Two new 2-(2-phenylethyl)chromones from Chinese eaglewood

Two new 2-(2-phenylethyl)chromones, (5S ^*,6R ^*,7S ^*)-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (1) and (5S ^*,6R ^*,7R ^*)-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (2), were isolated from the Chinese eaglewood of Aquilaria sinensis (Lour.) Gilg. Their structures were established by detailed MS and NMR spectroscopic analysis, as well as comparison with the literature data.     

酞丁安对映体合成及其抗单纯疱疹病毒活性评价

酞丁安(3-酞酰亚胺-2-氧-正丁醛双缩氨硫脲,TDA)是药物研究所创制的抗病毒新药。为了研究其对映异构体(R),(S)-TDA对病毒活性及毒性是否有差异,并与消旋酞丁安(RS)-TDA的抗病毒活性及毒性进行比较,本文分别用已知构型的(R)-与(S)-丙氨酸为原料,通过缩合等6步反应,得到光学活性的(R)-,(S)-TDA,并与外消旋酞丁安比较其抗病毒活性及毒性。三者的抗单纯疱疹病毒活性与对细胞的毒性差别不大,说明消旋酞丁安临床使用是安全有效的。     

Zur Totalsynthese des 5-Acetoxy-6-methoxykawains

Total Synthesis of 5-Acetoxy-6-methoxykawain The oxidation of 5-hydroxy-4-methoxy-6-trans-styryl-2H-pyran-2-one ( 6 ) by periodic acid in methanol gives rise to racem.-4,6-dimethoxy-6-trans-styryl-2,5-pyrandione ( 7 ). The yield is 35% Compound 7 is the key intermediate¹⁾ for the total synthesis of (5S, 6S)-(+)-acetoxy-4,6-dimethoxy-6-trans-styryl-5,6-dihydro-2H-pyran-2-one ( 1 ).     

A novel kainate receptor ligand [H]-(2S,4R)-4-methylglutamate: Pharmacological characterization in rabbit brain membranes

Since kainate evokes large non-desensitizing currents at α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, kainate is of limited use in discriminating between AMPA and kainate receptors. Following recent reports that (2S,4R)-4-methylglutamate is a kainate receptor-selective agonist, we have radiolabelled and subsequently characterized the binding of [³H]-(2S,4R)-4-methylglutamate to rabbit whole-brain membranes. [³H]-(2S,4R)-4-methylglutamate binding was rapid, reversible and labelled two sites (KD1 = 3.67 ± 0.50 nM/B_max1 = 0.54 ± 0.03 pmol/mg protein and K_D2 = 281.66 ± 12.33 nM/ B_max2 = 1.77 ± 0.09 pmol/mg protein). [³H]-(2S,4R)-4-methylglutamate binding was displaced by several non-NMDA receptor ligands: domoate > kainate -quisqualate -glutamate > 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX) (S)-AMPA = (S)-5-fluorowillardiine > NMDA. Neither the metabotropic glutamate receptor agonists (1S,3R)-ACPD or -AP4, together with the -glutamate uptake inhibitor -trans-2,4-PDC, influenced binding when tested at 100 μM. We conclude that [³H]-(2S,4R)-4-methylglutamate is a useful radioligand for labelling kainate receptors. It possesses high selectivity, and possesses a pharmacology similar to that for rat cloned low-affinity (Glu5 and 6) kainate receptor subunits.     

