|Chemopreventive effects of selected dietary & medicinal phenolic substances of some medicinal plants|
A wide array of phenolic substances, particularly those present in dietary and medicinal plants, possess substantial anticarcinogenic and antimutagenic activities. The majority of these naturally occurring phenolics retain antioxidative and anti-inflammatory properties which appear to contribute to their chemopreventive or chemoprotective activity.
As for example, capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide), a pungent ingredient of hot chili pepper (Capsicum), protects against experimentally-induced mutagenesis and tumorigenesis. It also induces apoptosis in various immortalized or malignant cell lines.
Plants of ginger family (Zingiberaceae) have been frequently and widely used as spices and also, in traditional oriental medicine.
Curcumin, a yellow ingredient from Turmeric (Curcuma longa L. , Zingiberaceae), has been extensively investigated for its cancer chemopreventive potential.
Yakuchinone A [1-(4'-hydroxy-3'-methoxyphenyl)-7-phenyl-3-heptanone] and yakuchinone B [1-(4'-hydroxy-3'-methoxyphenyl)-7-phenylhept-1-en-3-one] present in Alpinia oxyphylla Miquel (Zingiberaceae) have inhibitory effects on phorbol ester-induced inflammation and skin carcinogenesis in mice, and oxidative stress in vitro.
These diarylheptanoids suppress phorbol ester-induced activation of ornithine decarboxylase and production of tumor necrosis factor-alpha or interleukin-1alpha and their mRNA expression.
They also nullified the phorbol ester-stimulated induction of activator protein 1 (AP-1) in cultured human promyelocytic leukemia (HL-60) cells.
In addition, both yakuchinone A and B induced apoptotic death in HL-60 cells.
Ginger (Zingiber officinale Roscoe, Zingiberaceae) contains such pungent ingredients as -gingerol and -paradol, which also have anti-tumor promotional and antiproliferative effects. Resveratrol (3, 5, 4'-trihydroxy-trans-stilbene), a phytoalexin found in grapes and other dietary and medicinal plants, and (-)-epigallocatechin gallate, a major antioxidative green tea polyphenol, exert striking inhibitory effects on diverse cellular events associated with multi-stage carcinogenesis.
In addition, these compounds have ability to suppress proliferation of human cancer cells via induction of apoptosis.