Sulfadoxine Research Articles

Exploring the antiviral activities of the FDA-approved drug sulfadoxine and its derivatives against Chikungunya virus.

Currently, there is no antiviral licensed to treat chikungunya fever, a disease caused by the infection with Alphavirus chikungunya (CHIKV). Treatment is based on analgesic and anti-inflammatory drugs to relieve symptoms. Our study aimed to evaluate the antiviral activity of sulfadoxine (SFX), an FDA-approved drug, and its derivatives complexed with silver(I) (AgSFX), salicylaldehyde Schiff base (SFX-SL), and with both Ag and SL (AgSFX-SL) against CHIKV. The anti-CHIKV activity of SFX and its derivatives was investigated using BHK-21 cells infected with CHIKV-nanoluc, a marker virus-carrying nanoluciferase reporter. Dose-response and time of drug-addition assays were performed in order to assess the antiviral effects of the compounds, as well as in silico data and ATR-FTIR analysis for insights on their mechanisms of action. The SFX inhibited 34% of CHIKV replication, while AgSFX, SFX-SL, and AgSFX-SL enhanced anti-CHIKV activity to 84%, 89%, and 95%, respectively. AgSFX, SFX-SL, and AgSFX-SL significantly decreased viral entry and post-entry to host cells, and the latter also protected cells against infection. Additionally, molecular docking calculations and ATR-FTIR analysis demonstrated interactions of SFX-SL, AgSFX, and AgSFX-SL with CHIKV. Collectively, our findings suggest that the addition of metal ions and/or Schiff base to SFX improved its antiviral activity against CHIKV.

Comparison of transfer of different sulphonamides from contaminated beeswax to honey.

No maximum residue limits in honey have been legislated in the EU for antimicrobial substances such as sulphonamides, and they are not permitted, therefore, for treating honey bees unless in a cascade system. Since sulphonamides are used illegally in apiculture to treat foulbrood, their residues can be found in honey and other apiculture products, including beeswax. The study aimed to assess the contamination of honey from beeswax containing residues of 10 sulphonamides (sulphadimethoxine (SDM), sulphadoxine (SDX), sulphamonomethoxine (SMM), sulphamethoxazole (SMX), sulphameter (SMT), sulphamethazine (SMZ), sulphamerazine (SMR), sulphadiazine (SDA), sulphathiazole (STZ) and sulphacetamide (SCA)). Wax-based foundations fortified with 10 sulphonamides at 10,000 μg/kg were evaluated for sulphonamide concentrations and then placed in a beehive so that honey bees (Apis mellifera L.) could build honeycombs with them. Frames of capped honey were taken out of the hives one month later and honey was sampled from them. The honeycombs were subsequently incubated in a laboratory at 35°C for five months, and honey was sampled monthly. The honey sulphonamide concentrations were measured using liquid chromatography-tandem mass spectrometry and compared to the wax-based foundation concentrations. The maximum transfers to honey of the initial amount of SDM, SDX, SMM, SMX, SMT, SMZ, SMR, SDA, STZ and SCA in the wax-based foundations were 42.6, 34.3, 31.7, 30.1, 29.5, 25.2, 18.7, 16.1, 9.5 and 8.6%, respectively. This study demonstrated that every tested sulphonamide could migrate from beeswax in antimicrobial-tainted honeycombs to honey, SDM having the highest migration potential and SCA the lowest.

In vitro and in vivo activities of a trithiolato-diRuthenium complex conjugated with sulfadoxine against the apicomplexan parasite Toxoplasma gondii

Organometallic compounds, including Ruthenium complexes, have been widely developed as anti-cancer chemotherapeutics, but have also attracted much interest as potential anti-parasitic drugs. Recently hybrid drugs composed of organometallic Ruthenium moieties that were complexed to different antimicrobial agents were synthesized. One of these compounds, a trithiolato-diRuthenium complex (RU) conjugated to sulfadoxine (SDX), inhibited proliferation of Toxoplasma gondii tachyzoites grown in human foreskin fibroblast (HFF) monolayers with an IC50 < 150 nM, while SDX and the non-modified RU complex applied either individually or as an equimolar mixture were much less potent. In addition, conjugation of SDX to RU lead to decreased HFF cytotoxicity. RU-SDX did not impair the in vitro proliferation of murine splenocytes at concentrations ranging from 0.1 to 0.5 μM but had an impact at 2 μM, and induced zebrafish embryotoxicity at 20 μM, but not at 2 or 0.2 μM. RU-SDX acted parasitostatic but not parasiticidal, and induced transient ultrastructural changes in the mitochondrial matrix of tachyzoites early during treatment. While other compounds that target the mitochondrion such as the uncouplers FCCP and CCCP and another trithiolato-Ruthenium complex conjugated to adenine affected the mitochondrial membrane potential, no such effect was detected for RU-SDX. Evaluation of the in vivo efficacy of RU-SDX in a murine T. gondii oocyst infection model comprised of non-pregnant outbred CD1 mice showed no effects on the cerebral parasite burden, but reduced parasite load in the eyes and in heart tissue.