Exploring relationships between mimic configuration,peptide conformation and biological activity in indolizidin‐2‐one amino acid analogs of gramicidin S*

Abstract: Indolizidin‐2‐one amino acids (I²aas, 6S‐ and 6R‐ 1 ) possessing 6S‐ and 6R‐ring‐fusion stereochemistry were introduced into the antimicrobial peptide gramicidin S (GS) to explore the relationships between configuration, peptide conformation and biological activity. Solution‐phase and solid‐phase techniques were used to synthesize three analogs with I²aa residues in place of the d ‐Phe‐Pro residues at the turn regions of GS: [(6S)‐I²aa^{4?5,4′?5′}]GS ( 2 ), [Lys^2,2′,(6S)‐I²aa^{4?5,4′?5′}]GS ( 3 ) and [(6R)‐I²aa^{4?5,4′?5′}]GS ( 4 ). Although conformational analysis of [I²aa^{4?5,4′?5′}]GS analogs 2?4 indicated that both ring‐fusion stereoisomers of I²aa gave peptides with CD and NMR spectral data characteristic of GS, the (6S)‐I²aa analogs 2 and 3 exhibited more intense CD curve shapes, as well as greater numbers of nonsequential NOE between opposing Val and Leu residues, relative to the (6R)‐I²aa analog 4 , suggesting a greater propensity for the (6S)‐diastereomer to adopt the β‐turn/antiparallel β‐pleated sheet conformation. In measurements of antibacterial and antifungal activity, the (6S)‐I²aa analog 2 exhibited significantly better potency than the (6R)‐I²aa diastereomer 4 . Relative to GS, [(6S)‐I²aa^{4?5,4′?5′}]GS ( 2 ) exhibited usually 1/2 to 1/4 antimicrobial activity as well as 1/4 hemolytic activity. In certain cases, antimicrobial and hemolytic activities of GS were shown to be dissociated through modification at the peptide turn regions with the (6S)‐I²aa diastereomer. The synthesis and evaluation of GS analogs 2?4 has furnished new insight into the importance of ring‐fusion stereochemistry for turn mimicry by indolizidin‐2‐one amino acids as well as novel antimicrobial peptides.     

Accumulation of 5-Ethyl-2′-deoxyuridine and its 5,6-Dihydro Prodrugs in Murine Lung and its Potential Clinical Application

The accumulation of 5-ethyl-2′-deoxyuridine (EDU), (–)-trans-(5S, 6S)-5-bromo-5-ethyl-6-methoxy-5,6-dihydro-2′-deoxyuridine [(5S, 6S)-BMEDU], (+)-trans-(5R, 6R)-5-bromo-5-ethyl-6-methoxy-5,6-dihydro-2′-deoxyuridine [(5R, 6R)-BMEDU], (+)-trans-(5.R, 6R)-5-bromo-5-ethyl-6-ethoxy-5, 6-dihydro-2′-deoxyuridine (BEEDU), (+)-trans-(5R, 6R)-5-bromo-5-ethyl-6-ethoxy-5,6-dihydro-5′-O-valeryl-2′- deoxyuridine (VBEEDU) and (+)-trans-(5R, 6R)-5-bromo-5-ethyl-6-ethoxy-5,6-dihydro-3′-5′-di-O-valeryl-2′-deoxyuridine (DVBEEDU) in lung and other tissues was investigated in male Balb-C mice following intravenous injection of the corresponding 4-¹⁴C-labelled compounds. EDU showed a rapid distribution into liver and lung immediately after injection, and the overall levels of radioactivity in blood, liver and lung were similar. The distribution of radioactivity in lung after injection of [4-¹⁴C](5S, 6S)-BMEDU and [4–14C](5R, 6R)-BMEDU were substantially different from one another and also from that of [4-¹⁴C]EDU. The radioactivity level present in lung samples after injection of both [4-¹⁴C](5S, 6S)-BMEDU and [4-¹⁴C](5R, 6R)-BMEDU was substantially higher than that in blood samples. Radioactivity levels present in lung samples taken at 18 min after injection of [4-¹⁴C]BEEDU were significantly higher (P < 0·05) than those for liver and blood samples. Although the radioactivity present in lung samples after injection of [4-¹⁴C]VBEEDU was significantly higher (P < 0·05) than those of liver and blood samples, [4-¹⁴C]VBEEDU did not provide a higher radioactivity level in lung samples than did [4-¹⁴C]BEEDU. The level of radioactivity in lung samples following injection of [4-¹⁴C]DVBEEDU was also higher than that of blood samples. EDU undergoes glycosidic bond cleavage to form EU in lung following intravenous injection into Balb-C mice. The concentrations of EDU and 5-ethyluracil (EU) following intravenous injection of EDU, and its prodrugs BEEDU and VBEEDU, were quantitated in lung and blood samples. In contrast to lung samples, EU was not detected in blood samples at 120 min post injection of EDU. The concentrations of both EDU and EU in lung tissues after injection of BEEDU and VBEEDU were substantially higher than those in blood samples.     

