Saturday, January 10, 2009

Resveratrol

Resveratrol

MW: 228
Formula: C14H12O3

Phytochemical:
Resveratrol

Synonyms: Trans-3,5,4'-trihydroxystilbene

Properties: Resveratrol is an antioxidant but its antioxidant properties are weaker that those of quercetin and epicatechin. It has anticancer properties and inhibits lipid peroxidation of low-density lipoprotein and prevents the cytotoxicity of oxidized LDL. Resveratrol also increases the activity of some antiretroviral drugs in vitro.

Antioxidant
In vitro studies have shown that resveratrol inhibits the oxidative damage caused by the heavy metal cadmium. The antioxidant activity of resveratrol reduces damage to endothelial cells exposed to nitrite radicals and protects skin cells against damage caused by UV radiation.

Anticancer
The antioxidant action of resveratrol helps to prevent damage to DNA but it also influences the transcriptions of genes responsible for redox metabolism and inhibits proliferartion of cancer cells. Resveratrol appears to decrease tumor promotion activity by inhibiting the enzyme cyclooxygenase-1, which converts arachidonic acid to substances that promote tumor growth.

Benefits for diabetes
Resveratrol may be benificial for diabetes. Administration of resveratrol may protect against oxidative damage caused by high glucose levels. It also reduces diabetic neuropathic pain.

Heart health
Resveratrol protects our heart and blood vessels by directly scavenging oxidants, which could cause oxidation of lipids, and by preventing apoptosis of endothelial cells. It may also help to prevent heart damage after a cardiac arrest. Reduced platelet aggregation has been attributes to resveratrol, thereby reducing the risk of atherosclerosis.

Increase of lifespan
Tests with animals have shown that that high food intake reduces lifespan. One study showed that resveratrol was able to able to increase the life span of mice on a high calorie diet.

Antitoxic
Many studies on animals have shown antitoxic effects of resveratrol. Resveratrol was able to reverse damages caused by the administration of the chemotherapeutic drug bleomycin. Resveratrol also helped to reduce brain damage and oxidative damage of the liver during ethanol intoxication. It also reduced kidney damage of rats treated with the antibiotic gentamicin.

Facts about Resveratrol: Resveratrol explains partly the French Paradox: the low incidence of heart disease among French people, who eat relatively a lot of unhealthy fat but drink resveratrol containing red wine.

Description: Resveratrol is a flavonol belonging to the group of flavonoids. It is produced by the plant as a defence against diseases.

Distribution: Resveratrol is present in many plants and fruits, including red grapes, eucalyptus, spruce, blueberries, mulberries, peanuts, giant knotweed. Also red wine contains a lot of it. The longer the grape juice is fermented with the grape skins the higher the resveratrol content will be.

Research Reviews: Resveratrol Promotes Clearance of Alzheimer's Disease
Resveratrol Inhibits TNF-alpha?Induced Proliferation and Matrix Metalloproteinase Expression in Human Vascular Smooth Muscle Cells

Ursolic acid

Ursolic acid


MW: 456.68
Formula: C30H48O3

Phytochemical:
Ursolic acid

Synonyms: Malol, micromerol, urson, prunol, (3b)-3-hydroxyurs-12-en-28-oic acid

Properties: Ursolic acid has medicinally action, both topically and internally. Ursolic acid is used in many cosmetic preparations for its anti-inflammatory, antitumor and antimicrobial properties.
Ursolic acid has antibacterial and antifungal activity. Tests have shown that Ursolic acid inhibits the growth of Candida albicans and Microsporium lenosum.
Ursolic acid has anti-inflammatory properties and is used in ointments to treat burns.
Topical application of ursolic acid inhibited TPA-induced initiation and promotion of tumor growth.

Description: Ursolic acid is a is a pentacyclic triterpenoid.

Distribution: Ursolic acid is present in many plants, including apples, bilberries, cranberries, elder flower, peppermint, lavender, oregano, thyme, hawthorn, prunes.

Tannins

Tannins

Tannins are polyphenols that are obtained from various parts of different plants belonging to multiple species. Deriving it name from the technical word ‘tanning’ that meant converting animal hides to leather through chemical processes; tannin is basically used for this function. It is found in abundance in the tree bark, wood, fruit, fruitpod, leaves, and roots and also in plant gall. Since earlier times, people obtained tannin for tanning from plants like wattle (Acacia sp.), oak (Quercus sp.), eucalyptus (Eucalyptus sp.), birch (Betula sp.), willow (Salix caprea), pine (Pinus sp.), quebracho (Scinopsis balansae).

