Antimalarial Activity of Highly Coordinative Fused Heterocycles Targeting ß-Hematin Crystallization.

The ß-hematin formation is a unique process adopted by Plasmodium sp. to detoxify free heme and represents a validated target to design new effective antimalarials. Most of the ß-hematin inhibitors are mainly based on 4-aminoquinolines, but the parasite has developed diverse defense mechanisms against this type of chemical system. Thus, the identification of other molecular chemical entities targeting the ß-hematin formation pathway is highly needed to evade resistance mechanisms associated with 4-aminoquinolines. Herein, we showed that the highly coordinative character can be a useful tool for the rational design of antimalarial agents targeting ß-hematin crystallization. From a small library consisting of five compound families with recognized antitrypanosomatid activity and coordinative abilities, a group of tetradentate 1,4-disubstituted phthalazin-aryl/heteroarylhydrazinyl derivatives were identified as potential antimalarials. They showed a remarkable curative response against Plasmodium berghei-infected mice with a significant reduction of the parasitemia, which was well correlated with their good inhibitory activities on ß-hematin crystallization (IC50 = 5-7 µM). Their in vitro inhibitory and in vivo responses were comparable to those found for a chloroquine reference. The active compounds showed moderate in vitro toxicity against peritoneal macrophages, a low hemolysis response, and a good in silico ADME profile, identifying compound 2f as a promising antimalarial agent for further experiments. Other less coordinative fused heterocycles exhibited moderate inhibitory responses toward ß-hematin crystallization and modest efficacy against the in vivo model. The complexation ability of the ligands with iron(III) was experimentally and theoretically determined, finding, in general, a good correlation between the complexation ability of the ligand and the inhibitory activity toward ß-hematin crystallization. These findings open new perspectives toward the rational design of antimalarial ß-hematin inhibitors based on the coordinative character as an alternative to the conventional ß-hematin inhibitors.

Synthesis and in silico ADME/Tox profiling studies of heterocyclic hybrids based on chloroquine scaffolds with potential antimalarial activity.

A series of heterocyclic chloroquine hybrids containing either a ß-phenethylamine fragment or a 2-aminoindane moiety were synthesized and screened in vitro as inhibitors of ß-hematin formation and in vivo for their antimalarial activity against chloroquine-sensitive strains of Plasmodium berghei ANKA. Although these new compounds were not found to be more active than chloroquine in vivo, all new compounds significantly reduced heme crystallization with IC50 values < 1 µM. Compounds 12 and 13 were able to inhibit heme crystallization with IC50 values of 0.39 ± 0.09 and 0.48 ± 0.02 µM, respectively, and these values were comparable to that of chloroquine with an IC50 value of 0.18 ± 0.03. It was also determined that the physicochemical and pharmacokinetic properties were moderately favorable after in silico evaluation, derivatives 8 and 10 did not present hepatotoxicity, and the in vitro hemolytic activity against red blood cells was found to be low. Spectral (infrared, nuclear magnetic resonance, and elemental analysis) data for all final compounds were consistent with the proposed structures.

Synthesis of 5H-indeno[1,2-b]pyridine derivatives: Antiproliferative and antimetastatic activities against two human prostate cancer cell lines.

This study describes the direct synthesis of 2-amino-4-(phenylsubstituted)-5H-indeno[1,2-b]pyridine-3-carbonitrile derivatives 5-21, through sequential multicomponent reaction of aromatic aldehydes, malononitrile, and 1-indanone in the presence of ammonium acetate and acetic acid (catalytic). The biological study showed that compound 10 significantly impeded proliferation of the cell lines PC-3, LNCaP, and MatLyLu. The antimetastatic effects of compound 10 could be related with inhibition of MMP9 in the PC-3 and LNCaP human cell lines. On the basis of a study of the structure-activity relationship of these compounds, we propose that the presence of two methoxy groups at positions 6 and 7 of the indeno nucleus and a 4-hydroxy-3-methoxy phenyl substitution pattern at position 4 of the pyridine ring is decisive for these types of molecules to exert very good antiproliferative and antimetastatic activities.

Synthesis and antimalarial and anticancer evaluation of 7-chlorquinoline-4-thiazoleacetic derivatives containing aryl hydrazide moieties.

Twelve 7-chloroquinoline derivatives were designed and synthesized using the principle of molecular hybridization through the coupling of 2-[2-(7-chloroquinolin-4-ylthio)-4-methylthiazol-5-yl]acetic acid 1 with various benzoyl hydrazines 2a-l. The synthetic compounds were tested as antimalarials. Some of them showed an efficient in vitro activity as inhibitors of ß-hematin formation and an in vivo activity in a murine model, resulting in compounds 8 and 9 as the most active ones with IC50 values of 0.65 ± 0.09 and 0.64 ± 0.16 µM, respectively. The effects of the compounds on the cell viability, cell cycle, and apoptosis induction of A549 and MCF-7 cancer cell lines were also examined. Our data showed that compounds 6 and 12 were the most active agents, decreasing the cell viability of MCF-7 cells with IC50 values of 15.41 and 12.99 µM, respectively. None of the compounds analyzed significantly affected the viability of peripheral blood mononuclear cells. Also, significant induction of apoptosis was observed when both cancer cell lines were incubated with compounds 6 and 12. In MCF-7 cells, treatment with these compounds led to cell cycle arrest in the G0/G1 phase. The results obtained suggest that these structures may be useful in developing new therapies for malaria and cancer treatment.

Synthesis, ß-hematin inhibition studies and antimalarial evaluation of new dehydroxy isoquine derivatives against Plasmodium berghei: A promising antimalarial agent.

Many people are affected by Malaria around the world, and the parasite is developing resistance against available drugs. Currently, isoquine and N-tert-butyl isoquine are some of the most promising antimalarial candidates that have already reached Phase I and II clinical trials, respectively. Nevertheless, pharmacodynamic studies have demonstrated that isoquine is highly sensitive to form O-glucuronide metabolite, which may affect its accumulation in tissues. To avoid the O-glucuronide formation and its negative influence in the accumulation process, a series of novel five dehydroxy isoquine derivatives were designed and prepared herein as potential antimalarial agents. By a simple three-step procedure, five dehydroxy isoquines were prepared and subsequently examined on the inhibition of haemozoin formation, the main target of the 4-aminoquinolines. Four derivatives displayed significant inhibitory activities at low IC50 values from 1.66 to 1.86 µM comparable to CQ. On the basis of the results, these four compounds were subsequently tested against Plasmodium berghei ANKA model in mice, showing to be as active as CQ with significant curative responses and parasitemia suppression in mice infected. On the other hand, these four compounds showed an acceptable non specific cytotoxicity on murine peritoneal macrophague and human erythrocyte cells. Thus, the presented data indicate that the dehydroxy isoquines 4b, 4c and 4e constitute promising cost-effective leads for the development of new antiplasmodial targeted at blood-stage malaria parasites.

Synthesis, crystal structure and effect of indeno[1,2-b]indole derivatives on prostate cancer in vitro. Potential effect against MMP-9.

A highly regiospecific synthesis of a series of indenoindoles is reported, together with X-ray studies and their activity against human prostate cancer cells PC-3 and LNCaP in vitro. The most effective compound 7,7-dimethyl-5-[(3,4-dichlorophenyl)]-(4bRS,9bRS)-dihydroxy-4b,5,6,7,8,9bhexahydro-indeno[1,2-b]indole-9,10-dione 7q reduced the viability in both cell lines in a time and dose-dependent manner. Inhibitory effects were also observed on the adhesion, migration, and invasion of the prostate cancer cells as well as on clonogenic possibly by inhibition of MMP-9 activity. Molecular docking of 7q and 6k into MMP-9 human active site was also performed to determine the probable binding mode.

Synthesis and antimalarial activity of urenyl Bis-chalcone in vitro and in vivo.

Some novel derivatives of Bis-chalcone were synthesized and characterized by their physical and spectral data. All the synthesized compounds were subsequently screened for in vitro globin hydrolysis, ß-hematin formation, and murine Plasmodium berghei, using chloroquine as the reference drug. Most of the synthesized compounds exhibited mild to moderate susceptibilities toward the parasite in comparison with the standard. The most active antimalarial compound was 1,1-Bis-[(3',4'-N-(urenylphenyl)-3-(3″,4″,5″-trimethoxyphenyl)]-2-propen-1-one 5, with a percentage of inhibition of heme polymerization of 87.05 ± 0.77, and this compound increased the survival time after infection, reduce the parasitemia and delay the progression of malaria.

Chronic diseases among older people and co-resident psychological morbidity: a 10/66 Dementia Research Group population-based survey.

