About Catechin, Gallic Acid, Quercetin, Pterostilbene

About Catechin

Catechin is a polyphenolic antioxidant plant metabolite. The term catechin is also commonly used to refer to the related family of flavonoids and the subgroup flavan-3-ols (or simply flavanols). Catechins are differentiated from the ketone-containing flavonoids such as quercitin and rutin, which are called flavonols.

An article by the Department of Food Science and Technology, The University of Georgia, Athens, Georgia USA published in January 2004: Major flavonoids in grape seeds and skins: antioxidant capacity of catechin, epicatechin, and gallic acid:

Grape seeds and skins are good sources of phytochemicals such as gallic acid, catechin, and epicatechin and are suitable raw materials for the production of antioxidative dietary supplements. These three major phenolic constituents of grape seeds contributed <26% to the antioxidant capacity measured as ORAC on the basis of the corrected concentrations of gallic acid, catechin, and epicatechin in grape byproducts. Peroxyl radical scavenging activities of phenolics present in grape seeds or skins in decreasing order were resveratrol > catechin > epicatechin = gallocatechin > gallic acid = ellagic acid. The results indicated that dimeric, trimeric, oligomeric, or polymeric procyanidins account for most of the superior antioxidant capacity of grape seeds. [35]

Health benefits of Catechin:

The health benefits of catechins have been studied extensively in humans and in animal models. Reduction in atherosclerotic plaques was seen in animal models. [36]

Reduction in carcinogenesis was seen in vitro, in human breast cancer cells. [37]

Many studies on health benefits have been linked to the catechin content. According to Norman Hollenberg, professor of medicine at Harvard Medical School, epicatechin can reduce the risk of four of the major health problems: stroke, heart failure, cancer and diabetes. He studied the Kuna people in Panama, who drink up to 40 cups of cocoa a week, and found that the prevalence of the “big four” is less than 10%. He believes that epicatechin should be considered essential to the diet and thus classed as a vitamin. [38]

According to this research [39], epigallocatechin-3-gallate is an antioxidant that helps protect the skin from UV radiation-induced damage and tumor formation.

Catechin is a histidine decarboxylase inhibitor. Thus, it inhibits the conversion of histidine to histamine, and so, is thought to be beneficial through reduction of potentially damaging, histamine-related local immune response(s).

Antibiotic effects: Green tea catechins have also been shown to possess antibiotic properties due to their role in disrupting a specific stage of the bacterial DNA replication process. [40]

DNA protection: Catechins, when combined with habitual exercise, have been shown to delay some forms of aging. Mice fed catechins showed decreased levels of aging, lowering of oxidative stress in mitochondria, and an increase in mRNA transcription of mitochondrial-related proteins. [41]

Anti-carcinogenic effects: In 2008 University of California, Los Angeles (UCLA), cancer researchers found that study participants who ate foods containing certain flavonoids seemed to be protected from developing lung cancer. Dr. Zhang, (professor of public health and epidemiology at the UCLA School of Public Health) said the flavonoids that appeared to be the most protective included catechin, found in strawberries and green and black teas; kaempferol, found in Brussels sprouts and apples; and quercetin, found in beans, onions (particularly red) and apples. [42]

MAO effects: Catechin and epicatechin are also selective monoamine oxidase inhibitors (MAOIs) of type MAO-B. [43]


About Gallic Acid

Gallic acid is an organic acid, also known as 3,4,5-trihydroxybenzoic acid. Despite its name, it does not contain gallium.

Gallic acid is commonly used in the pharmaceutical industry. It is used as a standard for determining the phenol content of various analytes by the Folin-Ciocalteau assay; results are reported in gallic acid equivalents. Gallic acid can also be used as a starting material in the synthesis of the psychedelic alkaloid mescaline.

Gallic acid seems to have anti-fungal and anti-viral properties. Gallic acid acts as a antioxidant and helps to protect our cells against oxidative damage. Gallic acid was found to show cytotoxicity against cancer cells, without harming healthy cells. Gallic acid is used as a remote astringent in cases of internal haemorrhage. Gallic acid is also used to treat albuminuria and diabetes. Some ointment to treat psoriasis and external haemorrhoids contain gallic acid.

Gallic acid is found in almost all plants. Plants known for their high gallic acid content include gallnuts, grapes, tea, hops and oak bark. Gallic acid does not combine with protein and has therefore no astringent taste.

About Quercetin

Quercetin is the most abundant of the flavonoids. Quercetin belongs to the flavonoids family and consist of 3 rings and 5 hydroxyl groups. Quercetin is also a building block for other flavonoids. Quercetin occurs in food as a aglycone (attached to a sugar molecule).

Quercetin is a plant-derived flavonoid, specifically a flavonol, used as a nutritional supplement. Laboratory studies show it may have anti-inflammatory and antioxidant properties and it is being investigated for a wide range of potential health benefits.

Quercetin has been shown to increase energy expenditure in rats, but only for short periods (fewer than 8 weeks). Effects of quercetin on exercise tolerance in mice have been associated with increased mitochondrial biogenesis.

The American Cancer Society says that while quercetin "has been promoted as being effective against a wide variety of diseases, including cancer," and "some early lab results appear promising, as of yet there is no reliable clinical evidence that quercetin can prevent or treat cancer in humans." In the amounts consumed in a healthy diet, quercetin "is unlikely to cause any major problems or benefits."

High dietary intake of fruits and vegetables is associated with reduction in cancer, and some scientists suspect quercetin may be partly responsible. Research shows that quercetin influences cellular mechanisms in vitro and in animal studies, and there is some evidence from human population studies that quercetin may, in a very limited fashion, reduce the risk of certain cancers. [44]

Quercetin is a powerful antioxidant. It is also a natural anti-histamine, and anti-inflammatory. Research shows that quercetin may help to prevent cancer, especially prostate cancer. Quercetin's antihistamine action may help to relieve allergic symptoms and asthma symptoms. The anti-inflammatory properties may help to reduce pain from disorders such as arthritis. Men who are concerned about prostate problems would also benefit from quercetin. Quercetin may also help reduce symptoms like fatigue, depression and anxiety. (source for this paragraph:

The University of Maryland, Medical Center published an article about quercetin and its benefits: “Quercetin acts like an antihistamine and an anti-inflammatory, and may help protect against heart disease and cancer.” The report further addresses quercetin in relation to: Allergies, asthma, hay fever and hives, heart disease, high cholesterol, hypertension, interstitial cystitis, prostatitis, rheumatoid arthritis and cancer. [45]

The U.S. Food and Drug Administration has not approved any health claims for quercetin. There is current early-stage clinical research on quercetin addressing safety and efficacy against sarcoidosis, asthma and glucose absorption in obesity and diabetes. [46]

Quercetin is the aglycone form of a number of other flavonoid glycosides, such as rutin and quercitrin, found in citrus fruit, buckwheat and onions. Quercetin forms the glycosides quercitrin and rutin together with rhamnose and rutinose, respectively. Quercetin is classified as IARC group 3 (no evidence of carcinogenicity in humans).

Res-Juventa Reserveratrol Complex

About Pterostilbene

Pterostilbene is a stilbenoid chemically related to resveratrol. It is thought to be the key compound found predominantly in grapes (and blueberries) that exhibit anti-cancer, anti-hypercholesterolemia, anti-hypertriglyceridemia properties, as well as fight off and reverse cognitive decline. It is believed that the compound also has anti-diabetic properties.

Extracts from a report by the United States Department of Agriculture, Agricultural Research Service, dated November/December 2006. [47]

You may not have heard of pterostilbene (pronounced “tero-STILL-bean”) yet. But this compound’s prospects for inhibiting breast cancer, diabetes, and LDL cholesterol in humans may soon make it as well known as other health-enhancing natural substances.

Standing to reap benefits from pterostilbene’s renown are producers of blueberries and grapes, two fruits known to contain this compound.

“The more we study pterostilbene, the more we see its huge potential in the human health field,” says chemist Agnes Rimando of ARSメs Natural Products Utilization Research Laboratory in Oxford, Mississippi. Her animal studies on the compound have led to several groundbreaking discoveries.

Pterostilbene is one of many aromatic hydrocarbons called “stilbenes.” It’s a derivative of resveratrol, a compound found in large quantities in the skins of red grapes. Resveratrol burst on the health scene more than a decade ago, when it was found to have cardiovascular and cancer-fighting benefits.

