Topical application of Gallic acid suppresses the 7,12-DMBA/Croton oil induced two-step skin carcinogenesis by modulating anti-oxidants and MMP-2/MMP-9 in Swiss albino mice Vimala Subramanian, Balaji Venkatesan, Anusha Tumala, Elangovan Vellaichamy ⇑ Department of Biochemistry, University of Madras, Guindy Campus, Chennai 600025, India article info Article history: Received 17 September 2013 Accepted 13 January 2014 Available online 18 January 2014 Keywords: Gallic acid Skin cancer Anticancer activity DMBA/Croton oil GST MMP abstract Gallic acid (GA – 3,4,5-trihydroxybenzoic acid), a dietary anti-oxidant has been shown to inhibit cancer cell growth in in vitro. Herein, we investigated the in vivo chemo preventive activity of GA on 7,12-Dim- ethylbenz[a]anthracene (DMBA)/Croton oil induced two-step skin carcinogenesis in Swiss albino mice. Skin tumor incidence and tumor volume were recorded during the 16 weeks of experimental period. In addition, LDH-isozyme shift, skin collagen content, activities of matrix metalloproteinases (MMP-2/ MMP-9) enzymes and enzymatic and non-enzymatic antioxidant were studied in the skin and serum of experimental mice. Tumor incidence was significantly increased in the DMBA/Croton oil induced mice (100%; p < 0.001) when compared to GA co-treated mice (60%; p < 0.01) and 5-FU treated mice (50%; p < 0.01). Skin collagen content, MMPs activities, LDH-isoenzymes and MMP-2/-9 expressions were increased in DMBA/Croton oil induced skin while decreased levels of enzymatic (GST, SOD, CAT & GPx) and non-enzymatic anti-oxidant (GSH) were noticed. On the other hand, GA co-treatment exhibited a sig- nificant protection by reverting back the altered levels of LDH-isoenzymes, antioxidants, collagen and MMP-2/MMP-9 activities. The results of this study indicate that topical application of GA inhibits DMBA/Croton oil induced two-stage skin carcinogenic process by modulating the antioxidants and MMPs (-2 & -9) in the mouse skin. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Skin is the largest organ of the human body, and is a major tar- get for toxic insult by a chemical mutagens and carcinogens in a day-to-day life (Simna et al., 2012). Throughout the world, the number of people affected by skin cancer is increasing due to in- creased exposure to environmental pollutants and UV rays (Narendhirakannan and Angeline Christie Hannah, 2013). Recent studies have also predicted that the number of people affected by this malady will be doubled by the year 2050 (Hayat et al., 2007). Although many synthetic drugs are commercially available to treat skin cancer; However, these drugs causes serious side ef- fects to patients such as nephrotoxicity, neurotoxicity, infertility, thromboembolic complications, hair loss, nausea, and myocardial infarction (Shabaruddin et al., 2013). Hence, there is a dire need to look for more efficacious agents with lesser side effects for the prevention and eradication of skin tumors. Number of recent evidence has shown that natural dietary anti- oxidants are capable of inhibiting cancer cell growth. Moreover, these natural antioxidants are reported to have the ability to en- hance the activities of detoxification enzyme components such as glutathione-S-transferase (GST). The activation of GST not only neutralizes the chemical carcinogens, but also preventing them from forming a DNA adducts in the genome (Liu et al., 1992). Fur- thermore, it has been suggested that these natural antioxidant compounds can be used in multiple ways, either as cancer preven- tive agents or even as cancer therapy drugs (Thornthwaite et al., 2013). Gallic acid (GA), a polyhydroxyphenolic compound, is abun- dantly present in leafy vegetables, fruits, and nuts such as gallnut, grapes, sumach, oak bark, green tea, apple peels (Atkinson et al., 2004; Chakraborty et al., 2009; Kim et al., 2006; Ng et al., 2004; Liao et al., 2012) and also present in onion and potato varieties (Albishi et al., 2013). GA exhibits variety of biological activities including antioxidant (Isuzugawa et al., 2001; Yogendra Kumar et al., 2013), anti-tumor (Agarwal et al., 2006; Liao et al., 2012; Lee et al., 2013; Locatelli et al., 2013), anti-inflammatory (Albishi et al., 2013) and anti-bacterial (Kang et al., 2008; Lee and Je, 2013). GA has been shown to inhibit gastric cancer cell growth in vitro by modulating the levels of MMP-2 and -9 and cytoskeletal reorganization (Ho et al., 2010). Furthermore, GA has also been http://dx.doi.org/10.1016/j.fct.2014.01.017 0278-6915/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +91 44 22202734. E-mail address: vellaie@gmail.com (E. Vellaichamy). Food and Chemical Toxicology 66 (2014) 44–55 Contents lists available at ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox