Sulfur-interrupted 8-amino side chain analogues of 4-methyl-5-[m-(trifluoromethyl)phenoxy]primaquine as potential antimalarial agents

Two isomeric sulfur-interrupted 8-amino side chain analogues of 4-methyl-5-[m-(trifluoromethyl)phenoxy]primaquine (2) were prepared and tested for antimalarial activity. The compounds were evaluated for blood schizonticidal activity against Plasmodium berghei in mice and radical curative activity against Plasmodium cynomolgi in rhesus monkeys. In addition, they were evaluated for causal prophylactic activity against Plasmodium berghei yoelii in mice. Both compounds were more active and less toxic than primaquine in the P. berghei screen. One of the compounds showed radical curative activity similar to primaquine but was less active than 2. One of the compounds was active at 160 mg/kg in the P. berghei yoelii screen; the other was not active.     

4,5-Disubstituted primaquine analogues as potential antimalarial agents

Three 4,5-disubstituted primaquine analogues were synthesized and evaluated for radical curative activity against Plasmodium cynomolgi in rhesus monkeys. One of the compounds showed moderate activity; however, none of the three compounds were as active as the lead compounds 5-methoxy-4-methylprimaquine and 4-(methoxy-methyl)-5-[m-(trifluoromethyl)phenoxy]primaquine.     

Peptide derivatives of primaquine as potential antimalarial agents

Three peptide derivatives of primaquine were synthesized. The compounds were tested for radical curative antimalarial activity against Plasmodium cynomolgi in rhesus monkeys and blood schizonticidal antimalarial activity against Plasmodium berghei in mice. All three peptide derivatives showed activity against P. cynomolgi greater than that expected for the primaquine content of each prodrug. The toxicity of one of the peptide derivatives was less than that of primaquine in mice.     

Synthesis of 2-benzyloxy and 2-benzylthio analogues of primaquine as potential antimalarials.

A series of 2-benzyloxy and 2-benzylthio analogues of primaquine has been synthesized and evaluated against Plasmodium berghei in the mouse and Plasmodium cynomolgi in the rhesus monkey. 8-Aminoquinoline toxicity, as measured in the Rane mouse screen, was reduced, and these compounds showed significant blood schizonticidal antimalarial activity in mice. In monkeys, significant tissue-schizonticidal activity was observed.     

伯氨喹类似物的合成及其抗鼠疟活性

报道10个4-甲基-5-取代苯氧基-6-甲氧基-8-[(1-乙基-4-氨基)丁氨基]喹啉(10a～j)的合成及其抗疟活性。鼠疟初筛结果表明,有3个化合物对鼠疟 Plasmodium yoeli 的病因性预防作用较强,其中10c的活性可达伯氨喹的4～8倍;同时,10c也有较强的杀血液裂殖体活性,对鼠疟 Plasmodium berghei 的抑制性治疗作用以ED₅₀和ED₉₀计算,为伯氨喹的2倍,其余多数化合物活性与伯氨喹相当,少数不如伯氨喹。     

Primaquine analogues: derivatives of 4-amino-2-methoxyacridine.

Based on the antimalarial activity of primaquine (1a) and its 4-methyl analogue 1b, 4-aminoacridinyl analogues, 4-[(4-amino-1-methylbutyl)amino]-2-methoxyacridine (2a) and 4-[(4-amino-1-methylbutyl)amino]-2-methoxy-9-methylacridine (2b), were prepared and evaluated as potential tissue schizonticidal agents. These compounds were found to be substantially less active than primaquine against Plasmodium cynomolgi in the rhesus monkey. The antileishmanial activity in hamsters of 4-[[6-(diethylamino)hexyl]amino]-2-methoxy-9-methylacridine (2d) was found to be considerably less than that of 8-[[6-(diethylamino)hexyl]amino]-6-methoxy-4-methylquinoline (1c).     

Antimalarials. 16. Synthesis of 2-substituted analogues of 8-[(4-amino-1-methylbutyl)amino]-6-methoxy-4-methyl-5-[3- (trifluoromethyl)phenoxy]quinoline as candidate antimalarials

A series of 2-substituted analogues of the exceptional drug 8-[(4-amino-1-methylbutyl)amino]-6-methoxy-4-methyl-5-[3- (trifluoromethyl)phenoxy]quinoline (I) were prepared and evaluated for both suppressive and prophylactic antimalarial activity. The preparation of analogues of compound I was of interest due to the high level of both blood and tissue schizonticidal activity demonstrated by this compound. One analogue, 8a, was found to be both more active and less toxic than the parent compound I. In addition, three analogues of example 8a were prepared. Although two of the three analogues showed significant antimalarial activity, both were inferior to compound 8a.     

Synthesis of some 4-substituted 8-amino-6-methoxyquinolines as potential antimalarials.

The 4-vinyl, 4-ethyl, and three 4-[beta-(arylthio)ethyl] derivatives of primaquine and other 8-aminoquinoline antimalarial agents were prepared for antimalarial evaluation. 8-[(4'-Amino-1'-methylbutyl)amino]-4-ethyl-6-methoxyquinoline (4-ethylprimaquine), which showed activity approximately equal to that of primaquine against Plasmodia cynomolgi in Rhesus monkey, was the most active of the compounds tested. 4-Ethylprimaquine was also less toxic than primaquine, as measured in the Rane mouse screen.     

