Manganese superoxide dismutase mediates the early release of mitochondrial cytochrome C and subsequent DNA fragmentation after permanent focal cerebral ischemia in mice

Recent studies have shown that release of mitochondrial cytochrome c is a critical step in the apoptosis process. We have reported that cytosolic redistribution of cytochrome c in vivo occurred after transient focal cerebral ischemia (FCI) in rats and preceded the peak of DNA fragmentation. Although the involvement of reactive oxygen species in the cytosolic redistribution of cytochrome c in vitro has been suggested, the detailed mechanism by which cytochrome c release is mediated in vivo has not yet been established. Also, the role of mitochondrial oxidative stress in cytochrome c release is unknown. These issues can be addressed using knock-out mutants that are deficient in the level of the mitochondrial antioxidant manganese superoxide dismutase (Mn-SOD). In this study we examined the subcellular distribution of the cytochrome c protein in both wild-type mice and heterozygous knock-outs of the Mn-SOD gene (Sod2 -/+) after permanent FCI, in which apoptosis is assumed to participate. Cytosolic cytochrome c was detected as early as 1 hr after ischemia, and correspondingly, mitochondrial cytochrome c showed a significant reduction 2 hr after ischemia (p < 0.01). Cytosolic accumulation of cytochrome c was significantly higher in Sod2 -/+ mice compared with wild-type animals (p < 0.05). N-benzyloxycarbonyl-val-ala-asp-fluoromethyl ketone (z-VAD.FMK), a nonselective caspase inhibitor, did not affect cytochrome c release after ischemia. A significant amount of DNA laddering was detected 24 hr after ischemia and increased in Sod2 -/+ mice. These data suggest that Mn-SOD blocks cytosolic release of cytochrome c and could thereby reduce apoptosis after permanent FCI.

Early decrease of apurinic/apyrimidinic endonuclease expression after transient focal cerebral ischemia in mice

The authors examined the protein expression of apurinic/apyrimidinic endonuclease (APE/Ref-1), a multifunctional protein in the DNA base excision repair pathway, before and after transient focal ischemia in mice. Immunohistochemistry showed the nuclear expression of APE/Ref-1 in the entire region of the control brains. Nuclear immunoreactivity was decreased as early as 5 minutes after 60 minutes of ischemia in the ischemic core, which was followed by a significant reduction of APE/Ref-1-positive cells in the entire middle cerebral artery territory. Western blot analysis of the sample from the nonischemic brain showed a characteristic 37-kDa band, which was reduced after ischemia. A significant amount of DNA fragmentation was observed at 24 hours, but not at 4 hours, after ischemia. The authors' data provide the first evidence that APE/Ref-1 rapidly decreases after transient focal ischemia, and that this reduction precedes the peak of DNA fragmentation in the brain regions that are destined to show necrosis and apoptosis. Although further examination is necessary to elucidate the direct relationship between the APE/Ref-1 decrease and ischemic necrosis and apoptosis, our results suggest the possibility that rapid decrease of APE/Ref-1 and the failure of the DNA repair mechanism may contribute to necrosis or apoptosis after transient focal ischemia.

Relationship between radical intensity and biological activity of cacao husk extracts

The relationship between radical intensity and biological activity of cacao husk extracts was investigated. Electron spin resonance (ESR) spectroscopy demonstrated that the radical intensity of hexane, acetone, methanol and 70% methanol extracts increased with water-solubility. Several fractions of these husk extracts, separated by different column chromatographies, significantly inhibited the cytopathic effect of human immunodeficiency virus (HIV) infection in parallel with their radical intensity. However, their cytotoxic activity against human leukemic and carcinoma cell lines is not always correlated with their radical intensity. Water-soluble and lipophilic compounds might induce cytotoxic activity by different mechanisms.

