Further studies on the pharmacological effect of the anti-inflammatory compound, bis[2-(E-2-octenoylamino)ethyl] disulfide

Further studies on the pharmacological effect of orally administered bis[2-(E-2-octenoyl-amino)ethyl] disulfide (compd. I-3) was examined by using several experimental models in vivo. Compound I-3 showed analgesic activity, inhibiting both acetic acid- and acetylcholine-induced writhings in mice. This compound also showed antipyretic activity against yeast-induced fever in rats, and significantly inhibited arachidonic acid-induced mortality in mice. However, it had no effect on serotonin-induced paw edema formation or platelet activating factor-acether-induced mortality in mice. The effects of compd. I-3 are suggested to be due to inhibition of prostaglandin biosynthesis.     

The inhibitory effect of bis[2-[(E)-2-octenoylamino]ethyl] disulfide on the cyclooxygenase pathway

Bis[2-[(E)-2-octenoylamino]ethyl] disulfide (compd. I-3) inhibited collagen- and arachidonic acid-induced rat platelet aggregation, although not adenosine 5'-diphosphate (ADP)-induced rat platelet aggregation. Based on these results, we then investigated the inhibitory effect of compd. I-3 on thromboxane B2 formation from arachidonic acid in rat platelets, and prostaglandin I2 formation in rat aortae. Compound I-3 inhibited both thromboxane B2 and prostaglandin I2 formation, suggesting that it has an inhibitory effect on cyclooxygenase. The inhibitory effect of compd. I-3 was confirmed in experiments using a crude preparation of sheep seminal vesicle microsomal prostaglandin synthetase. These findings suggested that compd. I-3 has an inhibitory effect on cyclooxygenase activity, like nonsteroidal anti-inflammatory drugs.     

Further studies on the anti-ulcerogenic effects of compound, 2-(E-2-decenoylamino)ethyl 2-(cyclohexylethyl) sulfide.

Tha anti-ulcerogenic mechanism of 2-(E-2-decenoylamino)ethyl 2-(cyclohexylethyl) sulfide (compd. III-1a) was investigated in various gastric defensive factors. Compound III-1a maintained the high molecular glycoprotein (relative content of Fr. I hexose) and accelerated hexosamine synthesis which were reduced by water immersion stress. But plaunotol did not have these actions. The lipid peroxide level in the gastric mucosa from water immersion stressed rat was lowered by the administration of compd. III-1a. Compound III-1a maintained prostaglandin E2 (PGE2) and PGI2 contents which were reduced in the early phase of the stress and accelerated PGs synthesis in the late phase of the stress. Furthermore, compd. III-1a maintained phospholipase A2 (PLA2) activity which was reduced by the stress. The plaunotol treated group showed the same tendency as the compd. III-1a treated group on the lipid peroxide level, PGE2 and PGI2 contents, and PLA2 activity, but the potency of plaunotol was less than that of compd. III-1a. Compound III-1a accelerated gastric cell proliferation in pyloric glands of hydrocortisone treated rats. Tetragastrin accelerated significantly the cell proliferation in fundic glands. The sucralfate treated group showed the same tendency as the compd. III-1a treated group but the potency of sucralfate was less than that of compd. III-1a. The results in the present study suggest that compd. III-1a has a protective action on gastric mucosa.     

Effects of 2-(E-2-decenoylamino)ethyl 2-(cyclohexylethyl) sulfide on various ulcer models in rats.

The effects of 2-(E-2-decenoylamino)ethyl 2-(cyclohexylethyl) sulfide (compd. III-1a) on various experimental ulcers were investigated. The oral administration of compd. III-1a at doses ranging from 30 to 300 mg/kg inhibited the acute gastric ulcerations induced by ethanol, HCl.aspirin and indomethacin in rats. Compound III-1a significantly inhibited the water immersion stress-induced gastric ulcer at doses of 3 mg/kg, p.o. The anti-ulcer activity of plaunotol as a reference drug was equivalent on an ethanol-induced ulcer to that of compd. III-1a, but weaker on HCl.aspirin, indomethacin and stress-induced ulcers than that of compd. III-1a. On indomethacin-produced gastric antral ulcer, compd. III-1a showed the same significant inhibitory activity as spizofurone did at a dose of 100 mg/kg, p.o. Compound III-1a also inhibited hemorrhagic shock-, diethyldithiocarbamic acid (DDC)-and platelet activating factor (PAF)-induced ulcers dose-dependently. Plaunotol only showed significant inhibitory activity on PAF-induced ulcer in these three ucler models. The consecutive administration of compd. III-1a (100 mg/kg, p.o.) twice a day significantly accelerated the healing of an acetic acid-induced ulcer and that of plaunotol (200 mg/kg, p.o.) showed the same activity. Moreover, orally administered compd. III-1a at a dose of 100 mg/kg decreased the gastric acid secretion in pylorus-ligated rats. The results in the present study suggest that compd. III-1a has the dual action on ulcer formation.     

