Recent studies on the anticancer activities of mistletoe (Viscum album) and its alkaloids.

Detailed methods for in vitro/in vivo evaluation of anticancer drugs, with special reference to mistletoe extracts, have been reviewed. Mistletoe extracts have been shown to possess significant antitumor activity, in vivo, against murine tumors, Lewis lung carcinoma, colon adenocarcinoma 38 and C3H mammary adenocarcinoma 16/C. Methods for the extraction of biologically active alkaloids from mistletoe and their anticancer activities are presented.

Comparative structure-activity relationships of antifolate triazines inhibiting murine tumor cells sensitive and resistant to methotrexate.

The inhibitory effect of 108 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(substituted-phenyl)-s-triazines on murine L5178Y tumor cells, resistant and sensitive to methotrexate (MTX), has been studied. From the pI50 values, quantitative structure-activity relationships have been formulated which show that the lipophilic triazines are much more inhibitory against resistant cells than methotrexate or hydrophilic triazines. The results are compared with the behavior of other antifolate drugs that have been used in chemotherapy, as well as with eight antitumor drugs that are not antifolates.

A comparison of the inhibition of growth of methotrexate-resistant and -sensitive leukemia cells in culture by triazines. Evidence for a new mechanism of cell resistance to methotrexate.

Forty-five 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(3-X-phenyl)-s-triazine inhibitors of dihydrofolate reductase (DHFR) and methotrexate (MTX) were tested on L5178Y/R murine tumor cell culture. The concentration of inhibitor causing a 50% decrease in growth rate was determined, and from these results a quantitative structure-activity relationship (QSAR) was developed. This QSAR is compared with QSAR for the same inhibitors acting on isolated DHFR and on L5178Y cell culture sensitive to MTX.

Comparison of quantitative structure-activity relationships of the inhibition of leukemia cells in culture with the inhibition of dihydrofolate reductase from leukemia cells and other cell types.

A set of 2,4-diamino-5-(3-X-phenyl)-s-triazines was used to inhibit the growth of tumor cells (L5178 leukemia) in culture. The molar concentration (C) of triazine causing 50% reduction in the rate of cell growth was used to develop a quantitative structure-activity relationship: log 1/C = 1.32 pi - 1.