Antagonist properties of a phosphono isoxazole amino acid at glutamate R1-4 (R,S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid receptor subtypes

All three subtypes of beta-adrenoceptors are coupled to stimulation of adenylyl cyclase activity via the stimulatory guanine-nucleotide-binding protein. Nevertheless, the beta3 adrenoceptor (beta3-AR) differs significantly from the other subtypes in terms of pharmacology. Most strikingly, it recognizes as agonists several compounds acting as potent beta1-AR and beta2-AR antagonists. Furthermore, the human beta3-AR is quite different from the animal beta3-AR. Molecular modelling studies followed by site-directed mutagenesis was used here to identify some of the amino acid residues which may be implicated in ligand binding and signal transduction of the beta3-AR. Three contiguous residues, valine-leucine-alanine, which are present in the first transmembrane domain at positions 48-50 of the human receptor but are absent in all known rodent sequences, were thought to be important for species specificity. When these three residues were deleted from the human receptor, no 'rodent-like' pharmacological profile was obtained in terms of either binding or adenylyl cyclase activation. Glycine at position 53, also in the first transmembrane domain in the human beta3-AR, has been suggested to participate in beta2-/beta3-AR subtype selectivity. Replacement of this glycine residue by phenylalanine, which is the residue present at the homologous position in the human beta2-AR, left the beta3-AR pharmacological profile unaltered in terms of specificity and selectivity. Aspartate residue 117, in the third transmembrane domain, has been found to be essential for ligand binding and consequently adenylyl cyclase activation in several bioamine receptors. When this residue was replaced by a leucine residue in the beta3-AR, ligand binding and signal transduction were suppressed. Finally, replacement of asparagine at position 312 in the sixth transmembrane domain by an alanine residue, led to alterations in the signal-transduction pathway.     

Excitatory amino acid receptor antagonists: resolution, absolute stereochemistry, and pharmacology of (S)- and (R)-2-amino-2-(5-tert-butyl-3-hydroxyisoxazol-4-yl)acetic acid (ATAA)

We have previously shown that (RS)-2-amino-2-(5-tert-butyl-3-hydroxyisoxazol-4-yl)acetic acid (ATAA) is an antagonist at N-methyl-D-aspartic acid (NMDA) and (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors. We have now resolved ATAA via diastereomeric salt formation using N-BOC protected ATAA and (R)- and (S)-phenylethylamine. Enantiomeric purities (ee > 98%) of (R)- and (S)-ATAA were determined using the Crownpak CR(-) and CR(+) columns, respectively. The absolute configuration of (R)-ATAA was established by an X-ray crystallographic analysis of the (R)-phenylethylamine salt of N-BOC-(R)-ATAA. Like ATAA, neither (R)- nor (S)-ATAA significantly affected (IC50 > 100 microM) the receptor binding of tritiated AMPA, kainic acid, or (RS)-3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid, the latter being a competitive NMDA antagonist. Electrophysiological experiments, using the rat cortical wedge preparation, showed the NMDA antagonist effect as well as the AMPA antagonist effect of ATAA to reside exclusively in the (R)-enantiomer (Ki = 75 +/- 5 microM and 57 +/- 1 microM, respectively). Neither (R)- nor (S)-ATAA significantly reduced kainic acid-induced excitation (Ki > 1,000 microM).     

Excitatory amino acid receptor ligands: resolution, absolute stereochemistry, and enantiopharmacology of 2-amino-3-(4-butyl-3-hydroxyisoxazol-5-yl)propionic acid

(RS)-2-Amino-3-(4-butyl-3-hydroxyisoxazol-5-yl)propionic acid (Bu-HIBO, 6) has previously been shown to be an agonist at (RS)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)propionic acid (AMPA) receptors and an inhibitor of CaCl2-dependent [3H]-(S)-glutamic acid binding (J. Med. Chem. 1992, 35, 3512-3519). To elucidate the pharmacological significance of this latter binding affinity, which is also shown by quisqualic acid (3) but not by AMPA, we have now resolved Bu-HIBO via diastereomeric salt formation using the diprotected Bu-HIBO derivative 11 and the enantiomers of 1-phenylethylamine (PEA). The absolute stereochemistry of (S)-Bu-HIBO (7) (ee = 99.0%) and (R)-Bu-HIBO (8) (ee > 99.6%) were established by an X-ray crystallographic analysis of compound 15, a salt of (R)-PEA, and diprotected 8. Circular dichroism spectra of 7 and 8 were recorded. Whereas 7 (IC50 = 0.64 microM) and 8 (IC50 = 0.57 microM) were equipotent as inhibitors of CaCl2-dependent [3H]-(S)-glutamic acid binding, neither enantiomer showed significant affinity for the synaptosomal (S)-glutamic acid uptake system(s). AMPA receptor affinity (IC50 = 0.48 microM) and agonism (EC50 = 17 microM) were shown to reside exclusively in the S-enantiomer, 7. Compounds 7 and 8 did not interact detectably with kainic acid or N-methyl-D-aspartic acid (NMDA) receptor sites. Neither 7 nor 8 affected the function of the metabotropic (S)-glutamic acid receptors mGlu2 and mGlu4a, expressed in CHO cells. Compound 8 was shown also to be inactive at mGlu1 alpha, whereas 7 was determined to be a moderately potent antagonist at mGlu1 alpha (Ki = 110 microM) and mGlu5a (Ki = 97 microM). Using the rat cortical wedge preparation, the AMPA receptor agonist effect of 7 was markedly potentiated by coadministration of 8 at 21 degrees C, but not at 2-4 degrees C. These observations together indicate that the potentiation of the AMPA receptor agonism of 7 by 8 is not mediated by metabotropic (S)-glutamate receptors but rather by the CaCl2-dependent (S)-glutamic acid binding system, which shows the characteristics of a transport mechanism. After intravenous administration in mice, 7 (ED50 = 44 mumol/kg) was slightly more potent than AMPA (1) (ED50 = 55 mumol/kg) and twice as potent as Bu-HIBO (6) (ED50 = 94 mumol/kg) as a convulsant, whereas 8 was inactive. After subcutaneous administration in mice, Bu-HIBO (ED50 = 110 mumol/kg) was twice as potent as AMPA (ED50 = 220 mumol/kg) as a convulsant. Since 7 and Bu-HIBO (EC50 = 37 microM) are much weaker than AMPA (EC50 = 3.5 microM) as AMPA receptor agonists in vitro, the presence of a butyl group in the molecules of Bu-HIBO and 7 seems to facilitate the penetration of these compounds through the blood-brain barrier.     

Cellular response to treatment with 4-(3-(2-chloroethyl)-3-nitrosoureido)-cis-cyclohexanecarboxylic acid, a water-soluble nitrosourea derivative

The lethal effects of 4-(3-(2-chloroethyl)-3-nitrosoureido)-cis-cyclohexanecarboxylic acid (cis-acid), a water-soluble nitrosourea derivative, were investigated on a human lymphoma cell line. The survival of asynchronous cells exposed to increasing concentrations of the drug was characterized by a threshold exponential curve (Do = 20 microgram/ml; Dq = 20 microgram/ml, 1 hour) similar to that of other nitrosourea derivatives. cis-Acid exerted its main killing effect on cells in early S and in late G2 phase. Cells in mid S and early G1 phase were tenfold more resistant. Changes in survival response as a function of cell cycle stage were reflected primarily by changes in the extent of the shoulder region of the survival curve. In contrast to other nitrosoureas, the lethal effectiveness of cis-acid in solution was stable and the drug could sterilize large numbers of cells in short periods of time. Another important major difference observed for cis-acid with respect to classic nitrosourea derivatives was the capacity of treated cells to recover from sublethal and potentially lethal damage. Our studies have shown that cis-acid is as effective in killing cultured human lymphoma cells as other nitrosoureas, but possibly with a mechanism different from that of these compounds. The major shortcoming noted for cis-acid, namely the capacity of treated cells to recover from drug-induced damage, is offset by the relatively long stability of its killing effect. This, and the fact that cis-acid can be administered in an aqueous solution, make this agent an appealing compound for clinical trials.     

Studies of the antagonist actions of (RS)-2-amino-3-[5-tert-butyl-3-(phosphonomethoxy)-4-isoxazolyl] propionic acid (ATPO) on non-NMDA receptors in cultured rat neurones

Whole-cell patch-clamp recordings from single cultured cortical neurones have been used to study the action of (RS)-2-amino-3-[5-tert-butyl-3-(phosphonomethoxy)-4-isoxazolyl+ ++]propionic acid (ATPO), which has previously been proposed to be a potent selective antagonist of 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptors. ATPO competitively reduced peak responses evoked by semi-rapid applications of AMPA (Ki = 16 microM) but had variable effects on plateau responses, which were on average unchanged. Following blockade of AMPA receptor desensitization by cyclothiazide (CTZ, 100 microM), the plateau responses were reduced by ATPO to a similar extent as the peak responses, indicating that ATPO reduces desensitization of AMPA receptors. Semi-rapid application of kainic acid (KA) and the KA receptor-selective agonist, (2S,4R)-4-methylglutamic acid (MeGlu) evoked non-desensitizing responses which were competitively antagonized by ATPO (Ki values: 27 and 23 microM, respectively). Responses to MeGlu were unaffected by CTZ (100 microM), but potentiated 3 fold following blockade of KA receptor desensitization by concanavalin A (Con A, 300 microg ml(-1)). Responses of spinal cord neurones to MeGlu were blocked by ATPO to a similar extent before and after blockade of KA receptor desensitization by Con A. Although selectively potentiated by Con A, plateau responses to MeGlu were reduced by 69.6% by the AMPA selective antagonist, GYKI 53655 (10 microM). The remaining component was further reduced by ATPO with a Ki of 36 microM, which was not significantly different from that in the absence of GYKI 53655, but was greater than that on responses to AMPA. It is concluded that ATPO is a moderate-potency competitive inhibitor of naturally expressed non-NMDA receptors.     

Modulation of the antitumor activity of 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosoure a by O(6)-methyl-2'-deoxyguanosine--a new inhibitor of O(6)-alkylguanine-DNA-alkyltransferase

O6-Methyl-2'-deoxyguanosine (O6-MedG), a novel inhibitor of O6-alkylguanine-DNA alkyltransferase (O6-AGT), has been synthesized. The ability of O6-MedG to deplete the O6-AGT activity in leukemia L1210 and melanoma B16 cells in vivo has been studied. After intraperitoneal administration of O6-MedG to mice bearing leukemia L1210 or melanoma B16, the activity of O6-AGT in tumour cells decreased by 50%. Pretreatment of leukemia L1210 bearing mice with O6-MedG (200 mg/kg) 24 hours prior to ACNU (15 mg/kg) administration resulted in six out of seven 60-day survivors. Treatment of mice with ACNU (15 mg/kg) alone increased the life span by 200%. Treatment of melanoma B16 bearing mice with O6-MedG and 3 hours thereafter with ACNU resulted in a 50% inhibition of tumour growth, whereas the inhibiting effect of ACNU alone was 16%. There was no difference in leukemia growth when L1210/BCNU bearing mice were treated with O6-MedG followed by ACNU treatment. In vivo ACNU (15 mg/kg) produced a deep and prolonged inhibition of DNA, RNA and protein synthesis in leukemia L1210 cells. The DNA synthesis in leukemia L1210/BCNU cells was shown to recover more rapidly than in L1210 cells. The activities of DNA-polymerases alpha and beta and, especially, of O6-AGT were elevated in ACNU-resistant leukemia cells as compared with ACNU-sensitive cells. The activation of some repairing enzymes, such as O6-AGT, DNA-polymerases alpha and beta as well as increased levels of GSH may play a role in the development of drug resistance to ACNU.     