Synthesis,Reactions, and Structure of 5-Cyano-4-ethoxy-1-ethoxycarbonyl-2-methylazuleno[1,8-b,c]pyran

Bicyclic azulene compounds, ethyl 4-(cyanoethoxycarbonylmethyl)-2-methylazulene-1-carboxylate (2) and ethyl 4-(cyanoethoxycarbonylmethyl)azulene-1-carboxylate (3) were prepared from ethyl 4-chloro-2-methylazulene-1-carboxylate (7) and ethyl 4-ethoxyazulene-1-carboxylate (8), respectively. Oxidation of 2 with DDQ gave the title compound, 5-cyano-4-ethoxy-1-ethoxycarbonyl-2-methylazuleno[1,8-b,c]pyran (1) and a minor compound, ethyl 4-cyanomethyl-2-methylazulene-1-carboxylate (9). Oxidation of 3 by DDQ produced only ethyl 4-cyanomethylazulene-1-carboxylate (10), Reaction of 1 with 100% H₃PO₄ at room temperature and 100 °C gave 5-cyano-4-ethoxy-2-methylazuleno[1,8-b,c]pyran (11) and 2-methyl-4,5-dihydrozuleno[1,8-b,c]pyran-4-one (12), respectively. All the new compounds were characterized by IR, UV-vis, NMR and Mass spectra, and the structure of 1 was determined by X-ray crystallography. Crystal data for 1; space group P2₁/n, a = 7.391(1), b = 9.660(5), c = 22.859(1) Å, B = 97.01(1)°, V = 1620.0(3) ų, Z = 4, with final residuals R = 0.047 and Rw = 0.055.     

Syntheses of 2-(2-arylethyl)imidazoles

Condensation of 2-methylimidazole with arylaldehyde 4 and subsequent reduction of the intermediate 5 with Raney-nickel gave 2-[2-(2,4-dichlorophenyl)ethyl]imidazole 2 . Compound 11 was prepared from compound 10 similarly. Reaction of compound 2 with methylsulfonyl chloride gave 1-methylsulfonyl-2-[2-(2,4-dichlorophenyl)ethyl]imidazole ( 7a ) in moderate yield. Nitration of compound 11 (Ar = 3-pyridyl) gave the desired nitro compounds 14 and 15 .     

2-(O-Phenylalkyl)phenoxy]alkylamines III: Synthesis and selective serotonin-2 receptor binding (2)

A series of 12-(2-phenylethyl)phenoxy]ethylpyrrolidine derivatives were synthesized, and their affinity for serotonin-2 (5-HT2) and dopamine-2 (D2) receptors was examined. Among them, compound 17, (2R,4R)-4-hydroxy-2-[2-[2-[2-(3-methoxyphenyl)ethyl]phenoxylethyl] -1-methylpyrrolidine hydrochloride, showed high 5-HT2 receptor affinity in vitro. This compound was a more potent inhibitor of ex vivo 5-HT-induced platelet aggregation than compound 3, which was previously shown to be more potent than ketanserin (1) and sarpogrelate (2a). However, compound 17 produced gastric irritation in rats. Therefore, we carried out a further derivatization of 17, and compound 45 (R-102444), a lauryl ester prodrug of compound 17, was found to be a promising candidate as an antithrombotic agent. Oral administration of R-102444 produced a marked inhibition of 5-HT-induced ex vivo platelet aggregation, and R-102444 did not cause any gastric irritation. The antiaggregatory effects of R-102444 were more potent than those of sarpogrelate (2a) and its active metabolite, M-1 (2b). In addition, R-102444 exhibited more potent antithrombotic effects than sarpogrelate in a rat photochemically-induced thrombosis model.     