Tannins are found as shapeless yellowish or light brown masses like powder, flakes or sponge. Interestingly, tannins are found almost in all plants and in all climates all over the world. Although algae, fungi and mosses do not contain much tannin. The percentage of tannins present in the plants, however, varies. While they are present in significant proportions in some plants, many others have too little of them. Tannins are usually found in large quantities in the bark of trees where they act as a barrier for micro-organisms like bacteria and fungi and protect the tree. Apart from tanning, tannins are also used in dyeing, photography, refining beer and wine as well as an astringent in medicines. Significantly, tannins form a vital element of tea!

While soluble, astringent materials are found in some plants like tea and coffee, tannins are supplemented to various processed foods, including ice-cream and caramel. They are also used as refining materials to precipitate proteins in wines and beer. As tannins often lower the absorption of some materials into the body, tannins are also often known as anti-nutrients. For example, tannins are found in tea and coffee and consuming too much of these beverages without milk may lead to calcium and iron deficiency in the body and often lead to osteoporosis (a diseases where bones become fragile) and anemia.

In order to counter these problems, it is advised that one should take tea or coffee between meals and not consecutively. In addition, adding milk or lemon juice to the tea helps in reducing or neutralizing tannins’ adverse actions on iron intake. Similarly, consuming food that is rich in vitamin C also helps in neutralizing tannin’s effects on iron absorption.

Tannins can be classified into two broad groups – hydrolysable tannins and condensed tannins.

Hydrolysable tannins are basically derived from simple phenolic acids like gallic acid or ellagic acid and when heated they give away pyrogallol. Pyrogallol is also known as hepatotoxic and has antiseptic as well as caustic properties. Owing to the hepatotoxic property, plants that have a concentration of tannins are not appropriate for application on open wounds. When out in the open air hydrolysable tannins normally change to a brownish color and are accountable for the brown color of many plant dyes.

On the other hand, condensed tannins, also known as non-hydrolysable tannins, do not split easily and hence it is difficult to analyze these. Condensed tannins are basically flavonoid dyes formed through bio-synthesis of flavins and catechins. When these non-hydrolysable tannins are heated up in acids they synthesize to yield a red insoluble substance known as tannin reds or phlobaphenes. Phlobaphenes are flushed precipitates found in some plants that have reddish tints and this is an indication that these plants have rich concentration of condensed tannins. When condensed tannins are heated, catechol emerges as the final product. Unlike hydrolysable tannins, condensed tannins do not possess any trace of hepatotoxicity or any adverse side effects and hence are favorable for use.

In addition to hydrolysable and condensed tannins, other examples of polyphenols include arbutin derived from uva ursi (Arctostaphylos uva-ursi), rugosin-D obtained from meadowsweet (Filipendula ulmaria) and sanguin H-6 from raspberry leaves (Rubus idaeus).

Interestingly, all tannins have several common properties amongst them. While the tannins are soluble in water and alcohol, they do not dissolve in organic solutions. Again, when reacted with nitrogenous bases, polysaccharides, some alkaloids, few glycosides and proteins all tannins form precipitates. Medically, tannins are used as antidotes to poisoning by alkaloids depending on their capacity to form insoluble tannates. However, only dilute solutions of tannins are applied for this work. Finally, almost all tannins consumed remain exuded during the digestive process, and different quantities of it enter the body fluids and are emitted by the kidney.

The above-mentioned properties of tannins should always be kept in mind while applying extracts from tannin-rich plants for medicinal purpose. Tannin is basically an astringent that means that it tauten the pores and pulls out liquids from plants. In plants, tannins are large astringents molecules that easily attaches with proteins. To find the truth about these properties of tannins you may try a few small experiments. If you put tannin on your skin, you will witness it to shrink and if you apply if on your face you will notice wrinkles appearing. At the same time, tannins help to draw out all irritants from the skin. These properties impart medicinal qualities to tannin which is applied on the skin to pull out poisons from bee stings or poison oak bringing in instant relief.