A new menthane-type monoterpenoid from fermented Illigera aromatica with Clonostachys rogersoniana 828H2

A new menthane-type monoterpenoid, illigerate E (1), as well as two known ones, (1R^*,3R^*,4S^*,6R^*)-6,8-dihydroxymenthol (2) and cis-4-hydroxy-5-(1-hydroxy-1-methylethyl)-2-methyl-2-cyclohexene-1-one (3), were isolated from fermented Illigera aromatica with Clonostachys rogersoniana 828H2. Their structures were identified by HRESIMS and 1D/2D NMR spectra. Their inhibitory effects of NO production in RAW 264.7 macrophages were estimated.     

Synthesis and Antiviral Activity of 5-Ethyl-5-halo-6-alkoxy-(or Azido)-5,6-dihydro-2′-deoxyuridine Diastereomers as Potential Prodrugs to 5-Ethyl-2′-deoxyuridine

A group of 5-ethyl-5-halo-6-alkoxy (or azido)-5,6-dihydro-2′-deoxyuridines, which differ in configuration at the C-5 and C-6 positions, were synthesized by the regiospecific addition of XR (X = I, Br, Cl; R = alkoxyl, azido) to the 5,6-olefinic bond of 5-ethyl-2′-deoxyuridine (EDU). In vitro antiviral (HSV-1, HSV-2, HCMV, VZV) activities were determined. Structure-activity studies showed that the C-5 halogeno (I, Br, Cl) and C-6 alkoxy (OMe, OEt) or azido, substituents were determinants of antiviral activity where the (5R,6R)- 5 and (5S,6S)- 6 diastereomers of 5-ethyl-5-iodo-6-methoxy-5,6-dihydro-2′-deoxyuridine exhibited greater potency against HSV-1, HSV-2, and HCMV than the related 5-chloro-6-ethoxy and 5-bromo (or chloro)-6-azido diastereomers. The most potent antiviral agents, (+)-trans-(5R,6R)- 5 and (?)-trans-(5S,6S)- 6 diastereomers of 5-ethyl-5-iodo-6-methoxy-5,6-dihydro-2′-deoxyuridine were approximately 2-to-8 fold more potent than the reference drug EDU against HSV-1 and HSV-2.     

The fate of S-propylcysteine in the rat

1. The metabolism of S-propylcysteine in the rat has been re-investigated. The previously known major metabolite has been isolated and identified as the mercapturic acid, N-acetyl-S-propylcysteine.

2. Several further metabolites have been isolated from the urine of rats treated with S-propyl[³⁵S]cysteine. These have been identified as S-propylcysteine-S-oxide, N-acetyl-S-(2-hydroxypropyl)cysteine, S-(propylthio)lactate, S-(2,3-dihydroxypropyl)cysteine and N-acetyl-S-(2-carboxyethyl)cysteine.

3. The metabolism of S-(2-hydroxypropyl)-, S-(3-hydroxypropyl)- and S-(2,3-dihydroxypropyl)[³⁵S]cysteine have been investigated in the rat. The results, integrated with those from the metabolism of S-propyl[³⁵S]cysteine, have enabled the pathways of S-propylcysteine to be deduced.