Elucidating the influence of some metal ions on the binding of antimalarial drugs to human serum albumin: spectroscopic approach

Influence of six metal ions viz. Mg2+, K+, Ca2+, Mn2+, Cu2+ and Ba2+ on the binding affinity of human serum albumin (HSA) towards three antimalarial drugs, namely, sulfadoxine (SDN), mefloquine (MEF) and lumefantrine (LUM) was investigated using fluorescence quenching titrations. The effects of metal ions (Mn2+, Cu2+ and Ba2+) were similar on the affinity of HSA towards SDN, MEF and LUM. Values of the association constant, Ka, for SDN/MEF/LUM ̶ HSA interactions in the presence of these metal ions, decreased significantly in the order: Mn2+ &gt; Cu2+ &gt; Ba2+. On the other hand, the presence of Mg2+, K+, and Ca2+ affected the binding affinity for these drugs differently. Whereas a slight increase in the Ka value of the SDN ̶ HSA complex was seen in the presence of Mg2+, Ca2+ produced a similar effect on the LUM ̶ HSA system. For MEF ̶ HSA and LUM ̶ HSA systems, effects of K+ and Mg2+ were similar, showing a decrease in the Ka value, being more effective with K+; however, this decrease was more significant than Mn2+, Cu2+ and Ba2+. Values of ‘n’ remained approximately equal to 1, hinting at a single binding site for each drug.

Determination of sulfadoxine and pyrimethamine in microvolume human plasma using ultra high performance liquid chromatography-tandam mass spectrometry

To support the pharmacokinetic study of sulfadoxine (SD) and pyrimethamine (PM) in pregnant women and children, sensitive methods with small sample volume are desirable. Here we report a method to determine SD and PM with microvolume plasma samples: 5 µL plasma samples were cleaned up by protein precipitation with acetonitrile. The deuterated analytes were used as the internal standards. The samples after cleanup were injected onto an ACE Excel SuperC18 column (50 × 2.1 mm, 1.7 μm, Hichrom Limited) connected to a Waters I class UPLC coupled with a Sciex Triple Quad 6500+ Mass Spectrometer and eluted with water and acetonitrile both containing 0.1% formic acid in a gradient mode at 0.8mL/min. Detection utilized ESI+ as the ion source and MRM as the quantification mode. The precursor-to-product ion transitions m/z 311→245 for SD and 249→233 for PM were selected for quantification. The ion transitions for the corresponding internal standards were 315→249 for SD-d4 and 254→235 for PM-d3. The simplest linear regression weighted by 1/x was used for the calibration curves. The calibration ranges were 1–200 µg/mL SD and 2 – 1000ng/mL PM. The mean (± standard deviation) recoveries were 94.3±3.2% (SD) and 97.0±1.5% (PM). The validated method was applied to analysis of 1719 clinical samples, demonstrating the method is suitable for the pharmacokinetic study with samples collected up to day 28 post-dose.

An electrochemical aptamer sensor for rapid quantification sulfadoxine based on synergistic signal amplification of indole and MWCNTs and its electrooxidation mechanism

Unreasonable disposal of sulfadoxine (SDX) causing food safety and eventually result water pollution, and shows great significance of detection. A sensitive unit Aptamer (Apt) was adopted to construct an electrochemical sensor BSA/Apt/indole/MWCNTs/GCE with the synergistic amplification of multi-walled carbon nanotubes (MWCNTs) and indole for the detection of SDX. Optimization of the conditions allowed the detection of SDX shows a wide linear range from 0.10 to 1000.00 µmol/L by differential pulse voltammetry (DPV). The LOD and sensitivity were determined to be 0.033 µmol/L and 0.29 µA/(µmol/L·cm²), respectively. The recovery rate of SDX in pork and lake water samples range 98.57 %−104.93 %, 93.6 %−106.2 %, respectively. Both the relative standard deviation (RSD) was lower than 7.40 %, which proved that the sensor has good practicability. In addition, DFT calculation was established that a restricted of B3LYP and a basis set of 6–31 G, the electrooxidation of SDX involves two-electron and one-proton transfer.

