Preprint Communication Version 1 This version is not peer-reviewed

Near Infrared Fluorophore-Tagged Chloroquine in Plasmodium falciparum Diagnostic Imaging

Version 1 : Received: 29 September 2018 / Approved: 29 September 2018 / Online: 29 September 2018 (10:15:33 CEST)

A peer-reviewed article of this Preprint also exists.

Chan, L.Y.; Teo, J.D.W.; Tan, K. .-W.; Sou, K.; Kwan, W.L.; Lee, C.-L.K. Near Infrared Fluorophore-Tagged Chloroquine in Plasmodium falciparum Diagnostic Imaging. Molecules 2018, 23, 2635. Chan, L.Y.; Teo, J.D.W.; Tan, K. .-W.; Sou, K.; Kwan, W.L.; Lee, C.-L.K. Near Infrared Fluorophore-Tagged Chloroquine in Plasmodium falciparum Diagnostic Imaging. Molecules 2018, 23, 2635.

Journal reference: Molecules 2018, 23, 2635
DOI: 10.3390/molecules23102635

Abstract

Chloroquine was among the first of several effective drug treatments against malaria until the onset of chloroquine resistance. In light of diminished clinical efficacy of chloroquine as an antimalarial therapeutic, there is potential in efforts to adapt chloroquine for other clinical applications, such as in combination therapies and in diagnostics. In this context, we designed and synthesized a novel asymmetrical squaraine dye coupled with chloroquine (SQR1-CQ). In this study, SQR1-CQ was used to label live Plasmodium falciparum (P. falciparum) parasite cultures of varying sensitivities towards chloroquine. SQR1-CQ positively stained ring, mature trophozoite and schizont stages of both chloroquine–sensitive and chloroquine–resistant P. falciparum strains. In addition, SQR1-CQ exhibited significantly higher fluorescence, when compared to a chloroquine-BODIPY (borondipyrromethene) conjugate. We also achieved successful SQR1-CQ labelling of P. falciparum directly on thin blood smear preparations. Drug efficacy experiments measuring half-maximal inhibitory concentration (IC50) showed lower concentration of effective inhibition against resistant strain K1 by SQR1-CQ compared to conventional chloroquine. Taken together, the versatile and highly fluorescent labelling capability of SQR1-CQ and promising preliminary IC50 findings potentiates it to be further developed as a promising diagnostic bioimaging tool with drug efficacy against chloroquine-resistant P. falciparum.

Subject Areas

squaraine dye; near infrared; fluorescence; chloroquine; malaria; Plasmodium falciparium

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