Six new 2-(2-phenylethyl)chromones from Agarwood

Six new chromones, 6-methoxy-2-[2-(3-methoxy-4-hydroxyphenyl)ethyllchromone (2), 6,8-dihydroxy-2-(2-phenylethyl)chromone (3), 6-hydroxy-2-[2-(4-hydroxyphenyl)ethyl]chromone (4), 6-hydroxy-2-[2-(2-hydroxyphenyl)ethyl]chromone (5), 7-hydroxy-2-(2-phenylethyl)chromone (6), and 6-hydroxy-7-methoxy-2-(2-phenylethyl)chromone (7) were isolated from the ether extract of agarwood in addition to a known compound, 2-(2-phenylethyl)chromone or flidersiachromone (1). Their structures were determined by spectroscopic methods including UV, IR, and NMR spectral data and comparisons with the calculated values using the hydroxyl and methoxyl substituent increments of the chromone ring.     

Formation of S-[2-carboxy-1-(1H-imidazol-4-yl) ethyl]glutathione, a new metabolite of L-histidine, from cis-urocanic acid and glutathione by the action of glutathione S-transferase

Exposure of the skin to sunlight results in an increase of the content of epidermal trans-urocanic acid, a key metabolite of L-histidine, and also in occurrence of the isomerization of trans-urocanic acid to the cis isomer. S-[2-Carboxy-1-(1H-imidazol-4-yl)ethyl]glutathione (GS(CIE)), an adduct of urocanic acid and glutathione, is a presumed origin of a urinary compound S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]-L-cysteine (Cys(CIE)). The formation of GS(CIE) is stimulated by exposing the skin to sunlight irradiation. In this study we investigated an enzymatic formation of GS(CIE) from glutathione and cis-urocanic acid by incubation with rat liver extract that contained glutathione S-transferase (GST) at high activity. The formation of GS(CIE) was suppressed significantly when a liver extract depleted of GST activity was used. Enzymatic degradation of GS(CIE) with gamma -glutamyl transpeptidase resulted in the formation of N-[S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]-L-cysteinyl]glycine, a metabolic intermediate between the glutathione adduct and Cys(CIE). A hydrolyzed product of GS(CIE) by HCl was identical with the urinary Cys(CIE). Compounds were analyzed by high-voltage paper electrophoresis, capillary electrophoresis, and fast atom bombardment mass spectrometry. From these results, we suggest that GS(CIE) formed from cis-urocanic acid and glutathione is an origin of the urinary compound Cys(CIE) and that the formation reaction is catalyzed mostly by the action of GST.     

Design, synthesis and antiinflammatory activity of a new indomethacin ester. 2-[N-[3-(3-(piperidinomethyl)phenoxy)propyl]carbamoylmethylthio]ethyl 1-(p-chlorobenzoyl)-5-methoxy-2-methyl-indole-3-acetate

A novel indomethacin ester prodrug, 2-[N-[3-(3-(piperidinomethyl)phenoxy)propyl]carbamoylmethylthio ]ethyl 1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetate (1) was prepared from a new histamine H2-receptor antagonist, N-[3-(3-(piperidinomethyl)phenoxy)propyl]-2-(2-hydroxyethylthio )acetamide (2) and indomethacin (3). The compound 1 was shown to be essentially similar to 3 in its antiinflammatory action and to almost completely inhibit carrageenin-induced hind-paw edema in the rat at a very high dose of 230 mg/kg (280 mumol/kg), which is comparable to that of 100 mg/kg (280 mumol/kg) of 3, without producing gastric lesions. On a molar basis, the acute gastric lesioning properties of 1 were near one-hundred times less than those of 3, resulting in over a twenty-fold improvement in the ratio of antiedema activity to ulcerogenicity. The effect of the co-administration of histamine H2-receptor antagonists on antiedema activity and ulcerogenicity caused by 3 is also discussed.     