Reduction of apurinic/apyrimidinic endonuclease expression after transient global cerebral ischemia in rats: implication of the failure of DNA repair in neuronal apoptosis

BACKGROUND AND PURPOSE

To clarify the relationship between apurinic/apyrimidinic endonuclease (APE/Ref-1), a multifunctional protein in the DNA base excision repair pathway, and delayed neuronal cell death associated with apoptosis, we examined the expression of APE/Ref-1 before and after transient global ischemia in rats.

METHODS

Global ischemia was induced by bilateral common carotid artery occlusion and hypotension. Expression of the APE/Ref-1 protein was evaluated by Western blot and immunohistochemical analyses. Apoptosis after global ischemia was observed by DNA electrophoresis and terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) staining.

RESULTS

Immunohistochemistry showed the nuclear expression of APE/Ref-1 in the control brains. Nuclear immunoreactivity of APE/Ref-1 was significantly decreased 2 days after 10 minutes of ischemia in the hippocampal CA1 subregion. Western blot analysis of a sample from the normal brains showed a characteristic 37-kDa band, which was reduced in the hippocampal CA1 subregion after ischemia. A significant amount of DNA fragmentation was observed at 3 days but not at 1 day after ischemia. Double staining with APE/Ref-1 and TUNEL clearly showed that the neurons that lost APE/Ref-1 immunoreactivity became TUNEL positive.

CONCLUSIONS

Our data provide evidence that APE/Ref-1 decreased in hippocampal CA1 neurons after transient global ischemia and that this reduction precedes DNA fragmentation, which is destined to cause apoptosis. Our results suggest the possibility that a decrease of APE/Ref-1 activity and the failure of DNA repair may underlie the mechanism of apoptosis after transient focal ischemia.

Anticoagulation after valve replacement: a multicenter retrospective study

Anticoagulant therapy after cardiac valve replacement was evaluated retrospectively in 1,200 patients attending 8 cardiac surgery clinics in the Tokyo area as part of the Tokyo Area Study on Anticoagulation After Cardiac Valve Replacement Using PT-INR (TAS). A prospective trial is also in progress and will be reported later. The prothrombin time international normalized ratio (PT-INR) was determined at the time of thromboembolic and bleeding complications in 1,200 patients. During the 5 year study period, thromboembolisms occurred in 21 patients, and bleeding complications occurred in 15 patients. In 71% of patients with thromboembolism and 47% of those with bleeding complications, the PT-INR was within the range of 1.6 to 2.8, which is the accepted therapeutic range in Japan. Therefore, the correct PT-INR therapeutic range for Japanese patients with mechanical heart valves needs to be reexamined, and data from the prospective TAS trial that is currently underway will be used for this purpose.

In vitro susceptibility of Helicobacter pylori to trifluoromethyl ketones

Heteroaromatic trifluoromethyl ketones (TFMK's) showed strong inhibitory activity against Helicobacter pylori. The MIC50 observed for 2-trifluoroacetonylbenzoxazole (1) is 20-fold more active than metronidazole and is only twice as high as that of clarithromycin. The inhibitory mode of TFMK's on Hp growth was not related to inhibition of urease.

Effectiveness of polyamidoamine dendrimers modified with tripeptide growth factor, glycyl-l-histidyl-l-lysine, for enhancement of function of hepatoma cells

Cationic polyamidoamine dendrimers are known to be highly branched cascade polymers. Tripeptide growth factor, glycyl-L-histidyl-L-lysine (GHK), was employed as a ligand for activation or attachment of cells from a rat hepatoma cell line, H4-H-E-C3, and immobilized at the terminus of the dendrimer (GHK-dendrimer) to develop a suitable surface for use as a culture substratum in the bioartificial liver support system (BAL). The growth of cells was inhibited by increasing the number of generations of GHK-dendrimers. On the other hand, urea synthesis and lidocaine clearance of the cells adhered on fifth generation GHK-dendrimers were enhanced much more than on first generation GHK-dendrimers. GHK was shown to act as a growth inhibitor and an activator of hepatoma cells. These properties of GHK are advantageous for the utilization of hepatoma cells in BAL. Ligand-modified dendrimers are very promising for the creation of a high-performance substratum for cell culture and high performance bioartificial organs, as well as for high-performance bioartificial liver systems. GHK may have the potential to be a highly useful ligand.

