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PubMed2006

Synthesis and evaluation of sequence-specific DNA alkylating agents: effect of alkylation subunits.

We have demonstrated that hairpin pyrrole (Py)- imidazole (Im) polyamide-CBI conjugates selectively alkylate predetermined sequences. In this study, we investigated the effect of alkylation subunits, for example conjugates 1-4 with three types of DNA alkylating units, and Py-Im polyamides with indole linker. Conjugate 3 and 4 selectively alkylated the predetermined sequences as described previously, while conjugates 1 and 2 alkylate at mismatched sites.

Antineoplastic Agents, Alkylating↗
PubMed2006

Synthesis and biological properties of gemini quaternary ammonium compounds, 5,5'-[2,2'-(alpha,omega-polymethylnedicarbonyldioxy)diethyl]bis-(3-alkyl-4-methylthiazolium iodide) and 5,5'-[2,2'-(p-phenylenedicarbonyldioxy)diethyl]bis(3-alkyl-4-methylthiazolium bromide).

We synthesized gemini quaternary ammonium compounds (gemini QACs) having two thiazolium moieties in a molecule, 5,5'-[2,2'-(alpha,omega-polymethylnedicarbonyldioxy)diethyl]bis(3-alkyl-4-methylthiazolium iodide) (5DEBT-m,n), on which the carbon number of the methylene chain linking the two thiazoles (m) is 2, 6 or 8 and that of the alkyl group (n) is 8, 10, 12, 14 or 16. 5,5'-[2,2'-(p-Phenylenedicarbonyldioxy)diethyl]bis(3-alkyl-4-methylthiazolium bromide) (5DEBT-P,n) was then synthesized, which is composed of a p-phenylene as the methylene spacer. For five gemini QAC series, in addition to the previously described 5DEBT-4,n to the four new compound series, their antimicrobial activities were determined. 5DEBT-m,10 and -P,10 exhibited a wide and strong bacteriostatic activity against gram-negative and -positive bacteria, fungi and then yeast in comparison with N-tetradecyl-5-(2-hydroxyethyl)-4-methylthiazolium iodide as a mono-QAC. The bactericidal activity of the 5DEBT series against Escherichia coli IFO 12713 and Staphylococcus aureus IFO 12732 was investigated on the basis of the effects of their alkyl chain length and their molecular hydrophobicity. It was found that the effect of theses factors on their activity significantly changes by the difference between the gram-negative and -positive bacteria. Although against the gram-negative bacterium, the change in the activity due to extension of the alkyl group for each compound affected the kind of methylene spacer, against the gram-positive bacterium, it was almost equal in spite of the methylene spacer. This result could be responsible for the bactericidal mechanism of the gemini QACs being influenced by the diversity of the steric structure participating in the methylene chain length and by the bacterium cell surface hydrophobicity.

Alkylation↗
PubMed1987

Embryotoxicity induced by alkylating agents. Some methodological aspects of DNA alkylation studies in murine embryos using ethylmethanesulfonate.

Synthesis and spectroscopic analysis of some alkylated DNA purine bases are described. HPLC separation methods are developed for the determination of DNA alkylation rates in mammalian embryonic tissues. Following treatment of pregnant mice with the ethylating agent ethylmethanesulfonate (EMS), an appreciable amount of alkylation (ethylation and methylation) was found in the nuclear DNA of the embryos during organogenesis. The results are discussed in context of our thesis that a certain amount of DNA alkylation in the embryos is correlated to the teratogenic potential of alkylating agents.

Adenine↗
PubMed1987

Thermochemistry of aqueous solutions of alkylated nucleic acid bases. VI. Enthalpies of hydration of 2-alkyl-9-methyladenines.

Enthalpies of solution in water, delta H0sol, and vant'Hoff enthalpies of sublimation, delta H0subl, were determined experimentally for a number of crystalline 2-alkyl derivatives of 9-methyladenine: m2(2,9)Ade, e2m9Ade, pr2m9Ade and but2m9Ade. Standard enthalpies of hydration, delta H0hydr derived from these data were corrected for the calculated cavity terms, delta H0cav, to yield enthalpies of interaction, delta H0int, of the solutes with their hydration shells. The apparent residual contribution of alkyl groups, R, to the enthalpy of interaction delta delta H0int (R) was found to increase linearly with the number of CH2 groups added upon alkyl substitution, whereas this contribution calculated per unit area of the water-accessible molecular surface, SB, of alkyl residues delta delta H0int (R): delta SB(R) appeared constant over the whole series of the compounds investigated. This indicates that alkyl groups substituted at the C(2) carbon atom of the adenine contribute additively to the van der Waals' part of the enthalpy of interaction and do not affect the electrostatic part of the energy of interaction of the solutes with their hydration shells.