Investigating sulfonamides - Human serum albumin interactions: A comprehensive approach using multi-spectroscopy, DFT calculations, and molecular docking

The environmental and health risks associated with sulfonamide antibiotics (SAs) are receiving increasing attention. Through multi-spectroscopy, density functional theory (DFT), and molecular docking, this study investigated the interaction features and mechanisms between six representative SAs and human serum albumin (HSA).Multi-spectroscopy analysis showed that the six SAs had significant binding capabilities with HSA. The order of binding constants at 298 K was as follows: sulfadoxine (SDX): 7.18 × 105 L mol−1 > sulfamethizole (SMT): 6.28 × 105 L mol−1 > sulfamerazine (SMR): 2.70 × 104 L mol−1 > sulfamonomethoxine (SMM): 2.54 × 104 L mol−1 > sulfamethazine (SMZ): 3.06 × 104 L mol−1 > sulfadimethoxine (SDM): 2.50 × 104 L mol−1. During the molecular docking process of the six SAs with HSA, the binding affinity range is from −7.4 kcal mol−1 to −8.6 kcal mol−1. Notably, the docking result of HSA-SDX reached the maximum of −8.6 kcal mol−1, indicating that SDX may possess the highest binding capacity to HSA. HSA-SDX binding, identified as a static quenching and exothermic process, is primarily driven by hydrogen bonds (H bonds) or van der Waals (vdW) interactions. The quenching processes of SMR/SMZ/SMM/SDX/SMT to HSA are a combination of dynamic and static quenching, indicating an endothermic reaction. Hydrophobic interactions are primarily accountable for SMR/SMZ/SMM/SDX/SMT and HSA binding. Competition binding results revealed that the primary HSA-SAs binding sites are in the subdomain IB of the HAS structure, consistent with the results of molecule docking.The correlation analysis based on DFT calculations revealed an inherent relationship between the structural chemical features of SAs and the binding performance of HSA-SAs. The dual descriptor (DD) and the electrophilic Fukui function were found to have a significant relationship (0.71 and −0.71, respectively) with the binding constants of HSA-SAs, predicting the binding performance of SAs and HSA. These insights have substantial scientific value for evaluating the environmental risks of SAs as well as understanding their impact on biological life activities.

Control of a sulfadoxine/trimethoprim combination in the competition horse: Elimination, metabolism and detection following an intravenous administration.

The combination of sulfadoxine (SDO) with trimethoprim (TMP) is widely used in veterinarian medicine. The aim of the present study was to compare excretion profiles and detection time windows of SDO and TMP in plasma and urine by means of a validated quantitative method. Eight horses received a single intravenous (i.v.) dose of 2.7 mg TMP and 13.4 mg SDO per kg bodyweight. Plasma and urine samples were collected up to 15 and 70 days post-administration, respectively. While urine samples underwent an enzymatic hydrolysis, plasma samples were proteolysed before further analysis. After solid-phase extraction, samples were analysed by liquid chromatography/electrospray ionisation tandem mass spectrometry in positive ionisation mode. The applied multiple reaction monitoring (MRM) method allowed the detection of SDO and TMP with a lower limit of detection of 0.03 ng/mL in plasma and 0.2 (SDO) and 0.4 ng/mL (TMP) in urine, respectively. In the present study, detection times for SDO were 15 days in plasma and 49 days in urine, respectively. TMP was detected for up to 7 days in plasma and up to 50 days in urine, respectively. The detection via the TMP metabolite 3-desmethyl-trimethoprim was possible for 70 days in urine. Detection times of the other confirmed metabolites N4 -acetylated sulfadoxine, hydroxytrimethoprim, trimethoprim-1-oxide and trimethoprim-3-oxide were significantly lower. In order to postulate reasonable screening limits (SLs) to control specific withdrawal times, a Monte Carlo simulation was performed for SDO. The proposed SL of 10 ng/mL SDO in blood and 300 ng/mL urine corresponds to a detection time of 4 days.