Cytosolic redistribution of cytochrome c after transient focal cerebral ischemia in rats

Recent in vitro cell-free studies have shown that cytochrome c release from mitochondria is a critical step in the apoptotic process. The present study examined the expression of cytochrome c protein after transient focal cerebral ischemia in rats, in which apoptosis was assumed to contribute to the expansion of the ischemic lesion. In situ labeling of DNA breaks in frozen sections after 90 minutes of middle cerebral artery (MCA) occlusion showed a significant number of striatal and cortical neurons, which were maximized at 24 hours after ischemia, exhibiting chromatin condensation, nuclear segmentation, and apoptotic bodies. Cytosolic localization of cytochrome c was detected immunohistochemically in the ischemic area as early as 4 hours after 90 minutes of MCA occlusion. Western blot analysis of the cytosolic fraction revealed a strong single 15-kDa band, characteristic of cytochrome c, only in the samples from the ischemic hemisphere. Western blot analysis of the mitochondrial fraction showed a significant amount of mitochondrial cytochrome c in nonischemic brain, which was decreased in ischemic brain 24 hours after ischemia. These results provide the first evidence that cytochrome c is being released from mitochondria to the cytosol after transient focal ischemia. Although further evaluation is necessary to elucidate its correlation with DNA fragmentation, our results suggest the possibility that cytochrome c release may play a role in DNA-damaged neuronal cell death after transient focal cerebral ischemia in rats.

Overexpression of SOD1 in transgenic rats protects vulnerable neurons against ischemic damage after global cerebral ischemia and reperfusion

Transient global cerebral ischemia resulting from cardiac arrest is known to cause selective death in vulnerable neurons, including hippocampal CA1 pyramidal neurons. It is postulated that oxygen radicals, superoxide in particular, are involved in cell death processes. To test this hypothesis, we first used in situ imaging of superoxide radical distribution by hydroethidine oxidation in vulnerable neurons. We then generated SOD1 transgenic (Tg) rats with a five-fold increase in copper zinc superoxide dismutase activity. The Tg rats and their non-Tg wild-type littermates were subjected to 10 min of global ischemia followed by 1 and 3 d of reperfusion. Neuronal damage, as assessed by cresyl violet staining and DNA fragmentation analysis, was significantly reduced in the hippocampal CA1 region, cortex, striatum, and thalamus in SOD1 Tg rats at 3 d, as compared with the non-Tg littermates. There were no changes in the hippocampal CA3 subregion and dentate gyrus, resistant areas in both SOD1 Tg and non-Tg rats. Quantitative analysis of the damaged CA1 subregion showed marked neuroprotection against transient global cerebral ischemia in SOD1 Tg rats. These results suggest that superoxide radicals play a role in the delayed ischemic death of hippocampal CA1 neurons. Our data also indicate that SOD1 Tg rats are useful tools for studying the role of oxygen radicals in the pathogenesis of neuronal death after transient global cerebral ischemia.

Cellular accumulation of extravasated serum protein and DNA fragmentation following vasogenic edema

Accumulation of serum protein has been demonstrated in injured brain cells following vasogenic brain edema. The present study was conducted to test whether this phenomenon is also observed in apoptotic cells as well as in necrotic cells. Apoptotic cell death has been implicated in a variety of brain injuries, including ischemia and trauma. Cold injury and focal cerebral ischemia-reperfusion were used to induce both vasogenic edema and apoptotic cell death. Evans blue extravasation was used to determine the cellular accumulation of serum albumin. Apoptotic cell death was evaluated by both morphological alterations and by terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) staining. Evans blue accumulation in cells was observed not only in the surrounding zone of the lesion after cold injury and in the entire ischemic area after focal ischemia, but was also detected in the regions remote from the primary injury site. Some of these cells demonstrated nuclei fragmentation. TUNEL staining confirmed that apoptosis was induced in the region where apoptotic cells were morphologically detected. These observations suggest that accumulation of the extravasated serum component is accompanied by apoptotic cell death following vasogenic brain edema.