Adenine↗
PubMed1994

A method for simultaneous identification of human active and active-site alkylated O6-methylguanine-DNA methyltransferase and its possible application for monitoring human exposure to alkylating carcinogens.

Cells resist the major mutagenic effects of alkylating agents by the action of O6-methylguanine-DNA methyltransferase (MGMT), which transfers the alkyl (R) group of O6-alkylguanine, produced in DNA by these chemicals, to a cysteine residue in its active site (formation of R-MGMT). We demonstrate that cellular R-MGMT (which represents a record or memory within the cells exposed to these chemicals) can be assayed by its sensitivity toward proteolysis by protease V8. The possible use of this assay for monitoring exposure to alkylating carcinogens was investigated by using cultured cells and a preliminary study with the use of human blood from normal subjects and patients undergoing chemotherapy. Cultured cell experiments show that R-MGMT is sufficiently stable for the monitoring purpose and its level bears a dose-response relationship to the concentrations of the alkylating agent used. Interestingly, experiments with blood from patients undergoing chemotherapy show a gradual formation of R-MGMT in 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea and an induced MGMT deficiency in cyclophosphamide-treated patients. The use of this methodology, which allows for the possible quantification of active MGMT (cellular DNA repair capacity) and R-MGMT (recent exposure) simultaneously, in monitoring human exposure to alkylating carcinogens is discussed.

Adolescent↗
PubMed1997

Synthesis, DNA binding and cytotoxicity of 1-[[omega-(9-acridinyl)amino]alkyl]carbonyl -3-(chloromethyl)-6-hydroxyindolines, a new class of DNA-targeted alkylating agents.

We report the first synthesis of examples of the seco-CI DNA alkylating moiety 3-(chloromethyl)-6-hydroxyindoline linked to a 9-aminoacridine DNA-intercalating unit (compounds 1a-1c). The sequence-specificity of DNA alkylation by these compounds was studied by the gel electrophoresis cleavage assay. In contrast to the known trimethoxyindole-linked compound (1d), which alkylates exclusively at N3 of adenines in the minor groove, the acridine-linked analogues (1a-1c) alkylate predominantly at the N7 of guanines in the major groove (the first CI analogues reported to do so), although DNase I footprinting experiments show that the initial non-covalent binding of 1a-1c is not base sequence selective. DNA unwinding experiments show that the acridine moiety of 1a-1c remains intercalated after alkylation.

Animals↗
PubMed1995

Structure-activity relationship studies of CNS agents, XIX: Quantitative analysis of the alkyl chain effects on the 5-HT1A and 5-HT2 receptor affinities of 4-alkyl-1-arylpiperazines and their analogs.

The 5-HT1A and 5-HT2 receptor affinity of a set of 44 N-alkylated 1-aryl-piperazines and their analogs has been analyzed: the n-hexyl derivatives were the most potent and the most selective 5-HT1A ligands of all the investigated N-alkyl homologues. The alkyl chain may stabilize the 5-HT1A receptor-ligand complex by hydrophobic forces. A set of the alkyl substituent contributions (CHT1A) for prediction of the 5-HT1A affinity of N-alkyl derivatives of 1-arylpiperazines and related compounds have been defined on the basis of the Free-Wilson analysis.

Animals↗
PubMed1992

Rapid synthesis of 2-desoxy-2-amino-3-phosphocholine-glycerinic-acid- alkylester, 1-alkyl-1-desoxy- and 1-O-alkyl-2-desoxy-2-amino-sn-glycero-3- phosphocholines, -3-phospho-N,N'-dimethylethanolamine and -3-phospho-Fmoc- serine-methylester.