Microwave spectrum, structure, and quantum chemical studies of a compound of potential astrochemical and astrobiological interest: Z-3-amino-2-propenenitrile

Z-3-Amino-2-propenenitrile, H2NCH=CHCN, a compound of astrochemical and astrobiological interest, has been studied by Stark and Fourier transform microwave spectroscopy along with eight of its isotopologues; the synthesis of five of these are reported. The spectra of the ground vibrational state and of three vibrationally excited states belonging to the two lowest normal modes were assigned for the parent species, whereas the ground states were assigned for the isotopologues. The frequency of the lowest in-plane bending fundamental vibration was determined to be 152(20) cm(-1) and the frequency of the lowest out-of-plane fundamental mode was found to be 176(20) cm(-1) by relative intensity measurements. A delicate problem is whether this compound is planar or slightly nonplanar. It was found that the rotational constants of the nine species cannot be used to conclude definitely whether the molecule is planar or not. The experimental dipole moment is mu(a) = 16.45(12), mu(b) = 2.86(6), mu(c) = 0 (assumed), and mu(tot.) = 16.70(12) x 10(-30) C m [5.01(4) D]. The quadrupole coupling constants of the two nitrogen nuclei are chi(aa) = -1.4917(21) and chi(cc) = 1.5644(24) MHz for the nitrogen atom of the cyano group and chi(aa) = 1.7262(18) and chi(cc) = -4.0591(17) MHz for the nitrogen atom of the amino group. Extensive quantum-chemical calculations have been performed, and the results obtained from these calculations have been compared with the experimental values. The equilibrium structures of vinylamine, vinyl cyanide, and Z-3-amino-2-propenenitrile have been calculated. These calculations have established that the equilibrium structure of the title compound is definitely nonplanar. However, the MP2/VQZ energy difference between the planar and nonplanar forms is small, only -423 J/mol. Z-Amino-2-propenenitrile and E-3-amino-2-propenenitrile are formed simply by mixing ammonia and cyanoacetylene at room temperature. A plausible reaction path has been modeled. G3 calculations indicate that the enthalpy (298.15 K, 1 atm) of the transition state is about 130 kJ/mol higher than the sum of the enthalpies of the reactants ammonia and cyanoacetylene. This energy difference is comparatively high, which indicates that both E- and Z-3-aminopropenenitrile are not likely to be formed in the gas phase in cold interstellar clouds via a collision between ammonia and cyanoacetylene. An alternative reaction between protonated cyanoacetylene (H-C[triple bond]C-C[triple bond]NH+) and ammonia is predicted to have a much lower activation energy than the reaction between the neutral molecules. Although protonated E- and Z-3-aminopropenenitrile in principle may be formed this way, it is more likely that a collision between NH3 and H-C[triple bond]C-C[triple bond]NH+ leads to NH4+ and H-C[triple bond]C-C[triple bond]N.     

Benzothiazoline derivatives. II. Preparation of N-substituted derivatives of 2-benzothiazolinethione by thiation of the 2-oxo analogs

Thuiation of the benzoate and acetate esters of 3-(2-hydroxyethyl)-2-benzothiazolinone (Ig) gave the corresponding thiones. The benzoate was then deblocked to yield 3-(2-hydroxyethyl)-2-benzothiazolinethione (Ik), a compound not accessible by direct addition or substitution. Attempts to introduce a chlorine (or bromine) atom in place of the hydroxy 1 group in the latter compound or its S-isomer, 2-(2-hydroxyethylthio)benzothiazole (11a), gave 2,3-dihydrothiazolo-[2,3-b ] benzothiazolium chloride (or bromide) (IIIa or b). The latter compound undergoes dihydrothiazolo ring opening when treated with sodium hydroxide or sodium sulfide to give bis[2-(2-benzolhiazolinon-,3-yl)ethyl]disulfide (IVc) or bis[2-(2-benzothiazolinethion-3-yl)ethyl] disulfide (lVb),respectively. 2-Benzothiazolinethione reacted with ethylenimine and with N-phenylethylenimine to give S-substituted derivatives. Addition to vinyl n-butyl ether gave the expected N-substituted derivative, which was found to undergo removal of the butyoxyethyl group when subjected to conventional conditions for ether cleavage.     

The synthesis of 1-[2-(dimethylamino)ethyl]-7,12-dihydro-3H-[2]-benzoxepino[4,3-e]indole : A potential antidepressant agent

The structures of doxepin and serotonin were overlayed using molecular graphics and 1 - [2-(dimethylamino)ethyl] - 7, 12 - dihydro - 3H - [2] - benzoxepino[4,3-e]indole(1) was proposed as a potential antidepressant agent. This paper deals with the synthesis of the title compound. Key steps in the synthesis include a regioselective electrophilic substitution at C-4 of ethyl 5-hydroxy-1-indolecarboxylate (4) and subsequent modification to 7,12-dihydro-3H-[2]-benzoxepino[4,3-e]indole(12). Standard procedures were then used to construct the dimethylaminoethyl side chain to yeild the title compound (1).     

