The Importance of Equol

Lung cancer is one of the most common malignant tumors, and it is one of the five most commonly diagnosed cancers in men (five cancers in descending order are lung, bronchus, stomach, esophagus, liver and colorectal cancers, respectively), and it is also on the list of corresponding cancers in women. It has been predicted that there will be about 4,292,000 newly diagnosed invasive cancer cases in China in 2015, which is equivalent to an average of nearly 12,000 newly diagnosed cases per day [1], of which 733,000 new cases and 610,000 deaths will occur in China, accounting for 17.1% and 21.7% of all tumor incidence and deaths, respectively.

 Estimated New Cancer Cases and Deaths (Thousands) by Sex: China, 2015

Lung cancer can be categorized into two main types: small cell lung carcinoma (SCLC) and non-small cell lung cancer (NSCLC), the former is a less common type of lung cancer found almost exclusively in heavy smokers [3], and the latter is the most common type of lung cancer. Although advances have been made in surgical approaches and comprehensive treatments for NSCLC patients, the prognosis of NSCLC patients is still unsatisfactory. Therefore, it has become extremely important to find more effective methods for the prevention and treatment of lung cancer.

A large number of studies have confirmed the preventive effect of fruits, vegetables, legumes and their specific antioxidants and active ingredients (e.g., phytoestrogens) on lung cancer[4]. Soy isoflavones are a type of phytoestrogens, and Equol, which was introduced to you in the last issue, has been emphasized by researchers because of its potential. Equol is the one with the highest estrogenic and antioxidant activity among soy isoflavones and their metabolites[5].

同种药物高剂量雌马酚组的Nrf2蛋白表达水平高于低剂量雌马酚组（图二）

同种药物高剂量雌马酚组小鼠血清中MDA/8-OHdG含量显著低于低剂量雌马酚组(图三）

HRE和HSE组肺癌发生率最低为13.3%(2/15) （图四）

In order to study the effects of Equol and the isomers corresponding of Equol on urethane-induced lung cancer and their possible mechanisms, C57BL/6 mice were used as the research subjects. 120 five-week-old male mice were randomly divided into 8 groups of 15 mice each, which were the lung tumor control group,genistein control group,low equol group,high equol group,low R-equol group, high R-equol group,high R-equol group,high S-equol group. Two dose groups of equol and its isomers corresponding were also set up to compare the effects of regular soy diet and high dose of equol on lung cancer. It was found that equol and its isomers corresponding may enhance the antioxidant capacity of mice (Figure 3) by up-regulating the expression of the Nrf2 gene (Figure 2), which in turn reduces the incidence of urethane-induced lung cancer (Figure 4). The study suggests that equol and isomers correspondingmay inhibit the development of lung cancer through antioxidant effects [2].

References:

[1]Chen W, Zheng R, Baade PD, et al. Cancer statistics in China, 2015. CA Cancer J Clin. 2016;66(2):115–132. doi: 10.3322/caac.21338.

[2]Yu X, Zou YQ, Wang Y, Chen ZK, Ma DF. [Equol and its enantiomers inhibited urethane-induced lung cancer in mice]. Beijing Da Xue Xue Bao Yi Xue Ban. 2022 Apr 18;54(2):244-248. Chinese. doi: 10.19723/j.issn.1671-167X.2022.02.007. PMID: 35435186; PMCID: PMC9069049.

[3]https://gleneagles.com.my/zh-chs/medical-specialties/oncology/lung-cancer

[4]Norat T, Aune D, Chan D, et al. Fruits and vegetables: Updating the epidemiologic evidence for the WCRF/AICR lifestyle recommendations for cancer prevention. Cancer Treat Res. 2014;159:35–50. doi: 10.1007/978-3-642-38007-5_3

[5] Muthyala RS, Ju YH, Sheng S, et al. Equol, a natural estrogenic metabolite from soy isoflavones: Convenient preparation and resolution of R- and S-equols and their differing binding and biological activity through estrogen receptors alpha and beta. Bioorg Med Chem. 2004;12(6):1559–1567. doi: 10.1016/j.bmc.2003.11.035