A convenient sequence for the rapid synthesis of 2-desoxy-2-amino-3-phosphocholine-glycerinic-acid-alkylester , 1-alkyl-1-desoxy- and 1-O-alkyl-2-amino-2-desoxy-3-phospho-derivatives is described. Key steps are the reaction of 1-carbonyloxyalkyl-, 1-alkyl- or 1-O-alkyl-amino-alcohols with phosphorus oxychloride to 1-carbonyloxyalkyl-, 1-alkyl- or 4-substituted 2-chloro-2-oxo-1,3,2-oxazaphospholane followed by nucleophilic displacement with choline tosylate, 1-bromoethane-2-ol or Fmoc-L-serine-methylester and subsequent hydrolysis to 2-amino-lysophospholipids giving the desired compounds in yields ranging between 68% and 81%. Several 2-amino-lysophospholipid analogs can then be prepared by this synthetic scheme utilizing the same oxazaphospholane intermediate. A brief method for the preparation of 2-amino-3-hydroxy-propionic-acid-pentyl- and -octylester from L-serine is described, opening a facile access to chiral precursors of phospholipid analogs.

Magnetic Resonance Spectroscopy↗
PubMed2004

Alpha-1-C-alkyl-1-deoxynojirimycin derivatives as potent and selective inhibitors of intestinal isomaltase: remarkable effect of the alkyl chain length on glycosidase inhibitory profile.

A series of alpha- and beta-1-C-alkyl-1-deoxynojirimycin derivatives was prepared and evaluated as glycosidase inhibitors. Biological assays showed a marked dependence of the selectivity and potency of the inhibitors upon the position of the alkyl chain (alpha-1-C-, beta-1-C- or N-alkyl derivatives). In addition, the efficiency of alpha-1-C-alkyl-1-deoxynojirimycin derivatives as intestinal isomaltase inhibitors increases with the length of the alkyl chain. The strongest inhibition was found for alpha-1-C -nonyl-1-deoxynojirimycin with an IC50=3.5 nM (25x more potent inhibitor than the shorter chain homologue carrying a C8 chain). These results demonstrate that subtle changes in the aglycon fragment may result in remarkable enzyme specificity.

1-Deoxynojirimycin↗
PubMed2002

Synthesis of 3-alkyl(aryl)-4-alkylidenamino-4,5-dihydro-1H-1,2,4-triazol-5-ones and 3-alkyl-4-alkylamino-4,5-dihydro-1H-1,2,4-triazol-5-ones as antitumor agents.

A series of 3-alkyl-4-phenylethylidenamino- (8) and 3-alkyl-4-(3-phenylallylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (9) was synthesized from the reaction of the corresponding 3-alkyl(aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (1), with phenylacetaldehyde and cinnamaldehyde. 3-Alkyl-4-(2-phenylethylamino)- (10) and 3-alkyl-4-(3-phenylpropylamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (11) were obtained from the selective reduction of compounds (8) and (9) with NaBH(4). The in vitro antitumor activity of the novel compounds was screened and the highest inhibition of tree tumor cell lines was observed for the compounds containing phenylethylenamino and phenylethylamino groups at position 4 of 1,2,4-triazol ring.

Antineoplastic Agents↗
PubMedDate not supplied

Preparation of N-alkylated pyridones via selective N-alkylation of 2-alkoxypyridines on solid phase.

Regioselective solid-phase synthesis of N-alkylated 2-pyridones has been carried out starting from 2-halopyridines. Variously substituted 2-halopyridines were linked to a Wang resin in quantitative yields to afford 2-alkoxypyridines. The coupled products were then reacted with a variety of alkyl halides, resulting in tandem alkylation and cleavage from the resin to generate N-alkylated pyridones with no detectable traces of O-alkylated products. The scope and limitations of this exceptionally selective reaction have been studied.

Journal Article↗
PubMed1996

Reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] with Alkyl Halides and Dihalides: Formation of the Alkyl- and the Dialkylantimony-Iron Carbonyl Complexes.

The reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] (1) with RX (R = Me, Et, n-Pr; X = I) in MeCN form the monoalkylated antimony complexes [Et(4)N](2)[RSb{Fe(CO)(4)}(3)] (R = Me, 2; R = Et, 4; R = n-Pr, 6) and the dialkylated antimony clusters [Et(4)N][R(2)Sb{Fe(CO)(4)}(2)] (R = Me, 3; R = Et, 5; R = n-Pr, 7), respectively. When [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] reacts with i-PrI, only the monoalkylated antimony complex [Et(4)N](2)[i-PrSb{Fe(CO)(4)}(3)] (8) is obtained. The mixed dialkylantimony complex [Et(4)N][MeEtSb{Fe(CO)(4)}(2)] (9) also can be synthesized from the reaction of 2 with EtI. While the reaction with Br(CH(2))(2)Br produces [Et(4)N](2)[BrSb{Fe(CO)(4)}(3)] (10), treatment with Cl(CH(2))(3)Br forms the monoalkylated product [Et(4)N](2)[Cl(CH(2))(3)Sb{Fe(CO)(4)}(3)] (11) and a dialkylated novel antimony-iron complex [Et(4)N][{&mgr;-(CH(2))(3)}Sb{Fe(CO)(4)}(3)] (12). On the other hand, the reaction with Br(CH(2))(4)Br forms the monoalkylated antimony product and the dialkylated antimony complex [Et(4)N][{&mgr;-(CH(2))(4)}Sb{Fe(CO)(4)}(2)] (13). Complexes 2-13 are characterized by spectroscopic methods or/and X-ray analyses. On the basis of these analyses, the core of the monoalkyl clusters consists of a central antimony atom tetrahedrally bonded to one alkyl group and three Fe(CO)(4) fragments and the dialkyl products are structurally similar to the monoalkyl clusters, with the central antimony bonded to two alkyl groups and two Fe(CO)(4) moieties in each case. The dialkyl complex 3 crystallizes in the monoclinic space group P2(1)/c with a = 13.014(8) Å, b = 11.527(8) Å, c = 17.085(5) Å, beta = 105.04(3) degrees, V = 2475(2) Å(3), and Z = 4. Crystals of 12 are orthorhombic, of space group Pbca, with a = 14.791(4) Å, b = 15.555(4) Å, c = 27.118(8) Å, V = 6239(3) Å(3), and Z = 8. The anion of cluster 12 exhibits a central antimony atom bonded to three Fe(CO)(4) fragments with a -(CH(2))(3)- group bridging between the Sb atom and one Fe(CO)(4) fragment. This paper discusses the details of the reactions of [Et(4)N](3)[Sb{Fe(CO)(4)}(4)] with a series of alkyl halides and dihalides. These reactions basically proceed via a novel double-alkylation pathway, and this facile methodology can as well provide a convenient route to a series of alkylated antimony-iron carbonyl clusters.

Journal Article↗
PubMed2003

Mechanistic studies of nickel(II) alkyl agostic cations and alkyl ethylene complexes: investigations of chain propagation and isomerization in (alpha-diimine)Ni(II)-catalyzed ethylene polymerization.

The synthesis of a series of (alpha-diimine)NiR(2) (R = Et, (n)Pr) complexes via Grignard alkylation of the corresponding (alpha-diimine)NiBr(2) precursors is presented. Protonation of these species by the oxonium acid [H(OEt(2))(2)](+)[BAr'(4)](-) at low temperatures yields cationic Ni(II) beta-agostic alkyl complexes which model relevant intermediates present in nickel-catalyzed olefin polymerization reactions. The highly dynamic nature of these agostic alkyl cations is quantitatively addressed using NMR line broadening techniques. Trapping of these complexes with ethylene provides cationic Ni alkyl ethylene species, which are used to determine rates of ethylene insertion into primary and secondary carbon centers. The Ni agostic alkyl cations are also trapped by CH(3)CN and Me(2)S to yield Ni(R)(L)(+) (L = CH(3)CN, Me(2)S) complexes, and the dynamic behavior of these species in the presence of varied [L] is discussed. The kinetic data obtained from these experiments are used to present an overall picture of the ethylene polymerization mechanism for (alpha-diimine)Ni catalysts, including effects of reaction temperature and ethylene pressure on catalyst activity, polyethylene branching, and polymer architecture. Detailed comparisons of these systems to the previously presented analogous palladium catalysts are made.

Journal Article↗
PubMed2002

Synthesis of indolizidines and pyrrolizidines through the [2 + 2]cycloaddition of five-membered endocyclic enecarbamates to alkyl ketenes. Unusual regioselectivity of Baeyer-Villiger ring expansions of alkyl aza-bicyclic cyclobutanones.