Antibiotic pollution of the Yellow River in China and its relationship with dissolved organic matter: Distribution and Source identification

Understanding the sources of antibiotics is important for managing antibiotic contamination and preventing environmental risks in the aquatic environment. In this study, the distribution of dissolved organic matter (DOM) and 24 antibiotics from four typical classes (quinolones, macrolides, sulfonamides and tetracyclines) in the Yellow River basin containing distinct sources of pollution was investigated. In particular, relationships between the antibiotic concentrations and fluorescent properties of DOM were to be established to identify antibiotic sources. A total of 22 antibiotics were detected, with maximum concentrations ranging from 0.27 to 30.14 ng/L in the mainstream of the Yellow River. Of these antibiotics, only erythromycin (ERY) and sulfamethoxazole (SMX) posed potential risks to aquatic organisms. Spatially, tetracyclines were mainly distributed in the upstream reaches of the river, and quinolones were largely distributed in the midstream. High levels of sulfonamides were present downstream of the investigated river. Only EYR belonging to the macrolide group was detected and had a high downstream concentration. EEM-PARAFAC analysis showed that DOM was composed of visible fulvic acid-like fluorescence fraction (C1), ultraviolet fulvic acid-like fluorescence fraction (C2) and protein-like fraction (C3). Using Pearson correlation analysis, this study demonstrated a close relationship between DOM spectral parameters and antibiotic concentrations in the Yellow River basin. Specifically, r (C3, C2) was significantly and positively correlated with the concentrations of SMX, sulfadoxine (SDX), and ERY, while humification index (HIX) had an opposite relationship with these antibiotics. These results suggested that SMX, SDX and ERY were mainly discharged from wastewater treatment plants into the mainstream of the Yellow River. This work provides a powerful demonstration that DOM plays an important role in indicating the occurrence and sources of antibiotics in the aquatic environment.

Global Analysis of Plasmodium falciparum Dihydropteroate Synthase Variants Associated with Sulfadoxine Resistance Reveals Variant Distribution and Mechanisms of Resistance: A Computational-Based Study.

The continual rise in sulfadoxine (SDX) resistance affects the therapeutic efficacy of sulfadoxine-pyrimethamine; therefore, careful monitoring will help guide its prolonged usage. Mutations in Plasmodium falciparum dihydropteroate synthase (Pfdhps) are being surveilled, based on their link with SDX resistance. However, there is a lack of continuous analyses and data on the potential effect of molecular markers on the Pfdhps structure and function. This study explored single-nucleotide polymorphisms (SNPs) in Pfdhps that were isolated in Africa and other countries, highlighting the regional distribution and its link with structure. In total, 6336 genomic sequences from 13 countries were subjected to SNPs, haplotypes, and structure-based analyses. The SNP analysis revealed that the key SDX resistance marker, A437G, was nearing fixation in all countries, peaking in Malawi. The mutation A613S was rare except in isolates from the Democratic Republic of Congo and Malawi. Molecular docking revealed a general loss of interactions when comparing mutant proteins to the wild-type protein. During MD simulations, SDX was released from the active site in mutants A581G and A613S before the end of run-time, whereas an unstable binding of SDX to mutant A613S and haplotype A437A/A581G/A613S was observed. Conformational changes in mutant A581G and the haplotypes A581G/A613S, A437G/A581G, and A437G/A581G/A613S were seen. The radius of gyration revealed an unfolding behavior for the A613S, K540E/A581G, and A437G/A581G systems. Overall, tracking such mutations by the continuous analysis of Pfdhps SNPs is encouraged. SNPs on the Pfdhps structure may cause protein-drug function loss, which could affect the applicability of SDX in preventing malaria in pregnant women and children.

