title: HPLC-based activity profiling for antiplasmodial compounds in the traditional Indonesian medicinal plant Carica papaya L.
abstract: BACKGROUND
  Leaf decoctions of Carica papaya have been traditionally used in some parts of Indonesia to treat and prevent malaria. Leaf extracts and fraction have been previously shown to possess antiplasmodial activity in vitro and in vivo.
  
  
  METHODS
  Antiplasmodial activity of extracts was confirmed and the active fractions in the extract were identified by HPLC-based activity profiling, a gradient HPLC fractionation of a single injection of the extract, followed by offline bioassay of the obtained microfractions. For preparative isolation of compounds, an alkaloidal fraction was obtained via adsorption on cationic ion exchange resin. Active compounds were purified by HPLC-MS and MPLC-ELSD. Structures were established by HR-ESI-MS and NMR spectroscopy. For compounds 5 and 7 absolute configuration was confirmed by comparison of experimental and calculated electronic circular dichroism (ECD) spectroscopy data, and by X-ray crystallography. Compounds were tested for bioactivity in vitro against four parasites (Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum), and in the Plasmodium berghei mouse model.
  
  
  RESULTS
  Profiling indicated flavonoids and alkaloids in the active time windows. A total of nine compounds were isolated. Four were known flavonols--manghaslin, clitorin, rutin, and nicotiflorin. Five compounds isolated from the alkaloidal fraction were piperidine alkaloids. Compounds 5 and 6 were inactive carpamic acid and methyl carpamate, while three alkaloids 7-9 showed high antiplasmodial activity and low cytotoxicity. When tested in the Plasmodium berghei mouse model, carpaine (7) did not increase the survival time of animals.
  
  
  CONCLUSIONS
  The antiplasmodial activity of papaya leaves could be linked to alkaloids. Among these, carpaine was highly active and selective in vitro. The high in vitro activity could not be substantiated with the in vivo murine model. Further investigations are needed to clarify the divergence between our negative in vivo results for carpaine, and previous reports of in vivo activity with papaya leaf extracts.
authors.affiliation: Division of Pharmaceutical Biology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, Basel 4056, Switzerland; Faculty of Pharmacy, Pancasila University, Jakarta 12640, Indonesia.
authors.forename: Tasqiah
authors.initials: T
authors.lastname: Julianti
authors.affiliation: Division of Pharmaceutical Biology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, Basel 4056, Switzerland.
authors.forename: Maria
authors.initials: M
authors.lastname: De Mieri
authors.affiliation: Division of Pharmaceutical Biology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, Basel 4056, Switzerland; Swiss Tropical and Public Health Institute, Basel 4051, Switzerland.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Zimmermann
authors.affiliation: Division of Pharmaceutical Biology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, Basel 4056, Switzerland; Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G. C., Evin, Tehran, Iran.
authors.forename: Samad N
authors.initials: SN
authors.lastname: Ebrahimi
authors.affiliation: Swiss Tropical and Public Health Institute, Basel 4051, Switzerland.
authors.forename: Marcel
authors.initials: M
authors.lastname: Kaiser
authors.affiliation: Inorganic Chemistry, Department of Chemistry, University of Basel, Basel 4056, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Neuburger
authors.affiliation: Division of Pharmaceutical Biology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, Basel 4056, Switzerland.
authors.forename: Melanie
authors.initials: M
authors.lastname: Raith
authors.affiliation: Swiss Tropical and Public Health Institute, Basel 4051, Switzerland.
authors.forename: Reto
authors.initials: R
authors.lastname: Brun
authors.affiliation: Division of Pharmaceutical Biology, Department of Pharmaceutical Sciences, University of Basel, Klingelbergstrasse 50, Basel 4056, Switzerland. Electronic address: matthias.hamburger@unibas.ch.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hamburger
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000302:isolation & purification / Q000494:pharmacology; D000977:Antiparasitic Agents / Q000302:isolation & purification / Q000494:pharmacology*; D029441:Carica / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002942:Circular Dichroism; D004195:Disease Models, Animal; D005260:Female; D007214:Indonesia; D009682:Magnetic Resonance Spectroscopy; D008288:Malaria / Q000188:drug therapy; D013058:Mass Spectrometry / Q000379:methods; D008518:Medicine, East Asian Traditional; D051379:Mice; D021261:Parasitic Sensitivity Tests; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves; D010962:Plasmodium berghei / Q000187:drug effects; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000962:Antimalarials; D000977:Antiparasitic Agents; D010936:Plant Extracts
keywords: Antiplasmodial; Carica papaya; Carpaine; Flavonol; HPLC-based activity profiling; Piperidine alkaloid