The other remedial values of tannins include application on burns to heal the injury and on cuts to stop bleeding. Tannin’s ability to form a strong ‘leather’ resistance on the exposed tissues helps in protecting the wounds from being affected further. While it stops infection from above, internally tannin continues to heal the wound. In case of third degree burns using strong tannin sources will not only prevent septicemia, but also help to save life. This traditional method has been practiced by most medicos in all countries. On the other hand, when a tannin-rich solution is poured on the flesh, it generates a sealing 'eschar' that often helps in growing new skin albeit temporarily. This technique requires repeated washing of the wound with tannins and this helps to eliminate the bacteria too. Hence, tannins are also said to have antiseptic properties. Interestingly, this practice is still followed in the primary health care centers in China and is also recommended as a first-aid treatment at places where emergency medical services are still inadequate or faulty.

Tannins can also be effective in curbing hemorrhages as well as restrict bare swellings. While tannins are proved haemostatics, they are also beneficial when applied on mucosal coating in mouth. Hence, herbs possessing tannins are widely used as mouthwashes, eyewashes, snuff and even as vaginal douches and also treat rectal disorders.

When applied internally, tannins affect the walls of the stomach and other digestive parts. They sour the mucus secretions and contract or squeeze the membranes in such a manner that secretions from the cells are restricted. The good thing is that tannins’ anti-inflammatory effect helps to control or curb all indications of gastritis, enteritis, oesophagitis and irritating bowel disorders. This action is possible by involving lymph stasis and neutralizing the autolytic enzymes. Conventionally, tannins have also been used to cure diarrhea. In most rural areas diarrhea is caused due to the irritation of the enteritis or the small intestine and is the reason for many deaths worldwide. Although diarrhea initially affects the large bowel, but a reflex action origination higher up aims at eliminating the disturbing material in the system as early as possible. Diarrhea many be considered to be a healthy action as it helps to remove the unwanted or disturbing substance from the system, but if it prolongs, it may lead to dehydration and nausea often resulting to death. Thus, in order to control the fierceness of diarrhea, application of an effective astringent medicine is recommended. An effective astringent does not stop the flow of the disturbing substance in the stomach, but helps in controlling the irritation in the small intestine.

In earlier days, bowel looseness was a result of infection in the small bowel. But in the contemporary society, there are other reasons than this for the disorder. Today looseness of bowel can occur even due to bowel tremor and worsening irritating diseases in the small or large bowel. This means that the application of tannins is restricted in bowel disorder cases these days. However, they can still be used to reduce irritations and control the ferocity of diarrhea. These days agents such as kaolin and morphine are also used to treat the looseness of bowel. Tannins, however, differ from them as they are purely applied on the basis of symptoms and have a healing effect on the bowel wall. At the same time, tannins restraint the entry of any unwanted pathogenic substances.

Although tannins are beneficial in treating bowel irritations and many other ailments, there is a need to restrict or limit the wanton use of tannins in order to avoid unwanted problems. It is a well-known fact that when reacted with all proteins (including dietary proteins) tannins form precipitates. But these tannin-proteins are too complex to be soaked into the blood stream and while they are in the digestive system they intend to restrict or retard the secretion of enzymes. Hence, it is important to restrict the usage of the medicines rich in tannins. This is particularly important when consuming tea and coffee without milk. As the astringent in these beverages retard the metabolism process, it is always advised that tea and coffee should be taken only lightly brewed. And it is even better to consume tea with milk or lemon juice that counteracts the effects of astringent.

In fact, the issue is pretty complex. For example caffeine is an alkaloid and is compounded by tannin. And hence it is available to the body more through coffee than tannin-rich tea. Nevertheless, the tannin effect has its advantages too. When milk is added to tea it not only forms an altogether different complex, but milk being a protein comes into action with the tannin in tea. So when we drink tea with milk, the tannin in tea is engaged with milk protein and hence does not affect any other protein in the digestive system.

There is a strong possibility that intrusion may take place between tannins and alkaloids as well as other pharmacological substances. Hence there can be lesser movement in plants with high degree of tannins or if tannin-rich medicines are supplemented to them. In fact, tannins also behave like mucilages as they too function as astringents only when they come in contact with the skin/ flesh surface or the digestive system’s wall at some point. However, when they are applied internally, tannins do not have any noticeable astringent action on the body organs or tissues. This is despite the fact that the astringent plants may include other ingredient with this function.

