5α-reduced glucocorticoids exhibit dissociated anti-inflammatory and metabolic effects

BACKGROUND AND PURPOSE

Dissociating anti-inflammatory efficacy from the metabolic side effects of glucocorticoids is an attractive therapeutic goal. 5α-Tetrahydro-corticosterone (5αTHB), produced from corticosterone by 5α-reductases, activates glucocorticoid receptors. This study compares the effects of 5αTHB on inflammation and metabolism in vitro and in vivo.

METHODS

Suppression of cytokine release by 5αTHB and corticosterone were studied following LPS activation of mouse bone marrow derived macrophages. In vivo the efficacy of these steroids to dysregulate metabolic homeostasis and modulate immune suppression and the responses to thioglycollate-induced peritonitis in C57BL/6 mice were studied following acute injection (1.5–15 mg) and chronic infusion (50 µg·day⁻¹, 14 days).

RESULTS

In macrophages, 5αTHB increased secretion of IL-10 similarly to corticosterone (180%, 340%; data are % vehicle, treated with 5αTHB and corticosterone, respectively) and suppressed LPS-induced secretion of TNF-α (21.9%, 74.2%) and IL-6 (16.4%, 69.4%). In mice with thioglycollate-induced peritonitis, both 5αTHB and corticosterone reduced the numbers of neutrophils (58.6%, 49.9%) and inflammatory monocytes (69.5%, 96.4%), and also suppressed MCP-1 (48.7%, 80.9%) and IL-6 (53.5%, 86.7%) in peritoneal exudate. In mice chronically infused with 5αTHB and corticosterone LPS-induced production of TNF-α from whole blood was suppressed to the same degree (63.2%, 37.2%). However, in contrast to corticosterone, 5αTHB did not induce body weight loss, increase blood pressure or induce hyperinsulinaemia.

CONCLUSIONS

5αTHB has anti-inflammatory effects in vitro and in vivo. At doses with equivalent anti-inflammatory efficacy to corticosterone, 5αTHB did not induce metabolic toxicity and thus may be a prototype for a safer anti-inflammatory drug.     

Dopaminergic unique affinity of tetrahydroberberine and l-tetrahydroberberine-d-camphor sulfonate.

l-Tetrahydroberberine-d-camphor sulfonate (THB-CS) possessed an inhibitory effect on apomorphine-induced chewing movement in a similar manner to that of tetrahydroberberine (THB). Both compounds enhanced barbiturate-induced hypnosis. They did not have an anticonvulsant effect on convulsive seizures induced by bicuculline, pentetrazole or strychnine. THB and THB-CS blocked dopamine-stimulated adenylate cyclase activity. These compounds showed almost equipotent affinities to dopamine D1 (3H-SCH-23390) and D2 (3H-spiperone) receptors but did not have significant affinity to mu-opioid, muscarinic and alpha 2-adrenergic receptors, and benzodiazepine binding sites. Furthermore, both compounds did not elicit cataleptogenic behavior, even at very high doses. These data suggest that THB and THB-CS have a central depressant effect through both D1 and D2 dopaminergic receptors and may have different modes of action from that of standard neuroleptics.     

四氢小檗红碱及其前药的比格犬药代动力学研究

目的建立同时定量检测比格犬全血中抗焦虑新药四氢小檗红碱(THB)及其前药9-乙酰四氢小檗红碱硫酸盐(ATHBS)的LC-MS/MS方法,并研究四氢小檗红碱在比格犬体内的药代动力学及生物利用度。方法建立检测全血中THB和ATHBS的LC-MS/MS方法,进行专属性、线性、回收率、稳定性、精密度和准确度等方法学验证。比格犬单次口服和静脉注射3 mg.kg-1ATHBS后考察了前药与活性代谢产物THB的血药浓度-时间变化,应用WinNonlin软件得到药代动力学参数和口服生物利用度。结果 ATHBS和THB在2～2 000μg·L-1的浓度范围内呈良好的线性(r>0.9985),定量下限均为2μg·L-1。THB和ATHBS的回收率分别大于78.74%和75.52%,日内和日间精密度(RSD)均在10.79%之内,准确度(RE)在-10.3%～3.92%的范围内。比格犬单次静注和口服ATHBS后,前药均能快速转化成为活性产物,血中浓度在60 min降至检测限之下。静注组THB在2 min达峰,Cmax为(605.99±102.88)μg·L-1,消除半衰期T12为(7.03±1.77)h,AUC(0-t)为(718.64±143.01)h·μg·L-1。口服组THB在15min达到(77.71±26.60)μg.L-1的峰值,药-时曲线在6 h出现第2个小峰,T 12为(5.89±3.95)h,AUC(0-t)为(179.62±91.64)h·μg·L-1,口服生物利用度为26.2%。结论建立的LC-MS/MS定量方法快速、简便、灵敏,可用于同时研究前药和THB的药代动力学。比格犬口服或静注ATHBS后,前药在体内可快速转化成为活性产物,THB达峰迅速,血药浓度消除较快,口服生物利用度较好。     

