OBJECTIVES: The possibility of developing antileishmanial drugs was evaluated by intervention in the parasite's iron metabolism, utilizing quercetin (Qr) under in vivo conditions, and identifying the target of this lipophilic metal chelator against Leishmania donovani. METHODS: Interaction between Qr and serum albumin (SA) was studied by using the intrinsic fluorescence of Qr as a probe. The effect of treatment with Qr and SA on the proliferation of amastigotes was determined by evaluating splenic parasite load. Disintegration of parasites in response to combination treatment was assessed from ultrastructural analysis using a transmission electron microscope. Quenching of the tyrosyl radical of ribonucleotide reductase (RR) in treated amastigotes was detected by an electron paramagnetic resonance study. RESULTS: Treatment with a combination of Qr and SA increased bioavailability of the flavonoid and proved to be of major advantage in promoting the effectiveness of Qr towards the repression of splenic parasite load from 75%, P < 0.01 to 95%, P < 0.002. Qr-mediated down-regulation of RR (P < 0.05), catalysing the rate-limiting step of DNA synthesis in the pathogens, could be related to the deprivation of the enzyme of iron which in turn destabilized the critical tyrosyl radical required for its catalysing activity. CONCLUSIONS: Results have implications for improved leishmanicidal action of Qr in combination with SA targeting RR and suggest future drug design based on interference with the parasite's iron metabolism under in vivo conditions.
OBJECTIVES: The possibility of developing antileishmanial drugs was evaluated by intervention in the parasite's iron metabolism, utilizing quercetin (Qr) under in vivo conditions, and identifying the target of this lipophilic metal chelator against Leishmania donovani. METHODS: Interaction between Qr and serum albumin (SA) was studied by using the intrinsic fluorescence of Qr as a probe. The effect of treatment with Qr and SA on the proliferation of amastigotes was determined by evaluating splenic parasite load. Disintegration of parasites in response to combination treatment was assessed from ultrastructural analysis using a transmission electron microscope. Quenching of the tyrosyl radical of ribonucleotide reductase (RR) in treated amastigotes was detected by an electron paramagnetic resonance study. RESULTS: Treatment with a combination of Qr and SA increased bioavailability of the flavonoid and proved to be of major advantage in promoting the effectiveness of Qr towards the repression of splenic parasite load from 75%, P < 0.01 to 95%, P < 0.002. Qr-mediated down-regulation of RR (P < 0.05), catalysing the rate-limiting step of DNA synthesis in the pathogens, could be related to the deprivation of the enzyme of iron which in turn destabilized the critical tyrosyl radical required for its catalysing activity. CONCLUSIONS: Results have implications for improved leishmanicidal action of Qr in combination with SA targeting RR and suggest future drug design based on interference with the parasite's iron metabolism under in vivo conditions.
Authors: Iris L K Wong; Kin-Fai Chan; Yun-Fu Chen; Zhao-Rong Lun; Tak Hang Chan; Larry M C Chow Journal: Antimicrob Agents Chemother Date: 2014-03-31 Impact factor: 5.191
Authors: Sara M Robledo; Wilson Cardona; Karen Ligardo; Jéssica Henao; Natalia Arbeláez; Andrés Montoya; Fernando Alzate; Juan M Pérez; Victor Arango; Iván D Vélez; Jairo Sáez Journal: Adv Pharmacol Sci Date: 2015-04-30
Authors: Camila Mesquita-Rodrigues; Rubem F S Menna-Barreto; Leonardo Sabóia-Vahia; Silvia A G Da-Silva; Elen M de Souza; Mariana C Waghabi; Patrícia Cuervo; José B De Jesus Journal: PLoS Negl Trop Dis Date: 2013-10-17