BACKGROUND: This is the first study to investigate the associations between chronic health conditions of older people and their impact on co-resident psychological morbidity using population-based samples in low and middle income countries (LAMICs). METHODS: Single-phase cross-sectional catchment area surveys were undertaken in urban sites in Cuba, Dominican Republic and Venezuela, and in rural and urban catchment areas in Mexico, Peru, India and China. All residents aged 65 years and over were interviewed with a co-resident key informant. Exposures were structured clinical diagnoses (10/66 and DSM-IV dementia and ICD-10 depression), self-reported diagnosis (stroke) and physical impairments. Mediating variables were dependence and disability (WHODAS 2.0), and the outcome was co-resident psychological morbidity assessed using SRQ-20. RESULTS: Poisson regression analysis was used to estimate the prevalence ratios (PRs) for the associations between health conditions and psychological morbidity in each site, and meta-analysis was used to pool the estimates. 11,988 pairs comprising a participant and a co-resident informant were included in the analysis. After meta-analysis, independent effects were noted for depression (PR2.11; 95% CI 1.82-2.45), dementia (PR 1.98; 95% CI 1.72-2.28), stroke (PR 1.42; 95% CI 1.17-1.71) and physical impairments (PR 1.17; 95% CI 1.13-1.21). The effects were partly mediated through disability and dependence. The mean population attributable fraction of total chronic conditions was 30.1%. CONCLUSION: The prevalence of co-resident psychological morbidity is higher among co-residents of older people with chronic conditions. This effect was prominent for, but not confined to, depression and dementia. Attention needs to be directed to chronic conditions.

Disturbance in hemoglobin metabolism and in vivo antimalarial activity of azole antimycotics.

Plasmodium parasites degrade host hemoglobin to obtain free amino acids, essential for protein synthesis. During this event, free toxic heme moieties crystallize spontaneously to produce a non-toxic pigment called hemozoin or ß-hematin. In this context, a group of azole antimycotics, clotrimazole (CTZ), ketoconazole (KTZ) and fluconazole (FCZ), were investigated for their abilities to inhibit ß-hematin synthesis (IßHS) and hemoglobin proteolysis (IHbP) in vitro. The ß-hematin synthesis was recorded by spectrophotometry at 405 nm and the hemoglobin proteolysis was determined by SDS-PAGE 12.5%, followed by densitometric analysis. Compounds were also assayed in vivo in a malaria murine model. CTZ and KTZ exhibited the maximal effects inhibiting both biochemical events, showing inhibition of ß-hematin synthesis (IC50 values of 12.4 ± 0.9 µM and 14.4 ± 1.4 µM respectively) and inhibition of hemoglobin proteolysis (80.1 ± 2.0% and 55.3 ± 3.6%, respectively). There is a broad correlation to the in vivo results, especially CTZ, which reduced the parasitemia (%P) of infected-mice at 4th day post-infection significantly compared to non-treated controls (12.4 ± 3.0% compared to 26.6 ± 3.7%, p = 0.014) and prolonged the survival days post-infection. The results indicated that the inhibition of the hemoglobin metabolism by the azole antimycotics could be responsible for their antimalarial effect.

Synthesis and biological evaluation of benzimidazole-5-carbohydrazide derivatives as antimalarial, cytotoxic and antitubercular agents.

A series of N'-substituted-2-(5-nitrofuran or 5-nitrothiophen-2-yl)-3H-benzo[d]imidazole-5-carbohydrazide derivatives were synthesized and investigated for their abilities to inhibit ß-hematin formation, hemoglobin hydrolysis and in vivo for their antimalarial efficacy in rodent Plasmodium berghei. Selected analogues were screened for their antitubercular activity against sensitive MTB H(37)Rv and multidrug-resistant MDR-MTB strains, and cytotoxic activity against a panel of human tumor cell lines and two nontumourogenic cell lines. Compounds 3a, 5a, f, 6g were the most promising as inhibitors of ß-hematin formation, however, their effect as inhibitors of hemoglobin hydrolysis were marginal. The most active compounds to emerge from the in vitro and in vivo murine studies were 3a and 6i, suggesting an antimalarial activity via inhibition of ß-hematin formation and are as efficient as chloroquine. The cytotoxic and antitubercular activities of the present compounds were not comparable with those of the standard drugs employed. But, however, compound 5b showed better antitubercular activity compared to rifampin against multidrug-resistant MDR-MTB strains. Compounds 3a, 6i and 5b showed a good safety index.

