Vascular activity of two silicon compounds, ALIS 409 and ALIS 421, novel multidrug-resistance reverting agents in cancer cells.
ABSTRACT The aim of this study was to investigate the effects of two novel multidrug-resistance reverting agents, ALIS 409 [1,3-dimethyl-1,3-p-fluorophenyl-1,3(3-morfolinopropyl)-1,3-disiloxan dihydrochloride] and ALIS 421 [1,3-dimethyl-1,3-(4-fluorophenyl)-1,3[3(4-buthyl)-(1-piperazinyl)-propyl]-1,3-disiloxan tetrahydrochloride], on vascular functions in vitro.
A comparison of their mechanical and electrophysiological actions in rat aorta rings and single rat tail artery myocytes, respectively, was performed.
In endothelium-denuded rat aorta rings, ALIS 409 and ALIS 421 antagonized 60 mM K(+)-induced contraction in a concentration-dependent manner with IC(50) values of 52.2 and 15.5 microM, respectively. ALIS 409 and ALIS 421 inhibited L-type Ca(2+) current recorded in artery myocytes in a concentration-dependent manner with IC(50) values of 6.4 and 5.6 microM, respectively. In rat aorta, ALIS 409 and ALIS 421 antagonized the sustained tonic contraction induced by phenylephrine with IC(50) values of 58.0 and 13.7 microM (endothelium-denuded rings) and of 73.9 and 31.9 microM (endothelium-intact rings), respectively. In endothelium-denuded rings, ryanodine reduced significantly the response to phenylephrine in the absence of extracellular Ca(2+) whereas nifedipine, ALIS 409 or ALIS 421 did not affect it. Phenylephrine-stimulated influx of extracellular Ca(2+) was markedly reduced when tissues were pretreated with ALIS 409, ALIS 421 or nifedipine, and stimulated when they were pretreated with ryanodine. Application of ALIS 409 (up to 100 microM) to intact rat aorta rings failed to induce mechanical responses.
Our results provide functional evidence that the myorelaxing effect elicited either by ALIS 409 or by ALIS 421 involved mainly the direct blockade of extracellular Ca(2+) influx. This effect, however, took place at concentrations much higher than those effective as modifiers of multidrug resistance in cancer cells.
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ABSTRACT: Multidrug-resistant and extensively drug-resistant tuberculosis (MDR/XDR-TB) are problematic to manage, especially in patients with acquired immune deficiency syndrome (AIDS). There is therefore a dire need for effective anti-MDR/XDR-TB agents. We have previously shown that agents that inhibit the efflux pumps of MDR bacteria and cancer cells also enhance killing of intracellular mycobacteria, possibly by increasing the availability of K(+) and Ca(2+) needed for the activation of lysosomal enzymes of the phagolysosomal unit. In this study, the newly synthesised and recently patented SILA 409 and 421 were tested for in vitro and ex vivo activity against XDR-TB. The minimum inhibitory concentration (MIC) of SILA compounds was determined by the BACTEC 460 TB system. The effect of each compound on the killing activity of human macrophages infected with XDR-TB was determined by exposing the macrophage that had phagocytosed the bacterium to the compounds and assessing the killing activity by colony-forming unit counting. Amongst the two compounds tested, SILA 421 was shown to have in vitro activity against XDR-TB (MIC<3.5mg/L) and to transform non-killing macrophages into effective killers of phagocytosed bacteria, without any cytotoxic activity. Because SILA 421 revealed good in vitro and ex vivo activities and is devoid of any cytotoxic activity, it is a potential candidate as an anti-MDR/XDR-TB drug.International journal of antimicrobial agents 05/2009; 33(5):479-82. DOI:10.1016/j.ijantimicag.2008.10.028 · 4.26 Impact Factor
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ABSTRACT: Bacteria and cancer cells frequently increase their resistance to chemotherapeutics as a consequence of therapy. Whenever studied, refractory response to chemotherapy is due to the over-expression of efflux pumps that render the bacterium or cancer cell resistant not only to the agent used for therapy, but to many, if not all other agents as well. Control over the efflux pump that bestows multidrug resistance has been a goal of research during the past decade. As a consequence of this search for inhibitors of efflux pumps, it has been noted that many agents which affect the efflux pump system of bacteria also have similar activity against efflux pumps of drug-resistant cancer cells. This review aims to identify such agents.Anticancer research 07/2012; 32(7):2947-57. · 1.87 Impact Factor
Article: Metalloid compounds as drugs[Show abstract] [Hide abstract]
ABSTRACT: The six elements commonly known as metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Metalloid containing compounds have been used as antiprotozoal drugs. Boron-based drugs, the benzoxaboroles have been exploited as potential treatments for neglected tropical diseases. Arsenic has been used as a medicinal agent and arsphenamine was the main drug used to treat syphilis. Arsenic trioxide has been approved for the treatment of acute promyelocytic leukemia. Pentavalent antimonials have been the recommended drug for visceral leishmaniasis and cutaneous leishmaniasis. Tellurium (IV) compounds may have important roles in thiol redox biological activity in the human body, and ammonium trichloro (dioxoethylene-O, O'-)tellurate (AS101) may be a promising agent for the treatment of Parkinson's disease. Organosilicon compounds have been shown to be effective in vitro multidrug-resistance reverting agents.Research in pharmaceutical sciences 03/2013; 8(3):145-158.