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PubMed1975

Quinoxaline studies. 23. Potential antimalarials. Substituted 5,8-dimethoxy-6-[N-(omega-dimethylaminoalkyl)amino]quinoxalines were prepared: the first series with identical 2,3-substituents H, CH3, C6H5, C6H4-4-Cl, and CH2C6H5; and the second with identical styryl groups CH=CHC6H5, CH=CHC6H4-4-Cl, CH=CHC6H3-3,4-Cl2, CH=CHC6H4-4-F, CH=CHC6H4-4-CF3, and CH=CHC6H4-4-NO2. None of the substances possessed antimalarial activity; several were toxic at highest dosage levels.

3-Hydrazinopyridazines substituted in position 6 with a primary amine, secondary amine, or an alkoxy group were synthesized and screened for antihypertensive activity. In general, the 6-dialklamino derivatives are the most active; the (2-hydroxypropyl)methylamino chain provides the best combination of high antihypertensive activity and toxicity.

Animals↗
PubMed1988

[Antimalarial activities: the last 40 years. Antimalarial action program].

Around the turn of the century there were about 250 million cases of malaria each year and 2.5 million deaths. The introduction of DDT-type insecticides with residual effect around 1940 led to much more effective prevention than previously. WHO has been assisting Member States with malaria control ever since its foundation in 1948. In about 1950 it was proved that spraying DDT inside houses could interrupt transmission and lead to eradication within three years by exhausting the reservoir. Around the same time the discovery of the first cases of anopheline resistance to DDT introduced an element of urgency. The principle of eradication was adopted for the Americas by the Pan American Sanitary Conference in 1954, and for the world as a whole by the World Health Assembly in 1955, though it was acknowledged that the application of the principle to tropical Africa would be premature. With the aid of WHO, and under the leadership of its Expert Committee on Malaria, most control programmes outside tropical Africa were converted into eradication programmes. The results of the first 10 years of the global eradication programme (1957-1966) were spectacular but uneven; there were reverses due to financial, administrative or operational problems, or to the resistance or behaviour of the vectors, or to the inadequate development of basic health services. In Africa, the pilot projects generally failed to interrupt transmission. A new and more flexible strategy was adopted in 1969, whereby countries were invited to revise their programmes to take local circumstances into account. These revisions showed that in many countries eradication was not possible in the short term, but in the majority of cases they did not manage to put forward any genuine alternative strategy. Resources became increasingly difficult to obtain, whereas the cost of insecticides and transport went up with the price of oil. Research, which had been neglected for some time, once again became the order of the day and great importance was attached to malaria when the Special Programme for Research and Training in Tropical Diseases (TDR) was set up by WHO, UNDP and the World Bank. Since 1978 the emphasis has been on integrating malaria control with the primary health care system and on integrating health with development.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2006

Effect of antimalarials on thrombosis and survival in patients with systemic lupus erythematosus.

Antimalarials have shown beneficial effects on systemic lupus erythematosus (SLE) activity. Our aim was to investigate whether antimalarials protect against thrombosis and influence survival in SLE patients. A prospective cohort including 232 patients with SLE were included in the study at the time of lupus diagnosis. End points were documented thrombosis and death due to any cause. A Cox regression-multiple-failure time survival analysis model was fitted to establish the effect of antimalarials on the development of thrombosis. Kaplan-Meier survival curves and propensity score adjusted-Cox regression analysis were performed to investigate the effect of antimalarials use on survival. Of our subjects, 204 patients (88%) were women. 230 patients (99%) were white. 150 patients (64%) had ever received antimalarials. Median time on antimalarials was 52 months (range three to 228 months). The Cox multiple-failure time survival analysis showed that taking antimalarials was protective against thrombosis (HR 0.28, 95% CI 0.08-0.90), while aPL-positivity (HR 3.16, 95% CI 1.45-6.88) and previous thrombosis (HR 3.85, 95% CI 1.50-9.91) increased the risk of thrombotic events. Twenty-three patients died, 19 of whom (83%) had never received antimalarials. No patient treated with antimalarials died of cardiovascular complications. Cumulative 15-year survival rates were 0.68 for never versus 0.95 for ever treated patients (P < 0.001). Age at diagnosis and propensity score-adjusted HR for antimalarials ever versus never users was 0.14 (95% CI 0.04-0.48). Our study shows a protective effect of antimalarials against thrombosis and an increased survival of SLE patients taking these drugs. These data support the routine use of antimalarials in all patients with SLE.

Adult↗
PubMed1999

The cholesterol lowering effect of antimalarial drugs is enhanced in patients with lupus taking corticosteroid drugs.

OBJECTIVE: To examine the relationship between antimalarial therapy and total cholesterol in patients with systemic lupus erythematosus (SLE) with or without steroid therapy. METHODS: Retrospective study for the University of Toronto Lupus Clinic database between 1976 and 1997. The effects of antimalarials on random total cholesterol levels were assessed in the following situations: patients not receiving steroids (part I) that either initiated or discontinued antimalarials; patients receiving steroids (part II) that were either on a stable dose or initiating antimalarials; and patients initiating steroids with or without antimalarials (part III). Paired t test, Fisher's exact test, and 2 way analysis of variance were used when appropriate. RESULTS: Initiation of antimalarials reduced the baseline total cholesterol by 4.1 % at 3 months in 53 patients (p = 0.020) and by 0.6% at 6 months in 30 patients (p = NS), while the cessation of antimalarials increased the total cholesterol by 3.6% at 3 months in 38 patients (p = NS) and 5.4% at 6 months in 22 patients (p = NS). In 181 patients taking steroids and antimalarials, the mean total cholesterol was 11% less than for 201 patients receiving a comparable dose of steroids alone (p = 0.0023). Initiation of antimalarials on a stable dose of steroids reduced the total cholesterol by 11.3% at 3 months in 29 patients (p = 0.0002) and 9.4% at 6 months in 20 patients (p = 0.004). For patients initiating steroids, the percentage increase in cholesterol was lower in those taking antimalarials compared to patients without antimalarial therapy (p = 0.0149). CONCLUSION: Antimalarials lower total cholesterol in patients receiving steroids and may minimize steroid induced hypercholesterolemia.