四氢小檗碱对离体兔主动脉环的作用和离体豚鼠结肠带平滑肌~(45)Ca内流的影响

THB和Ver相似,对KCl和NE所致兔主动脉环收缩,呈非竞争性拮抗,THB的作用弱于Ver。THB对KCl所致的兔主动脉环收缩的松弛作用,能被20 mmol/L CaCl_2所对抗。 THB,THP和Ver明显抑制80 mmol/L KCl所致的豚鼠结肠带平滑肌细胞的~(43)Ca内流。THB的作用与THP相当,但均弱于Ver。     

Functional significance of a natural allelic variant of human carbonyl reductase 3 (CBR3).

Human carbonyl reductase (CBR) activity accounts for a significant fraction of the metabolism of endogenous and xenobiotic carbonyl compounds. It is possible that genetic polymorphisms in CBR1 and CBR3 are key for the wide interindividual variability in the disposition of CBR drug substrates. We pinpointed a single nucleotide polymorphism in CBR3 (CBR3 V244M) that encodes for a V244 to M244 change. Blacks showed a higher frequency of the M244 allele (q = 0.51, n = 49) than did whites (q = 0.31, n = 70; p = 0.003). In addition, DNA variation panels from 10 ethnic groups presented a wide range of CBR3 V244M genotype distributions. Kinetic experiments with the recombinant CBR3 protein variants and menadione revealed that CBR3 M244 has significantly higher V(max) than does CBR3 V244 (V(max) CBR3 M244 = 40.6 +/- 1.3 micromol/min x mg versus V(max) CBR3 V244 = 19.6 +/- 2.0 micromol/min x mg, p = 0.002). In contrast, both isoforms presented similar K(m) values (K(m) CBR3 M244 = 22.9 +/- 2.9 microM versus K(m) CBR3 V244 = 24.6 +/- 3.2 microM, p = 0.43). Assays with NADP(H) demonstrated a higher V(maxNADP(H)) (1.6-fold) and increased catalytic efficiency (V(maxNADP(H))/K(mNADP(H))) for CBR3 M244 compared with CBR3 V244 (p = 0.013). Comparative three-dimensional analyses based on the structure of the homologous porcine carbonyl reductase suggested that the V244M substitution is positioned in a region critical for interactions with the NADP(H) cofactor. These studies demonstrate that the common CBR3 V244M polymorphism encodes for CBR3 isoforms with distinctive enzymatic properties.     

Isolation of isoflavones inhibiting DOPA decarboxylase from fungi and streptomyces.

By screening of culture filtrates of fungi and streptomyces for activity in inhibit dopa decarboxylase the following isoflavone compounds were obtained: psi-tectorigenen (I), genistein (II), orobol (IV), 8-hydroxygenistein (V) and a new compound (III). III was elucidated to be 3', 4', 5, 7-tetrahydroxy-8methoxy isoflavone. Among these isoflavones, IV and III showed the strongest activity in inhibiting dopa decarboxylase. All these isoflavones also inhibited histidine decarboxylase and catechol-O-methyltrasnferase. Activities of these compounds to inhibit tyrosine hydroxylase and dopamine beta-hydroxylase were examined. Orobol which showed no or only slight inhibition of tyrosine hydroxylase and dopamine beta-hydroxylase exhibited a significant hypotensive effect on spontaneously hypertensive rats.     