Synthesis of 2,4-disubstituted 6-methoxy-8-aminoquinoline analogues as potential antiparasitics

A series of 2,4-disubstituted 8-aminoquinoline analogues were synthesized and evaluated against Plasmodium berghei in mice and Leishmania donovani in hamsters. 8-[[6-(Diethylamino)hexyl]amino]-2-ethyl-6-methoxy-4-methylquinoline (8a) possessed significant activity against L. donovani. 2-Ethyl-4-methylprimaquine (7a) was evaluated against Plasmodium cynomolgi in rhesus monkey and found to have activity equal to that of primaquine.     

Synthesis of 4-alkyl and 4-(beta-alkylvinyl) derivatives of primaquine as potential antimalarials.

4(beta-Alkylvinyl)-6-methoxy-8-nitroquinolines (6) were prepared from 6-methoxy-8-nitroquinoline-4-carboxaldehyde (5) via a Wittig reaction. Stannous chloride reduction of 6 gave 4-(beta-alkylvinyl)-8-amino-6-methoxyquinolines (8), whereas catalytic reduction of 6 using Raney nickel catalyst gave 4-alkyl-8-amino-6-methoxyquinolines (7). Alkylation of 7 and 8 with 4-iodo-1-phthalimidopentane, followed by removal of the phthaloyl-protecting group with hydrazine, gave 4-alkyl and 4-(beta-alkylvinyl) derivatives of primiquine, respectively. These compounds were evaluated for antimalarial activity against P. berghei and P. berghei yoelii in mice and against P. cynomolgi in rhesus monkeys. Several of the compounds were active in the P. bergheii yoelii screen. None of the compounds showed significant activity in the other two screens.     

抗疟药的研究 Ⅺ.4-甲基-5取代苯氧基伯喹的合成及其抗疟作用

本文报道了6个4-甲基-5取代苯氧基-6-甲氧基-8-(1-甲基-4-氨基丁氨基)喹啉(Ⅲ)的合成。除Ⅲ₃外,所有化合物对鼠疟P.berghei的抑制性治疗作用和对鼠疟P.yoelii的病因性预防作用均优干伯喹,其中以Ⅲ₁最强。Ⅲ₁口服治疗作用的SD₅₀和SD₉₀分别为0.65 mg/kg和1.60 mg/kg,口服预防作用的最小有效剂量(MED)和最小完全有效剂量(MFAD)分别为2.5mg/kg和5.0 mg/kg。对这类化合物的根治作用和毒性试验正在进行中。     

Antimalarials. 10. Synthesis of 4-substituted primaquine analogues as candidate antimalarials.

Primaquine (I) has been extensively used in combination with other drugs in the radical cure of relapsing malaria as well as for prophylaxis or the interruption of transmission. This, coupled with the activity data reported for 4-methylprimaquine (II), has led to the synthesis of a series of 14 4-substituted analogues of I. In addition, three side-chain analogues of II were prepared. The compounds were tested for suppressive antimalarial activity against Plasmodium berghei in the Rane mouse screen and for radical curative activity against Plasmodium cynomolgi in the rhesus monkey. Four of the 17 compounds prepared (1a, 9c, 15, and 17) exhibited activity in at least one of the test systems.     

抗疟新药咯萘啶及其类似物的合成

作者等根据一些抗疟药的构效关系,合成了一种新化合物2-甲氧基-7-氯-10-[3′,5′-双(四氢吡咯次甲基)一4′-羟基苯胺基]苯骈[b]1,5-萘啶(Ⅰ),代号7351,定名咯萘啶。它对红内期裂殖体的作用显著,毒性低。之后,又合成了它的类似物Ⅱ,这些类似物大多数对鼠疟Plasmodiumberghei的红内期均具有不同程度的作用,其中Ⅱ_1～6,9.10等的作用与Ⅰ相当。对子孢子诱发感染的鼠疟P.yoelii的作用以化合物Ⅰ、Ⅱ_{1,3,5,6,9,10,12,15}等为最强,优于伯喹对照组。值得注意的是,这类化合物既对血液转种的鼠疟P.berghei具有显著的作用,同时对子孢子感染的鼠疟P.yoelii也具有显著的作用。     

Antimalarials. 11. Synthesis of 3- and 5-aminoquinolines as potential antimalarials.

A series of 3-quinolinediamines (1g, 2c, and 3e) structurally related to primaquine and 4-methylprimaquine have been prepared and tested for antimalarial activity against Plasmodium berghei in mice and antileishmanial activity against Leishmania donovani in the hamster. All were inactive. In addition, three 5-quinolinediamines (4b, 5, and 6) were prepared. All were inactive against Leishmania donovani in hamsters. One of the examples, 6, was curative against Plasmodium cynmolgi in the rhesus monkey.     

