RESUMO
Looking at a new putative target for the large spectrum antiparasitic drug ivermectin, we recently showed that avermectin-derived drugs are active against promastigote and amastigote forms of Leishmania amazonensis at low micromolar concentrations. However, we then reported that at this concentration range ivermectin is also able to inhibit three important mammalian P-type ATPases so that unacceptable adverse effects could occur if this drug were used at such high doses therapeutically. The present work aimed to test the activity of ten ivermectin analogs on these rat ATPases in search of a compound with similar leishmanicidal activity but with no effect on the mammalian (host) ATPases at effective concentrations. We synthesized three new ivermectin analogs for testing on rat SERCA (1a and 1b), Na+, K+-ATPase (α1 and α2/α3 isoforms) and H+/K+-ATPase activity, along with seven analogs already characterized for their leishmanicidal activity. Our main finding is that one of the prepared derivatives, Δ²,³-ivermectin ethyl secoester 8, is equipotent to ivermectin 1 for the in vitro leishmanicidal effects but is nearly without effect on the rat ATPases, indicating that it could have a better therapeutic index in vivo and could serve as a candidate for hit-to-lead progression. This conclusion is further supported by the fact that compound 8 produced only 6% (vs 77% for ivermectin) inhibition of the human kidney enzyme at 5 µM, a concentration corresponding to the IC50 for the activity against L. amazonensis amastigotes.
Assuntos
Adenosina Trifosfatases/antagonistas & inibidores , Ivermectina/análogos & derivados , Ivermectina/farmacologia , Leishmania/efeitos dos fármacos , Tripanossomicidas/farmacologia , Adenosina Trifosfatases/metabolismo , Estruturas Animais/enzimologia , Animais , Biocatálise/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , ATPase Trocadora de Hidrogênio-Potássio/metabolismo , Humanos , Concentração Inibidora 50 , Ivermectina/efeitos adversos , Rim/enzimologia , Leishmania mexicana/efeitos dos fármacos , Masculino , Estrutura Molecular , Inibidores da Bomba de Prótons , Ratos , Ratos Wistar , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/antagonistas & inibidores , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores , ATPase Trocadora de Sódio-Potássio/metabolismo , Relação Estrutura-Atividade , Tripanossomicidas/efeitos adversosRESUMO
Deregulation of cell proliferation and apoptosis is linked to malignant cell development. Leukemia is the most frequent cancer in children, and plants are important sources for new potential anti-cancer agents. Although anti-tumoral effects have been shown for Pterodon pubescens extracts, the mechanisms are still obscure. This study describes in Pterodon pubescens a furane diterpene only reported in Pterodon polygalaeflorus, the methyl-6α-acetoxy-7ß-hydroxyvouacapan-17ß-oate, indicated by HRMS and 13C-NMR analysis, and demonstrates some mechanisms of the anti-leukemia action of its terpene subfraction SF5. SF5 induced cytotoxic and anti-proliferative effects on K562 cells. Increased sub-G1 nuclei and Annexin V+-FITC cells confirmed apoptosis of leukemic cells by treatment of these cells with SF5. Down-regulation of DNMT1 gene transcription and over-expression of Apaf-1 mRNA suggested that SF5 may be inducing apoptosis of K562 cells by epigenetic up-regulation of pro-apoptotic proteins involved in the mitochondrial intrinsic pathway.
Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Fabaceae/química , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Leucemia/genética , Extratos Vegetais/farmacologia , Proliferação de Células/efeitos dos fármacos , Diterpenos/química , Diterpenos/farmacologia , Citometria de Fluxo , Expressão Gênica/efeitos dos fármacos , Humanos , Células K562 , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
In the present study a family of macrocyclic and acyclic analogues as well as seco-analogues of avermectins were prepared from commercial Ivermectin (IVM) and their antileishmanial activity assayed against axenic promastigote and intracellular amastigote forms of Leishmania amazonensis. Contrarily to the filaricidal activity, the leishmanicidal potentiality of avermectin analogues does not appear to depend on the integrity of the non-conjugated Delta(3,4)-hexahydrobenzofuran moiety. Conjugated Delta(2,3)-IVM or its corresponding conjugated secoester show higher anti-leishmania activity than the parent compound. Surprisingly, the diglycosylated northern sub-unit exhibits the same anti-amastigote potentiality as the southern hexahydrobenzofuran. As expected for compounds derived from the widely used Ivermectin antibiotic, little toxicity has been noticed for most of the novel analogues prepared.
Assuntos
Ivermectina/análogos & derivados , Ivermectina/química , Tripanossomicidas/síntese química , Animais , Benzofuranos , Dissacarídeos , Ivermectina/síntese química , Ivermectina/farmacologia , Ivermectina/toxicidade , Leishmania mexicana/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Macrófagos/parasitologia , Camundongos , Testes de Sensibilidade Parasitária , Relação Estrutura-Atividade , Tripanossomicidas/farmacologia , Tripanossomicidas/toxicidadeRESUMO
This report describes the isolation and characterization of kalanchosine dimalate (KMC), an anti-inflammatory salt from the fresh juice of the aerial parts of Kalanchoe brasiliensis. KMC comprises the new metabolite kalanchosine (1) and malic acid (2) in a 1:2 stoichiometric ratio. Kalanchosine (1), 3,6-diamino-4,5-dihydroxyoctanedioic acid, is the first naturally occurring dimeric bis(gamma-hydroxy-beta-amino acid) and is at least partially responsible for the anti-inflammatory properties of K. brasiliensis.