Studies at the time examined resveratrol’s role in an apparent phenomenon in which people in France live long lives despite diets very high in saturated fat and cholesterol. It has been theorized, though not yet proven, that red wine’s prevalence in the French diet lowers incidence of cardiovascular disease.

Originally isolated from red sandalwood (Pterocarpus santalinus), pterostilbene had already been touted for its fungicidal and antidiabetic properties—and showed potential for lowering blood glucose—when Rimando started experimenting with it in the early 1990s.

“Actually, I isolated pterostilbene from a plant from Thailand back when I was a graduate student at the University of Illinois at Chicago (UIC),” says Rimando. “At that time, I found it to be toxic to a few cancer cell lines, especially breast cancer cells. Later, I had a renewed interest in whether pterostilbene might inhibit cancer when resveratrol was reported to have cancer-preventive activity.”

Through experiments using mice, rats, and hamsters, Rimando and collaborators have since helped add chapters to what’s known about pterostilbene and what it can do.

Major Findings

Rimando and UIC collaborators made a huge discovery in 2002, when -- in tests using rat mammary glands -- they found that pterostilbene possessed cancer-fighting properties at similar effective concentrations as resveratrol. Also in that study, Rimando, Oxford plant physiologist Stephen Duke, and scientists at the University of Buenos Aires in Argentina found that pterostilbene is a powerful antioxidant.

Then, in 2004, Rimando solidified pterostilbene’s standing with two major announcements to the American Chemical Society. Pterostilbene was already known to exist in very small amounts in red-skinned grapes.

Heartening Results

Then, Rimando announced that pterostilbene can help lower cholesterol and prevent heart disease.

This conclusion was the result of animal studies Rimando did with colleagues at the University of Mississippi and with chemist Wallace H. Yokoyama of ARS’s Processed Foods Research Unit in Albany, California.

They found that pterostilbene was similar in activity to ciprofibrate, a commercial drug that lowers LDL cholesterol and triglycerides. “But ciprofibrate can have side effects such as muscle pain and nausea,” says Rimando. “Pterostilbene targets the same specific receptor as ciprofibrate, but it’s likely to have fewer side effects.”

The focus of this work was to determine the ability of pterostilbene and related compoundsto activate the peroxisome proliferator activated receptor alpha, or PPARa, a protein in the cell nucleus associated with metabolism that modulates blood lipid levels.

Triglycerides, the chemical form in which fats occur in plants and animals, are a combination of three fatty acids with glycerol. As with cholesterol, elevated levels of triglycerides in the blood have been linked to cardiovascular diseases. Rimando and her colleagues found that the triglyceride-lowering ability of pterostilbene rivals that of ciprofibrate.

The announcements generated a wave of attention for pterostilbene, not only in the United States but in other countries as well. At least two news organizations in Great Britain directly attributed a boom in British blueberry sales to Rimando’s findings. And the Oxford lab’s results have since been cited by companies marketing products ranging from blueberry extract to juice concentrate to commercially available pterostilbene itself.

Latest Revelations

In her latest studies, Rimando and scientists at the University of Medical Science in Poznañ, Poland, led by Renata Mikstacka, showed pterostilbene’s potential as a cancer-inhibiting compound with regard to inhibiting enzymes that activate chemical carcinogens. Using mice cells, they demonstrated that pterostilbene, as well as other analogs of resveratrol, potently inhibits an enzyme called “cytochrome P450.”

Cytochromes are found within the cells of animals, plants, bacteria, and other microorganisms that transport electrons. They’re also a factor in people’s varying response to drugs and toxins entering their bodies. Cytochrome P450 enzymes activate a variety of compounds known as “procarcinogens,” which can turn substances such as cigarette smoke and pesticides into carcinogens.

“Pterostilbene showed strong inhibitory activity -- much more than Resveratrol -- against a particular form of cytochrome P450,” Rimando says. “This may explain the cancer-preventive property it demonstrated in a mouse mammary gland culture assay.” But she warns that more studies are needed to explain this process as well as those of other trans-resveratrol compounds.

As for where pterostilbene research goes from here, Rimando says, “I hope that some clinical studies can be conducted, either within ARS or by outside scientists, that will verify lab-animal results that allude to pterostilbene’s health benefits for humans.” -- By Luis Pons, Agricultural Research Service InformationStaff.


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