium semitectum*, *F. fusiformis*, and *Alternaria altternata* can be hindered by gallic acid [22, 35]. The ethyl acetate extract and its sub-fraction from red raspberry (*Rubus idaeus*) fruit have high level of antifungal activities against the *Candida albicans*, *C. glabrata*, and *C. parapsilosis* strains of fungi due to their antimicrobial activities of tannins. These fungal strains form drug-resistant biofilms inside the oral cavity responsible for dental caries, periodontal disease, and denture stomatitis. However, the activity of extract was dose dependent, and 25 and 12.5 μg/mL of 80% ripe fruit extract was more effective as antiadherence or antibacterial agents against the microbial films formations [35].

Immune system plays a very significant role to cope up with infectious agents

like bacteria, virus, fungus, pollens, and parasites. Some experiments show that tannins modulate human immune system in a highly positive manner, thus tannins act as immunomodulatory agents in the battle against infectious diseases. Leishmaniosis, a disease that caused by parasitic protozoan's complex, comprise of more than 20 different species of *Leishmania* genus. Its conventional treatments are highly expensive, and lead to many side effects; moreover, protozoan resistance to treatments has been reported. Two most important tannins, gallic acid (GA) and ellagic acid (EA), were tested for antileishmania, cytotoxic, and immunomodulatory activities. Both GA and EA significantly reduced the infection and infectivity of macrophages infected by *L. major*. Moreover, both GA and EA induced high immunomodulatory activity of macrophage cells that proved by enhanced phagocytic capability, lysosomal volume, nitrite release, and

**126**

intracellular calcium in macrophages. Therefore, tannins can be used as potential therapeutic agents against the leishmaniosis [36].
