NUTRmON AND CANCER, 47(2), 156-163 Copyright © 2003, Lawrence Erlbaum Associates, Inc. Inhibitory Effect of Water-Soluble Derivative of Propolis and Its Polyphenolic Compounds on Tumor Growth and Metastasizing Ability: A Possible Mode of Antitumor Action Nada Oriolic, Lidija Sver, Svjetlana Terzic, Zoran Tadie, and Ivan Basic Abstract: Polyphenolic compounds are widely distributed in the plant kingdom and display a variety of biological activi- ties, including chemoprevention and tumor growth inhibi- tion. Propolis is made up of a variety of polyphenolic com- pounds. We compared how the routes of administration of polyphenolic compounds deriving from propolis and of propolis itselfaffect the growth and metastatic potential of a transplantable mammary carcinoma (MCa) of the CBA mouse. The influence of tested compounds on local tumor growth was also studied. Metastases in the lung were gener- ated by 2 x 1()5 tumor cells injected intravenously (N). A wa- ter-soluble derivative of propolis (WSDP) and polyphenolic compounds (caffeic acid, CA, and CA phenethyl ester, CAPE) were given to mice per os (PO) or intraperitoneally (IP) before or after tumor cell inoculation. Tested com- pounds significantly decreased the number of lung colonies. When mice were inoculated with 1()5 MCa cells in the exact site of subcutaneous injection of different doses of WSDp, CA, or CAPE, tumor growth was inhibited, and survival of treated mice was prolonged. Antitumor activity, according to the results obtained, is mostly related to the immunomod- ulatory properties of the compounds and their capacity to in- duce apoptosis and necrosis. In conclusion, results presented here indicate that WSDp, CA, and CAPE could be potential useful tools in the control of tumor growth in experimental tu- mor models when administrated PO; because PO adminis- tration is the easiest way of introducing a compound used for prevention and/or cure of any disease, it is likely that this ar- ticle has reached the goal of the investigation. Introduction Propolis is alleged to exhibit broad-spectrum activities, including antibiotic (1), antiinflammatory (2), antioxidant (3), antiviral, and tumor cell arrest (4--7). A report on immu- nomodulatory activities of aqueous extracts of propolis (8) showed that a water-soluble extract of propolis (WSDP) in- creased the protection from gram-negative infections proba- bly via macrophage activation. From the literature it seems clear that antibiotic activities, immune modulatory properties as well as antiinflammatory, wound healing, and antitumor effects may be due to different components of the individual ethanolic or aqueous extracts of propolis. At least 200 differ- ent constituents of propolis are defined as terpenes, various phenylpropane derivatives such as caffeic acid (CA) esters, flavonoids, amino acids, or a large number of aldehydes and ketones (9,10). We have demonstrated that WSDP given intraperitoneally (lP) to mice suppressed the growth of a mammary carcinoma (MCa) in mice (11). CA phenethyl ester (CAPE) exhibits differential toxicity to cancer cells versus normal cells (12,13). CAPE was re- ported to be a lipoxygenase inhibitor with antioxidant prop- erties (14,15). Inhibition of the tumor promoter-mediated oxidative processes by CAPE has also been reported (16). Recent studies demonstrated that CAPE and several addi- tional CA esters inhibited azoxymethane-induced colonic preneoplastic lesions and enzyme activities, including orni- thine decarboxylase, tyrosine kinase, and lipoxygenase, as- sociated with colon carcinogenesis (13,17-19). Inhibitory ef- fect CA on tumor promotion in mouse skin has been shown (20). However, until now no studies on local antitumor activ- ity of CA have been done. The aim of this investigation was to compare how the routes (oral and/or systemic) of administration of polyphenolic com- pounds deriving from propolis and of propolis itselfinfluence the growth and metastatic potential of a transplantable MCa of CBA mouse and to study their effect on modulation ofimmune reaction and apoptosis and necrosis ofMCacells, respectively. Materials and Methods Animal Studies Animal studies were carried out according to the guide- lines in force in the Republic of Croatia (Law on the Welfare N. Orsolic, Z. Tadic, and I. Basic are affiliated with the Department of Animal Physiology, Faculty of Science. L'niversity of Zagreb, Rooseveltov trg 6, 10000 Zagreb, Croatia. L. Sver is affiliated with the Department of Biology, Veterinary Faculty, University of Zagreb. Heinzelova 55, 10000 Zagreb, Croatia. S. Terzic is affiliated with the Croatian Veterinary Institute, Savska c. 143, Zagreb, Croatia.