While obtaining tannins, it is best to collect the tannin-rich tree barks in the spring for this is the time when the juices begin to come up in the trees and the leaves being to sprout. During this time, you need not work hard to peel off the bark; they will come out without much effort. Although people may use bark collected during any time of the year, during spring the concentration of tannin is maximum in the bark. The concentration of tannin is more in the inner bark (cambium layer) of the tree. In addition, an older tree has more tannin than a younger one and there is more tannin in the lower parts of the tree than the upper parts. Then there are again different timings for de-barking different trees for tannin. It is said that a fir tree can be de-barked for tannin only when it is 30 years old, while it is best to de-bark an oak tree between 15 and 30 years. However, there is difference of opinion in this regard, as many others are of the view that the best time to de-bark oak trees for tannin is between 30 and 35 years.

However, if one is interested in obtaining tree barks for tannin, it is best to buy the shredded barks sold at the saw mills. But before you purchase such shredded barks from the saw mills you must ascertain that the logs or the barks had not been left in the open to be soaked in the rain. Rain-soaked shredded bark is not of much use as it does not contain high tannin levels as tannin is soluble in water and if left in the rain will drain out with other sap. For best results, the barks should be dried in the sun and stored dry. When the bark is stored dry, it can be used for an indefinite period without these losing their tannin content. Besides, dry bark is always easy to grind and extract tannin.

Tannin has several industrial uses as preservatives. In dry wood and leather, tannin averts rotting, changing of shape and decay by bacteria and fungi. It also repels insects and herbivores and protects the plants. Bacteria and fungi cannot grow on plants or wood containing tannin by restricting the flow of extra-cellular microbial enzymes. As a result of this, micro-organisms are not allowed to develop colonies in plants containing tannin or timber and leather treated with the substance. Most significantly, tannins destroy the microbe’s metabolism process by depriving them of iron and other metal ions through restriction of oxidative phosphorylation.

Before concluding, it is worthwhile to mention that the exclusive properties and actions of tannin may initiate many to undertake research in industries related to paint manufacture, construction, wood preservation, bath and tiles as well as leather. The most important properties of tannin that can be taken up for innovation is of course its preservative action.

Friday, January 9, 2009

Ellagic Acid

Ellagic Acid

MW: 302.19
Formula: C14H6C8

Phytochemical:
Ellagic Acid

Synonyms: Benzoaric acid, eleagic acid, elagostasine, gallogen.

Properties: Ellagic acid has antioxidant, anti-mutagen and anti-cancer properties. Studies have shown the anti-cancer activity on cancer cells of the breast, oesophagus, skin, colon, prostate and pancreas. More specifically, ellagic acid prevents the destruction of P53 gene by cancer cells. Ellagic acid can bind with cancer causing molecules, thereby making them inactive. In their studie The effects of dietary ellagic acid on rat hepatic and esophageal mucosal cytochromes P450 and phase II enzymes. Ahn D et al showed that ellagic acid causes a decrease in total hepatic mucosal cytochromes and an increase in some hepatic phase II enzyme activities, thereby enhancing the ability of the target tissues to detoxify the reactive intermediates. Ellagic acid showed also a chemoprotective effect against various chemically induced cancers.
A study by Thresiamma KC and Kuttan R.Indian (Indian Journal Physiology and Pharmacology, 1996 October) indicate that oral administration of ellagic acid by rats can circumvent the carbon tetrachloride toxicity and subsequent fibrosis of the liver.

Ellagic acid has also antiviral and antibacterial activities.

Facts about Ellagic Acid: Plants produce ellagic acid to protect themselves from microbiological infection and pests.

Description: Ellagic acid is a fused four-ring polyphenol. Pure ellagic acid is a cream to light yellow crystalline solid.

Distribution: Ellagic acid is present in many red fruits and berries, including raspberries, strawberries, blackberries, cranberries, pomegranate and some nuts including pecans and walnuts. The highest levels of ellagic acid are found in raspberries. In plants ellagic acid is present in the form of ellagitannin, which is ellagic acid bound to a sugar molecule.

Research Reviews: Pomegranate Juice Ellagitannin Metabolites Are Present in Human Plasma and Some Persist in Urine for Up to 48 Hours
Chemoprevention of esophageal tumorigenesis by dietary administration of lyophilized black raspberries.

Coumarin

Coumarin

MW: 146.14
Formula: C9H6O2

Phytochemical:
Coumarin

Synonyms: 1,2-Benzopyrone, 2H-1-Benzopyran-2-one

Properties: Coumarin has blood-thinning, anti-fungicidal and anti-tumor activities. Coumarin should not be taken while using anticoagulants. Coumarin increases the blood flow in the veins and decreases capillary permeability. Coumarin can be toxic when used at high doses for a long period

Facts about Coumarin: Coumarin seems to work as a pesticide in the plants that produce it. Coumarin is responsible for the sweet smell of new mown hay.

Description: Coumarin is a phytochemical with a vanilla like flavour. Coumarin is a oxygen heterocycle. Coumarin can occur either free or combined with the sugar glucose (coumarin glycoside).

Distribution: Coumarin is found in several plants, including tonka beans, lavender, licorice, strawberries, apricots, cherries, cinnamon, and sweet clover.

Beta-Carotene

Beta-Carotene

MW: 536.87
Formula: C40H56

Phytochemical:
Beta-Carotene

Synonyms: Pro-vitamin A

Properties: Beta-carotene has received a lot of attention as potential anti-cancer and anti-aging phytochemical. Beta-carotene is a powerful antioxidant, protecting the cells of the body from damage caused by free radicals. Studies indicate that diets low in beta-carotene can increase the body's susceptibility to damage from free radicals, resulting in an increased risk of chronic diseases like heart disease and cancers. Beta-carotene supplements may help reduce sun induced skin damage. Smokers should avoid large doses of beta carotene supplements. Beta-carotene is one of the many carotenoids that our body can convert into vitamin A (retinol).
Anti-cancer
Beta-carotene acts as an anti-cancer agent through its antioxidant property but it also seems to stimulate cell to cell communication. Poor communication between cells may eventually lead to cancer. However, beta-carotene may cause adverse effects on smokers. Two studies indicate that heavy smokers and drinkers may have an increased risk of lung cancer or heart disease, when taking daily more than 20 mg synthetic beta-carotene as supplements. A study by Harvard School of Public Health published in January 2004 issue of Cancer Epidemiology Biomarkers and Prevention indicates that beta-carotene consumed as part of natural foods has no such negative effects.
Skin protection
Studies have demonstrated that beta-carotene may be used for skin protection: it reduces UV-induced redness of the skin and improves melasma. Beta-carotene is often use in supplements or topical creams to protect our skin. Too much intake of beta-carotene can result in carotenodermia, a condition that shows a yellowish discoloration of the skin. This is reversible and harmless.
Heart health
Epidemiological studies show that beta-carotene may improve our heart health by decreasing blood pressure. Beta-carotene may also help to prevent arteriosclerosis by inhibiting the oxidation of lipids.

Facts about Beta-Carotene: Beta-Carotene is a yellow pigment naturally occurring in fruits and vegetables. It also known as a provitamin because it can be converted in our body into vitamin A after oxidative cleavage by beta-carotene 15, 150-dioxygenase. In plants, beta-carotene, acts as an anti-oxidant and neutralizes singlet oxygen radicals formed during photosynthesis. Cooking improves the availability of carotenoids in foods. However, prolonged cooking should be avoided to prevent the formation of change of beta-carotene into the cis-configuration.

Description: Beta-carotene is the most common form of carotene and belongs to the group of terpenoids. Pure beta-carotene is red to purple colored oil. It is not soluble in water. Beta-carotene which is used in drinks is encapsulated with starch or gelatin to make it soluble.

Distribution: Beta-carotene occurs in colored fruits and vegetables such as mango, apricot, sweet potatoes, carrots, kale, broccoli, spinach, turnip greens, winter squash and collard greens.

Caffeine

Caffeine

MW: 194.19
Formula: C8H10N4O2

Phytochemical:
Caffeine

Synonyms: 1,3,7-Trimethylxanthin

Properties: Caffeine acts on the nervous system by blocking adenosine receptor thereby slowing down nerve cell acitivity. Caffeine stimulates the central nervous system, respiration and blood circulation. Caffeine also acts as a diuretic. Caffeine increases the circulation and oxidation of fatty acids. This is why caffeine is used by sportsmen to increase fatty acid metabolism. Caffeine is often used in combination with aspirin to treat headaches. Caffeine can also have negative impact on health, especially if overdosed. There is evidence that too much caffeine can reduce bone density and caffeine is not recommended for pregnant women. Moderation is the key to caffeine consumption.

Facts about Caffeine: Caffeine containing plants have been used by different cultures over centuries. Tea from caffeine containing plants was used to treat headaches, coughs and even plague. Only recently caffeine is used to stay awake and relieve fatigue. Caffeine is now one of the most widely used phytochemical.
Caffeine is not addictive but it can be habbit forming. Although caffeine is not toxic to humans in normal levels, it is very toxic to animals, such as dogs and horses.

Description: Caffeine is a water-soluble alkaloid. Pure caffeine is a white odourless crystalline powder with a very bitter taste. Caffeine is closely related to other alkaloids such as theophylline (mainly found in tea) and theobromine (mainly found in cacao beans). The difference between these three molecules is the position of the methyl groups.

Distribution: Caffeine is found in many everyday products, including tea, cola nuts, coffee, chocolate, mate and guarana. It is also found in some softdrinks (mainly colas and energy drinks) where it is artificially added.

Flavonoids

Phytochemical:
Flavonoids

Properties: Flavonoids have antioxidant activity. Flavonoids are becoming very popular because they have many health promoting effects. Some of the activities attributed to flavonoids include: anti-allergic, anti-cancer, antioxidant, anti-inflammatory and anti-viral. The flavonoids quercetin is known for its ability to relieve hay fever, eszema, sinusitis and asthma.
Epidemiological studies have illustrated that heart diseases are inversely related to flavonoid intake. Studies have shown that flavonoids prevent the oxidation of low-density lipoprotein thereby reducing the risk for the development of atherosclerosis.
The contribution of flavonoids to the total antioxidant activity of components in food can be very high because daily intake can vary between 50 to 500 mg.
Red wine contains high levels of flavonoids, mainly quercetin and rutin. The high intake of red wine (and flavonoids) by the French might explain why they suffer less from coronary heart disease then other Europeans, although their consumption of cholesterol rich foods is higher (French paradox). Many studies have confirmed that one or two glasses of red wine daily can protect against heart disease.
Tea flavonoids have many health benefits. Tea flavonoids reduce the oxidation of low-density lipoprotein, lowers the blood levels of cholesterol and triglycerides.
Soy flavonoids (isoflavones) can also reduce blood cholesterol and can help to prevent osteoporis. Soy flavonoids are also used to ease menopausal symptoms.

Description: Flavonoids are water soluble polyphenolic molecules containing 15 carbon atoms. Flavonoids belong to the polyphenol family. Flavanoids can be visualized as two benzene rings which are joined together with a short three carbon chain. One of the carbons of the short chain is always connected to a carbon of one of the benzene rings, either directly or through an oxygen bridge, thereby forming a third middle ring, which can be five or six-membered. The flavonoids consist of 6 major subgroups: chalcone, flavone, flavonol, flavanone, anthocyanins and isoflavonoids.
Together with carotenes, flavanoids are also responsible for the coloring of fruits, vegetables and herbs.

Distribution: Flavonoids are found in most plant material. The most important dietary sources are fruits, tea and soybean. Green and black tea contains about 25% percent flavonoids. Other important sources of flavonoids are apple (quercetin), citrus fruits (rutin and hesperidin),

Research Reviews: A flavonoid fraction from cranberry extract inhibits proliferation of human tumor cell lines
Flavonoids and Heart Health: Proceedings of the ILSI North America Flavonoids Workshop, May 31-June 1, 2005, Washington (USA)

Glycosides

Introduction

Glycosides are compounds containing a carbohydrate and a noncarbohydrate residue in the same molecule.

The carbohydrate residue is attached by an acetal linkage at carbon atom 1 to a noncarbohydrate residue or AGLYCONE.

The nonsugar component is known as the AGLYCONE. The sugar component is called the GLYCONE.

If the carbohydrate portion is glucose, the resulting compound is a GLUCOSIDE.

An example is the methyl glucoside formed when a solution of glucose in boiling methyl alcohol is treated with 0.5% HCl as a catalyst.
The aglycone may be methyl alcohol, glycerol, a sterol, a phenol, etc. An acetal has two ether functions at a single carbon atom.
CLASSIFICATION OF GLYCOSIDES

When the chemical nature of the aglycone group is used as the basis of systematization, the classification is as follows:
SAPONIN GLYCOSIDES

Saponin glycosides are divided into 2 types based on the chemical structure of their aglycones (sapogenins). Saponins on hydrolysis yield an aglycone known as "sapogenin".

The so-called NEUTRAL saponins are derivatives of STEROIDS with spiroketal side chains. The ACID saponins possess triterpenoid structures.