Inhibitory effects of bis(2-aminohexyl)disulfide and its analogues on polymorphonuclear leukocyte functions in vitro.

Water soluble analogues of the anti-inflammatory compound, bis(2-aminopropyl)disulfide dihydrochloride (compd. I) with a butyl (II), phenyl (III), benzyl (IV) or pyrrolidinyl group (V) instead of the methyl group were synthesized, and their effects on the functions of cells related to inflammation were studied in vitro. Compounds II, III and IV showed much higher inhibitory activity than compd. I on formyl Met-Leu-Phe (FMLP)-induced O2(-)-generation of polymorphonuclear leukocytes (PMNs) and platelet aggregation. Compound II showed the strongest activity among the compounds (IC50 values: 2.6 microM). The inhibition of O2(-)-generation of PMNs by compd. II was the most effective when FMLP was used as a stimulant rather than when phorbol myristate acetate, A-23187 and opsonized zymosan were used. However, compd. II was not an O2(-)-scavenger. Compounds II, III and IV significantly inhibited a series of activation processes in PMNs, chemotaxis, phagocytosis and lysosomal enzyme release at doses ranging from 10 to 100 microM. Under these doses, compds II, III and IV did not affect the histamine release from mast cells or the hemolysis of erythrocytes. These results strongly suggest that the anti-inflammatory action caused by compd. II and its analogues was at least partly due to inhibition of several functions of PMNs and platelets.     

Chemistry of 6 -pyrido[4,3- ]carbazoles part II: synthetic approaches to 6 -9-methoxy-5, 11-dimethylpyrido[4,3- ] fluorenes

Synthetic approaches to 6 -9-methoxy-5, 11-dimethylpyrido[4,3- ] fluorene are described, thus 2-[1-(4-pyridyl)ethyl]6-methoxyindanone has been reacted with vinylmagnesium bromide to yield 2-[1-(4-pyridyl)ethyl]-6 methoxy-1-vinyl-1-indanol. However, on dehydration this compound rearranges to 2-[1-(4-pyridyl)ethyl]-3-ethylidene-5-methoxyindene rather than the required isomer 3-ethylidine-2-[1-(4-pyridyl)ethyl]-5-methoxyindane needed fro pericyclic ring-closure to the pyrido[4,3- ]fluorene system. Reaction of -2-[1-methyl-1-(4-pyridyl)methylene]-6-methoxyindanone with ethylene triphenylphosphorane similarly gives 6-methoxy-spiro-2-[1-(2,3-dimethyl-3-(4-pyridyl)-cyclopropyl) indanone rather than the desired indane.     

Synthesis, crystal structure, studies in solution and cytotoxicity of two new fluorescent platinum(II) compounds containing anthracene derivatives as a carrier ligand

Two new cytotoxic fluorescent platinum(II) compounds, cis-[Pt(A9opy)Cl2] (1) and cis-[Pt(A9pyp)(DMSO)Cl2] (2),have been designed, synthesized, and characterized by IR, 1H NMR, and 195Pt NMR spectroscopy; electrospray ionization mass spectrometry (ESI-MS); and single-crystal X-ray diffraction. The carrier ligands selected for thesynthesis of these fluorescent platinum(II) compounds are E-2-[1-(9-anthryl)-3-oxo-3-prop-2-enylpyridine] (abbreviatedas A9opy) and E-1-(9-anthryl)-3-(2-pyridyl)-2-propenone (abbreviated as A9pyp). The compound cis-[Pt(A9opy)Cl2](1) comprises a peculiar cis-platinum(II) organometallic compound, in which the platinum(II) ion is bound to the photoisomerizable carbon-carbon double bond of the carrier ligand. The effects of the metal-ion coordination on the photoisomerization of the carbon-carbon double bond of the ligand have been studied. In contrast, the carrier ligand A9pyp used for the synthesis of the cis-[Pt(A9pyp)(DMSO)Cl2] compound (2) does not undergo such anisomerization process and remains in the E conformation, while coordinated to the platinum(II) ion through the nitrogen of the pyridine ring. In addition to the synthesis and characterization, solution studies of both compounds have also been performed in detail, including NMR and ESI-MS spectroscopy. Moreover, a high degree of cytotoxicactivity of compound 1 was found, as compared to cisplatin and its corresponding platinum-free molecule, in a series of human tumor cell lines. Compound 2 was also found to be highly active against these cell lines but appeared less active compared to the platinum-free molecule.     

