title: Resonance Raman spectroscopy can detect structural changes in haemozoin (malaria pigment) following incubation with chloroquine in infected erythrocytes.
abstract: Resonance Raman spectroscopy was applied to monitor the effects of chloroquine (CQ) treatment on cultures of Plasmodium falciparum trophozoites. A number of bands assigned to A(1g) and B(1g) modes characteristic of the haemozoin aggregate are reduced in intensity in the CQ-treated cells, however, no bands from the CQ are observed. The intensity changes are attributed to intermolecular drug binding of the CQ in a sandwich type complex between ferriprotoporphyrin IX (FePPIX) dimer units. It is postulated that the CQ binds via pi-pi interactions between adjacent and orientated porphyrins thereby disrupting the haemozoin aggregate and reducing excitonic interactions between adjacent haems. The results show the potential of Raman microscopy as a screening tool for FePPIX:drug interactions in live cells.
authors.affiliation: Centre for Biospectroscopy and School of Chemistry, Monash University, Clayton, Vic. 3800, Australia.
authors.forename: Grant T
authors.initials: GT
authors.lastname: Webster
authors.forename: Leann
authors.initials: L
authors.lastname: Tilley
authors.forename: Samantha
authors.initials: S
authors.lastname: Deed
authors.forename: Don
authors.initials: D
authors.lastname: McNaughton
authors.forename: Bayden R
authors.initials: BR
authors.lastname: Wood
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000737:chemistry / Q000494:pharmacology*; D002738:Chloroquine / Q000737:chemistry / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects / Q000469:parasitology*; D006420:Hemeproteins / Q000737:chemistry*; D006427:Hemin / Q000737:chemistry; D006801:Humans; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000254:growth & development; D013059:Spectrum Analysis, Raman; D053058:Trophozoites / Q000187:drug effects
chemical_list: D000962:Antimalarials; D006420:Hemeproteins; C020753:hemozoin; D006427:Hemin; D002738:Chloroquine