43例创伤性肝破裂手术治疗体会

目的总结创伤性肝破裂手术治疗,提高肝破裂的诊治水平。方法对43例创伤性肝破裂,分别采用单纯修补、清创性肝切除、清创止血后大网膜填塞、规则性肝切除、纤维蛋白粘胶粘合等方法。结果43例肝破裂治愈40例,治愈率93％,死亡3例,死亡率7％。结论创伤性肝破裂伤情复杂,合并伤多,早期诊断及治疗较困难,在处理肝破裂的同时,重视合并伤的及时处理,是提高治愈率、降低死亡率和并发症的关键。     

酸浆宿萼的化学成分

目的研究茄科植物酸浆宿萼(Physalis alkekengiL.var.franchetii(Mast.)Makino)的化学成分。方法用体积分数为80%的乙醇溶液对酸浆宿萼进行加热回流提取,回收乙醇,浓缩后用水混悬,依次用环己烷、乙酸乙酯萃取,取乙酸乙酯层经硅胶柱色谱,CHCl3MeOH混合溶剂做梯度洗脱;CHCl3MeOH体积比为100∶2、100∶6,洗脱部分以及萃取后的水层再次经硅胶柱色谱、Sephadex LH 20柱色谱、反相ODS开放柱色谱及RP HPLC等,共得到7个化合物;利用其理化性质和波谱学分析数据,鉴定化学结构。结果分离得到了7个化合物中4个为酸浆苦素类化合物,分别鉴定为酸浆苦素D(Ⅰ)、酸浆苦素L(Ⅱ)、酸浆苦素O(Ⅲ)、4,7二脱氢新酸浆苦素B(Ⅳ);3个黄酮类化合物,分别鉴定为木犀草素(Ⅴ)、商陆素(Ⅵ)、木犀草素7,4′二OβD葡萄糖苷(Ⅶ)。结论商陆素(Ⅵ)、木犀草素7,4′二OβD葡萄糖苷(Ⅶ)为首次从该植物中分离得到的2个已知化合物。     

Substrate-dependent effect of acetonitrile on human liver microsomal cytochrome P450 2C9 (CYP2C9) activity.

Acetonitrile is an organic solvent commonly used to increase the solubility of lipophilic substrates for in vitro studies. In this study, we examined its effect on four reactions (diclofenac hydroxylation, tolbutamide methyl hydroxylation, phenytoin hydroxylation, and celecoxib methyl hydroxylation) catalyzed by human liver microsomes and by the recombinant CYP2C9. In both cases, the effect of acetonitrile on activity was found to be substrate-dependent. Namely, it increased diclofenac 4'-hydroxylase and tolbutamide methyl hydroxylase activities, but decreased celecoxib methyl hydroxylase activity in a concentration-dependent manner. By comparison, hydroxylation of phenytoin was resistant to its effect. The presence of acetonitrile (3%, v/v) gave rise to a lower K(m) and a higher V(max) for diclofenac hydroxylase in both liver microsomes and recombinant CYP2C9 preparations (87 and 52% increase in V(max)/K(m) ratio, respectively). On the other hand, the inhibitory effect of the solvent (1%, v/v) toward celecoxib hydroxylase was characterized by a decrease in V(max) (human liver microsomes) or a change in both K(m) and V(max) (rCYP2C9), leading to 25 and 46% decrease in V(max)/K(m) for both systems. The results of this study underscore the need for careful evaluation of solvent effects before initiation of inhibition or cytochrome P450 reaction phenotyping studies.     

Concomitant induction of microsomal epoxide hydrolase and UDP-glucuronosyltransferase activities by dipyridine compounds.

The coordinated response of the major rat hepatic phase II xenobiotic-metabolizing enzymes following 3-day exposure to diaryl compounds was investigated. Four diaryl compounds containing heterocyclic nitrogen atoms elevated microsomal epoxide hydrolase activity from 2- to 4-fold. Equivalent compounds lacking the heteroatom, when given in the same dosing regimen (75 mg/kg, ig, daily for 3 days), did not induce this or any other drug-metabolizing enzyme activity. Epoxide hydrolase activity closely paralleled UDP-glucuronosyltransferase activity toward three aglycones: 4-nitrophenol (r = 0.87), morphine (r = 0.84), and 1-naphthol (r = 0.78). There was less correlation (r = 0.60) between epoxide hydrolase activity and both UDP-glucuronosyltransferase activity toward testosterone and cytosolic glutathione S-transferase activity. There was no correlation between microsomal epoxide hydrolase activity and cytochrome P-450 or the monooxygenase reaction (4-nitrophenol hydroxylase) preferentially induced by pyridine-containing compounds. Induction of rat hepatic microsomal epoxide hydrolase activity by some pyridine-containing compounds appears coordinately regulated with glucuronidation rather than oxidation enzymes.     