2-[2-(4, 6-二甲基)-嘧啶基]-4-苯基-1, 2, 4-恶二唑烷-3, 5-二酮的合成

异氰酸苯酯和N-[2-(4, 6-二甲基)-嘧啶基]-羟胺(5)反应生成1-[2-(4, 6-二甲基)-嘧啶基]-1-羟基-3-苯基脲(6)。化合物(6)在三乙胺存在下和氯甲酸乙酯反应生成2-[2-(4, 6-二甲基)-嘧啶基]-4-苯基-1, 2, 4-恶二唑烷-3, 5-二酮(1)。     

(Z)-1-[2-(三苄基锡基)乙烯基]环庚醇及其衍生物的合成和性质

通过三苄基氢化锡与1-乙快基环庚醇发生加成反应，得到了一种有机锡化合物 ：(Z)-1-[2-(三苄基锡基)乙烯基]环庚醇(1)．化合物1与I2，Br2和IC1按1：1和1 ：2摩尔比投料进行卤化反应，得到6种构型保持的有机锡一卤化物2-4及二卤化物 5-7．有机锡一卤化物3与KOH乙醇溶液反应，得到了相应的有机锡氢氧化物8．以上 8种新化合物均通过熔点测定、元素分析、锡含量测定、红外光谱、核磁共振氢谱 对其结构进行了表征．并对其中的有机锡化合物1，3，4，6，7进行了体外抗P388 血癌活性测定，其中有机锡化合物4，6，7表现出强效．     

Stereospezifität der neuroleptischen Wirkung und Chiralität von (+)-3-{2-[4-(8-Fluor-2-methyl-10,11-dihydrodibenzo[b,f]thiepin-10-yl)-1-piperazinyl]-äthyl}-2-oxazolidinon (16). 4. Mitteilung über tricyclische Antidepressiva und Neuroleptica

Stereospecifity of the neuroleptic activity and chirality of (+)-3-{2-[4-(8-fluoro-2-methyl-10, 11-dihydrodibenzo[b,f]thiepin-10-yl)-1-piperazinyl]ethyl}-2-oxazolidinone (16). The synthesis and stereospecific neuroleptic action in animals of the (+)-enantiomer of 3-{2-[4-(8-fluoro-2-methyl-10,11-dihydrodibenzo [b,f]thiepin-10-yl)-1-piperazinyl]ethyl}-2-oxazolidinone ( 16 ) are briefly described. The (10S)-configuration of this compound was determined by X-ray diffraction.     

Determination of S-[2-carboxy-1-(1H-imidazol-4-yl)ethyl]glutathione, a novel metabolite of L-histidine, in tissue extracts from sunlight-irradiated rat by capillary electrophoresis.

Exposure of the skin to sunlight results in an increase in the content of epidermal urocanic acid, a key metabolite of L-histidine, and some portions of the metabolite penetrate into the body fluid. S-[2-Carboxy-1-(1H-imidazol-4-yl)ethyl]glutathione (GS(CIE)), an adduct of glutathione and urocanic acid, was proposed to be an origin of a urinary compound, S-[2-carboxy-1-(1 H-imidazol-4-yl)ethyl]-L-cysteine (Cys(CIE)). Various catabolites of Cys(CIE) were also isolated from human urine previously. However, no direct evidence to show the existence of GS(CIE) as a biological material had been found. By using capillary electrophoresis, the glutathione adduct has now been found in the extracts of rat tissues from the kidney, liver, skin and blood when the rat was kept under conditions of sunlight irradiation after the fur on the dorsal skin had been clipped. On the other hand, no or a trace of GS(CIE) was determined in rat tissue extracts when the animal was kept indoor in usual manner. The glutathione adduct was isolated from the kidney extract of the sunlight-irradiated rat using ion-exchangers and high-voltage paper electrophoresis, and determined by fast-atom-bombardment mass spectrometry. These results indicate that GS(CIE) formation actually occurs in the body and that the formation is accelerated by exposing the rat to sunlight irradiation. From these findings, we propose an alternative pathway of histidine metabolism which is initiated by the adduction of urocanic acid to glutathione to form GS(CIE) and terminates with the formation of the urinary compounds via Cys(CIE).