Planta Med 2011; 77(15): 1749-1753
DOI: 10.1055/s-0030-1271080
Analytical Studies
Original Papers
© Georg Thieme Verlag KG Stuttgart · New York

Identification of Oleamide in Guatteria recurvisepala by LC/MS-Based Plasmodium falciparum Thioredoxin Reductase Ligand Binding Method

Ranjith Munigunti1 , Nicholas Nelson1 , Vanisree Mulabagal1 , Mahabir P. Gupta2 , Reto Brun3 , Angela I. Calderón1
  • 1Department of Pharmacal Sciences, Harrison School of Pharmacy, Auburn University, Auburn, Alabama, USA
  • 2Centro de Investigaciones Farmacognósticas de la Flora Panameña, CIFLORPAN, Universidad de Panamá, Panamá, R. de Panamá
  • 3Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
Further Information

Publication History

received January 5, 2011 revised April 10, 2011

accepted April 13, 2011

Publication Date:
12 May 2011 (eFirst)

Abstract

Our current research on applications of mass spectrometry to natural product drug discovery against malaria aims to screen plant extracts for new ligands to Plasmodium falciparum thioredoxin reductase (PfTrxR) followed by their identification and structure elucidation. PfTrxR is involved in the antioxidant defense and redox regulation of the parasite and is validated as a promising target for therapeutic intervention against malaria. In the present study, detannified methanol extracts from Guatteria recurvisepala, Licania kallunkiae, and Topobea watsonii were screened for ligands to PfTrxR using ultrafiltration and liquid chromatography/mass spectrometry-based binding experiments. The PfTrxR ligand identified in the extract of Guatteria recurvisepala displayed a relative binding affinity of 3.5-fold when incubated with 1 µM PfTrxR. The ligand corresponding to the protonated molecule m/z 282.2792 [M + H]+ was eluted at a retention time of 17.95 min in a 20-min gradient of 95 % B consisting of (A) 0.1 % formic acid in 95 % H2O-5 % ACN, and (B) 0.1 % formic acid in 95 % ACN-5% H2O in an LC-QTOF-MS. Tandem MS of the protonated molecule m/z 282.2792 [M + H]+, C18H36NO (DBE: 2; error: 1.13 ppm) resulted in two daughter ions m/z 265.2516 [M + H-NH3]+ (DBE: 3; error: 0.35 ppm) and m/z 247.2405 [M + H-NH3-H2O] +, (DBE: 4; error: 2.26 ppm). The PfTrxR ligand was identified as oleamide and confirmed by comparison of the retention time, molecular formula, accurate mass, and double bond equivalence with the standard oleamide. This is the first report on the identification of oleamide as a PfTrxR ligand from Guatteria recurvisepala R. E. Fr. and the corresponding in vitro activity against P. falciparum strain K1 (IC50 4.29 µg/mL).

References

Dr. Angela I. Calderón

Department of Pharmacal Sciences
Harrison School of Pharmacy
Auburn University

4306B Walker Building

Auburn, AL 36849

USA

Phone: +1 33 48 44 83 33

Fax: +1 33 48 44 83 31

Email: aic0001@auburn.edu