Potent 4-aryl- or 4-arylalkyl-substituted 3-isoxazolol GABA(A) antagonists: synthesis, pharmacology, and molecular modeling

We have previously described a series of competitive GABA(A) antagonists derived from the low-efficacy partial agonist 5-(4-piperidyl)-3-isoxazolol (4-PIOL, 4). The 2-naphthylmethyl analogue, 4-(2-naphthylmethyl)-5-(4-piperidyl)-3-isoxazolol (5), provided affinity for the GABA(A) receptor site higher than that of the standard GABA(A) receptor antagonist, SR 95531 (3). Molecular modeling studies of these compounds exposed a cavity at the receptor recognition site capable of accommodating aromatic groups of substantial size in the 4-position in the 3-isoxazolol ring. Here we present a series of analogues of 5, with various substituents in different positions in the naphthyl ring system (6a-k), and compounds with aromatic substituents directly attached to the 4-position of the 3-isoxazolol ring (7l-n). The compounds have been pharmacologically characterized using receptor-binding assays and electrophysiological whole-cell patch-clamp techniques. All of the tested compounds show affinity for the GABA(A) receptor site. While the 5-, 7-, and 8-bromo analogues, 6b-d, showed receptor affinities (K(i) = 45, 109, and 80 nM, respectively) comparable with that of 5 (K(i) = 49 nM), the 1-bromo analogue, 6a, provided the highest receptor affinity of the series (K(i) = 10 nM). Introduction of a series of different substituents in the 1-position in the 2-naphthyl ring system led to compounds, 6e-k, with retained high affinity for the GABA(A) receptor (K(i) = 16-250 nM). Introduction of a phenyl ring directly into the 4-position on the 3-isoxazolol ring gave a 41-fold increase in affinity relative to that of 4-PIOL. In whole-cell patch-clamp recordings from cultured cerebral cortical neurons, all of the tested compounds were able to inhibit the effect of the specific GABA(A) agonist isoguvacine, 6a showing antagonist potency (IC(50) = 42 nM) markedly higher than that of 3 (IC(50) = 240 nM). Molecular modeling studies, based on the compounds described, emphasized the importance of the distal ring in 5 for receptor affinity and the considerable dimensions of the proposed receptor cavity. Furthermore, the phenyl rings in 7l and in 6k were shown to represent highly favorable positions for an aromatic ring in previously unexplored receptor regions in terms of a pharmacophore model.     

Enzymatic reduction of arsenic compounds in mammalian systems: reduction of arsenate to arsenite by human liver arsenate reductase

An arsenate (As(V)) reductase has been partially purified from human liver. Its apparent molecular mass is approximately 72 kDa. The enzyme required a thiol and a heat stable cofactor for activity. The cofactor is less than 3 kDa in size. The thiol requirement can be satisfied by dithiothreitol (DTT). However, the extent of stimulation of reductase activity by glutathione, thioredoxin, or reduced lipoic acid was negligible compared to that of DTT. The heat stable cofactor does not appear to be Cu(2+), Mn(2+), Zn(2+), Mg(2+), or Ca(2+). The enzyme does not reduce monomethylarsonic acid (MMA(V)). The isolation and characterization of this enzyme demonstrates that in humans, the reduction of arsenate to arsenite is enzymatically catalyzed and is not solely the result of chemical reduction by glutathione as has been proposed in the past.     