(3R,4S)-3-[4-(4-fluorophenyl)-4-hydroxypiperidin-1-yl]chroman-4,7-diol: a conformationally restricted analogue of the NR2B subtype-selective NMDA antagonist (1S,2S)-1-(4-hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)- 1-propanol

(1S,2S)-1-(4-Hydroxyphenyl)-2-(4-hydroxy-4-phenylpiperidino)-1-propanol (CP-101,606, 1) is a recently described antagonist of N-methyl-D-aspartate (NMDA) receptors containing the NR2B subunit. In the present study, the optimal orientation of compounds of this structural type for their receptor was explored. Tethering of the pendent methyl group of 1 to the phenolic aromatic ring via an oxygen atom prevents rotation about the central portion of the molecule. Several of the new chromanol compounds have high affinity for the racemic [3H]CP-101,606 binding site on the NMDA receptor and protect against glutamate toxicity in cultured hippocampal neurons. The new ring caused a change in the stereochemical preference of the receptor-cis (erythro) compounds had better affinity for the receptor than the trans isomers. Computational studies suggest that steric interactions between the pendent methyl group and the phenol ring in the acyclic series determine which structures can best fit the receptor. The chromanol analogue, (3R,4S)-3-[4-(4-fluorophenyl)-4-hydroxypiperidin-1- yl]chroman-4,7-diol (12a, CP-283,097), was found to possess potency and selectivity comparable to CP-101,606. Thus 12a is a new tool to explore the function of the NR2B-containing NMDA receptors.     

2-氨基-4-(4-甲氧基苯基)-6-(哌啶-1-基)-3,5-二腈基吡啶的三组分合成与表征

在甲醇溶剂中,以丙二腈、4-甲氧基苯甲醛、哌啶为原料,常温下经三组分一锅法合成得到了未见文献报道的新化合物2-氨基-4-(4-甲氧苯基)-6-(哌啶-1-基)-3,5-二腈基吡啶,收率40%.其化学结构经过1H NMR、MS及单晶衍射进行表征.     

Comparison of the effects of R-(-)-2-amino-1-(2,5-dimethoxy-4-methylphenyl) propane (DOM), r-(-)-2-amino-1-(2,5-dimethoxy-4-methylphenyl) butane (BL-3912A) and 5-hydroxytryptamine on non-innervated vascular smooth muscle

Human growth hormone (HGH) and somatomedin (Sm) concentrations have been studied in a group of newborns. Plasma HGH values were 41.17 +/- 24.26 (SD) ng/ml (14.00-90.00 ng/ml) and the Sm value was 0.59 +/- 0.43 (SD) U/ml (0.18-1.8 U/ml); the difference between these values and the ones observed in normal adults (2.45 +/- 2.53 (SD) ng/ml and 1.16 +/- 0.28 (SD) U/ml respectively) were statistically significant. While growth hormone values were higher than in normal adult controls, somatomedin was significantly decreased. It is possible that the dissociation between human growth hormone and somatomedin in newborn could reflect a reduced biosynthesis of the somatomedin-generating system and consequently a lack of a feed-back control on GH exerted by somatomedin.     

Light-stimulated release of dopamine from the primate retina is blocked by 1-2-amino-4-phosphonobutyric acid (APB)

Can the coupling effect among different amino acid components be used to improve the prediction of protein structural classes? The answer is yes according to the study by Chou and Zhang (Crit. Rev. Biochem. Mol. Biol. 30:275-349, 1995), but a completely opposite conclusion was drawn by Eisenhaber et al. when using a different dataset constructed by themselves (Proteins 25:169-179, 1996). To resolve such a perplexing problem, predictions were performed by various approaches for the datasets from an objective database, the SCOP database (Murzin, Brenner, Hubbard, and Chothia. J. Mol. Biol. 247:536-540, 1995). According to SCOP, the classification of structural classes for protein domains is based on the evolutionary relationship and on the principles that govern the 3D structure of proteins, and hence is more natural and reliable. The results from both resubstitution tests and jackknife tests indicate that the overall rates of correct prediction by the algorithm incorporated with the coupling effect among different amino acid components are significantly higher than those by the algorithms without using such an effect. It is elucidated through an analysis that the main reasons for Eisenhaber et al. to have reached an opposite conclusion are the result of (1) misusing the component-coupled algorithm, and (2) using a conceptually incorrect rule to classify protein structural classes. The formulation and analysis presented in this article are conducive to clarify these problems, helping correctly to apply the prediction algorithm and interpret the results.     

