Cell-growth inhibition assays

TABLE 5.1 IC50 (nM) Values from Cell-Growth Inhibition Assays... 

An unusual observation in this transport study [272] was that the D-enantiomer of quinaspar ((VIII.70)) was taken up very efficiently, with a value of 7.7 /xM as compared with 5.0 xM for MTX and 38 /xM for l-(VIII.70). The ratio of free intracellular drug to external drug was 8.9 for d-(VIII.70) as compared to 5.4 for l-(VIII.70). However, the rate constant for efflux was 3-fold higher for D-(VIII.70) than for l-(VIII.70). It may be recalled that, in cell growth inhibition assays [51], the two enantiomers had proved to be... 

Table 1 IC50 [37] Values from cell-growth inhibition assays...

FIGURE 5.35 Growth inhibition assay of three human cancerous cell lines, with dendritic prodrug 38 in the presence ( ) and absence ( ) of PGA cells were incubated for 72 h. 

Fig. 3. Cross-resistance profiles for the 41M/41McisR, CH 1/CH1 c sR and A2 780/A2780cisR pairs of human ovarian-carcinoma cell lines for cisplatin itself carboplatin, tetraplatin (1,2-diaminocyclohexane)tetrachloroplatinum(IV)), JM216, JM118 (the major metabolite of JM216) andAMD473. Resistance Factor = IC50 resistant/parent cell line. Drug exposure was for 96 h, sulforhodamine B growth-inhibition assay, bars = SEM, n = 3-4.

Whole cell growth inhibition screens combined with subsequent target identification using molecular methods have proven viable approaches to the discovery of novel antibacterial inhibitors. Andries and colleagues (2005) at Johnson Johnson employed whole cell assays to discover a series of antimycobacterial diarylquinolines (DARQs). Chemical optimization of a lead compound led to DARQ derivatives exhibiting potent in vitro activities against several mycobacteria including Mycobacterium tuberculosis (Andries et al., 2005 Ji et al., 2006), with MICs below 0.5 pg/mL. Antimycobacterial efficacy in vivo was confirmed for three of the derivatives. 

A second index of biocompatibility was the quantitative analysis of cell growth inhibition, again on mouse fibroblast L929 cells, induced by the liquid components of the adhesive system and water extracts of two solid crosslinked materials. Table IV is a summary of the percent inhibition of cell growth (percent ICG). The mean protein values at 4 °C have been subtracted from the mean protein values (five test samples) at 37 °C for each treatment condition. The percent inhibition of cell growth (percent ICG) is shown for each treatment condition. The precision of the assay is approximately 10%. 

Antibacterial activity has been reported for 8,10-dideazafolic acid (IV.213) [145]. In growth inhibition assays against S. faecium and L. casei at a folate concentration of 2.2 nM in the medium, IC50 values of 3.2 and 23 nM, respectively, were obtained. The corresponding values for MTX were 0.34 and 0.22 nM. Thus, (IV.213) was 10-fold less active than MTX against S. faecium but 100-fold less active against L. casei. Activity against tumour cells in culture was not reported. 

As part of the preclinical studies on these agents, a number of studies aimed at selecting the most promising member of the series for eventual clinical trial were carried out [48]. In vitro growth inhibition assays were performed with additional L1210 murine leukaemia cell lines with growth requirements somewhat different from those used earlier, and this time it was found that the... 

Uptake of the amides into L1210 cells, was considerably slower than that of the parent acid, as indicated by values for unidirectional influx (measured by titration of drug in cell lysates with DHFR) or X values for competitive inhibition of [ H]MTX transport [240]. The values of the amides ranged from 3.3 rM for (VIII.188) to 48 rM for (VIII.194), while the for MTX uptake by these cells was 3.3 /rM. First-order rate constants for efflux, on the other hand, were hardly affected by y-substitution. Transport into the cells was therefore predicted to be the limiting event for cell growth inhibition, and this was experimentally borne out by growth inhibition assays with... 

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