4. The oxidative metabolism of a number of S-alkyl cysteines is discussed.     

山蒟化学成分研究(Ⅱ)

从胡椒科植物山蒟(Piper hancei Maxim)中分得两个新木脂素成分(Ⅰ,Ⅱ)及三个生物碱(Ⅲ,Ⅳ,Ⅴ)。Ⅰ经光谱(IR,UV,MS,¹HNMR,¹³CNMR,APT-¹³SCNMR,2 D-HNMR)分析等证明其结构为rel-(7 S,8 S,1′R,3′S,4′R)-1′烯丙基-7-(3,4-二甲氧基苯基)-4′-羟基-5′-甲氧基-8-甲基-2′-氧双环[3.2.1]辛-5′-烯,为新结构,命名为山蒟醇(hancinol)。经光谱鉴定Ⅱ为burchellin,Ⅲ,Ⅳ,Ⅴ分别为风藤酰胺(futoamide)、荜拨明宁碱(piperlonguminine)和N-异丁基-反-2-反～4-癸二烯酰胺。后四种均首次从该植物中得到。     

Stereoselective drug distribution and anticoagulant potency of the enantiomers of phenprocoumon in rats

The elimination, distribution and anticoagulant activity of S(—)-, R(+)-, and R,S(±)-phenprocoumon were determined in male Wistar-Lewis rats after intravenous injection of a single dose of 0·6 mg kg^?1. From the plasma concentrations which elicited the same anticoagulant effect, S(—)-phenprocoumon was 4 to 5 times more potent than R(+)-phenprocoumon. The potency of the racemate was between those of the enantiomers. The mean biologic half-life of the S(—)-enantiomer was shorter (12·5 h) than that of R(+)-phenprocoumon (17·8 h). No differences were observed in the apparent volume of distribution. However, the mean liver: plasma concentration ratio was higher for the S(—)-(6·9) than for the R(+)-enantiomer (5·2). At a total concentration of 16·8 μg ml^?1 the percentage of unbound drug in rat serum was significantly higher for the S(—)- (1·13%) than that for the R(+)-enantiomer (0·76%). Values obtained for the racemate were always between those of the enantiomers. It is concluded that stereoselective differences in the distribution between plasma and liver, and consequently in the rate of elimination are most likely due to stereoselective differences in serum protein binding. The greater anticoagulant potency of the S(—)- over the R(+)-enantiomer, cannot be explained primarily by the observed pharmacokinetic differences.     

In-vitro Pharmacology of Sarpogrelate and the Enantiomers of its Major Metabolite: 5-HT2A Receptor Specificity,Stereoselectivity and Modulation of Ritanserin-induced Depression of 5-HT Contractions in Rat Tail Artery

