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C I Hong

Publications and source records attributed to C I Hong.

At least 37 records · Page 2Linked to original sources
PubMed1986

Nucleoside conjugates. 7. Synthesis and antitumor activity of 1-beta-D-arabinofuranosylcytosine conjugates of ether lipids.

Three new 1-beta-D-arabinofuranosylcytosine conjugates of ether lipids (alkyl glycerols) linked by a pyrophosphate diester bond have been prepared and evaluated against mouse leukemia L1210 and P388. These include ara-CDP-rac-1-O-hexadecyl-2-O-palmitoylglycerol (9a) (ara-CDP = 1-beta-D-arabinofuranosylcytosine 5'-diphosphate), ara-CDP-rac-1-O-octadecyl-2-O-palmitoylglycerol (9b), and ara-CDP-rac-1-O-octadecyl-2-O-methylglycerol (9c). Among them, conjugate 9a produced significant increase in life span (200-293%) in mice bearing ip and ic implanted L1210 lymphoic leukemia at a total dose of 400-500 mg (406-508 mumol/kg). Significant schedule dependence was not observed when the conjugate was given ip once daily on day 1, days 1, 5, and 9, and days 1-5. The new conjugates are water soluble by sonication.

Animals↗
PubMed1986

1-beta-D-arabinofuranosylcytosine conjugates of thioether phospholipids as a new class of potential antitumor drugs.

Three 1-beta-D-arabinofuranosylcytosine (ara-C) conjugates of 1-S-alkyl-phospholipids (thioether phospholipids) were tested for their antitumor efficacies against L1210 and P388 leukemia in mice. These include 1-beta-D-arabinofuranosylcytosine 5'-diphosphate-rac-1-S-hexadecyl-2-0-palmitoyl-1-thioglycerol (ara-CDP-beta-palmitoyl-DL-thiochimyl alcohol, I), ara-CDP-rac-1-S-octadecyl-2-0-palmitoyl-1-thioglycerol (ara-CDP-beta-palmitoyl-DL-thiobatyl alcohol, II), and ara-CDP-rac-1-S-octadecyl-2-0-hexadecyl-1-thioglycerol (ara-CDP-beta-cetyl-DL-thiobatyl alcohol, III). Conjugates I and II produced significant increase in life span (293-379%) and longterm survivors among mice bearing i.p. implanted L1210 lymphoid leukemia at a total dose of 400 mg (389-400 mumol)/kg. Conjugate II also displayed a strong antitumor activity against i.c. implanted L1210 leukemia in mice with an ILS range of 160-200% at a total dose of 300-450 mg (292-438 mumol/kg. Significant schedule dependency was not observed when the conjugates were administered i.p. once daily with following schedules: qd l; 1,5, 9; 1-5; and 1-9, but single doses typically produced the best effects. The i.p. administration of conjugate II gave the best results on survival of i.p. inoculated L1210 leukemic mice, then followed by the s.c. and i.m. treatments. The i.v. treatment produced a lower activity than the others. Conjugate II also exhibited a strong antitumor activity against i.p. implanted P388 leukemia in mice with ILS values of greater than 255-greater than 329% with 3-5 45-day survivors at a total dose of 300-500 mg (292-486 mumol)/kg (qd 1 or 1-5). The new conjugates I and II displayed a comparable or somewhat higher activity than the previous diacyl and 1-0-alkyl analogs.

Animals↗
PubMed1985

Nucleoside conjugates. 6. Synthesis and comparison of antitumor activity of 1-beta-D-arabinofuranosylcytosine conjugates of corticosteroids and selected lipophilic alcohols.