Drug resistance and population structure of Plasmodium falciparum and Plasmodium vivax in the Peruvian Amazon

Malaria is a major health problem in Peru despite substantial progress achieved by the ongoing malaria elimination program. This study explored the population genetics of 63 Plasmodium falciparum and 170 P. vivax cases collected in the Peruvian Amazon Basin between 2015 and 2019. Microscopy and PCR were used for malaria detection and positive samples were genotyped at neutral and drug resistance-associated regions. The P. falciparum population exhibited a low nucleotide diversity (π = 0.02) whereas the P. vivax population presented a higher genetic diversity (π = 0.34). All P. falciparum samples (n = 63) carried chloroquine (CQ) resistant mutations on Pfcrt. Most P. falciparum samples (53 out of 54) carried sulfadoxine (SD) resistant mutations on Pfdhfr and Pfdhps. No evidence was found of artemisinin resistance mutations on kelch13. Population structure showed that a single cluster accounted for 93.4% of the P. falciparum samples whereas three clusters were found for P. vivax. Our study shows a low genetic diversity for both species with significant differences in genetic sub-structuring. The high prevalence of CQ-resistance mutations could be a result of indirect selection pressures driven by the P. vivax treatment scheme. These results could be useful for public health authorities to safeguard the progress that Peru has achieved towards malaria elimination.

UHPLC-MS/MS Analysis of Antibiotics Transfer and Concentrations in Porcine Oral Fluid after Intramuscular Application.

The monitoring of antibiotic use in animals is a crucial element to ensure food safety. The main goal of this study was to analyse the distribution of selected antibiotics to porcine oral fluid, as well as to demonstrate that an oral fluid is an alternative to other biological matrices used in the control of antibacterials. Therefore, an animal study with pigs treated using seven different antibiotics was performed. Sulfadoxine (SDX) with trimethoprim (TRMP), lincomycin (LIN), tiamulin (TIAM), tylosin (TYL), amoxicillin (AMX) and penicillin G (PEN G) were injected intramuscularly to pigs, and concentrations of these analytes in the oral fluid were assessed. Ultra-high-performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS) was used to quantify the analytes. On the first day of medication, the highest concentrations for SDX and TRMP at the level of 22,300 µg/kg and 14,100 µg/kg were found, respectively. The concentrations of LIN (10,500 µg/kg) and TIAM (7600 µg/kg) were also relatively high. The peak of TYL was recorded on the second day of drug administration. Most of the analytes were present in oral fluid for 30 days, apart from TYL, which was detected for 27 days. It was found that AMX and PEN G were quantified only for 5 and 8 days, respectively, at very low concentrations. It was found that oral fluid can be used for the verification of antibiotics on pig farms.

Spectrophotometric Determination of Sulfadoxine Drug use Cloud point and Flow injection Methods in Pharmaceutical Formulations

New simple sensitive spectrophotometric methods are developed for the estimation of Sulfadoxine (SFD) in pure and pharmaceutical formulations. The first method includes a conversion primary amine to azo-dye by reacting sulfadoxine with sodium nitrite and hydrochloric acid followed by coupling with4-methoxyphenol in alkaline medium to obtain a stable reddish-orange colored dye at λmax495nm. Concentration ranges 0.25-60 μg / mL, obeyed Beer's law, correlation coefficient was 0.9996, molar absorptivity was 0.589×104L.mol-1.cm-1 and the detection limit was 0.157μg/mL. The second method was cloud point extraction (CPE) for estimating trace amount in an aqueous solution that produced from diazotization and measuring with a UV-visible spectrophotometer as are reddish-purple colored product at λmax500 nm. The concentration range obeyed the Beer's law was 0.25-6μg / mL, correlation coefficient was 0.9998, molar absorptivity was 0.877×105L.mol-1.cm-1, detection limit was 0.023μg/mL, pre-concentration factor was 25 and Distribution coefficient(D) was 320.88. The last method was flow injection analysis it’s simple for estimation the sulfadoxine. The concentration range was1-150μg / mL, obeyed Beer's law,the correlation coefficient was 0.9997, molar absorptivity was 0.273×104L.mol-1.cm-1 and the detection limit was 0.375μg/mL. The offered methods were successful, useful for estimating sulfadoxine in traditional medications

HPLC-UV Method Development and Validation for Sulfadoxine from its Potential Interfering Impurities

