Cancer phytotherapeutics: role for flavonoids at the cellular level

Abstract

Dietary foods and fruits possess an array of flavonoids with unique chemical structure and diverse bioactivities relevant to cancer. Numerous epidemiological studies have validated the inverse relation between the consumption of flavonoids and the risk of cancer. Flavonoids possess cancer blocking and suppressing effects. Flavonoids modulate various CYPs involved in carcinogen activation and scavenging reactive species formed from carcinogens by CYP-mediated reactions. They induce biosynthesis of several CYPs. They are involved in the regulation of enzymes of phase-II responsible for xenobiotic biotransformation and colon microflora. Since cytochromes P450, P-gp and phase-II enzymes are involved in the metabolism of drugs and in the processes of chemical carcinogenesis, interactions of flavonoids with these systems hold great promise for their therapeutic potential. The role of flavonoids also includes the inhibition of activation of pro-carcinogens, inhibition of proliferation of cancer cells, selective death of cancer cells by apoptosis, inhibition of metastasis and angiogenesis, activation of immune response against cancer cells, modulation of the inflammatory cascade and the modulation of drug resistance. This has greatly extended the goal of cancer therapy from eradicating the affected cells to control of the cancer phenotype. Phytotherapy is being used in combination with other therapies as phytonutrients have been shown to work by nutrient synergy.

Specific Deuteration in Patuletin and Related Flavonoids via Keto–Enol Tautomerism: Solvent‐ and Temperature‐Dependent 1H‐NMR Studies

“…Various biological activities attributed to flavonoids, e.g., antimicrobial [2] [6a] [18a] [25], anticancer [28], anti-HIV-1 integrase [6b], as well as plateletaggregation inhibitory [29a] [29b] [30], and UV-protection properties [2] [31] depend on the structure of these compounds, particularly on the number of free OH groups at the molecular-skeleton parent. There are also reports of flavonoids inhibiting the activities of an array of enzymes [29b].…”

Staying a Step Ahead of Cancer

“…Some foods do contain anticancer compounds. Phytonutrients, often found in pungent and bitter vegetables, include resveratrol in grapes and curcumin in turmeric (Azari et al 2009, Feeney 2004, Greenlee, Hershman and Jacobson 2009, Holst and Williamson 2008, Kale, Gawande and Kotwal 2008, Kaur, Agarwal and Agarwal 2009, Lanzotti 2006, Mates et al 2011, Mattoo et al 2010, McGrath and Spigelman 2008, Neto 2007, Surh 2008, Wahlqvist and Lee 2007, Wenefrida et al 2009). Other molecules, including sulforaphane and genistein, an isoflavone found in soybeans, are currently being tested as pharmaceutical agents in cancer prevention (Ali et al 2005, Caetano et al 2006, Takahashi et al 2006, Shenouda et al 2004.…”

Inhibition of Carcinogen-Activating Cytochrome P450 Enzymes by Xenobiotic Chemicals in Relation to Antimutagenicity and Anticarcinogenicity

“…anti-oxidative and anti-mutagenic activities, thus preventing cancer, heart disease, bone loss, and a number of diseases (121)(122)(123). These biological activities are reported to vary with the number and substitution positions of hydroxyl and/or methoxy groups in the flavonoid molecules (124)(125)(126).…”