瑞香素的抗疟作用及其高效液相色谱分析方法

目的研究中药瑞香素在体外和体内的杀疟原虫裂殖体作用、抗红细胞外期疟原虫作用及其高效液相色谱(HPLC)分析方法。方法在恶性疟原虫FCC1株常规体外培养中测试瑞香素杀裂殖体活性,并按“4d抑制试验”在感染伯氏疟原虫ANKA株的小鼠中测定不同剂量瑞香素的体内抗疟活性。于癌症研究所(ICR)小鼠腹腔注射约氏疟原虫子孢子后0.5h灌胃给药,连续4d。不同剂量的瑞香素及瑞香素与伯氨喹(PQ)配伍用药的抗疟作用分别以第8天ICR小鼠阴性率及第12天或第13天ICR小鼠每千个红细胞被原虫感染数评价。再以高效液相色谱及质谱的方法分析鉴定瑞香素及其两个结构类似物:香豆素,7-羟基香豆素。结果体外试验中瑞香素在1~10滋mol/L剂量范围内有明显杀裂殖体作用,而体内试验中按第5天减虫率与感染鼠在30d内的平均生存天数评价,50或100mg·kg-1·d-1×4d瑞香素灌胃以及10、50或100mg·kg-1·d-1×4d瑞香素腹腔注射给药在伯氏疟原虫ANKA株感染鼠中的抗疟作用与10mg·kg-1·d-1×4d氯喹(CQ)灌胃的疗效相似。瑞香素的剂量范围为每天10～100mg/kg,连服4d,第8天原虫阴性小鼠数及第12天红细胞被感染程度与对照组相比差异均无显著性;瑞香素每天50mg/kg和每天PQ5mg/kg配伍组的第8天小鼠阴性率与PQ每天10mg/kg组相当。运用特定的高效液相色     

戊喹及其异构体环取代衍生物的合成和抗疟活性

合成了戊喹及其异构体 Win-5037以及它们的环取代衍生物14个。初步药理试验表明,大多数化合物对感染伯氏疟原虫的鼠的抑制性治疗显示中等活性,但除4-甲基衍生物(10a,b)外均低于伯氨喹。对鼠约氏疟原虫感染的病因性预防作用除4-甲基戊喹(10b),5-间氟苯氧基-2-苯氧基-Win-5037(9)外均不及伯氨喹。在猴疟根治试验中仅2-苯氧基-Win-5037(5a)的作用与伯氨喹相当。     

根治间日疟化合物:2,5-双取代苯氧基伯喹衍生物的合成

作者等按Mislow等法先合成6-甲氧基-8-硝基-N-甲基-1 H-喹啉-2-酮后,在喹啉环2位及5位分别引入氯和溴,然后在2、5两位代入相同的取代苯氧基,再经还原、缩合、氯解等反应,最后合成了一类新的2,5-双取代苯氧基伯喹衍生物。化合物1,13和19对子孢子感染的鼠疟P.yoelii有效。     

2-甲基-5-取代苯氧基伯氨喹的合成及其抗疟活性

为寻找高效低毒的间日疟根治药,合成了7个2-甲基-5-取代苯氧基伯氨喹Ⅱ_1～7,以与强效的4-甲基取代类似物比较,探索构效关系。初步生物评价结果表明,化合物Ⅱ_1～7对鼠疟Plasmodium berghei的抑制性治疗作用及对鼠疟P.yoelii的病因性预防作用均明显弱于其4-甲基对应物,略低于伯氨喹。     

Antimalarial activity of novel 5-aryl-8-aminoquinoline derivatives

In an attempt to separate the antimalarial activity of tafenoquine (3) from its hemolytic side effects in glucose-6-phosphate dehydrogenase (G6PD) deficiency patients, a series of 5-aryl-8-aminoquinoline derivatives was prepared and assessed for antimalarial activities. The new compounds were found metabolically stable in human and mouse microsomal preparations, with t(1/2) > 60 min, and were equal to or more potent than primaquine (2) and 3 against Plasmodium falciparum cell growth. The new agents were more active against the chloroquine (CQ) resistant clone than to the CQ-sensitive clone. Analogues with electron donating groups showed better activity than those with electron withdrawing substituents. Compounds 4bc, 4bd, and 4be showed comparable therapeutic index (TI) to that of 2 and 3, with TI ranging from 5 to 8 based on IC(50) data. The new compounds showed no significant causal prophylactic activity in mice infected with Plasmodium berghei sporozoites, but are substantially less toxic than 2 and 3 in mouse tests.     

Discovery of a bulky 2-tert-butyl group containing primaquine analogue that exhibits potent blood-schizontocidal antimalarial activities and complete elimination of methemoglobin toxicity

To eliminate an unwarranted metabolic pathway of the quinoline ring, a set of two compounds, where C-2 position of the antimalarial drug primaquine is blocked by metabolically stable bulky alkyl group are synthesized. Compound 2 [R = C(CH(3))(3)] of the series has produced excellent antimalarial efficacy against P. berghei and highly virulent multidrug-resistant P. yoelii nigeriensis strain in vivo. Compound 2 was also evaluated for methemoglobin (MetHb) toxicity. This study describes the discovery of a highly potent blood-schizontocidal antimalarial analogue 2, completely devoid of MetHb toxicity.