The anticarcinogenic potential of essential oil and aqueous infusion from caper (Capparis spinosa L.) Tea Kulisic-Bilusic a,b,⇑ , Ingrid Schmöller b , Kerstin Schnäbele b , Laura Siracusa c , Giuseppe Ruberto c a Faculty of Chemistry and Technology, University of Split, Teslina 10, 21000 Split, Croatia b Technical University of Münich, Department of Food and Nutrition, Chair of the Biofunctionality of Food, Life Science Center Weihenstephan, Hochfeldweg 1, 85354 Freising, Germany c Istituto del C.N.R. di Chimica Biomolecolare, Via Paolo Gaifami 18, I-95126 Catania, Italy article info Article history: Received 24 June 2011 Received in revised form 14 September 2011 Accepted 12 October 2011 Available online 10 November 2011 Keywords: Caper Essential oil Aqueous infusion Anticancer activity Cell cycle NF-jB activity HT-29 cells abstract The present study assessed the influence of essential oil and aqueous infusion from wild-grown caper (Capparis spinosa L.) on cell growth, NF-jB activation, apoptosis and cell cycle in the human colon carci- noma cell line, HT-29. Methyl isothiocyanate (92.06%), a degradation product of glucosinolate glucocapp- arin, was detected as major component of essential oil from caper leaves and flower buds. Aqueous infusion of caper showed an interesting and variegate compositional pattern containing several phenolic compounds, among which a flavonol glycoside, rutin (quercetin 3-O-rutinoside, 50.7%) and 5-caffeoyl- quinic acid (chlorogenic acid, 17.5%) were detected as dominant. Caper essential oil and aqueous infusion showed time- and dose-dependent high inhibitory effect on HT-29 cell proliferation. In addition, they induced the inhibition on nuclear factor jB (NF-jB) activity in a dose-dependent manner, while they did not show any effect on apoptosis in HT-29 cells. Flow cytometric analysis indicated that treatment with caper essential oil and aqueous infusion resulted in G 2 /M cell cycle arrest in a dose-dependent man- ner. Presented results suggest that caper contains volatile and non-volatile compounds which potentially can play an important role in colon cancer prevention. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Several important human diseases may be caused by oxidative stress (cancer, atherosclerosis, hypertension, diabetes, ischaemia, chronic inflammatory disease, rheumatoid arthritis, inflammatory bowel disease, disorders of the nervous system, Alzheimer’s dis- ease) (Halliwell & Gutteridge, 2001). Many plant-derived antioxi- dants have been experimentally proved and used as effective protection against free radical induced tissue damage and oxidative stress. Processes that prevent free radical formation are important mechanism in cancer prevention (Lampe, 2003). Colorectal cancer is among the most prevalent and deadly cancers in Western coun- tries and is the most susceptible to modification by dietary factors (Wang et al., 2000; Johnson, 2004). Several commonly used herbs and herbal extracts have been identified by the National Cancer Institute as possessing cancer-preventing properties (garlic, onions, basil, mints, thyme, oregano, sage, rosemary, green tea, fennel, parsley, caraway, celery) (Craig, 1999). These plants contain a vari- ety of biologically active secondary metabolites (glucosinolates, flavonoids, phenolic acids, alkaloids) many of which can inhibit cell proliferation and induce apoptosis, or suppress the NF-jB activa- tion pathway (Aggarwal & Shishoida, 2004; Johnson, 2004; Lampe, 2003). It was shown that certain isothiocyanates (degradation products of glucosinolates, compounds present in caper) can affect the cell cycle and induce apoptosis in HT-29 human colon cancer cells (Gamet-Payrastre et al., 2000). Several epidemiological studies indicated that the dietary consumption of isothiocyanates-contain- ing foods inversely correlates with the risk of developing lung, breast, and colon cancers, providing evidence that they have a po- tential to prevent cancer in humans (Nakamura, 2009). Flavonoids, the most abundant secondary metabolites in fruit and vegetables, have been shown to interact with cellular signal pathways control- ling the proliferation, differentiation and apoptosis of various tumour cells, including those derived from the alimentary tract (Le Marchand, 2002). Caper (Capparis spinosa L.) is an aromatic plant, characteristic for the Mediterranean diet. It is very good sources of glucosinolates (glucocapparin, glucoiberin, sinigrin, glucobrassicin), flavonoids (rutin, kaempferol), phenolic acids, alkaloids, which are known to provide health-improving benefits due to their various biological activities (antioxidant, anticancerogenic, antimicrobial, antimuta- genic). In our previous studies, we analysed the chemical composi- tion of the essential oil and aqueous infusions of wild-grown caper from Croatia and evaluated its antioxidant activity by different methods (DPPH radical scavenging test, the b-carotene bleaching method, TBARS assay, the copper-induced oxidation of human 0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2011.10.074 ⇑ Corresponding author at: Faculty of Chemistry and Technology, University of Split, Teslina 10, 21000 Split, Croatia. Tel.: + 385 21 329 465; fax: + 385 21 329 461. E-mail address: tea@ktf-split.hr (T. Kulisic-Bilusic). Food Chemistry 132 (2012) 261–267 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem