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Results for “Camptothecin”

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At least 19 recordsLinked to original sources

PubMed1977

Effect of camptothecin and adriamycin on bleomycin-induced tritiated thymidine triphosphate incorporation in a rat nuclear system.

We investigated the effect of camptothecin and adriamycin on [3H]TTP incorporation and bleomycin-stimulated [3H]TTP incorporation in host liver and hepatoma nuclei of rats. Camptothecin neither stimulated nor inhibited incorporation in the regular nuclear incorporating system. Bleomycin stimulated incorporation to a much greater extent in host liver nuclei and slow-growing hepatomas than it did in the fast-growing hepatoma 7777. Addition of camptothecin to bleomycin stimulated incorporation of [3H]TTP even further. This camptothecin stimulation was slightly greater in hepatoma nuclei than it was in host liver nuclei. Adriamycin inhibited [3H]TTP incorporation in the regular system as well as the bleomycin-induced incorporation. Hepatoma nuclei were more sensitive to this inhibition than were host liver nuclei. Sucrose density gradients indicated that camptothecin caused DNA strand scissions in addition to those produced by bleomycin. Camptothecin alone produced some single-strand but no double-strand scissions. The action of bleomycin was dependent on sulfhydryl-reducing agents. Camptothecin could partially substitute for this requirement. Adriamycin did not produce DNA breaks as determined by neutral or alkaline sucrose density gradients. Despite complete inhibition of bleomycin-induced [3H]TTP incorporation, adriamycin did not prevent bleomycin-induced DNA breaks. The inhibitory effect of adriamycin might have been on the repair system.

Animals↗

PubMed1977

Protein content and enzyme levels of cultured chick embryo cells treated with camptothecin and actinomycin D.

The alkaloid camptothecin uncouples the growth and adivision of chick embryo cells. At a moderate dose (0.5 microgram/ml) it inhibits the incorporation of thymidine but not of uridine and leucine and the cell protein content increases and reaches twice that of control after 4 days of treatment. Twelve hours after addition of the drug, the activities per cell of the mitochondrial enzymes poly A hydrolase (EC 3.1. 4.21), cytochrome c oxidase (EC 1.9.3.1), and succinate dehydrogenase (EC 1.3.99.1) are greater than that of the control and keep increasing for at least 96 H. The increase in the activities of the mitochondrial enzymes precede that of NADPH-cytochrome c reductase (EC 1.6.2.4) and cytidine triphosphatase (EC 3.6.1.15), which are microsomal and plasma membranes enzymes respectively. Actinomycin D (0.01 microgram/ml) also inhibits the multiplication of the chick cells and the synthesis of DNA. The protein content of the actinomycin D treated cells decreases to 70% of the control by day 2. Nevertheless, the activities of the mitochondrial enzymes increase over that of the control but to a smaller extent that with camptothecin. The activities of the enzymes of the other organelles are not stimulated. Camptothecin at a higher dose (5.0 microgram/ml) induces effects similar to those of actinomycin D.

Animals↗

PubMedDate not supplied

Plant anticancer agents X. Isolation of camptothecin and 9-methoxycamptothecin from Ervatamia heyneana.

The anticancer activity of the roots of Ervatamia heyneana (Apocynaceae) was found to be due principally to the known alkaloid, camptothecin (1). The closely related, but less active, 9-methoxycamptothecin (2) was also obtained. This is the first reported isolation of these biogenetically interesting alkaloids from the indole alkaloid rich Apocynaceae.

Antineoplastic Agents, Phytogenic↗

PubMed1979

Studies of the effect of chloramphenicol, ethidium bromide and camptothecin on the reproduction of Rous sarcoma virus in infected chick embryo cells.

A function for mitochondria in the reproduction of Rous sarcoma virus (RSV) in chronically and newly infected chick embryo cells was studied by using chloramphenicol and ethidium bromide. Chloramphenicol (CAM) and ethidium bromide (EB) were both shown to decrease the rate of growth of infected chick embryo cells and to inhibit the synthesis of mitochondrial macromolecules. Both drugs however had little or no effect on the incorporation of labelled leucine, thymidine and uridine into total cellular macromolecules. Neither CAM (80 microgram/ml) nor EB (0.4 microgram/ml) inhibited the production of infectious virus. In contrast, camptothecin, an inhibitor of cellular but not mitochondrial macromolecular synthesis, was shown to depress the production of infectious virus. The results indicate that the mitochondrial macromolecular synthesis machinery of RSV-infected chick embryo cells does not contribute to virus production.

Animals↗

PubMed1977