7,8-Benzoflavone Carcinogenic?

7,8-benzoflavone October 14th, 2009 – A search on Google for 7,8-benzoflavone yields a link to a blogger who appears to have the opinion that 7,8-benzoflavone is a dangerous carcinogenic substance. They based this opinion on several studies which combined high levels of well known cancer causing substances, with 7,8-benzoflavone. They provided no references showing 7,8-benzoflavone is a carcinogenic substance in and of itself.

The first reference discusses the carcinogenbenzo[a]pyreneas being highly carcinogenic and that when combined with 7,8-benzoflavone, this can increase the rate of tumor formation. While this is true, this particular study foundzero tumor formation when 7,8-benzoflavone was used alone, and it in fact inhibited tumor formation caused by the more potent carcinogen7,12-dimethylbenz(a)anthracene(DMBA), thus offering a net protective effect against tumor formation. (1)

Other studies have also shown 7,8-benzoflavone has protective effects against cancer by inducing 2-hydroxylation of estrogens, thus increasing the clearance of estrogens and reducing cancer risk. (2-4)

Isolating flavonoids and carcinogens together in an in-vitro environment is a popular cancer research practice for studying the metabolism of cancer causing substances. Virtually all natural flavonoids (exp., quercetin, tangeretin, chrysin or nobiletin) have been found to negatively or positively metabolize carcinogenic chemicals in special test tube environments. However the research clearly shows a net anti-cancer effect from naturally occurring flavones. (5-7)

-Eric Potratz
Founder & President


1. Hydrocarbon Hydroxylase- and Polycyclic Hydrocarbon Tumorigenesis: Effect of the Enzyme Inhibitor 7,8-Benzoflavone on Tumorigenesis and Macromolecule Binding.
Nadao Kinoshita et al.
Proc Natl Acad Sci U S A. 1972 April; 69(4): 824-828

2. Modulation of rabbit and human hepatic cytochrome P-450-catalyzed steroid hydroxylations by alpha-naphthoflavone
GE Schwab, JL Raucy and EF Johnson
Volume 33, Issue 5, pp. 493-499, 05/01/1988

3. Regioselective 2-hydroxylation of 17beta-estradiol by rat cytochrome P4501B1.
M Rahman, C Hayes Sutter, GL Emmert, and TR Sutter
Toxicol Appl Pharmacol, November 1, 2006; 216(3): 469-78.

4. Naturally occurring coumarins inhibit 7,12-dimethylbenz[a]anthracene DNA adduct formation in mouse mammary gland
Misty Prince, Cheryl T. Campbell, Taylor A. Robertson, Amy J. Wells, and Heather E. Kleiner
Carcinogenesis, Jun 2006; 27: 1204 – 1213.

5. Dietary Flavonoids and the Risk of Colorectal Cancer
Evropi Theodoratou, et al.
Cancer Epidemiol. Biomarkers Prev., Apr 2007; 16: 684 – 693

6. Flavonoids and the Risk of Oral and Pharyngeal Cancer: A
Case-Control Study from Italy
Lagiou, et al.
Cancer Epidemiol. Biomarkers Prev., Aug 2007; 16: 1621 – 1625.

7. A Review of the Epidemiological Evidence on Tea, Flavonoids, and Lung Cancer
Ilja C. W. Arts
J. Nutr., Aug 2008; 138: 1561S – 1566S

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