Ketoconazole, a cytochrome P(450) inhibitor can potentiate the antimalarial action of α/β arteether against MDR Plasmodium yoelii nigeriensis

Antimalarial activity and sensitization of chrysosplenetin against artemisinin-resistant genotype Plasmodium berghei K173 potentially via dual-mechanism of maintaining host P-glycoprotein homeostasis mediated by NF-κB p52 or PXR/CAR signaling pathways and regulating heme/haemozoin metabolism

This study investigated antimalarial efficacy and sensitization of chrysosplenetin against artemisinin-resistant Plasmodium berghei K173 and potential molecular mechanism. Our data indicated a risk of artemisinin resistance because a higher parasitaemia% and lower inhibition% under artemisinin treatment against resistant parasites than those in the sensitive groups were observed. Two non-antimalarial components, verapamil and chrysosplentin, being P-gp inhibitors, possessed a strong efficacy against resistant parasites but it was not the case for Bcrp inhibitor novobiocin. Artemisinin-chrysosplenetin combination improved artemisinin susceptibility of resistant P. berghei. Artemisinin activated intestinal P-gp and Abcb1/Abcg2 expressions and suppressed Bcrp whereas chrysosplenetin reversed them. Resistant parasite infection led to a decreased haemozoin in organs or an increased heme in peripheral bloods compared with the sensitives; however, that in Abcb1-deficient knockout (KO)-resistant mice reversely got increased or decreased versus wild type (WT)-resistant animals. Chrysosplenetin as well as rifampin (nuclear receptor agonist) increased the transcription levels of PXR/CAR while showed a versatile regulation on hepatic and enternal PXR/CAR in WT- or KO-sensitive or -resistant parasites. Oppositely, hepatic and enteric NF-κB p52 mRNA decreased conformably in WT but increased in KO-resistant mice. NF-κB pathway potentially involved in the mechanism of chrysosplenetin on inhibiting P-gp expressions while PXR/CAR play a more complicated role in this mechanism.

Molecular and immunological characterization of the calcyclin binding protein in rodent malaria parasite

Malaria remains as a global life-threatening disorder due to the emergence of resistance against standard antimalarials. Consequently, there is a serious need to better understand the biology of the malaria parasite in order to determine appropriate targets for new interventions. Calcyclin binding protein (CacyBP) is a multi-functional and multi-ligand protein that is not well characterized in malaria disease. In this study, we have cloned CacyBP from rodent species Plasmodium yoelii nigeriensis and purified the recombinant protein to carry out its detailed molecular, biophysical and immunological characterization. Molecular characterization indicates that PyCacyBP is a ∼27 kDa protein in parasite lysate and exists in monomer and dimer forms. Bioinformatic analysis of CacyBP showed significant sequence and structural similarities between rodent and human malaria parasites. CacyBP is expressed in all blood stages of P. yoelii nigeriensis parasite. In silico studies proposed the immunogenic potential of CacyBP. The rPyCacyBP immunized mice exhibited elevated levels of IgG1, IgG2a, IgG2b and IgG3 in their serum. Notably, cellular immune response in splenocytes from immunized mice showed increased expression of pro-inflammatory cytokines such as IL-12, IFN-γ and TNF-α. This CacyBP exhibited pro-inflammatory immune response in rodent host. These finding revealed that CacyBP may have the potential to boost the host immunity for protection against malaria infection. The present study provides basis for further exploration of the biological function of CacyBP in malaria parasite.

Multipurpose Drugs Active Against Both Plasmodium spp. and Microorganisms: Potential Application for New Drug Development

Malaria, a disease caused by the protozoan parasites Plasmodium spp., is still causing serious problems in endemic regions in the world. Although the WHO recommends artemisinin combination therapies for the treatment of malaria patients, the emergence of artemisinin-resistant parasites has become a serious issue and underscores the need for the development of new antimalarial drugs. On the other hand, new and re-emergences of infectious diseases, such as the influenza pandemic, Ebola virus disease, and COVID-19, are urging the world to develop effective chemotherapeutic agents against the causative viruses, which are not achieved to the desired level yet. In this review article, we describe existing drugs which are active against both Plasmodium spp. and microorganisms including viruses, bacteria, and fungi. We also focus on the current knowledge about the mechanism of actions of these drugs. Our major aims of this article are to describe examples of drugs that kill both Plasmodium parasites and other microbes and to provide valuable information to help find new ideas for developing novel drugs, rather than merely augmenting already existing drug repurposing efforts.

An epigrammatic status of the 'azole'-based antimalarial drugs

The development of multidrug resistance in the malarial parasite has sabotaged majority of the eradication efforts by restraining the inhibition profile of first line as well as second line antimalarial drugs, thus necessitating the development of novel pharmaceutics constructed on appropriate scaffolds with superior potency against the drug-resistant and drug-susceptible Plasmodium parasite. Over the past decades, the infectious malarial parasite has developed resistance against most of the contemporary therapeutics, thus necessitating the rational development of novel approaches principally focused on MDR malaria. This review presents an epigrammatic collation of the epidemiology and the contemporary antimalarial therapeutics based on the 'azole' motif.

