title: Chemical composition of the ethanolic propolis extracts and its effect on HeLa cells.
abstract: BACKGROUND
  Propolis is a resinous hive product collected by honeybees from various plant sources. It is widely used in traditional medicine and is reported to have a broad spectrum of pharmacological effects (antibacterial, antihepatoxic, antioxidative, anti-inflammatory, etc.). Thus the aim of this study was to assess cytotoxic effect of various ethanol propolis extractions on the cervical tumor cell line (HeLa) and compare it with their phenolic acids and flavonoids composition.
  
  
  METHODS
  Twenty samples of raw propolis were collected from 17 localities of Croatia (I-XVII), 2 of Bosnia and Hercegovina (XVIII, XIX) and 1 of Macedonia (XX). Reverse phase HPLC was used to determine the chemical composition of polyphenols. Biological experiments were carried out in vitro on cervix adenocarcinoma cell line (HeLa).
  
  
  RESULTS
  Phenolic acids (ferulic acid, p-coumaric acid, caffeic acid) and flavonoids (tectochrysin, galangin, pinocembrin, pinocembrin-7-methylether, chrysin, apigenin, kaempferol, quercetin) have been determined using HPLC analysis in 20 ethanolic propolis extracts. All samples contain tectochrysin in ranges of 0.1988 mg/g (XVIII) to 1.2004 mg/g (III), while caffeic acid and quercetin have not been found. Flavonoid that is most abundant is galangin in ranges from 0.3706 mg/g (XVII) to 47.4879 mg/g (IX). The samples of propolis numbers I, VI and X applied in the investigated concentration range manifested significant reduction of cell growth. GI(50) value as indicator of cytotoxicity among propolis samples showed that propolis number VII is the most effective (GI(50) =76 μg/ml) followed by propolis nos. XV, XVIII and I.
  
  
  CONCLUSIONS
  Antiproliferative and cytotoxic effect of propolis on the HeLa cells is not correlating with the concentration of particular components but on establishing the possible synergistic antiproliferative activity of individual phenolic acid and flavonoids. Differences in the chemical composition lead to diversity in biological activity of propolis samples.
authors.affiliation: Department of Medicinal Chemistry, Faculty of Pharmacy and Biochemistry, University of Zagreb, A. Kovačića 1, 10000 Zagreb, Croatia.
authors.forename: Monika
authors.initials: M
authors.lastname: Barbarić
authors.forename: Katarina
authors.initials: K
authors.lastname: Mišković
authors.forename: Mirza
authors.initials: M
authors.lastname: Bojić
authors.forename: Mirela Baus
authors.initials: MB
authors.lastname: Lončar
authors.forename: Asja
authors.initials: A
authors.lastname: Smolčić-Bubalo
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Debeljak
authors.forename: Marica
authors.initials: M
authors.lastname: Medić-Šarić
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000032:analysis / Q000494:pharmacology*; D056705:Apitherapy; D002470:Cell Survival / Q000187:drug effects*; D002851:Chromatography, High Pressure Liquid; D005061:Europe, Eastern; D005260:Female; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D062385:Hydroxybenzoates / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D015394:Molecular Structure; D008517:Phytotherapy; D011429:Propolis / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D005419:Flavonoids; D062385:Hydroxybenzoates; D011429:Propolis