Structural optimization affording 2-(R)-(1-(R)-3, 5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluoro)phenyl-4- (3-oxo-1,2,4-triazol-5-yl)methylmorpholine, a potent, orally active, long-acting morpholine acetal human NK-1 receptor antagonist

Structural modifications requiring novel synthetic chemistry were made to the morpholine acetal human neurokinin-1 (hNK-1) receptor antagonist 4, and this resulted in the discovery of 2-(R)-(1-(R)-3, 5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluoro)phenyl-4-(3-ox o-1 ,2,4-triazol-5-yl)methyl morpholine (17). This modified compound is a potent, long-acting hNK-1 receptor antagonist as evidenced by its ability to displace [125I]Substance P from hNK-1 receptors stably expressed in CHO cells (IC50 = 0.09 +/- 0.06 nM) and by the measurement of the rates of association (k1 = 2.8 +/- 1.1 x 10(8) M-1 min-1) and dissociation (k-1 = 0.0054 +/- 0.003 min-1) of 17 from hNK-1 expressed in Sf9 membranes which yields Kd = 19 +/- 12 pM and a t1/2 for receptor occupancy equal to 154 +/- 75 min. Inflammation in the guinea pig induced by a resiniferatoxin challenge (with NK-1 receptor activation mediating the subsequent increase in vascular permeability) is inhibited in a dose-dependent manner by the oral preadmininstration of 17 (IC50 (1 h) = 0.008 mg/kg; IC90 (24 h) = 1.8 mg/kg), indicating that this compound has good oral bioavailbility and peripheral duration of action. Central hNK-1 receptor stimulation is also inhibited by the systemic preadministration of 17 as shown by its ability to block an NK-1 agonist-induced foot tapping response in gerbils (IC50 (4 h) = 0.04 +/- 0.006 mg/kg; IC50 (24 h) = 0.33 +/- 0.017 mg/kg) and by its antiemetic actions in the ferret against cisplatin challenge. The activity of 17 at extended time points in these preclinical animal models sets it apart from earlier morpholine antagonists (such as 4), and the piperidine antagonists 2 and 3 and could prove to be an advantage in the treatment of chronic disorders related to the actions of Substance P. In part on the basis of these data, 17 has been identified as a potential clinical candidate for the treatment of peripheral pain, migraine, chemotherapy-induced emesis, and various psychiatric disorders.     

Nephrotoxic potential of 2-amino-5-chlorophenol and 4-amino-3-chlorophenol in Fischer 344 rats: comparisons with 2- and 4-chloroaniline and 2- and 4-aminophenol

Nephrotoxicity occurs following intraperitoneal (i.p.) administration of 2-chloroaniline or 4-chloroaniline hydrochloride to Fischer 344 rats, but the nephrotoxicant chemical species and mechanism of nephrotoxicity are unknown. The purpose of this study was to evaluate the in vivo and in vitro nephrotoxic potential of 2-amino-5-chlorophenol and 4-amino-3-chlorophenol, metabolites of 4-chloroaniline and 2-chloroaniline. A comparison was also made between the nephrotoxic potential of the aminochlorophenols and the corresponding aminophenols to examine the effect of adding a chloride group on the nephrotoxic potential of the animophenols. Male Fischer 344 rats (4/group) were given an i.p. injection of a chloroaniline or aminochlorophenol hydrochloride (1.5 mmol/kg), and aminophenol (1.0 or 1.5 mmol/kg), or vehicle, and renal function monitored at 24 and 48 h. Both aminochlorophenols induced smaller and fewer renal effects that the parent chloroanilenes in vivo. Also, 4-aminophenol was markedly more potent as a nephrotoxicant that 4-amino-3-chlorophenol, while 2-aminophenol and 2-amino-5-chlorophenol induced only mild change in renal function. In vitro, the phenolic compounds reduce p-aminohippurate accumulation by renal cortical slices at bath concentrations of 0.01 mM, while a bath concentration of 0.50 mM or greater was required for the chloroanilines. However, all compounds reduced tetraethylammonium accumulation at bath concentrations of 0.1-0.5 mM or greater. These results indicate that extrarenally-produced aminochlorophenol metabolites do not contribute to the mechanism of chloroaniline nephrotoxicity. Also, the reduced nephrotoxic potential of 4-amino-3-chlorophenol compared to 4-aminophenol could result from an altered ability of the aminochlorophenol to redox cycle or form conjugates.     