Five new P1-(steroid-21-yl)-P2-(1-beta-D-arabinofuranosylcytosin-5'-yl)pyro phosphates (ara-CDP-steroids), five 1-beta-D-arabinofuranosylcytosine 5'-O-(alkyl)phosphates (ara-CMP-alkyl esters), and two P1-(alkyl)-P2-(1-beta-D-arabinofuranosylcytosin-5'-yl)pyrophosphat e (ara-CDP-alkyl esters) have been prepared and evaluated against L1210 lymphoid leukemia in culture and in mice (C3D2F1/J). These include ara-CDP-11-deoxycorticosterone (6a), ara-CDP-cortisone (6c), ara-CDP-corticosterone (6d), ara-CDP-cortexolone (6e), and ara-CDP-prednisone (6g), ara-CMP hexadecyl ester (7a), ara-CMP 1-cyclohexylmethyl ester (7b), ara-CMP 1-adamantylmethyl ester (7c), ara-CMP 2-(1-adamanthyl)ethyl ester (7d), ara-CMP 2-chloroethyl ester (7e), ara-CDP hexadecyl ester (9a), and ara-CDP 1-cyclohexylmethyl ester (9b). The in vitro antitumor results indicated that ara-CDP-steroids were as active as the previously reported ara-CMP-steroids and that ara-CMP and ara-CDP-alkyl esters were less growth inhibiting than ara-CDP-steroids and ara-C. However, the in vivo antitumor results indicated that ara-CDP-steroids were generally less effective than the previous monophosphate derivatives. Among them ara-CDP-corticosterone (6d) and the known ara-CDP-cortisol (6b) showed greater efficacy than ara-C with ILS value of 152% and 209%, respectively, at the optimal dose of 40 and 80 (mg/kg)/day for 9 days, while that of ara-C was 138% at the optimum dose of 9.2 (mg/kg)/day. Generally, ara-CMP alkyl esters (7a-e), given ip to the L1210 leukemic mice, were found to be toxic and ineffective. However, ara-CDP hexadecyl ester (9a) showed marginal activity (ILS, 38%). These preliminary results support the thesis that the ara-C conjugates of this type may require a lipophilic and naturally occurring moiety for improved efficacy.

Adrenal Cortex Hormones↗
PubMed1984

Nucleoside conjugates V: Synthesis and biological activity of 9-(beta-D-arabinofuranosyl)adenine conjugates of corticosteroids.

Eight 5'-(steroid-21-phosphoryl)-9-(beta-D-arabinofuranosyl)-adenines (IV-XI) have been prepared and evaluated against L1210 lymphoid leukemia in culture. These include the 9-(beta-D-arabinofuranosyl)adenine conjugates of hydrocortisone (IV), cortisone (V), corticosterone (VI), cortexolone (VII), 11-deoxycorticosterone (VIII), prednisolone (IX), prednisone (X), and dexamethasone (XI). Conjugates IV, IX, X, and XI inhibited the in vitro growth of L1210 lymphoid leukemia cells by 50% (ED50) at a concentration of 2.3-7.8 microM, while 9-(beta-D-arabinofuranosyl)adenine (vidarabine, I) and its 5'-monophosphate (II) each showed ED50 value of 30 microM. All of the conjugates were enzymatically hydrolyzed to the corresponding steroid and II, the latter undergoing further hydrolysis to I, by phosphodiesterase I, 5'-nucleotidase, and acid phosphatase. However, these conjugates were resistant to hydrolysis by alkaline phosphatase and adenosine deaminase.

Adenosine Deaminase↗
PubMed1984

1-beta-D-arabinofuranosylcytosine-phospholipid conjugates as prodrugs of Ara-C.

The L-, D-, and D,L-isomers of 1-beta-D-arabinofuranosylcytosine 5'-diphosphate-1,2-dipalmitin, new prodrugs of ara-C5, have been evaluated for antitumor activity in L1210 lymphoid leukemic mice. The L-isomer produced significant increase in life span (ILS), and longterm survivors among mice bearing i.p. and i.c. implanted L1210 leukemia and the maximal ILS values found were greater than 543 and greater than 374% with five and four 45-day survivors out of six mice, respectively, at the optimal single doses of 300 mg/kg and 125 mg/kg. The D- and D,L-isomers also displayed significant in vivo antitumor activity against both i.p. and i.c. implanted L1210 leukemia in mice with ILS range of 144-293% at a total dose of 125-250 mg/kg. Significant schedule dependency was not observed when the conjugates were administered i.p. once daily for 5 days, once every 4 days, or as a single dose, but single doses typically produced the best effects. The L-isomer was found to be a more effective prodrug of ara-C than its isomers and other lipophilic prodrugs, 5'-O-palmitoyl-ara-C and N4-acyl-ara-C. Unlike the latter prodrugs, the new conjugates are water soluble by sonication method.