Objective: To address the separation of interfering potential impurities associated with the drug is always a daunting task. We present the method validation and quantitative determination of sulfadoxine (SUL), an anti-malarial drug with the most important interfering impurities present in pharmaceutical dosages and bulk samples using HPLC-UV method. Methods: The UV detection was obtained at 270 nm and SUL is separated on Sunfire C18 (25 cm x 4.6 mm x 5 μm) column at 45°C with a flow rate of 1.0 mL/min in a mobile phase (CH3COOH: CH3CN). The stress testing (acidic/basic/oxidative) was performed using HPLC for SUL and its impurities, showing the highly efficient separation peaks between degradant and drug products. Results: The developed method was found to be highly accurate and sensitive in regulation with ICH guidelines. Also, it was found to be free from interference from degradation products which allows the stability indicating capability of developed HPLC-UV method for SUL for validation in bulk drugs. Conclusion: The main advantages of the present method; (a) Separation achieved in 30 minutes, (b) MS compatible mobile phase renders this developed method can be directly adapted to LC-MS without any major modifications in the near future, and (c) separation of twelve impurities on Sunfire C18 column. The CFs (correction factors) had been calculated for all the impurities. It was found to be 1.6 (IMP IX), 1.70 (IMP XI) and in between 0.8-1.3 for all other impurities. The LOD of the developed method for all the analytes was in the range of 0.05 to 0.11 μg/mL and the LOQ values were in the range of 0.17 to 0.36 μg/mL.

Investigations on the influence of energy source on time-dependent hormesis: A case study of sulfadoxine to Aliivibrio fischeri in different cultivation systems

Hormesis is a biphasic dose-response relationship featured by low-dose stimulation and high-dose inhibition. Although the hormetic phenomenon has been extensively studied over the past decades, there is little information regarding the influence of energy source on the occurrence of hormesis, especially the time-dependent one. In this study, to explore the role of cultivation system's energy source in time-dependent hormesis, the toxic dose-responses of Aliivibrio fischeri (A. fischeri) bioluminescence to Sulfadoxine (SDX) during 24 h were determined in four cultivation systems with different energy source conditions. The results indicated that the time-dependent hormetic effects were induced by SDX in all cultivation systems: SDX triggered hormetic phenomenon on the bioluminescence at each growth stage over 24 h in the cultivation systems with sufficient and insufficient energy source; due to the diauxic growth of A. fischeri under multiple energy source conditions, the hormetic effects of SDX gradually disappeared after the preferred energy source was used up. It was speculated that the inhibitory action of SDX was derived from its interaction with DHPS to impede the synthesis of proteins, and SDX bound with AC to upregulate the quorum sensing (QS) system to exhibit the stimulatory action. Comparing the time-dependent hormesis in each cultivation system, it was obtained that the energy source could impact the hourly maximum stimulatory rate, the EC50 of SDX, and the time point that hormesis occurred, which might result from the influence of energy source on the stimulatory and inhibitory actions of SDX through regulating the metabolic system (individual level) and QS system (group level) of bacteria. This study clarifies the importance of energy source for hormesis occurrence, which may further promote the development of hormesis.

Validated Spectrophotometric Methods for Simultaneous Determination of Sulphadoxine and trimethoprim in a Veterinary Pharmaceutical Dosage Form

Validated Spectrophotometric Methods for Simultaneous Determination of Sulphadoxine and trimethoprim in a Veterinary Pharmaceutical Dosage Form

Effect of sulfadoxine-pyrimethamine doses for prevention of malaria during pregnancy in hypoendemic area in Tanzania

BackgroundMalaria in pregnancy increases the risk of deleterious maternal and birth outcomes. The use of ≥ 3 doses of sulfadoxine-pyrimethamine (SP) for intermittent preventive treatment of malaria (IPTp-SP) is recommended for preventing the consequences of malaria during pregnancy. This study assessed the effect of IPTp-SP for prevention of malaria during pregnancy in low transmission settings.MethodsA cross-sectional study that involved consecutively selected 1161 pregnant women was conducted at Mwananyamala regional referral hospital in Dar es Salaam. Assessment of the uptake of IPTp-SP was done by extracting information from antenatal clinic cards. Maternal venous blood, cord blood, placental blood and placental biopsy were collected for assessment of anaemia and malaria. High performance liquid chromatography with ultraviolet detection (HPLC-UV) was used to detect and quantify sulfadoxine (SDX). Dried blood spots (DBS) of placental blood were collected for determination of sub-microscopic malaria using polymerase chain reaction (PCR).ResultsIn total, 397 (34.2%) pregnant women reported to have used sub-optimal doses (≤ 2) while 764 (65.8%) used optimal doses (≥ 3) of IPTp-SP at the time of delivery. The prevalence of placental malaria as determined by histology was 3.6%. Submicroscopic placental malaria was detected in 1.4% of the study participants. Women with peripheral malaria had six times risk of maternal anaemia than those who were malaria negative (aOR, 5.83; 95% CI 1.10–30.92; p = 0.04). The geometric mean plasma SDX concentration was 10.76 ± 2.51 μg/mL. Sub-optimal IPTp-SP dose was not associated with placental malaria, premature delivery and fetal anaemia. The use of ≤ 2 doses of IPTp-SP increased the risk of maternal anaemia by 1.36-fold compared to ≥ 3 doses (aOR, 1.36; 95% CI 1.04–1.79; p = 0.02).ConclusionThe use of < 2 doses of IPTp-SP increased the risk of maternal anaemia. However, sub-optimal doses (≤ 2 doses) were not associated with increased the risk of malaria parasitaemia, fetal anaemia and preterm delivery among pregnant women in low malaria transmission setting. The use of optimal doses (≥ 3 doses) of IPTp-SP and complementary interventions should continue even in areas with low malaria transmission.