Disturbance in hemoglobin metabolism and in vivo antimalarial activity of azole antimycotics / Alteración en el metabolismo de la hemoglobina y actividad antimalárica in vivo de azoles antimicóticos

Plasmodium parasites degrade host hemoglobin to obtain free amino acids, essential for protein synthesis. During this event, free toxic heme moieties crystallize spontaneously to produce a non-toxic pigment called hemozoin or ß-hematin. In this context, a group of azole antimycotics, clotrimazole (CTZ), ketoconazole (KTZ) and fluconazole (FCZ), were investigated for their abilities to inhibit ß-hematin synthesis (IßHS) and hemoglobin proteolysis (IHbP) in vitro. The ß-hematin synthesis was recorded by spectrophotometry at 405 nm and the hemoglobin proteolysis was determined by SDS-PAGE 12.5 percent, followed by densitometric analysis. Compounds were also assayed in vivo in a malaria murine model. CTZ and KTZ exhibited the maximal effects inhibiting both biochemical events, showing inhibition of β-hematin synthesis (IC50 values of 12.4 ± 0.9 µM and 14.4 ± 1.4 µM respectively) and inhibition of hemoglobin proteolysis (80.1 ± 2.0 percent and 55.3 ± 3.6 percent, respectively). There is a broad correlation to the in vivo results, especially CTZ, which reduced the parasitemia ( percentP) of infected-mice at 4th day post-infection significantly compared to non-treated controls (12.4 ± 3.0 percent compared to 26.6 ± 3.7 percent, p = 0.014) and prolonged the survival days post-infection. The results indicated that the inhibition of the hemoglobin metabolism by the azole antimycotics could be responsible for their antimalarial effect.

Los parásitos del género Plasmodium degradan la hemoglobina hospedera obteniendo aminoácidos libres para su síntesis proteica. Durante este evento, unidades de hemo libre tóxicas cristalizan espontáneamente formando un pigmento no tóxico denominado ß-hematina. En este trabajo, se investigó la capacidad de un grupo de azoles antimicóticos: clotrimazol (CTZ), ketoconazol (KTZ) y fluconazol (FCZ), en inhibir la síntesis de ß-hematina y la proteólisis de la globina. La síntesis de ß-hematina se registro por espectrofotometría a 405 nm y la proteólisis de la hemoglobina se determino por SDS-PAGE 15 por ciento seguido por análisis densitométrico de las bandas de hemoglobina intactas. Los compuestos fueron también ensayados in vivo en un modelo de malaria murina. CTZ y KTZ inhibieron la síntesis de ß-hematina con CI50 entre 10 y 15 µM y bloquearon la proteólisis de la hemoglobina (80.01 ± 2.04 por ciento y 55.33 ± 3.57 por ciento, respectivamente). En relación directa con los resultados encontrados in vitro, el CTZ redujo la parasitemia de ratones infectados en forma significativa, así como prolongó lo días de sobrevivencia post-infección en comparación con animales controles no tratados. Se sugiere así que la inhibición del metabolismo de la hemoglobina por los antimicóticos azólicos pudiera ser el mecanismo responsable de su actividad antimalárica.

Tenossinovites De Quervain: uma nova proposta no tratamento cirúrgico / De Quervain’s tenosynovitis: a new proposal of surgical treatment

Introdução: A tenossinovite estenosante De Quervain caracteriza-se por ser a inflamação da bainha do abdutor longo e extensor curto do polegar, no primeiro compartimento dorsal do punho, acometendo mais frequentemente as mulheres na faixa etária entre 30 e 50 anos. Essa doença está associada principalmente a trauma crônico secundário e sobrecarga das atividades diárias das mãos e punho, podendo também ser causada por outros fatores, mas em muitos casos não há uma causa bem definida. Objetivo: O objetivo deste trabalho é apresentar nossa casuística de tenossinovite de De Quervain no Ambulatório de Cirurgia da Mão, os diferentes tratamentos e uma nova proposta cirúrgica utilizando um retalho fáscio-gorduroso de vizinhança. Resultados: Com a técnica proposta foram obtidos resultados satisfatórios, diminuindo as recidivas, com boa recuperação funcional e rápido retorno dos pacientes às atividades cotidianas.