Animals↗
PubMed1983

1-beta-D-arabinofuranosylcytosine conjugates of corticosteroids as potential antitumor agents.

The antitumor activity and toxicity of two new 1-beta-D-arabinofuranosyl-cytosine (ara-C) conjugates of cortisol and corticosterone linked through a phosphodiester bond between the 5' and 21 positions of the respective moieties (cortisol- and corticosterone-p-ara-C) were investigated in L1210 lymphoid leukemia cells in mice. They are highly active against both i.p.- and i.c.-implanted ara-C-sensitive lymphoid leukemia in mice, exceeding the activity produced by the parent drug, ara-C. For example, corticosterone-p-ara-C exhibited the respective ILS values of 306% at 50 mg/kg/day X 9 and 294% at 75 mg/kg/day X 9 on survivals of i.p.- and i.c.-inoculated L1210 leukemic mice. The effectiveness of the conjugates seems to depend on schedules of the treatments. The 9-day continuous treatments showed a better therapeutic effectiveness than those with either a 5-day, a single or a widely spaced (q 4d., 1, 5, 9) treatment. However, they were found to be marginally effective against i.p.-implanted ara-C-resistant L1210 leukemia in mice. They were also inhibitory against proliferation of human leukemia-lymphoid cells in culture. Their superior antitumor activity and resistance to cytidine deaminase suggests that they serve as a prodrug form of ara-C or ara-CMP.

Animals↗
PubMed1983

Intraarterial 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and systemic chemotherapy for malignant gliomas: a follow-up study.

Twenty-five adults who harbored malignant gliomas received 72 courses of intraarterial 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) (100 mg/m2) and 67 courses of systemic vincristine (1.0 mg/m2) and procarbazine (100 mg/m2) as induction therapy (BVP) followed by 106 courses of systemic 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (methyl-CCNU) (130 mg/m2), vincristine, and procarbazine as maintenance therapy (MVP). With a 6-week interval between each treatment, the median and range for the number of courses of BVP were 3 and 1 to 4 and those for MVP were 3 and 0 to 14, respectively. Fifteen patients (60%) responded to both BVP and MVP, and 10 (40%) did not. The overall median survival time was 12.7 months (range, 1.8 to 48.5+ months). Two of 3 patients who had recurrent gliomas responded and survived for 37+ to 45+ months. Seven of 10 who had nonirradiated glioblastomas responded and survived for 9 to 22 months. Four who had nonirradiated anaplastic astrocytomas all responded and survived for 38+ to 48.5+ months. Two who also received radiotherapy (1 glioblastoma and 1 primitive neuroectodermal tumor) benefited and survived for 16.9 and 28.5+ months. All who did not respond favorably died within 8 months. During the infusion of BCNU, complications included transient orbital and head pain, periorbital and scleral erythema in all patients, and a focal seizure in 1 (4%). During the 6-month induction periods, leukopenia and thrombocytopenia occurred in 1 (4%), deep vein thrombosis occurred in 9 (36%), pulmonary emboli occurred in 8 (32%), upper respiratory infections occurred in 6 (24%), pneumonia occurred in 9 (36%), and herpes zoster occurred in 1 (4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

Phospholipid-nucleoside conjugates. 3. Syntheses and preliminary biological evaluation of 1-beta-D-arabinofuranosylcytosine 5'-monophosphate-L-1,2-dipalmitin and selected 1-beta-D-arabinofuranosylcytosine 5-diphosphate-L-1,2-diacylglycerols.