The total syntheses of two indolizidine skeletons and of the necine base (+/-)-platynecine were accomplished in a concise manner with good overall yields starting from a common five-membered endocyclic enecarbamate. These syntheses feature a [2 + 2]cycloaddition of the five-membered endocyclic enecarbamate 5 to alkylketenes that proceeded in high yields and with high stereoselectivity to provide an endo alkyl cycloadduct as the major or only product. The minor exo alkyl cycloadducts, which can be observed in some [2 + 2]cycloadditions, seem to derive from the endo cycloadduct, the putative kinetic product, by epimerization. An unusual regioselectivity was observed for the Baeyer-Villiger oxidation of 7-alkyl-2-azabicyclic cyclobutanones. Endo-7-alkyl cycloadducts ring-expanded exclusively to a gamma-lactone in which oxygen is inserted into the C6-C7 bond in preference to the bridgehead C5-C6 bond. With the exo-7-alkyl cycloadduct the regioselectivity of the Baeyer-Villiger oxidation is drastically reduced, leading to mixtures of regioisomeric lactones in a ratio of approximately 1.5 to 1. It is hypothesized that the steric strain built into the Criegee cyclobutane intermediate is the regioselective controlling factor in these oxidations, overriding any stereoelectronic bias for ring expansion. A rationale for the mechanism of the [2 + 2]cycloaddition involving enecarbamates and ketenes is presented, which seems to involve the participation of an N-acyliminium-enolate intermediate.

Carbamates↗
PubMed2005

Tetrabutylammonium alkyl carboxylate surfactants in aqueous solution: self-association behavior, solution nanostructure, and comparison with tetrabutylammonium alkyl sulfate surfactants.

A series of long and ultralong chain tetrabutylammonium alkyl carboxylate (TBACm, TBA = tetrabutylammonium ion; Cm = carboxylate ion C(m-1)H(2)(m-1)CO(2)(-) of total carbon number m) surfactants have been obtained by direct neutralization of the fatty acids with m = 12, 14, 18, 22, and 24 by tetrabutylammonium hydroxide. Time-resolved fluorescence quenching has been used to determine the micelle aggregation number (N) of the surfactants with m = 12, 14, and 18 in the temperature range 10-50 degrees C and of the surfactants with m = 22 and 24 in the temperature range 25-60 degrees C. In all instances the values of N were well below those that can be calculated for the maximum spherical micelle formed by surfactants with the same alkyl chain as the investigated surfactants on the basis of the oil drop model for the micelle core. The microstructure of selected solutions of TBAC22 was examined using transmission electron microscopy at cryogenic temperature and compared to the microstructure of solutions of TBA dodecyl and tetradecyl sulfates. These observations generally confirmed the findings of TRFQ. The self-association behavior of these anionic surfactants with TBA counterions is explained on the basis of the large size and the hydrophobicity of the tetrabutylammonium ions. The important differences in behavior that have been evidenced between tetrabutylammonium alkyl carboxylates and alkyl sulfates are discussed in terms of differences in distribution of the surfactant electrical charge on the headgroup and alkyl chain predicted by quantum chemical calculations (Langmuir 1999, 15, 7546).

Journal Article↗
PubMed2005

Kinetic resolution and parallel kinetic resolution of methyl (+/-)-5-alkyl-cyclopentene-1-carboxylates for the asymmetric synthesis of 5-alkyl-cispentacin derivatives.

Conjugate addition of lithium dibenzylamide to methyl 5-isopropyl, 5-phenyl- and 5-tert-butyl-cyclopentene-1-carboxylates occurs with high levels of substrate control (>88% de), with preferential addition to the face of the cyclic alpha,beta-unsaturated acceptor anti- to the stereodirecting 5-alkyl substituent. Treatment of a range of methyl (+/-)-5-alkyl-cyclopentene-1-carboxylates with both lithium (+/-)-N-benzyl-N-alpha-methylbenzylamide and lithium (+/-)-N-3,4-dimethoxybenzyl-N-alpha-methylbenzylamide indicates significant enantiorecognition in their mutual kinetic resolutions, with preferential addition anti- to the 5-alkyl substituent, giving the 1,2-syn-1,5-anti-arrangement (E >16) after enolate protonation anti- to the amino functionality. The kinetic resolution of a range of methyl (+/-)-5-alkyl-cyclopentene-1-carboxylates with lithium (S)-N-benzyl-N-alpha-methylbenzylamide, and their efficient parallel kinetic resolution with a pseudoenantiomeric mixture of lithium (S)-N-benzyl-N-alpha-methylbenzylamide and lithium (R)-N-3,4-dimethoxybenzyl-N-alpha-methylbenzylamide are also demonstrated, giving a range of 5-alkyl-cispentacin derivatives in >98% de and high ee after N-deprotection.

