Drugs online research references
Anticancer Res. 1997 Jan-Feb;17(1A):481-6.
Inhibition of the transport function of membrane proteins by some substituted phenothiazines in E. coli and multidrug resistant tumor cells.
Molnar J, Hever A, Fakla I, Fischer J, Ocsovski I, Aszalos A.
Institute of Microbiology, Albert Szent-Gyorgyi Medical University, Szeged, Hungary.
Efflux-pumps mediated by P-glycoprotein increase the level of resistance to antibiotics in bacteria and to cytostatics in tumor cells due to decreased drug accumulation, and are also involved in the operation of blood brain barrier. Different compounds are able to enhance drug retention in the cells by inhibiting the efflux-pump mechanism of multidrug resistant (mdr) cancer cells and bacteria. The effects of substituted chlorpromazines were studied on a hemolysin producing and antibiotic resistant plasmid carrying E coli, and rhodamine uptake of multidrug resistant (mdr 1 gene expressing) mouse lymphoma cells. Hemolysin transporter protein encoding plasmids were eliminated from E. coli by a representative phenothiazine namely promethazine. Minimal inhibitory concentrations of tetracyclin and promethazine were lower for plasmidless bacteria as compared to the parent, plasmid carrying strains. The antibiotic resistance plasmid was cured of the R-plasmid of E. coli JE 2571, however, the ring substituted derivatives were less effective then parent compounds. The effect of some substituted phenothiazines on P-glycoprotein efflux-pump of mouse lymphoma cells were studied. The majority of ring substituted derivatives reversed the mdr of tumor cells. The 3,7,8-trihydroxy- and 7,8-dihydroxy derivatives of chlorpromazine were effective as P-glycoprotein blockers, however, 7,8-diacetoxy-, 7,8dimetoxy-, 7-semicarbazone-, and 5-oxo-chlorpromazine derivatives had only moderate effect. A tomato lectin, specific for blood brain capillary endothelium was able to modify the activity of P-glycoprotein in tumor cells. Phenothiazine and tomato lectin had some antagonism in tumor cells. Our results suggest that the inhibition of P-glycoprotein function in murine tumor cells and inhibition of transporter protein in E. coli bacteria may depend on pi-electron superdelocalizibility and electrophile binding of the compounds to the transporter proteins. The intracellular accumulation of antibiotics or chemotherapeutics increased as a consequence of decreased drug efflux in both bacterial and tumor cell systems. The inhibition of the drug effux-pump is the same for all individual cells of the population. These results can be realized by combination chemotherapy, however, antiplasmid effect itself cannot be exploited in this respect because the resistance was reversed in a part of the population only. The similarity with mdr P-glycoprotein in tumor cells and brain capillary endothels provides a good model for molecules opening the blood brain barrier.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9066699&dopt=Abstract
Brain Res. 1997 Feb 14;748(1-2):184-8.
Chlorpromazine reduces toxicity and Ca2+ uptake induced by amyloid beta protein (25-35) in vitro.
Ueda K, Yagami T, Asakura K, Kawasaki K.
CNS Research Laboratories, Shionogi & Co. Ltd., Toyonaka, Osaka, Japan.
Amyloid beta protein (A beta), has been reported to be toxic to neurons in vitro. However, the molecular mechanism leading to neuronal death remains unknown. Here we report protective effects of phenothiazines, a class of neuroleptic agent, against A beta toxicity in primary cultures of rat cortical neurons and PC12 cells. beta(25-35), an active sequence of A beta, showed dose-dependent reduction of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide dye (MTT) reductivity, and chlorpromazine (CPZ), promethazine or trifluoperazine restored it at micromolar concentration. The significant increase in Ca2+ uptake by chronic treatment of beta(25-35) was reduced not only by nimodipine but also by CPZ. These results suggest that phenothiazines attenuate beta(25-35) toxicity possibly by reducing of Ca2+ influx through L-type Ca2+ channels.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9067460&dopt=Abstract
Dermatology. 1997;194(2):131-5.
Phototoxic properties of neuroleptic drugs.
Eberlein-Konig B, Bindl A, Przybilla B.
Dermatologische Klinik und Poliklinik der Ludwig-Maximilians-Universitat Munchen, Deutschland.
BACKGROUND: Photo-induced eruptions are well-known adverse effects of some neuroleptic drugs, particularly chlorpromazine. OBJECTIVE: By a photohemolysis test we assessed in vitro the phototoxic properties of 12 phenothiazines (chlorpromazine, dixyrazine, fluphenazine, levomepromazine, perazine, perphenazine, promazine, promethazine, prothipendyl, thioridazine, trifluoperazine, triflupromazine) and 5 thioxanthenes (chlorprothixene, clopenthixol, flupenthixol, thiothixene, zuclopenthixol). METHODS: Human erythrocytes from 3 donors were incubated with the compounds and irradiated with light sources rich in UVA or UVB, respectively. Doses were up to 100 J/cm2 UVA or up to 1,600 mJ/cm2 UVB. Photo-induced hemolysis was calculated as percentage of complete hemolysis. RESULTS: Photo-induced hemolysis >10% due to radiation rich in UVA was found with chlorpromazine (maximal median: 98%), dixyrazine (100%), fluphenazine (84%), perazine (100%), perphenazine (100%), promazine (16%), promethazine (25%), prothipendyl (96%), trifluoperazine (100%), triflupromazine (76%), chlorprothixene (100%) and thiothixene (31%). UVB-rich radiation induced hemolysis only with chlorpromazine (73%), dixyrazine (45%) and perazine (60%). CONCLUSION: Most neuroleptics are strongly phototoxic in vitro indicating a potential risk for photo-induced reactions also to occur in patients treated with these drugs.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9094460&dopt=Abstract
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