Intraoperative TEE during mitral valve repair: does it predict early and late postoperative mitral valve dysfunction?

BACKGROUND

Intraoperative transesophageal echocardiography (TEE) using color Doppler flow mapping can accurately measure residual mitral regurgitation (MR), but it is unknown to what extent such measurements correlate with those obtained with postoperative transthoracic echocardiography (TTE).

METHODS

We used intraoperative TEE (based on direct planimetry of the maximal regurgitant jet area) to measure residual MR in 42 patients who underwent mitral valve reconstruction for MR and compared these measurements with those obtained with early and late postoperative TTE.

RESULTS

Residual MR as measured by intraoperative TEE correlated significantly with values obtained with both early (r = 0.66; p < 0.0001) and late (r = 0.71; p < 0.0001) postoperative TTE. Forty patients with no or trivial MR (< or =2 cm2) as measured by intraoperative TEE also had no or trivial MR as measured by early (probability of 87.5%) and late (probability of 80.0%) postoperative TEE. Of the 40 patients, 6 had clinically insignificant mild MR (< or =4 cm2) when measured by late postoperative TTE. Two other patients in whom intraoperative TEE showed mild MR developed moderate regurgitation about 3 months later.

CONCLUSIONS

Intraoperative TEE correlates with early and late postoperative TTE in measurement of residual MR, suggesting it can reliably predict early and late postoperative mitral valve dysfunction.

Cyanoglycosylation products of 17-O-acetyl-testosterone

17-O-Acetyl testosterone, which has no susceptible hydroxyl or carboxyl group for glycosylation, was glycosylated with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide in the presence of a mixed catalyst, Hg(CN)2 and HgBr2, in benzene-nitromethane. Reaction occurred on the alpha, beta-unsaturated ketone on the six-membered A-ring to give six 3-O-glycosides, each bearing a cyano group at the 3- or 5-position of the aglycon, and a 3-O-glycoside bearing a CONH2 group at the 3-position. Structural analyses of these products were carried out by various NMR (1H, 13C NMR, 1H-1H and 1H-13C COSY, HMBC, and DEPT), FABMS and X-ray analyses. The mechanisms of the formations of the products are discussed. It was determined that mercuric cyanide was essential as a catalyst for the progress of the cyanoglycosylation.

[Hemorrhage exerts different effects on variabilities of heart rate and blood pressure in dogs]

The aim of the present study was to evaluate the effects of hemorrhage on heart rate variability (HRV) and blood pressure variability (BPV) as indicators of autonomic nervous system (ANS) and hypovolemia. We induced hemorrhagic hypovolemia in 7 dogs by removing blood in graded stages (0%, 10%, 20%, 30%, 40% of the estimated blood volume; EBV). HR was unchanged during hemorrhage, while mean BP decreased significantly after 30% EBV hemorrhage. Low frequency component (LF: 0.04-0.15 Hz) of HRV significantly increased after 20% EBV hemorrhage but high frequency component (HF: 0.15-0.4 Hz) of HRV was not altered. LF of BPV increased significantly stepwise after 20% EBV hemorrhage and HF of BPV increased significantly after 30% EBV hemorrhage, showing that both LF and HF of BPV might indicate the degree of hypovolemia. During hemorrhage LF of HRV and BPV increased and HF of HRV was unchanged, indicating the shift of the autonomic balance toward sympathetic dominance. An excellent quantitative correlation between LF of BPV and the degree of hypovolemia was demonstrated during graded hemorrhage, while LF of HRV plateaued at its maximum value at 20% EBV hemorrhage. In conclusion, our study suggests that the spectral analysis of HRV and BPV during graded hemorrhage shows different characteristics in the quantitative evaluation of ANS and hypovolemia.