Facile design of lidocaine-loaded polymeric hydrogel to persuade effects of local anesthesia drug delivery system: complete in vitro and in vivo toxicity analyses

The principal goal of the present investigation was to enterprise new and effective drug delivery vesicle for the sustained delivery of local anesthetic lidocaine hydrochloride (LDC), using a novel combination of copolymeric hydrogel with tetrahydroxyborate (COP–THB) to improve bioactivity and therapeutic potential. To support this contention, the physical and mechanical properties, rheological characteristics, and component release of candidate formulations were investigated. An optimized formulation of COP–THB containing LDC to an upper maximum concentration of 1.5% w/w was assessed for drug crystallization. The biocompatibility of the prepared COP–THB hydrogel was exhibited strong cell survival (96%) and growth compatibility on L929 fibroblast cell lines, which was confirmed by using methods of MTT assay and microscopic observations. The COP–THB hydrogel release pattern is distinct from that of COP–THB/LDC hydrogels by the slow-release rate and the low percentage of cumulative release. In vivo evaluations were demonstrated the anesthetic effects and toxicity value of treated samples by using mice models. In addition, COP–THB/LDC hydrogels significantly inhibit in vivo tumor growth in mice model and effectively reduced it is in vivo toxicity. The pharmacological evaluation showed that encapsulation of LDC in COP–THB hydrogels prolonged its anesthetic action with favorable in vitro and in vivo compatibility. This novel design may theoretically be used in promising studies involving the controlled release of local anesthetics.

Highlights

• Development a modified sustained release system for the local anesthetic lidocaine.
• PVP-THB hydrogel to improve the pharmacological properties of the drug and their anesthetic activities.
• Profiles of PVP-THB/LDC showed that the effective release of associated lidocaine.
• This new formulation could potentially be used in future local anesthetics.

     

Pharmacological evaluation of the beta-adrenoceptor agonist and thromboxane receptor blocking properties of 1-benzyl substituted trimetoquinol analogues

The beta 1- and beta 2-adrenoceptor agonist and thromboxane A2 (TXA2) antagonist properties of trimetoquinol (TMQ, I) and 1-benzyl substituted TMQ analogues [3'-iodo-4',5'-dimethoxy TMQ, II; 3',5'-diiodo-4'-dimethoxy TMQ, III; 3',4'-dimethoxy-5'-nitro TMQ, IV; 3',4'-dimethoxy-5'-amino TMQ; V; and 3',4'-dimethoxy TMQ, VI] were studied in guinea pig atria (beta 1) and trachea (beta 2), and in rat thoracic aorta and human platelets, respectively. The rank order of agonist activities in beta 1- and beta 2-adrenoceptor tissues was IV greater than or equal to I greater than II greater than V greater than III greater than VI and I greater than II = IV = V greater than VI greater than III, respectively. An increase of beta 2/beta 1-selectivity (2- to 3-fold) was observed for analogues V and VI as compared to TMQ. The rank order of inhibitory potency against U46619-induced contraction of rat aorta and human platelet aggregation and secretion was the same (I = II = III greater than IV greater than V greater than VI). The results show that varying the substituents at the 3'- and 5'-positions of the trimethoxybenzyl group of TMQ produces compounds which give different profiles of biological activity for beta-adrenoceptor agonism versus TXA2 antagonism. Certain TMQ analogues, notably analogue V, showed a greater selectivity as beta 2-receptor agonists and TXA2 antagonists in vascular smooth muscle than the parent drug (TMQ), and the iodinated analogues (II and III) have promise as potential radioligands or photoaffinity probes for thromboxane A2 receptors.     

Behavioral pharmacology of berberine-type alkaloids. (2) Central depressant effects of tetrahydroberberine (THB) and related compounds]

The behavioral effects of tetrahydroberberine (THB), tetrahydrocoptisine (THC), tetrahydropalmatine (THP) and tetrahydrojateorrhizine (THJ) were compared with those of chlorpromazine (CPZ) and benzodiazepines in mice and rats. Effects of THB were also determined by electroencephalography (EEG) in rabbits. THB was found to pharmacologically exert various actions similar to those of CPZ which is a major tranquilizer, however, the actions of THB were weaker than those of CPZ. Although THB alone did not induce catalepsy, it enhanced the cataleptogenic action of CPZ. At a dose over the effective levels, THB did not lower normal body temperature or induce muscle relaxation and loss of righting reflex. EEG activities in the frontal cortex areas were markedly affected by THB, e.g., fast waves in spontaneous EEG were converted to slow waves. THB and CPZ in a similar manner elicited a sustaining increase in hippocampal afterdischarge, but the action of THB was weaker than that of CPZ. The acute toxicity of THB was lower than that of CPZ and benzodiazepines and the depressant activity of THB almost equalled that of THC and THP, whereas the activity of 1-THB was 1.5 times as great as that of THB. These data indicate that THB, THC and THP may be a new type of tranquilizer.     