Introduction: De Quervain’s stenosing tenosynovitis it is characterized by being the inflammation of the hem of the long and extending abductor short of the thumb, in the 1st number compartment of the fist, more frequently attacking the women in the age group between 30 and 50 years. That pathology is associated mainly to secondary chronic trauma and overload of the daily activities of the hands and fist, could also be caused by other factors, but in many cases no there is a very defined cause. Results: All the patients had a faster and satisfactory evolution with an amazing come back to their quotidian activities.

Modification of oxidative status in Plasmodium berghei-infected erythrocytes by E-2-chloro-8-methyl-3-[(4'-methoxy-1'-indanoyl)-2'-methyliden]-quinoline compared to chloroquine.

E-2-chloro-8-methyl-3-[(4'-methoxy-1'-indanoyl)-2'-methyliden]-quinoline (IQ) is a new quinoline derivative which has been reported as a haemoglobin degradation and ss-haematin formation inhibitor. The haemoglobin proteolysis induced by Plasmodium parasites represents a source of amino acids and haeme, leading to oxidative stress in infected cells. In this paper, we evaluated oxidative status in Plasmodium berghei-infected erythrocytes in the presence of IQ using chloroquine (CQ) as a control. After haemolysis, superoxide dismutase (SOD), catalase, glutathione cycle and NADPH + H+-dependent dehydrogenase enzyme activities were investigated. Lipid peroxidation was also assayed to evaluate lipid damage. The results showed that the overall activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were significantly diminished by IQ (by 53.5% and 100%, respectively). Glutathione peroxidase activity was also lowered (31%) in conjunction with a higher GSSG/GSH ratio. As a compensatory response, overall SOD activity increased and lipid peroxidation decreased, protecting the cells from the haemolysis caused by the infection. CQ shared most of the effects showed by IQ; however it was able to inhibit the activity of isocitrate dehydrogenase and glutathione-S-transferase. In conclusion, IQ could be a candidate for further studies in malaria research interfering with the oxidative status in Plasmodium berghei infection.

Modification of oxidative status in Plasmodium berghei-infected erythrocytes by E-2-chloro-8-methyl-3-[(4'-methoxy-1'-indanoyl)-2'-methyliden]-quinoline compared to chloroquine

E-2-chloro-8-methyl-3-[(4'-methoxy-1'-indanoyl)-2'-methyliden]-quinoline (IQ) is a new quinoline derivative which has been reported as a haemoglobin degradation and ß-haematin formation inhibitor. The haemoglobin proteolysis induced by Plasmodium parasites represents a source of amino acids and haeme, leading to oxidative stress in infected cells. In this paper, we evaluated oxidative status in Plasmodium berghei-infected erythrocytes in the presence of IQ using chloroquine (CQ) as a control. After haemolysis, superoxide dismutase (SOD), catalase, glutathione cycle and NADPH + H+-dependent dehydrogenase enzyme activities were investigated. Lipid peroxidation was also assayed to evaluate lipid damage. The results showed that the overall activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were significantly diminished by IQ (by 53.5 percent and 100 percent, respectively). Glutathione peroxidase activity was also lowered (31 percent) in conjunction with a higher GSSG/GSH ratio. As a compensatory response, overall SOD activity increased and lipid peroxidation decreased, protecting the cells from the haemolysis caused by the infection. CQ shared most of the effects showed by IQ; however it was able to inhibit the activity of isocitrate dehydrogenase and glutathione-S-transferase. In conclusion, IQ could be a candidate for further studies in malaria research interfering with the oxidative status in Plasmodium berghei infection.

Synthesis and antimalarial activities of optically active labdane-type diterpenes.

An efficient method for the synthesis of optically active labdane-type diterpenes from (+)-manool 8 is described. We prepared the natural labdane-type diterpene 5 via key intermediate peroxide 9, and synthetic hydroxybutenolides 6 and 7 via a furan photosensitised oxygenation reaction of labdafuran (14). Compounds 5, 6, 7 and 9 were evaluated as inhibitors of the beta-haematin formation and globin proteolysis, and then were assayed in a malarial murine model. Compound 9 was the most promising compound, showing a positive correlation between in vitro and in vivo activities.

Effect of dequalinium on the oxidative stress in Plasmodium berghei-infected erythrocytes.

