title: Antimicrobial, antioxidant and anti-tyrosinase properties of extracts of the Mediterranean parasitic plant Cytinus hypocistis.
abstract: BACKGROUND
  Cytinus is an endophytic parasitic plant occurring in South Africa, Madagascar, and in the Mediterranean region. We have extracted the inflorescences (the only visible part of the plant, emerging from the host roots at the time of blossom) of Cytinus hypocistis collected in Sardinia, Italy, and explored the antimicrobial, antioxidant, anti-tyrosinase, and cytotoxic activities of the extracts.
  
  
  METHODS
  Extracts from C. hypocistis were prepared using increasing polarity solvents: cyclohexane, ethanol, and water. Phenolic composition were determined through spectrophotometric assays, and antioxidant activity with both electron-transfer and hydrogen-atom assays. Nine different bacterial strains, including clinical isolate methicillin-resistant Staphylococcus aureus, were used in agar diffusion method. Cytotoxicity was tested using against the B16F10 melanoma cell line.
  
  
  RESULTS
  While cyclohexane extracts where biologically inactive, ethanolic and aqueous extracts displayed an intriguing activity against several Gram-positive bacterial strains, including methicillin-resistant S. aureus, and against the Gram-negative Acinetobacter baumanii. Compared to the conventional antibiotics like cloxacillin, ampicillin, and oxytetracycline, C. hypocistis extracts were less active in absolute terms, but displayed a wider spectrum (notably, cloxacillin and ampicillin were inactive against methicillin-resistant S. aureus). The ethanolic extract of C. hypocistis was found to be particularly rich in polyphenols, in most part hydrolysable tannins. The antioxidant activity of extracts, tested with several methodologies, resulted to be particularly high in the case of ethanolic extracts, in accordance with the composition in phenolics. In detail, ethanol extracts presented about a twofold higher activity than the water sample when tested through the oxygen radical absorbance capacity-pyrogallol red (ORAC-PYR) assay. Cytotoxicity analysis against the B16F10 melanoma cell line showed that both extracts have not significant cytotoxic effect, even at the highest dose (1000 µg/mL). Tests showed that ethanolic extracts also had the greatest tyrosinase inhibition activity, indicating that C. hypocistis-derived substances could find application in food formulations as anti-browning agents.
  
  
  CONCLUSIONS
  Overall, these results point to the need of further studies on C. hypocistis extracts, aimed at isolating and fully characterizing its biologically active compounds.
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria, Complesso Universitario, SP Monserrato-Sestu Km 0.700, 09042, Monserrato, CA, Italy. pzucca@unica.it.|Consorzio UNO, Oristano, Italy. pzucca@unica.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Zucca
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria, Complesso Universitario, SP Monserrato-Sestu Km 0.700, 09042, Monserrato, CA, Italy. manuela.pintus@gmail.com.
authors.forename: Manuela
authors.initials: M
authors.lastname: Pintus
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria, Complesso Universitario, SP Monserrato-Sestu Km 0.700, 09042, Monserrato, CA, Italy. giorgia.manzo@unica.it.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Manzo
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria, Complesso Universitario, SP Monserrato-Sestu Km 0.700, 09042, Monserrato, CA, Italy. nieddu@unica.it.
authors.forename: Mariella
authors.initials: M
authors.lastname: Nieddu
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria, Complesso Universitario, SP Monserrato-Sestu Km 0.700, 09042, Monserrato, CA, Italy. daniela.steri@unica.it.
authors.forename: Daniela
authors.initials: D
authors.lastname: Steri
authors.affiliation: Department of Biomedical Sciences, University of Cagliari, Cittadella Universitaria, Complesso Universitario, SP Monserrato-Sestu Km 0.700, 09042, Monserrato, CA, Italy. rinaldi@unica.it.
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Rinaldi
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects / Q000254:growth & development; D000818:Animals; D000890:Anti-Infective Agents / Q000302:isolation & purification* / Q000494:pharmacology; D000975:Antioxidants / Q000302:isolation & purification* / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003510:Cyclohexanes / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology; D000431:Ethanol / Q000737:chemistry; D056626:Inflorescence / Q000737:chemistry; D059625:Liquid-Liquid Extraction / Q000379:methods; D019660:Malvaceae / Q000737:chemistry*; D019083:Mediterranean Region; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D051379:Mice; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry; D059808:Polyphenols / Q000302:isolation & purification / Q000494:pharmacology; D012997:Solvents / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000890:Anti-Infective Agents; D000975:Antioxidants; D003510:Cyclohexanes; D004791:Enzyme Inhibitors; D010936:Plant Extracts; D059808:Polyphenols; D012997:Solvents; D014867:Water; D000431:Ethanol; C506365:Cyclohexane; D014442:Monophenol Monooxygenase