Natural products for prevention, treatment of liver cancer
SCIENTISTS have endorsed dietary natural products for the prevention and treatment of liver cancer.
According to a recent study published in the journal Nutrients and titled “Dietary Natural Products for Prevention and Treatment of Liver Cancer”, accumulating evidence suggested that many dietary natural products could be potential sources for prevention and treatment of liver cancer. The following are notable for their potential anti- hepatoma properties, including: grapes, black currant, plum, pomegranate and the isolated flavonoids, tannins, proanthocyanidins; cruciferous vegetables ( isothiocyanates), French beans ( lectins), tomatoes ( lycopene and tomatine), asparagus ( polysaccharides and saponins); garlic ( organo- sulphur compounds), turmeric ( curcumin), ginger ( 6shogaol and 6- gingerol); and soy, rice bran, and polysaccharides from edible macro- fungi.
The researchers led by Prof. Yue Zhou of Sun Yat- Sen University, Guangzhou, China, concluded: “These dietary natural products and their active components could affect the development and progression of liver cancer in various ways, such as inhibiting tumor cell growth and metastasis, protecting against liver carcinogens, immune- modulating and enhancing effects of chemotherapeutic drugs. In the future, attention should be paid to the isolation of active compounds, the illustration of action mechanisms, bioavailability, potential toxicity and adverse effects, and more studies are required concerning the clinical efficacy of dietary natural products and their bioactive components.”
Several studies have shown that, globally, liver cancer is the second most common cause of cancer death, accounting for more than 700,000 deaths every year. Hepatocellular carcinoma ( HCC) is the major type of liver cancer ( 70 per cent– 80 per cent), followed by intrahepatic cholangiocarcinoma. The main risk factors for liver cancer are hepatitis B/ hepatitis C virus infection, alcohol consumption, aflatoxin B1 and metabolic disorders. Liver
cancer is usually an aggressive malignancy associated with poor prognosis, and the five- year survival rate is estimated to be less than nine per cent.
Surgical interventions including liver resection, liver transplantation and percutaneous ablation are regarded as the most effective approach with curative potential for liver cancer. Unfortunately, due to numerous lesions, and extra- hepatic metastasis, only about 20 per cent of liver cancer patients are suitable for surgery. On the other hand, chemotherapeutic drugs for liver cancer are limited, and Sorafenib is the most common prescription. The large phase III trials demonstrated that Sorafenib could improve overall survival and time to progression. However, its clinical bene
fits remains modest, and it was reported that Sorafenib was useful for around 30 per cent patients and drug resistance developed within six months. Furthermore, problems such as hepatotoxicity, recurrence, drug resistance and other adverse effects exist in current therapeutics, which urge researchers to find alternative treatment.
Diet plays a pivotal role in cancers. Epidemiological studies suggested that decreased overall cancer risks might be correlated with regular intake of a high fibre, low fat diet accompanied by significant consumption of fruits and vegetables. Therefore, dietary natural products could provide novel and fascinating preventive or therapeutic options for liver cancer. Researchers have found a variety of anticancer effects of dietary natural products, such as inhibiting tumour cell growth and metastasis, protecting against liver carcinogens, immuno- modulating and enhancing effects of chemotherapeutic drugs.
Furthermore, many dietary natural products displayed selective inhibition against cancer cells. This discrimination is very important for liver cancer treatment, since the majority of patients suffers from severely compromised liver function or liver cirrhosis and cannot afford further losses of normal liver cells.
Grape
Grape products are well- recognised healthy dietary components against many pathophysiologic processes. Stilbenes, anthocyanins, and procyanidins, which are abundant in grape skin, seeds and red wines, have been reported to possess strong antioxidant and anti- inflammatory properties. A team isolated two fractions ( TP- 4 and TP- 6) from grape cell culture with strong chemo- preventive properties in an in vitro human DNA topoisomerase II assay. TP- 6, the procyanidin- rich fraction, selectively inhibited cell viability of Hepg2 cancer cells, yet caused no toxicity to normal PK15 pig kidney cells. Liver cancer is enriched with blood vessels, and angiogenesis plays a key role in cancer metastasis and relapse. The treatment of grape procyanidin in a liver cancer xenograft model exerted anti- angiogenic activity in a dose dependent manner by suppressing proliferation of vascular endothelial cells. Researchers also suggested a possible anti- carcinogenic use against HCC for grape seed extracts from winery waste. The seed extract treatment in Hepg2 cells induced DNA damage, enhanced NO production, p53 upregulation and significant decrease of total PARP expression, thus promoting apoptosis.
Black currant
Black currant ( Ribes nigrum L.) fruits are widely consumed, and are known to possess strong antioxidant and anti- inflammatory activities due to high content of anthocyanins ( 250 mg/ 100 g fresh fruit), which have been suggested to have potent anti- tumor properties.