[Pitfalls in echocardiographic diagnosis of mitral bileaflet prolapse]

Preoperative echocardiography provides good planning information for successful repair of mitral valve regurgitation, but identifying the prolapse of both the anterior and posterior leaflets is sometimes difficult. To clarify the cause of this problem, preoperative echocardiographic findings and intraoperative observations of the prolapse were analyzed in 124 patients with non-rheumatic pure mitral regurgitation. In 48 patients with final diagnoses of bileaflet prolapse, 16 (33%) were considered to have only single leaflet prolapse before the operation. Anterior leaflet prolapse was overlooked in 14, and prolapse of either of its commissural segments was the least detectable by echocardiography. Chordal rupture was seen more in the posterior leaflet than in the anterior leaflet. Movement of the anterior leaflet may be influenced by a prolapsed and hypermobile posterior leaflet and/or regurgitant jet flow caused by the posterior leaflet prolapse.

6,12-dihydro-1-benzopyrano[3,4-b][1,4]benzothiazin-6-ones: synthesis and mdr reversal in tumor cells

Six 6,12-dihydro-1-benzopyrano[3,4-b][1,4]benzothiazin-6-ones and three coumarins were systematically investigated for reversal of multidrug resistance of bacteria and cancer cells in model experiments. 7-Methylcoumarin was able to eliminate the E. coli plasmid significantly; however, the other derivatives were ineffective. Four of 6,12-dihydro-1-benzopyrano[3,4-b] [1,4]benzothiazin-6-ones had a moderate effect on the multidrug resistance efflux pump of mouse lymphoma cells in vitro. Despite of the similarity of resistance mechanisms of bacteria and tumor cells, the reversal of drug resistance in bacteria and in cancer cells is not uniform because the structure-activity requirements are apparently different.

[A study of minimally invasive direct coronary artery bypass (MIDCAB): comparison of low risk group and high risk group]

We started to perform MIDCAB for the cases of markedly low cardiac function from June, 1996 and obtained satisfactory results. So we expanded the indications to include only left anterior descending artery (LAD) lesion from June, 1997 and have since performed this operation on 14 cases. The 14 cases of MIDCAB were divided into two groups, Group L consisting of 6 low risk cases: 1 lesion alone without any complications involving other organ before operation and Group H made up of 8 high risk cases: multi branch lesion but rated as high risk because of the extracorporeal circulation being used. Both Group L and Group H were free of operation death and hospital death. In Group L, all the cases underwent operation without blood transfusion, the period of postoperative stay in ICU was not longer than 1 day, on catecholamine was required after operation and complications were not found either. The patency of the graft was 100 percent. The patients were discharged 13.7 days after operation. In Group H, 2 cases required blood transfusion and 3 cases required catecholamine after operation. Complication arising from operative wound were noted in 3 cases. One GEA graft to the right coronary artery and one LITA to the LAD buried in the muscle were occluded. After operation, hospital stay for 23.9 days was required. In Group L, the postoperative course was excellent, so MIDCAB was considered indicated well for this group. In Group H too, the selection of MIDCAB was considered adequate that the risk of conventional CABG is considered much higher.

Relationship between radical intensity and cytotoxic activity of dopamine-related compounds

Millimolar concentrations of dopamine (DA), norepinephrine (NE), and 3,4-dihydroxyphenylacetic acid (DOPAC) were cytotoxic to human promyelocytic leukemiC HL-60 cells. However, their metabolites (3,4-dihydroxymandelic acid (DOMA), 3-methoxytyramine (MT), normetanephrine (NMN)) and six synthetic derivatives (which have two OCH3 groups replacing two OH groups on catechol backbone) displayed much lower cytotoxic activity. Three active compounds, but not other less potent compounds, produced radicals under alkaline conditions. All active compounds significantly enhanced the decay of ascorbic acid endogenously present in rat brain homogenate, whereas all synthetic derivatives were inactive. Ascorbic acid induced apoptotic cell death in HL-60 cells and the apoptosis induction was significantly reduced by simultaneous addition of (DA). The cytotoxic activity of (DA) was also neutralized by ascorbic acid. These data suggest the possible interaction between (DA) and ascorbic acid.

