May 30 2007 post. Last week, looking up studies on ellagic acid and cancer, an endless task! (just to give an idea: PubMed has more than 700 entries for ellagic acid, and 129 for ellagic acid and cancer !), I stumbled upon anthocyanins (try to pronounce that!), which are flavonoids whose main purpose is to give colour to most flowers and fruit. According to Wikipedia, they are water-soluble vacuolar flavonoid pigments that appear red to blue, according to pH. They are synthesized by organisms of the plant kingdom and bacteria, and have been observed to occur in all tissues of higher plants, providing color in leaves, stems, roots, flowers, and fruits.
These pigments are mostly found in blackberries, blueberries, strawberries, elderberries, grapes and plums, as reported by The Columbus Dispatch: http://tinyurl.com/ypxgj5 The darker the fruit, the more anthocyanins it has. In plants, anthocyanins act as a sunscreen, absorbing high-frequency blue-green light. As antioxidants, they scavenge free radicals that form in plant tissue through ultraviolet radiation. Fascinating. And there is more: Anthocyanins appear to work by inhibiting compounds that weaken the immune system and stimulate tissue inflammation. They also seek out and destroy harmful free-radical molecules that circulate in the body, attack cells and cause aging, heart disease and cancer. Exactly how they do this, however, remains a mystery. University of Pittsburgh research has shown that a form of anthocyanin called cyanidin-3-rutinoside is a strong antioxidant and is similar to compounds called polyphenols, which are found in green tea. And it causes cancer cells to break down. The Pittsburgh scientists found that cyanidin-3-rutinoside caused potent oxidants called peroxides to accumulate and kill leukemia cells. Anthocyanins appear particularly useful for people who have had cancer surgery and are at risk of recurrence. Now how about that?
The 2007 study cited in the Columbus Dispatch can be read at: http://tinyurl.com/yozmkd Researchers added the above-mentioned cyanidin-3-rutinoside to several leukaemia and lymphoma cell lines, and found that it induced apoptosis in the malignant cells without affecting normal cells. Aha! The abstract concludes: These results indicate that cyanidin-3-rutinoside has the potential to be used in leukemia therapy with the advantages of being widely available and selective against tumors.
A 2004 study (http://tinyurl.com/25ewmn) shows that the anti-cancer (apoptotic!) and anti-inflammatory properties of anthocyanidins work at a molecular level. They are chemopreventive based on the: (i) inhibition of anthocyanidins in cell transformation through targeting mitogen-activated protein kinase (MAPK) pathway and activator protein 1 (AP-1) factor; (ii) suppression of anthocyanidins in inflammation and carcinogenesis through targeting nuclear factor kappa B (NF-ÃŽÂºB) pathway and cyclooxygenase 2 (COX-2) gene; (iii) apoptotic induction of cancer cells by anthocyanidins through reactive oxygen species (ROS) / c-Jun NH2-terminal kinase (JNK)-mediated caspase activation. Now, let me see. COX-2, NF-kB, ROS, kinases haven’t I heard those mentioned somewhere?
For an excellent overview of anthocyanins, see http://tinyurl.com/ywckdk. Anthocyanin isolates and anthocyanin-rich mixtures of bioflavonoids may provide protection from DNA cleavage, estrogenic activity (altering development of hormone-dependent disease symptoms), enzyme inhibition, boosting production of cytokines (thus regulating immune responses), anti-inflammatory activity, lipid peroxidation, decreasing capillary permeability and fragility, and membrane strengthening. This is a very interesting comprehensive study, and I cannot possibly summarize it properly. Among other things, it examines how anthocyanins protect from cardiovascular disease and pancreatic disorders, can perhaps help prevent diabetes and obesity, enhance memory and modulate cognitive and motor function, and defend our lungs against pleurisy and inflammation in general. Wow! This fascinating study also discusses bioavailability issues, which are part of the anthocyanin enigma, i.e., what happens after we swallow these pigments.
Another 2004 study (http://tinyurl.com/2aa8Ãƒâ€”4) informs us that anthocyanins have been part of the human diet for centuries, and have been used by Native Americans, Europeans and Chinese to treat hypertension, pyrexia, liver disorders, dysentery and diarrhoea, urinary problems including kidney stones and urinary tract infections, and the common cold. Recent studies have shown, among other things, that they protect against liver injuries, lower blood pressure, improve eyesight, have strong anti-inflammatory and antimicrobial activities, and suppress the proliferation of human cancer cells. This study also raises a few pertinent questions. For instance, how do anthocyanins provide all these health benefits: on their own, or by interacting with other phenolic compounds? What happens to anthocyanin molecules after ingestion? Reports on bioavailability of anthocyanins indicate that less than 1% of consumed anthocyanins is detectable in human plasma and urine. Okay, so clearly more studies are needed. But the potential is there. In the meantime, I am going outside to munch on some colourful flowers and fruits.
A few studies: Leukaemia cells and a Hibiscus anthocyanin: http://tinyurl.com/2uhfw2; Lung cancer and anthocyanins: http://tinyurl.com/3bmlkl; Colon cancer prevention and anthocyanins: http://tinyurl.com/2eld4c; see also http://tinyurl.com/2xl3go; Cranberries and cancer; interesting study that examines colon, oral and prostate cancer cell lines: http://tinyurl.com/283k7k; Retinal disorders and anthocyanins (bilberry extract): http://tinyurl.com/279gu2; Heart disease and anthocyanins (elderberry extract): http://tinyurl.com/2xjs4d