Several new phospholipid-ara-C conjugates have been prepared and tested as prodrugs of the parent ara-C. The new derivative include ara-CMP-L-dipalmitin, ara-CDP-L-distearin, ara-CDP-L dimyristin, ara-CDP-L-diolein, and the radioactively labeled derivative ara-CDP-L-di[1-14C]palmitin. In addition, the unusually stable ara-CMP-L-dipalmitin-N-phosphoryldicyclohexylurea adduct was isolated as a crystalline solid (two diastereomers) in the reaction sequence to prepare ara-CMP-L-dipalmitin. The new prodrugs were solubilized by sonication methods and tested for their antiproliferative activity in vitro against mouse myeloma MPC-11 cells and against L1210 lymphoid leukemia. Such studies demonstrated that the antiproliferative activities of the prodrugs (as determined by ED50) were less that ara-C on a molar basis. In the mouse myeloma cell line some evidence was obtained that the antiproliferative activity was related to the chain length of the fatty acid side chains in the prodrugs. In in vivo studies against L1210 lymphoid leukemia in mice, the prodrugs were shown to be much more effective than ara-C, with the overall efficacy apparently being independent of the length of the fatty acid side chain. Some evidence was obtained in the vivo studies that the ara-CDP-L-dimyristin, which bears the shortest fatty acid side chain, was more toxic at the higher dosages than the longer chain length derivatives.

Animals↗
PubMed1981

Phospholipid derivatives of nucleoside analogs as prodrugs with enhanced catabolic stability.

The nucleoside 5'-diphosphate-L-1,2-dipalmitin derivatives of 1-beta-D-arabinofuranosylcytosine (ara-C), 9-beta-D-arabinofuranosyladenine (ara-A), and tubercidin have been synthesized, and their cytotoxicity has been evaluated against a mouse myeloma cell line (MPC-11) in vitro and against L1210 lymphoid leukemia both in vitro and in vivo. Sonication methods were utilized to solubilize these lipophilic derivatives in aqueous solution in order to facilitate such biological evaluation; the ara-A derivative resisted solubilization by several techniques. The nucleoside:phospholipid conjugates of ara-C and tubercidin both were cytotoxic towards the two cell lines, and detailed experiments were cytotoxic towards the two cell lines, and detailed experiments were carried out to show that the new derivatives (a) were not degraded in the medium prior to cellular uptake and (b) acted as prodrugs or molecular depots of the parent nucleoside analog. In addition, 1-beta-D-arabinofuranosylcytosine 5'-diphosphate'5'-L-1,2-dipalmitin was not a substrate for cytidine deaminase (cytidine aminohydrolase, EC 3.5.4.5), the primary enzyme responsible for the rapid catabolism of ara-C. In in vivo studies against L1210 lymphoid leukemia in mice, the 1-beta-D-arabinofuranosylcytosine 5'-diphosphate-5'-L-1,2-dipalmitin showed an increased efficacy (increased life span, 260%) relative to the parent ara-C (increased life span, 89%) regardless of treatment schedule used, whereas the tubercidin 5'-diphosphate-5'-L-1,2-dipalmitin appeared extremely toxic even at low dosages. That 1-beta-D-arabinofuranosylcytosine 5'-diphosphate-5'-L-1,2-dipalmitin was acting as a sustained release drug in vivo was demonstrated by utilizing a single dose administered on Days -1, 0, +1, and +2 relative to inoculation of the L1210 lymphoid leukemia cells on Day 0. Again, a much increased efficacy relative to the best treatment using ara-C was apparent. The potential advantages and the biochemical rationale for the development of these novel prodrugs are discussed.

Animals↗
PubMed1980

Nucleoside conjugates as potential antitumor agents. 3. Synthesis and antitumor activity of 1-(beta-D-arabinofuranosyl)cytosine conjugates of corticosteroids.