The new antiplatelet agent sarpogrelate (MCI-9042), its major metabolite (R,S)-1-[2-[2-(3-methoxyphe-nyl)ethyl]phenoxy]-3-(dimethylamino)-2-propanol ((R,S)-M-1) and the enantiomers of (R,S)-M-1 were studied as antagonists at 5-HT_2A receptors, 5-HT₁-like receptors, 5-HT₃ receptors, α₁-adrenoceptors, β-adrenoceptors, histamine H₁ receptors, histamine H₂ receptors and muscarinic M₃ receptors in various functional in-vitro assays. Sarpogrelate, (R,S)-M-1, (S)-M-1 and (S)-M-1, respectively, were competitive antagonists of 5-hydroxytryptamine (5-HT) at 5-HT_2A receptors of rat tail artery with calculated pA₂ values of 8·53, 9·04, 9·00 and 8·81, respectively. Sarpogrelate lacked prominent 5-HT_t like, 5-HT₃, β, H_t, H₂ and M₃ antagonist activity and weakly blocked α₁-adrenoceptors (pK_B = 6·30). (S)-M-1 showed weak affinity for 5-HT₁-like receptors (pK_B = 6·30), α₁ (pK_B = 6·80) and β (pK_B = 6·54) adrenoceptors, while (R)-M-1 was a weak antagonist at histamine H₁ receptors (pK_B = 6·49). Stereoselectivity of M-1 enantiomers was low. (R)-M-1 showed 1·6-fold, 2·3-fold and 2·5-fold higher antagonist activity than (S)-M-1 for 5-HT_2A, H₁ and M₃ receptor, respectively. Affinity at β-adrenoceptors and 5-HT₁-like receptors was 5-fold and 3-fold higher for (S)-M-1 than for (R)-M-1. The depression of the maximum effect of 5-HT-induced contractions of rat-tail artery which amounted to 58–72% in the presence of ritanserin (1 nm ), was totally prevented after preincubation with sarpogrelate (1 μm ) and (R)- and (S)-M-1 (30 and 300 nm ), respectively, and partially prevented after preincubation with (R)- and (S)-M-1 (0·3-3 nm ). (R)- and (S)-M-1 failed to differ in restoring the ritanserin-induced depression of the 5-HT maximum response. It is concluded that sarpogrelate, its major metabolite (R, S)-M-1 and M-1 enantiomers are specific antagonists of 5-HT at 5-HT_2A receptors. The stereochemical configuration of the ligands does not seem to be crucial for binding to the 5-HT_2A receptor. Like ketanserin, sarpogrelate and M-1 enantiomers appear to be allosteric activators of the 5-HT_2A receptor system in rat tail artery.     

Chemical Constituents from the Leaves of Magnolia Denudata

Abstract

20 compounds were isolated from the leaves of Magnolia denudata including 16 lignans, which belong to 6 structural types. Except for (7R, 8S, 1′S) -δ^8′ - 1′, 4′ - dihydro - 5′- methoxy - 3, 4 -methylenedioxy - 4′ - oxo -7.O.2′, 8.1′ - neolignan (6), magliflonenone (9), 2,5′ - diene-2′, 8′- epoxy - 5′ - methoxy - 8 - methyl - 4′ - oxo - 3,4-methylenedioxy - spiro (5,5) - undecane (10), veraguensin (16) and β-sitosterol (20), the other 15 compounds were obtained from this species for the first time. The absolute configurations of 3 compounds (1,4,10) were determined by CD spectroscopy for the first time. The anti-inflammatory activities of compounds 1, 2 and 16 were assessed and 2 was shown to have significant inhibition effect on mice hind-paw edema induced by carrageenan.     

The Effects of Danshen (Salvia miltiorrhiza) on Warfarin Pharmacodynamics and Pharmacokinetics of Warfarin Enantiomers in Rats

The effects of Danshen (Salvia miltiorrhiza), a popular traditional Chinese medicinal herb on the pharmacokinetics and pharmacodynamics of R- and S-warfarin stereoisomers were studied in rats. After a single oral dose of racemic warfarin (2 mg kg^?1), treatment with oral Danshen extract (5 g kg^?1, twice daily) for 3 days significantly altered the overall pharmacokinetics of both R- and S-warfarin and increased the plasma concentrations of both enantiomers over a period of 24 h and the prothrombin time over 2 days. At steady-state levels of racemic warfarin (0·2 mg kg^?1 day^?1 for 5 days) the 3-day treatment of Danshen extract (5 g kg^?1, twice daily) not only prolonged the prothrombin time but also increased the steady-state plasma concentrations of R- and S-warfarin. The results indicate that Danshen extracts can increase the absorption rate constant, area under plasma concentration-time curves, maximum concentrations and elimination half-lives, but decreases the clearances and apparent volume of distribution of both R- and S-warfarin. The pharmacokinetic and pharmacodynamic interactions of warfarin during co-treatment with Danshen extract observed in this study indicate an explanation for the clinically observed incidents of exaggerated warfarin adverse effects when traditional Chinese medicinal herbs or herbal products such as Danshen and Danggui (observed in a previous study) were co-administered.     