(2Z,4E)-5-(5,6-dichloro-2-indolyl)-2-methoxy-N-(1,2,2,6,6- pentamethylpiperidin-4-yl)-2,4-pentadienamide, a novel, potent and selective inhibitor of the osteoclast V-ATPase

Optimisation of a novel series of osteoclast ATPase inhibitors led to (2Z,4E)-5-(5,6-dichloro-2-indolyl)-2-methoxy-N-(1,2,2,6,6- pentamethylpiperidin-4-yl)-2,4-pentadienamide (1) that was the most potent compound in an in vitro osteoclast ATPase assay and in human bone resorption assays. Two of the possible geometric isomers have also been prepared and shown to be significantly less potent than 1.     

新试剂1-(4-安替比林)-3-(对苯甲酸)-三氮烯的合成及其应用研究

以4-氨基安替比林和对氨基苯甲酸为原料,经重氮化和偶联两步反应合成了一个新的三氮烯类显色剂:1-(4-安替比林)-3-(对苯甲酸)-三氮烯(ABTA),并用红外光谱和元素分析对其结构进行了表征.同时,研究了新试剂与Pd(Ⅱ)的显色反应条件,建立了一个测定钯的光度分析新方法.在最佳实验条件下,Pd(Ⅱ)的质量浓度在0.25～2.8μg/ml范围内符合比尔定律, 其摩尔吸光系数ε=2.87×104 L/(mol·cm),大量常见离子对Pd(Ⅱ)的测定不干扰.该方法用于催化剂样品中钯的测定,结果令人满意.     

Pharmacodynamics of 2-(4-benzyl-piperidino)-1-(4-hydroxyphenyl)-1-propanol (Ifenprodil). (3) Effects on the autonomic, peripheral and central nervous systems

Effects of ifenprodil tartrate, a potent vasodilator, on the autonomic, peripheral and central nerve system were studied in experimental animals. In isolated vas deferens of guinea pigs, the contraction in response to noradrenaline and sympathetic nerve stimulation was competetively antagonized by ifenprodil 10(-7)--10(-5) M (pA2: 7.69 against noradrenaline). Ifenprodil (50 approximately 1,000 mug/kg i.v.) inhibited the contraction of cat nictitating membrane and dog urinary bladder induced by sympathetic nerve stimulation. Ifenprodil (250 approximately 1,000 mug/kg i.v.) lowered adrenaline-induced lethality (ED50: 360 mug/kg). The drug produced a hypermotility of guinea pig uterus, and showed a transient hypertonus of dog gut which was abolished by atropine. Ifenprodil (10 approximately 20 mg/kg i.v.) inhibited the propulsion of charcoal meal in mice. In Shay rats, more than 10 mg/kg i.m. of the drug inhibited the secretion of acid gastric juice and the ulceration. Ifenprodil showed a potent local anesthetic action in the guinea pig cornea and skin. The spontaneous EEG of rabbits showed a resting pattern (0.25 approximately 2 mg/kg i.v.) followed by an arousal pattern (5 approximately 10 mg/kg). Ifenprodil (20 approximately 100 mg/kg p.o.) potentiated a hypnosis induced by barbital, and potentiated pentylenetetrazol, strychnine and picrotoxin induced convulsion. The drug (20 and 100 mg/kg p.o.) lowered the body temperature of rats. From these results it is concluded that ifenprodil produces a blocking action of alpha-adrenoceptors in various smooth muscle preparations and a direct relaxation of the smooth muscle itself without affecting the motor and central nerve systems.     

Preparation and antirheumatic activity of optically active 2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298)

2-Acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanonic acid (KE-298) is an antirheumatic agent. To elucidate the effects of optically active KE-298, we resolved the racemic acid and obtained the two optical isomers. (+)-KE-298 was converted to the 4-bromobenzyl ester derivative and the absolute structure was confirmed as (S) by X-ray crystallographic analysis. The pharmacological activities of the optical isomers and racemic KE-298 were compared by using the characteristic tests for KE-298. Though (+)-KE-298 showed a stronger suppressive effect on rat adjuvant arthritis than (-)-KE-298, no difference between the two isomers was detected in in vitro tests (enhancing effect on lymphocyte transformation, IL-1 antagonistic effect).