Six 5'-(steroid-21-phosphoryl)-1-(beta-D-arabinofuranosyl)cytosines have been prepared and evaluated against L1210 lymphoid leukemia in culture and in mice (C3D2F1/J). These include the ara-C conjugates of 11-deoxycorticosterone (5a), corticosterone (5b), cortexolone (5c), fludrocortisone (5d), 6 alpha-methylprednisolone (5e), and dexamethasone (5f). When the optimum dosage of ara-C [38 (mumol/kg)/day X 5] was given to mice bearing L1210, the ILS value found was 89%. A simple mixture of each steroid and ara-C gave ILS values that were on the whole significantly less than that of the parent nucleoside. However, of six conjugates, all but two (5d and 5f) were more active than ara-C at their optimal doses. Both corticosterone- (5b) and cortexolone-p-ara-C (5c) were especially effective at the respective optimal doses of 76.7 and 115 (mumol/kg)/day X 5. These gave ILS values of 200% each. All of the conjugates were demonstrated to be enzymatically hydrolyzed to the corresponding steroid and ara-CMP, and the latter was further shown to be hydrolyzed to ara-C by phosphodiesterase I, 5'-nucleotidase, and acid phosphatase. However, they were shown to be resistant to hydrolysis by alkaline phosphatase.

Adrenal Cortex Hormones↗
PubMed1979

Metabolic fate of N6-benzyladenosine and N6-benzyladenosine-5'-phosphate in rats.

The radiolabeled antitumor nucleoside (14C-8)-N6-benzyladenosine and its (14C-8)-5'-phosphate were administered to rats intravenously, and their metabolic fate was studied. Twenty-nine percent of the radioactivity was recovered in the 48-hr urine collection after (14C-8)-N6-benzyladenosine administration. The following metabolites were isolated: unchanged N6-benzyladenosine (20%), adenine (12%), uric acid (5%), and N6-benzyladenine (0.3%). In the case of (14C-8)-N6-benzyladenosine-5'-phosphate, a total of 28% of the radioactivity was recovered in the 48-hr urine collection and the following metabolites were isolated: N6-benzyladenosine (40%), uric acid (12%), adenine (trace), and unidentified urea derivatives (30%). Metabolism of N6-benzyladenosine appears to involve N-debenzylation to some extent, followed by conversion to adenine and uric acid. N6-Benzyladenosine and its 5'-phosphate differ from other adenosine analogs in being retained in significant amounts by the animals.

Adenosine↗
PubMed1979

Nucleoside conjugates as potential antitumor agents. 2. Synthesis and biological activity of 1-(beta-D-arabinofuranosyl)cytosine conjugates of prednisolone and prednisone.

Two of the new anticancer drugs recently synthesized in our laboratory from conjugation of ara-C2 and several corticosteroids linked through a phosphodiester bond include prednisolone- (I) and prednisone-p-ara-C (II). They were demonstrated to be enzymatically hydrolyzed to the corresponding steroid and ara-CMP and the latter was further shown to be hydrolyzed to ara-C by phosphodiesterase I, snake venom, 5'-nucleotidase, and acid phosphatase. However, the conjugates were shown to be resistant to hydrolysis by alkaline phosphatase. The activity of conjugates I and II against L1210 lymphoid leukemia in female mice (C3D2F1/J) was significantly greater than that of ara-C alone or in combination with the steroid. In fact, when the optimum dosage of 75 (mumol/kg)/day x 5 was used, the administration of ara-C alone was followed by an increased life span (ILS) of 45%. This result is similar to that previously reported. With the same equimolar doses of mixtures of ara-C and either prednisolone or prednisone, the ILS values were 40 and 44%, respectively. However, when the conjugates were used, the ILS values were 89 and 100% respectively. These findings seem promising and have provided the bases for continued study of these new compounds.

Animals↗
PubMed1978

Synthesis and biological activity of N6-(n-alkylureido)purine ribonucleosides and their 5'-phosphates.