Enantioselective synthesis of (R)- and (S)-2-methyl-[3,3,2-2H3] alanines

The synthesis of optically pure (R)- and (S)-2-methyl-[3,3,3-²H₃] alanines of biological interest is described. The stereochemistry of the reaction of the lithio derivative of (R)-(©)-2,5-dimethoxy-3-benzyl-3-methyl-3, 6-dihydropyrazine with alkyl and deuterated alkyl iodides is discussed. The configuration of the newly formed center of chirality in (R)- and (S)-2-methyl-[3,3,3-²H₃] alanines is derived from ¹ H NMR.     

Topical Delivery of 5-Fluorouracil and 6-Mercaptopurine by Their Alkylcarbonyloxymethyl Prodrugs from Water: Vehicle Effects on Design of Prodrugs

Purpose. To determine whether the fluxes through hairless mouse skin for three homologous series of prodrugs of 5-fluorouracil (5-FU, 1) and 6-mercaptopurine (6-MP, 2) from saturated aqueous suspensions show dependencies on aqueous (S _AQ) and isopropyl myristate (S _IPM) solubilities similar to those shown by the identical compounds delivered from IPM. Methods. Flux through hairless mouse skin from water (J _MAQ) and solubility data were measured for a homologous series of six 3-alkylcarbonyloxymethyl (ACOM) prodrugs of 5-FU (3-ACOM-5-FU), and five 6-ACOM-6-MP prodrugs, then combined with literature data for five bis-6,9-ACOM-6-MP prodrugs to give a data base. Multiple linear regression using SPSS 7.5 was performed on log S _IPM, log S _AQ, molecular weight and log J _MAQ data to determine the best fit coefficients to the transformed Potts-Guy equation: log J _MAQ = x + y log S _IPM + (1 - y) log S _AQ + z MW. Permeability coefficients (P _MAQ) were calculated from J _MAQ/S _AQ. Results. The best fit coefficients for the flux from AQ(J _MAQ)were x = -1.497, y = 0.660 and z = -0.00469 (r ² = 0.765) with an average error of prediction equal to 0.193 log units. The best fit coefficients for the flux from IPM (J _MIPM) were x = -0.557, y = 0.536 and z = -0.00261 (r ² = 0.941) with an average error of prediction equal to 0.109 log units. For all three series, log P _MAQ increased whereas log P _MIPM decreased with increasing alkyl chain lengths in the promoiety and with decreasing solubility parameter values. Conclusions. The transformed Potts-Guy equation can be used to predict J _MAQ but with less certainty than J _MIPM. S _IPM and S _AQ have consistently been shown to have a positive influence on J _MIPM, and now on J _MAQ, with a balance between the two solubilities being obviously important. The previous observation that log P _MAQ increased with lipophilicity is an artifact of normalizing J _MAQ by S _AQ.     

虎眼万年青的化学成分

目的：研究栽培于长白山区的虎眼万年青Ornithogalum caudatum Ait全草的化学成分。 方法：用各种色谱技术进行分离和纯化,用ESIMS,IR,¹HNMR,¹³CNMR,DEPT,¹H-¹H COSY, ¹H-¹³C COSY, HMBC和NOESY等波谱数据分析鉴定结构。结果：从虎眼万年青全草中分离得到3个化合物,其中化合物I为新化合物,其结构鉴定为（25S, 23S, 24S）-螺甾-Δ⁵⁽⁶⁾-烯-1β, 3β,23,24-四醇-1-O-α-L-吡喃鼠李糖基-（1→2） ［β-D-吡喃木糖基-(1→3)］-α-L-吡喃阿拉伯糖苷(I),另外2个已知化合物为海柯皂苷元-3-O-{β- D-吡喃葡糖基（1→2）-［β-D-吡喃木糖基（1→3）］-β-D-吡喃葡糖基（1→4）-β-D-吡喃半乳糖苷}(II)和β-谷甾醇(III)。结论：化合物I为新化合物,命名为虎眼万年青苷A,化合物II和III是首次从该植物中分得的已知化合物。     