[Coronary artery bypass grafting with arterial graft alone: radial artery and inferior epigastric artery used in combination]

We experienced 8 cases in which Coronary Artery Bypass Grafting (CABG) was performed by the arterial graft alone with radial artery (RA) and inferior epigastric artery (IEA) used in addition to internal thoracic artery (ITA) and right gastroepiploic artery (RGEA). All the patients were male ranging in age from 50 to 66 years (mean 57.5 year). The number of anastomosis was 3 to 5 branches (mean 3.6 branches). IEA was anastomosed with LITA and used as a composite graft in all cases. As for the proximal anastomosis of RA it was anastomosesd with ascending aorta. On postoperative radiography of graft, LITA, RITA, IEA and RA were all patent and RGEA was occluded only in one anastomosis where it was sequentially used (96.6%). All the patients followed a satisfactory postoperative course, and no case developed any major complications.

CONCLUSION

The use of IEA and RA made it possible to perform CABG using only the artery with excellent postoperative results and early patency rate of the graft.

Right-sided partial sternotomy for minimally invasive valve operation: "open door method"

A simple technique for minimally invasive valve operations is described. With a 10-cm midline skin incision, excellent exposure of both the mitral and aortic valves is achieved through a right-sided partial sternotomy, which enables us to perform easy repair or replacement of these valves.

The development of a new mouse model of global ischemia: focus on the relationships between ischemia duration, anesthesia, cerebral vasculature, and neuronal injury following global ischemia in mice

A new model for mouse global ischemia is presented, and the relationship of ischemia duration, cerebral vasculature, and ischemic neuronal injury has been determined. CD-1 mice anesthetized by chloral hydrate were subjected to global ischemia by bilateral common carotid artery occlusion under controlled ventilation for 3, 5, and 10 min. After evaluating the patency of the posterior communicating artery (PcomA) as hypoplastic or normoplastic, neuronal injury was independently determined in the striatum, cortex, and hippocampus in each hemisphere. Ischemic injury was strongly correlated with not only ischemia duration, but also with the patency of the PcomAs. Furthermore, neuronal injury developed in a delayed fashion after 3-min ischemia, while it was maximized at 24 h after 10-min ischemia. Physiological studies showed the induction of slight hypotension as compared with inhalation anesthesia, and improvement of blood gas data relative to spontaneous respiration. These data demonstrate the usefulness of this method to induce selective vulnerability and delayed neuronal cell death in mice, and to provide a useful model to study the detailed mechanism of global ischemia using transgenic or knockout mutant mice.

Mitochondrial susceptibility to oxidative stress exacerbates cerebral infarction that follows permanent focal cerebral ischemia in mutant mice with manganese superoxide dismutase deficiency

Mitochondrial injury has been implicated in ischemic neuronal injury. Mitochondria, producing adenosine triphosphate by virtue of electron flow, have been shown to be both the sites of superoxide anion (O2-) production and the target of free radical attacks. We evaluated these mechanisms in an in vivo cerebral ischemia model, using mutant mice with a heterozygous knock-out gene (Sod2 -/+) encoding mitochondrial manganese superoxide dismutase (Mn-SOD). Sod2 -/+ mice demonstrated a prominent increase in O2- production under normal physiological conditions and in ischemia, as evidenced by specific oxidation of a fluorescent probe, hydroethidine, reflecting decreased activity of Mn-SOD. A mitochondrial viability assay that used rhodamine 123, which is accumulated by transmembrane potential of viable mitochondria, demonstrated accelerated development of mitochondrial injury. This rapid progress of ischemic injury resulted in exacerbation of infarct size and hemisphere enlargement, causing advanced neurological deficits but without altering DNA fragmentation induction. The present study suggests that O2- overproduced in a mitochondrial compartment, when uncoupled from antioxidant defenses, induces impairment of mitochondrial function and causes exacerbation of cerebral infarction after ischemia.