The bisquinoline drug dequalinium (DQ) has demonstrated remarkable activity against some infection diseases, including malaria. Oxidative stress represents a biochemical target for potential antimalarials. In this work, we have tested the ability of this compound to modify the oxidative status in Plasmodium berghei-infected erythrocytes. After hemolysis, activities of superoxide dismutase (SOD), catalase (CAT), glutathione cycle, and dehydrogenase enzymes were investigated. The activity of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGLD) in infected cells were diminished by this drug compared to controls (300% and 80% approximately, respectively), while glutathione peroxidase (GPx), glutathione transferase (GST), and glutathione levels were also lowered. As a compensatory response, we could appreciate an increase of SOD activity (20% approximately) in infected cells treated with DQ; however, catalase was not affected by the compound. Lipid peroxidation was also decreased by this drug, protecting the cells from the hemolysis caused by the infection. In conclusion, oxidative stress represents a biochemical event which is modulated by DQ, interfering with the antioxidant regular activities in P. berghei infection.

Synthesis and antimalarial activity of pyrazolo and pyrimido benzothiazine dioxide derivatives.

A series of phenylsubstituted pyrazolo and pyrimido benzothiazine dioxide derivatives were synthesized and investigated for their abilities to inhibit beta-hematin formation, hemoglobin hydrolysis and in vivo for their antimalarial efficacy in rodent Plasmodium berghei. Compounds 3-amino-7-chloro-9-(2'-methylphenyl)-1,9-dihydro-pyrazolo-[4,3-b]benzothiazine 4,4-dioxide 2b and 2,4-diamino-8-chloro-10H-phenyl-pyrimido-[5,4-b]benzothiazine 5,5-dioxide 3a were the most promising as inhibitors of hemoglobin hydrolysis, however, their effect as inhibitors of beta-hematin formation was marginal, except for compound 3-amino-7-chloro-9-(3'-chlorophenyl)-1,9dihydro-pyrazolo-[4,3-b]benzothiazine 4,4-dioxide 2g. The most active compound to emerge from the in vitro and in vivo murine studies was 2b, suggesting an antimalarial activity via inhibition of hemoglobin hydrolysis, however, not as efficient as chloroquine.

Synthesis of chlorovinyl sulfones as structural analogs of chalcones and their antiplasmodial activities.

The synthesis of novel chlorovinyl sulfone-like chalcone derivatives and their antimalarial activity against cultured Plasmodium falciparum parasites, hemozoin formation, hemoglobin hydrolysis and murine malaria model are described. Compounds were prepared via Claisen-Schmidt condensation from available chloromethylphenyl sulfones with substituted aldehydes. Antiplasmodial IC(50) activity of these compounds ranged between 0.025 and 10 microM, those that blocked P. falciparum development at low micro molar concentrations were tested in a murine Plasmodium berghei model, and these compounds delayed the progression of malaria but did not eradicate infections. Much effort and attention are needed for discovery and development of new and less toxic antimalarial drugs.

Carcinoma metastático de mama para couro cabeludo / Breast carcinoma metastatic to the scalp

Apesar de as neoplasias metastáticas para a cabeça e pescoço serem raras quando comparadas com as neoplasias primárias, o carcinoma metastático de mama tem sido descrito em diversos sítios da cabeça e pescoço. Este é um caso de uma paciente com adenocarcinoma de mama que evoluiu com metástase para couro cabeludo.

Although the metastasis to head and neck are rare when compared with primary neoplasms, metastatic carcinoma from breast has been described in many sites of head and neck. This is a case of a patient with adenocarcinoma of breast that developed metastasis to the scalp.

Synthesis, antimalarial activity, structure-activity relationship analysis of thieno-[3,2-b]benzothiazine S,S-dioxide analogs.

An improved procedure for the synthesis of 3-amino-9-arylsubstituted-thieno[3,2-b]benzothiazine S,S-dioxide 2-decarboxylated is reported. Thieno-[3,2-b]benzothiazine S,S-dioxide derivatives were investigated for their abilities to inhibit beta-hematin formation, hemoglobin hydrolysis and in vivo for their efficacy in rodent Plasmodium berghei. Compounds 5j-o were the most promising as inhibitors of hemoglobin hydrolysis, however, the compounds are not as efficient as chloroquine. A structure-activity relationship (SAR) study was carried out in this series. Our results allow us to determine the minimal structural requirements to produce the biological response.