Syntheses and biological activities of 12 N6-(n-alkylureido)purine ribonucleosides (alkyl chain length of 1--10, 16, and 18 carbons) and three N6-(n-alkylureido)purine ribonucleoside 5'-phosphates (chain length of 4, 9, and 10 carbons) are described. The N6-(n-alkylureido)purine ribonucleosides were prepared by a reaction of (2',3',5'-tri-O-acetyl-beta-D-ribofuranosyl)-9H-purine-6-carbamate and n-alkylamine in refluxing pyridine. The 5'-nucleotides were prepared by direct phosphorylation of the corresponding ribonucleoside with phosphorus oxychloride and triethyl phosphate. Some N6-(n-alkylureido)purine ribonucleosides (n-octyl, n-nonyl, and n-decyl) and their nucleotides showed a marked antiproliferative activity against L-1210 cells in culture.

Animals↗
PubMed1976

Synthesis and biological activities of some N4-substituted 4-aminopyrazolo(3,4-d)pyrimidines.

Syntheses and biological activities of 26 N4-substituted 4-aminopyrazolo[3,4-d]pyrimidines as analogs of naturally occurring modified nucleic acid bases, N-(purin-6-ylcarbamoyl)-L-threonine and N6-(delta2-isopentenyl)adenine, are described. 4-Aminopyrazolo[3,4-d]pyrimidine was converted into the desired intermediate, ethyl pyrazolo[3,4-d]pyrimidine-4-carbamate (2). 4-Ureidopyrazolo[3,4-d]pyrimidines (6-26) were prepared by displacement of the ethoxy group of the carbamate 2 by amino acids and a variety of amines and by a reaction of 4-aminopyrazolo[3,4-d]pyrimidine (1) with isocyanates. N4-Alkylaminopyrazolo[3,4-d]pyrimidines were generally prepared by displacement of the chlorine from 4-chloropyrazolo[3,4-d]pyrimidine with various amines. Several analogs exhibited moderate to very good growth inhibitory activities against cultured L1210 leukemia and 6410 human leukemic myeloblasts.

Animals↗
PubMed1975

Synthesis properties of the naturally occurring N-[(9-beta-D-ribofuranosylpurin-6-yl)-N-methylcarbamoyl]-L-threonine (mt-6A) and other related synthetic analogs.

The naturally occurring modified nucleoside, N-[(9-beta-D-ribofuranosylpurin-6-yl)-N-methylcarbamoyl]-L-threonine (mt6A), and the corresponding glycine analog mg6A were synthesized from N6-methyl-2',3',5'-tri-O-acetyladenosine and the appropriately blocked isocyanates derived from threonine and glycine. The natural mt6A isolated from Escherichia coli tRNA (F. Kimura-Harada et al. (1972), Biochemistry 11, 3910), from wheat embryo tRNA (R. Cunningham and M. W. Gray (1974), Biochemistry 13, 543), and from rat liver tRNA (Rogg et al. (1975), Eur. J. Biochem. 53, 115) was found to be identical with the synthetic mt6A in paper and thin-layer chromatography and electrophoresis. Several analogs of the parent 6-ureidopurine ribonucleoside, N-[(9-beta-D-ribofuranosylpurin-6-yl)carbamoyl]-L-thronine (t6A), were also prepared. Starting from 2',3',5'-tri-O-acetylguanosine and 2',3',5'-tri-O-acetylcytidine and the above isocyanates, the t6A analogs, N-[(9-beta-D-ribofuranosyl-6-oxo-1H-purin-2-yl)carbamoyl]-L-threonine (t2G) and N-[(1-beta-D-ribofuranosyl-2-oxypyrimidin-4-yl)carbamoyl]-L-threonine (t4C), were prepared. Also synthesized were the corresponding glycine analogs, g2G and g4C, from guanosine and cytidine, respectively. The 2'-deoxyribosyl analog, N-[(9-beta-D-2'-deoxyribofuranosylpurin-6-yl)carbamoyl]-L-threonine (2'-deoxy-t6A), and the arabinosyl derivative, N-[(9-beta-D-arabinofuranosylpurin-6-yl)carbamoyl]-L-threonine (t6AraA), were synthesized from the appropriate urethane and the requisite amino acid. The ureido group in mt6A could not be hydrolyzed by the enzymes urease, peptidase, and protease. Various chemical and biological properties of the naturally occurring mt6A and the related analogs are discussed.

Chromatography, Paper↗