The main pathway leading to both types of sapogenins is similar and involves the head-to-tail coupling of acetate units. However, a branch occurs, after the formation of the triterpenoid hydrocarbon, squalene, that leads to steroids in one direction and to cyclic triterpenoids in the other.

Glycyrrhiza is the dried rhizome and roots of Glycyrrhiza glabra. Glycyrrhiza contains:

1. A saponin glycoside called Glycyrrhizin (glycyrrhizinic acid).

Glycyrrhizin is the Ca2+ and K+ salts of glycyrrhizinic acid.

Glycyrrhizinic acid is 50 times sweeter than sugar (sucrose). Upon hydrolysis, the glycoside loses its sweet taste and is converted to the aglycone glycyrrhetinic acid plus two molecules of glucuronic acid.

Glycyrrhetinic acid is a pentacyclic triterpenoid derivative of the beta-amyrin type. It has expectorant and antitussive properties (Chandler,1985). Expectorants are used to decrease the viscosity of tenacious mucus, or to increase the secretion of mucus in dry irritant unproductive cough, thereby, lubricating the air passages and making coughing more productive. It is used considerably as a flavoring agent and is frequently employed to mask the taste of bitter drugs such as aloe, quinine etc.

Glycyrrhetinic acid inhibits the enzymes (15-hydroxyprostaglandin dehydrogenase & delta 13-prostaglandin) that metabolise the prostaglandins, PGE2 and PGF2alpha to their respective 15 keto-13,14-dihydro metabolites which are INACTIVE. This causes an increased level of prostaglandins in the digestive system. Prostaglandins inhibit gastric secretion but stimulate pancreatic secretion and mucous secretion in the intestines and markedly increase intestinal motility. They also cause cell proliferation in the stomach. The effect on gastric acid secretion, promotion of mucous secretion and cell proliferation shows why licorice has potential in treating peptic ulcer.

PGF2alpha stimulates activity of the uterus during pregnancy and can cause abortion, therefore, licorice should not be taken during pregnancy.

The structure of glycyrrhetinic acid is similar to that of cortisone. Both molecules are flat and similar at position 3 and 11.

This might be the basis for licorice's anti-inflammatory action.

3-Beta-D-(monoglucuronyl)18-beta-glycyrrhetinic acid, a metabolite of glycyrrhetinic acid inhibits 11-beta-hydroxysteroid dehydrogenase which converts ACTIVE cortisol to INACTIVE cortisone in the kidneys. The increased amounts of cortisol binds to the unprotected, unspecific mineralocorticoid receptors and induce sodium and fluid retention, hypokalaemia, hypertension and inhibition of the RENIN-ANGIOTENSIN-ALDOSTERONE system. Licorice should not be given to patients with a known history of high blood pressure. A prolonged usage of licorice can also cause the formation of cataracts.

Glycyrrhizin inhibits liver cell injury caused by many chemicals and is used in the treatment of chronic hepatitis and cirrhosis in Japan. It also inhibits the growth of several DNA and RNA viruses, inactivating herpes simplex virus particles irreversibly.

CARDIAC GLYCOSIDES

COMING SOON

DIGITALIS

COMING SOON




FRIEDLI ENTERPRISES
Georges-Louis Friedli, PgDip., MSc., PhD.
georges-louis@friedli.com

REFERENCES

Benediktsson, R. and Edwards, C.R. (1994)Apparent mineralocorticoid excess. J. Hum. Hypertens. May;8(5):371-375.

Black, R. L., Oglesby, R. B., von Sallmann, L., and Bunim, J. L. (1960). Posterior subcapsular cataracts induced by corticosteroids in patients with rheumatoid arthritis. J.A.M.A.174: 166-171.

Chandler, R.F. (1985). Canadian Pharmaceutical Journal 118: 420-424.

Edwards, C.R., Benediktsson, R., Lindsay, R.S. and Seckl, J.R. (1996)11 beta-Hydroxysteroid dehydrogenases: key enzymes in determining tissue-specific glucocorticoid effects. Steroids Apr;61(4):263-269

Heikens, J., Fliers, E., Endert, E., Ackermans, M. and van Montfrans, G. (1995)Liquorice-induced hypertension--a new understanding of an old disease: case report and brief review. Neth. J. Med. Nov;47(5):230-234

Hikino, H. and Kiso, Y. Natural Products for Liver Diseases. "In Economic and Medicinal Plant Research. Vol.2, ed. H. Wagner, H. Hikino, and N. R. Farnsworth. Academic Press. London.1988.

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