Investigation of volatile organic biomarkers derived from Plasmodium falciparum in vitroReport as inadecuate




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Malaria Journal

, 11:314

First Online: 07 September 2012Received: 09 June 2012Accepted: 04 September 2012

Abstract

BackgroundThere remains a need for techniques that improve the sensitive detection of viable Plasmodium falciparum as part of diagnosis and therapeutic monitoring in clinical studies and usual-care management of malaria infections. A non-invasive breath test based on P. falciparum- associated specific volatile organic compounds VOCs could fill this gap and provide insights into parasite metabolism and pathogenicity. The aim of this study was to determine whether VOCs are present in the headspace above in vitro P. falciparum cultures.

MethodsA novel, custom-designed apparatus was developed to enable efficient headspace sampling of infected and non-infected cultures. Conditions were optimized to support cultures of high parasitaemia >20% to improve the potential detection of parasite-specific VOCs. A number of techniques for VOC analysis were investigated including solid phase micro-extraction using two different polarity fibres, and purge and trap-thermal desorption, each coupled to gas chromatography–mass spectrometry. Each experiment and analysis method was performed at least on two occasions. VOCs were identified by comparing their mass spectra against commercial mass spectral libraries.

ResultsNo unique malarial-specific VOCs could be detected relative to those in the control red blood cell cultures. This could reflect sequestration of VOCs into cell membranes and-or culture media but solvent extractions of supernatants and cell lysates using hexane, dichloromethane and ethyl acetate also showed no obvious difference compared to control non-parasitized cultures.

ConclusionsFuture in vivo studies analysing the breath of patients with severe malaria who are harbouring a parasite biomass that is significantly greater than achievable in vitro may yet reveal specific clinically-useful volatile chemical biomarkers.

KeywordsMalaria Plasmodium falciparum Volatile organic compounds Solid phase micro-extraction Organic biomarkers AbbreviationsGC-MSGas chromatography–mass spectrometry

PDMSPolydimethylsiloxane

RBCRed blood cells

SPMESolid phase micro-extraction

VOCsVolatile organic compounds.

Electronic supplementary materialThe online version of this article doi:10.1186-1475-2875-11-314 contains supplementary material, which is available to authorized users.

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Author: Rina PM Wong - Gavin R Flematti - Timothy ME Davis

Source: https://link.springer.com/



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