Chrysosplenetin inhibits artemisinin efflux in P-gp-over-expressing Caco-2 cells and reverses P-gp/MDR1 mRNA up-regulated expression induced by artemisinin in mouse small intestine

CONTEXT

CYP3A4 and P-gp together form a highly efficient barrier for orally absorbed drugs and always share the same substrates. Our previous work revealed that chrysosplenetin (CHR) significantly augmented the rat plasma level and anti-malarial efficacy of artemisinin (ART), partially due to the uncompetitive inhibition effect of CHR on rat CYP3A. But the impact of CHR on P-gp is still unknown.

OBJECTIVE

The present study investigates whether CHR interferes with P-gp-mediated efflux of ART and elucidates the underlying mechanism.

MATERIALS AND METHODS

P-gp-over-expressing Caco-2 cells were treated with ART (10 μM) or ART-CHR (1:2, 10:20 μM) in ART bidirectional transport experiment. ART concentration was determined by UHPLC-MS/MS method. Healthy male ICR mice were randomly divided into nine groups (n = 6) including negative control (0.5% CMC-Na solution, 13 mL/kg), ART alone (40 mg/kg), verapamil (positive control, 40 mg/kg), ART-verapamil (1:1, 40:40 mg/kg), CHR alone (80 mg/kg), ART-CHR (1:0.1, 40:4 mg/kg), ART-CHR (1:1, 40:40 mg/kg), ART-CHR (1:2, 40:80 mg/kg) and ART-CHR (1:4, 40:160 mg/kg). The drugs were administrated intragastrically for seven consecutive days. MDR1 and P-gp expression levels in mice small intestine were examined by performing RT-PCR and western blot analysis. ABC coupling ATPase activity was also determined.

RESULTS

After combined with CHR (1:2), Papp (AP-BL) and Papp (BL-AP) of ART changed to 4.29 × 10 - 8 (increased 1.79-fold) and 2.85 × 10 - 8 cm/s (decreased 1.24-fold) from 2.40 × 10 - 8 and 3.54 × 10 - 8 cm/s, respectively. Efflux ratio (PBA/PAB) declined 2.21-fold (p < 0.01) versus to ART alone. ART significantly up-regulated both MDR1 mRNA and P-gp levels compared with vehicle, while CHR in combination ratio of 0:1, 0.1:1, 1:1, 2:1 and 4:1 with ART, reversed them to normal levels as well as negative control (p < 0.05). The ATPase activities in ART-CHR 1:4 and CHR alone groups achieved a slight increase (p < 0.05) when compared with ART alone.

DISCUSSION AND CONCLUSION

These results confirm that CHR inhibited P-gp activity and reverse the up-regulated P-gp and MDR1 levels induced by ART. It suggested that CHR potentially can be used as a P-gp reversal agent to obstruct ART multidrug resistance.

Assessment of Clinical Pharmacokinetic Drug-Drug Interaction of Antimalarial Drugs α/β-Arteether and Sulfadoxine-Pyrimethamine

Antimalarial drug combination therapy is now being widely used for the treatment of uncomplicated malaria. The objective of the present study was to investigate the effects of coadministration of intramuscular α/β-arteether (α/β-AE) and oral sulfadoxine-pyrimethamine (SP) on the pharmacokinetic properties of each drug as a drug-drug interaction study to support the development of a fixed-dose combination therapy. A single-dose, open-label, crossover clinical trial was conducted in healthy adult Indian male volunteers (18 to 45 years, n = 13) who received a single dose of AE or SP or a combination dose of AE and SP. Blood samples were collected up to 21 days postadministration, and concentrations of α-AE, β-AE, sulfadoxine, and pyrimethamine were determined by using a validated liquid chromatography-tandem mass spectrometry method. Pharmacokinetic parameters were calculated and statistically analyzed to calculate the geometric mean ratio and confidence interval. Following single-dose coadministration of intramuscular AE and oral SP, the pharmacokinetic properties of α/β-AE were not significantly affected, and α/β-AE had no significant effect on the pharmacokinetic properties of SP in these selected groups of healthy volunteers. However, more investigations are needed to explore this further. (This study has been registered in the clinical trial registry of India under approval no. CTRI/2011/11/002155.).

Arteether resistance reversal by ketoconazole/fluconazole in rodent malaria parasite Plasmodium vinckei

Artemisinin and its derivative arteether (ART) are fast acting antimalarial drugs against chloroquine-resistant. There are several partner drugs that are identified as a potential drug for artemisinin combination therapy (ACT) to develop as the antimalarial drug. Limited studies have been carried out in ART drug combination that may have more promising as ACT for resistant Plasmodium parasite. Here, we are the first to show the ART drug resistance reversal in Plasmodium vinckei by using antifungal azole compounds ketoconazole (KTZ) and fluconazole (FCZ). Our previous study has shown that higher antioxidant enzyme, glutathione, and less hemozoin may be correlated with ART resistance in P. vinckei (PvAR). We further hypothesized that glutathione and heme catabolism may be interfered by KTZ and FCZ, resulting in an increased efficacy of ART in PvAR parasite. The results of present study demonstrate synergetic effect of KTZ and FCZ against PvAR parasite, since none of the mice developed infection up to day 10 after combination with ART. These results further showed that ED90 of ART was reduced from 17.23 to 2.19 and 2.56 mg/kg when used in combination with KTZ and FCZ, respectively. Resultant, activity enhancement index (AEI) of ART is significantly increased to 8.60 and 6.73 with partner agents. These studies propose the possibility of ART drug combination that may be helpful in prolonging the life of drug and a promising lead to reduce the chance of resistance development of artemisinin and its derivative.