Carbazoylierungen und Thiocarbazoylierungen von 2-Thioxo-thiazolidinen

Carbazoylations and Thiocarbazoylations of 2-Thioxo-thiazolidines¹⁾ Reactions of thiazolidine-2-thione (1) with carbazic and thiocarbazic acid chlorides 5 lead to S-substitution products 6 which only in case of the carb-azoic derivatives can be thermally rearranged to N-carbazoyl derivatives 7. Not rearrangeable heteroaromatic thiazoles 9 are obtained from 5 and 5-methylen-thiazolidine-2-thione (8). Thiazolidine-2,4-dione (10) only yields N-substitution products 11.     

Stereoselectivity in metabolism of ifosfamide by CYP3A4 and CYP2B6

The aim was to identify the hepatic cytochromes P450 (CYPs) responsible for the enantioselective metabolism of ifosfamide (IFA). The 4-hydroxylation, N²- and N³-dechloroethylation of IFA enantiomers were monitored simultaneously in the same metabolic systems using GC/MS and pseudoracemate techniques. In human and rat liver microsomes, (R)-IFA was preferentially metabolized via 4-hydroxylation, whereas its antipode was biotransformed in favour of N-dechloroethylation. CYP3A4 was the major enzyme responsible for metabolism of IFA enantiomers in human liver. The study also revealed that CYP3A (human CYP3A4/5 and rat CYP3A1/2) and CYP2B (human CYP2B6 and rat CYP2B1/2) enantioselectively mediated the 4-hydroxylation, N²- and N³-dechloroethylation of IFA. CYP3A preferentially supported the formation of (R)-4-hydroxyIFA (HOIF), (R)-N²-dechloroethylIFA (N2D) and (R)-N³-dechloroethylIFA (N3D), whereas CYP2B preferentially mediated the generation of (S)-HOIF, (S)-N2D and (S)-N3D. The enantioselective metabolism of IFA by CYP3A4 and CYP2B1 was confirmed in cDNA transfected V79 cells.     

Identification of human cytochrome P450 isoforms involved in the metabolism of S-2-[4-(3-methyl-2-thienyl)phenyl]propionic acid

1. To identify the cytochrome P450 (CYP) isoenzymes responsible for the major metabolic pathways of S-2-[4-(3-methyl-2-thienyl)phenyl] propionic acid (S-MTPPA) in man, the metabolism of S-MTPPA was examined using human liver microsomes and microsomes containing cDNA-expressed CYP isozymes (CYP1A2, 2A6, 2B6, 2C9-Arg, 2C9-Cys, 2C19, 2D6-Val, 2E1 and 3A4). 2. S-MTPPA was mainly oxidized to the 5-hydroxylated metabolite of the thiophene ring (MA6) with human liver microsomes in the presence of NADPH. The formation of MA6 was inhibited by SKF 525-A, suggesting that CYP plays role in the formation of MA6. 3. Eadie-Hofstee plots for the 5-hydroxylation of S-MTPPA in the range 5-100 μM were linear for all samples studied, suggesting that the formation of MA6 by human liver microsomes follows simple Michaelis-Menten kinetics. Apparent V_max = 1.42±0.64 nmol/min/mg protein; K_m = 12±5 μM. 4. Among the CYP inhibitors examined (α-naphthoflavone, sulphaphenazole, omeprazole, quinidine and troleandomycin), sulphaphenazole (a CYP2C9 inhibitor) showed the most potent inhibitory effect on the 5-hydroxylation of S-MTPPA by human liver microsomes. 5. When incubated with microsomes containing cDNA-expressed CYP isozymes, S-MTPPA was substantially oxidized to MA6 only by CYP2C9. 6. These results suggest that formation of the major metabolite of S-MTPPA, MA6, in human liver microsomes is catalysed predominantly by a single CYP isoenzyme, namely CYP2C9.