Birth Outcomes Similar with Dihydroartemisinin–Piperaquine vs. Standard Malaria Preventive Treatment in Pregnancy

Intermittent preventive treatment with sulfadoxine–pyrimethamine (S–P) is recommended during pregnancy in malaria-endemic areas, but parasite

Structure of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase–dihydropteroate synthase from Plasmodium vivax sheds light on drug resistance

The genomes of the malaria-causing Plasmodium parasites encode a protein fused of 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) and dihydropteroate synthase (DHPS) domains that catalyze sequential reactions in the folate biosynthetic pathway. Whereas higher organisms derive folate from their diet and lack the enzymes for its synthesis, most eubacteria and a number of lower eukaryotes including malaria parasites synthesize tetrahydrofolate via DHPS. Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) HPPK-DHPSs are currently targets of drugs like sulfadoxine (SDX). The SDX effectiveness as an antimalarial drug is increasingly diminished by the rise and spread of drug-resistant mutations. Here, we present the crystal structure of PvHPPK-DHPS in complex with four substrates/analogs, revealing the bifunctional PvHPPK-DHPS architecture in an unprecedented state of enzymatic activation. SDX's effect on HPPK-DHPS is due to 4-amino benzoic acid (pABA) mimicry, and the PvHPPK-DHPS structure sheds light on the SDX-binding cavity, as well as on mutations that effect SDX potency. We mapped five dominant drug resistance mutations in PvHPPK-DHPS: S382A, A383G, K512E/D, A553G, and V585A, most of which occur individually or in clusters proximal to the pABA-binding site. We found that these resistance mutations subtly alter the intricate enzyme/pABA/SDX interactions such that DHPS affinity for pABA is diminished only moderately, but its affinity for SDX is changed substantially. In conclusion, the PvHPPK-DHPS structure rationalizes and unravels the structural bases for SDX resistance mutations and highlights architectural features in HPPK-DHPSs from malaria parasites that can form the basis for developing next-generation anti-folate agents to combat malaria parasites.

Thin-layer Chromatographic Method for Quantification of Sulfonamides in Chicken Meat

The sulfonamides are a widely used group of antimicrobials in veterinary practice especially in developing countries due to their broad spectrum of activity, availability, and low cost. The objective of this study was to establish a thin-layer chromatographic (TLC) method to detect residues of commonly used sulfonamides in Sri Lanka in chicken. The TLC method separated sulfadiazine (SDZ), sulfadoxine (SD), sulfamethazine (SMZ), sulfathiazole (STZ), and sulfaquinoxaline (SQ) on silica gel plates using chloroform: n_butanol (90:10). Sulfonamides densitometric measurements were conducted by derivatising with fluorescamine and scanning the separated bands at 366 nm. The quantity of the sulfonamide in samples was calculated using a standard calibration curve obtained by plotting values of peak area against sulfonamide concentrations at 200, 150, 100, 50, 30, and 25 ng/g. The mean percentage recoveries were 80–120% while the intra-day and inter-day precision was 3–22% and 6–42% respectively. The SD had the highest limit of detection (LOD) and limit of quantification (LOQ) values of 60 and 100 ng/g respectively. The LOD of all the other analytes were 40 ng/g, and STZ had the lowest LOQ values of 50 ng/g. A reliable, inexpensive, simple, liquid-liquid extraction method for the rapid analysis of five sulfonamides at maximum residue limit (MRL) in chicken using TLC was developed.