The primary in vitro anticancer activity of "half-mustard type" phenothiazines in NCI's revised anticancer screening paradigm

Some new phenothiazines have been synthesized on the basis of previous studies. The anticancer activity of "half-mustard type" phenothiazines was investigated on sixty different cancer cell lines in vitro. The percentage of growth (PG), 50% inhibition of growth (GI50), the tumor growth inhibition (TGI) and the concentration required for 50% lethality of cells (IC50) were examined and calculated in the presence of various (from 10(-4) to 10(-8) M) concentrations of phenothiazine alkylurea derivatives. The following cell lines were involved in the study: 6 leukemia, 9 non-small-cell lung cancer, 7 colon cancer, 6 central nervous system cancer, 8 melanoma, 6 ovarian cancer, 8 renal cancer, 2 prostate and 8 breast cancer cell lines. The antileukemic activity of four chloroethyl-substituted phenothiazine-alkylureas was shown by considerable growth inhibition, in the 10(-5) M range, of the six different leukemia cell lines. The 50% inhibition of growth was nearly the same for the four compounds on all cell lines. Tumor growth inhibition (TGI) and IC50 value to cells varied from -4.0 to -4.66. The two derivatives with the butylene bridge were more effective than propylene linked compounds against the CCRP-CEM, HL60 (TB), K-562 and MOLT-4 cell lines. However, the anti-leukemic activity of the derivatives was nearly the same for RPMT 8226 and SR cell lines. The substituent at the 2- position of phenothiazine ring and the length of the linker between the side chain nitrogen and the phenothiazine ring system are apparently important for antileukemic activity. Four of the 9 non-small-cell lung cancer cell lines were sensitive, while the other 5 cell lines were not. The compounds had a slight growth inhibitory effect on colon cell carcinoma and melanoma cells in which case the butylene linker seemed to be more effective than the propylene linker. At the same time, all of the compounds were weak or mostly inactive on cancer cells from the central nervous system. One ovarian cancer line of the 6, the IGROVI was sensitive to butylurea phenothiazines, however, the other five were not sensitive at all. The difference in the sensitivity of various renal cell carcinomas was significant: 5 lines were not sensitive, three of them (786-0, RXF-393 and TK-10) were sensitive to only butylene-substituted phenothiazine-ureas, propylene substitution resulted in ineffective compounds. The compounds were not able to inhibit the 2 prostate and 4 breast cancer cell lines, even at 10(-4) M. It was interesting that propylene-linked ureas were more effective than butylene-linked derivatives on MCF-7, but butylene-linked derivatives were more effective than propylene-linked compounds on MDA MB-231 and MDA-N. In addition, MDA MB 435 was more sensitive to the trifluoromethyl derivatives than the compounds without this substituent. Since the phthalimido-alkyl phenothiazines were not active at the first level of prescreen, these compounds were omitted from this study. The drug sensitivity of some cancer cell lines was not uniform for the different groups, therefore we postulate that the resistance can be related to some kind of (existing) drug-efflux mechanism. Apparently, the tumor specificity of phenothiazine alkylureas is more related to the leukemia specificity of alkylureas than to any CNS or lung specificity of phenothiazines.

Biological activity of 6,12-dihydro-1-benzopyrano[3,4-b][1,4]benzothiazin-6-ones

Ten 6,12-dihydro-1-benzopyrano[3,4-b][1,4]benzothiazin-6-ones (Coumarins)[1-7] and related coumarins [8-10] were compared for their cytotoxic activity and radical intensity. Among these compounds, compound 7 showed highest cytotoxic activity against human promyelocytic leukemic HL-60 cells. Compound 7 produced radicals under alkaline conditions, and showed the lowest pi-spin density at S-atom of the molecule, suggesting the delocalization of pi-spin density. These data suggest the possible relation between radical intensity and biological activity.