Journal Article↗
PubMed1994

[Study on new anti-rust disinfectants. III. Effect of alkyl chain length of N-alkyl-N-(2-hydroxy-3-phenoxy)propyl-N,N-dimethylammonium butyl phosphate on the antibacterial activity].

New anti-rust quaternary ammonium salts such as N-alkyl-N-(2-hydroxy-3-phenoxy)propyl-N,N-dimethylammonium butyl phosphate (5) [alkyl homologues are octyl (5a), decyl (5b), dodecyl (5c), tetradecyl (5d), hexadecyl (5e), and octadecyl (5f)] were synthesized in order to find the relationship between the alkyl length and the antibacterial activities. N-Alkyl-N-(2-hydroxy-3-phenoxy)propyl-N,N-dimethylammonium chloride (6) [alkyl homologues are dodecyl (6c), tetradecyl (6d), hexadecyl (6e)] were used as standard compounds in the quantitative analysis. 5c and 6c showed antibacterial activities and these activities were nearly equal to that of benzalkonium chloride (BAC), but, the activities shown by 5e, 5f and 6e were insufficient. 5c-e, showed excellent anti-rust effects, but 6c-e showed insufficient effects, because the former had a butyl phosphate anion and the latter had a chloride anion as a counter ion. 5a, b were insoluble in water. 5c showed a cloud point at 61.5 degrees C and 5d showed a cloud point at 72.0 degrees C at a 10% concentration in water. This phenomenon is similar to those of non-ionic surfactants. 5e was freely soluble in water.

Bacteria↗
PubMed1983

Cytotoxicity of alkyl-lysophospholipid derivatives and low-alkyl-cleavage enzyme activities in rat brain tumor cells.

Alkyl-lysophospholipids (ALP) and related derivatives inhibited the in vitro incorporation of [3H]thymidine into seven different permanent cell lines derived from rat brain tumors. The cytostatic effect of ALP was dependent on dosage and incubation time. Naturally occurring 2-lysophosphatidylcholine did not exhibit cytostatic effects; under these conditions, the incorporation rates of [3H]thymidine were generally more than 100% of the controls. The trypan blue dye exclusion test, which was used to assess severe cell damage, correlated with the extent that [3H]thymidine incorporation was inhibited by ALP. Preincubation of ALP (rac-1-octadecyl-lyso-glycero-3-phosphocholine) for more than 8 min with a tetrahydropteridine-dependent O-alkyl cleavage enzyme preparation from rat liver microsomes destroyed almost all of the cytotoxic properties of ALP when tested at a concentration that previously inhibited tumor growth by more than 50%. [3H]Thymidine incorporation rates were greater than 100% for astrocytoma cells incubated with ALP after exposure to the alkyl cleavage enzyme. Comparison of the microsomal activities of the tetrahydropteridine-dependent alkyl-cleavage enzyme present in astrocytoma 78-FR-G-299 cells and the pleomorphic glioma 78-FR-G-219/S4 cells to that found in normal skin fibroblasts and rat livers revealed a markedly reduced activity in the neoplastic cell lines. Moreover, those tumor cells that were more resistant to ALP cytotoxicity (pleomorphic glioma, 78-FR-G-219/S4) had a 3-fold higher tetrahydropteridine-dependent cleavage activity than a more cytotoxic sensitive line (astrocytoma cells, 78-FR-G-299). Our results indicate that the low-alkyl-cleavage enzyme activities in these neoplastic cells in comparison to normal cells might be a factor in explaining the relatively high cytotoxicity of ALP in tumor cells.

Animals↗