Antimalarials↗
PubMedDate not supplied

Ligand-based virtual screening and in silico design of new antimalarial compounds using nonstochastic and stochastic total and atom-type quadratic maps.

Malaria has been one of the most significant public health problems for centuries. It affects many tropical and subtropical regions of the world. The increasing resistance of Plasmodium spp. to existing therapies has heightened alarms about malaria in the international health community. Nowadays, there is a pressing need for identifying and developing new drug-based antimalarial therapies. In an effort to overcome this problem, the main purpose of this study is to develop simple linear discriminant-based quantitative structure-activity relationship (QSAR) models for the classification and prediction of antimalarial activity using some of the TOMOCOMD-CARDD (TOpological MOlecular COMputer Design-Computer Aided "Rational" Drug Design) fingerprints, so as to enable computational screening from virtual combinatorial datasets. In this sense, a database of 1562 organic chemicals having great structural variability, 597 of them antimalarial agents and 965 compounds having other clinical uses, was analyzed and presented as a helpful tool, not only for theoretical chemists but also for other researchers in this area. This series of compounds was processed by a k-means cluster analysis in order to design training and predicting sets. Afterward, two linear classification functions were derived in order to discriminate between antimalarial and nonantimalarial compounds. The models (including nonstochastic and stochastic indices) correctly classify more than 93% of the compound set, in both training and external prediction datasets. They showed high Matthews' correlation coefficients, 0.889 and 0.866 for the training set and 0.855 and 0.857 for the test one. The models' predictivity was also assessed and validated by the random removal of 10% of the compounds to form a new test set, for which predictions were made using the models. The overall means of the correct classification for this process (leave group 10% full-out cross validation) using the equations with nonstochastic and stochastic atom-based quadratic fingerprints were 93.93% and 92.77%, respectively. The quadratic maps-based TOMOCOMD-CARDD approach implemented in this work was successfully compared with four of the most useful models for antimalarials selection reported to date. The developed models were then used in a simulation of a virtual search for Ras FTase (FTase = farnesyltransferase) inhibitors with antimalarial activity; 70% and 100% of the 10 inhibitors used in this virtual search were correctly classified, showing the ability of the models to identify new lead antimalarials. Finally, these two QSAR models were used in the identification of previously unknown antimalarials. In this sense, three synthetic intermediaries of quinolinic compounds were evaluated as active/inactive ones using the developed models. The synthesis and biological evaluation of these chemicals against two malaria strains, using chloroquine as a reference, was performed. An accuracy of 100% with the theoretical predictions was observed. Compound 3 showed antimalarial activity, being the first report of an arylaminomethylenemalonate having such behavior. This result opens a door to a virtual study considering a higher variability of the structural core already evaluated, as well as of other chemicals not included in this study. We conclude that the approach described here seems to be a promising QSAR tool for the molecular discovery of novel classes of antimalarial drugs, which may meet the dual challenges posed by drug-resistant parasites and the rapid progression of malaria illnesses.

Algorithms↗
PubMed2003

Metabolites of febrifugine and its synthetic analogue by mouse liver S9 and their antimalarial activity against Plasmodium malaria parasite.

Quinazolinone type alkaloids, febrifugine (1) and isofebrifugine (2), isolated from Dichroa febrifuga roots, show powerful antimalarial activity against Plasmodium falciparum. Unfortunately, their emetic effect and other undesirable side effects have precluded their clinical use for malaria. Because of their antimalarial potency, analogues were searched for, with the goal of preserving the strong antimalarial activity, while dramatically reducing side effects. We expected that compounds useful in drug development would exist in metabolites derived from 1 and Df-1 (3), the condensation product of 1 with acetone, by mouse liver S9. Feb-A and -B (4 and 5) were isolated as the major metabolites of 1. In addition to 4 and 5, feb-C and -D (6 and 7) were also purified from the metabolic mixture of 3. Compounds 4 and 5 were compounds oxidized at C-6 and C-2 of the quinazolinone ring of 1, respectively. Compounds 6 and 7, derived from 3, also bear febrifugine type structures in which the 4' '- and 6' '-positions of the piperidine ring of 1 were oxidized. In vitro antimalarial and cytotoxic tests using synthetically obtained racemic 4-6 and enantiomerically pure 7 demonstrated that 4 and 6 had antimalarial activity against P. falciparum, of similar potency to that of 1, with high selectivity. The antimalarial activity of 5 and 7, however, was dramatically decreased in the test. The in vitro antimalarial activity of analogues 22 and 43, which are stereoisomers of 4 and 6, was also evaluated, showing that 22 is active. The results suggest that basicity of both the 1- and the 1' '-nitrogen atoms of 1 is crucial in conferring powerful antimalarial activity. Racemic 4 and 6 exhibited powerful in vivo antimalarial activity against mouse malaria P. berghei, and especially, no serious side effects were observed with 4. Thus, the metabolite 4 appears to be a promising lead compound for the development of new types of antimalarial drugs.

Administration, Oral↗