Effects of apomorphine enantiomers and of lisuride on 3,4-dihydroxyphenylalanine production in striatal synaptosomes

The effects of lisuride and of the R(-)- and S(+)-enantiomers of apomorphine were examined on 3,4-dihydroxyphenylalanine (DOPA) production by striatal synaptosomes and by crude, soluble striatal tyrosine hydroxylase. Due to their catechol structure, the enantiomers were almost equally effective in blocking soluble tyrosine hydroxylase (EC 1.14.16.2) (IC50 = 470 and 890 nM for R(-)- and S(+)-apomorphine, respectively), provided incubations were performed at pH 7.2 with 1 mM tetrahydrobiopterin as cofactor. The enantiomers were similarly effective in blocking synaptosomal DOPA production (IC50 = 410 and 970 nM for R(-)- and S(+)-apomorphine, respectively). As S(+)-apomorphine but not R(-)-apomorphine is considered to be a dopamine antagonist, these results support the assumption that the block of synaptosomal DOPA production by both apomorphine enantiomers is due to a direct inhibition of tyrosine hydroxylase. Lisuride at high concentrations (10-100 microM) blocked DOPA production in striatal synaptosomes; simultaneously, intrasynaptosomal dopamine was depleted. These data support the assumption that lisuride inhibits DOPA production indirectly, similar to reserpine. In accordance with this assumption, lisuride was without effect on DOPA production in dopamine-depleted synaptosomes. These results demonstrate that inhibition of synaptosomal DOPA production by at least some dopamine agonists may be explained by direct inhibitory effects on tyrosine hydroxylase.     

N10-substituted 5,8-dideazafolate inhibitors of glycinamide ribonucleotide transformylase

A series of 5,8-dideazafolates bearing ethyl, isopropyl, cyclopropylmethyl, propargyl, 3-cyanopropyl, carboxymethyl, 2-carboxyethyl, phenacyl, 3-fluorobenzyl, and 5-uracilylmethyl substituents at N10 were tested as inhibitors of purified L5178Y glycinamide ribonucleotide transformylase (GAR TFase), which requires 10-formyltetrahydrofolate as cofactor. All of these cofactor analogues exhibited competitive inhibition against N10-formyl-5,8-dideazafolate, with Ki's ranging from 2 to 32 microM.     

2-Amino-3-aroyl-4,5-alkylthiophenes: agonist allosteric enhancers at human A(1) adenosine receptors.

2-Amino-3-benzoylthiophenes are allosteric enhancers (AE) of agonist activity at the A(1) adenosine receptor. The present report describes syntheses and assays of the AE activity at the human A(1)AR (hA(1)AR) of a panel of compounds consisting of nine 2-amino-3-aroylthiophenes (3a-i), eight 2-amino-3-benzoyl-4,5-dimethylthiophenes (12a-h), three 3-aroyl-2-carboxy-4,5-dimethylthiophenes (15a-c), 10 2-amino-3-benzoyl-5,6-dihydro-4H-cyclopenta[b]thiophenes (17a-j), 14 2-amino-3-benzoyl-4,5,6,7-tetrahydrobenzo[b]thiophenes (18a-n), and 15 2-amino-3-benzoyl-5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophenes (19a-o). An in vitro assay employing the A(1)AR agonist [(125)I]ABA and membranes from CHO-K1 cells stably expressing the hA(1)AR measured, as an index of AE activity, the ability of a candidate AE to stabilize the agonist-A(1)AR-G protein ternary complex. Compounds 3a-i had little or no AE activity, and compounds 12a-h had only modest activity, evidence that AE activity depended absolutely on the presence of at least a methyl group at C-4 and C-5. Compounds 17a-c lacked AE activity, suggesting the 2-amino group is essential. Polymethylene bridges linked thiophene C-4 and C-5 of compounds 17a-j, 18a-n, and 19a-o. AE activity increased with the size of the -(CH(2))(n)()- bridge, n = 3 < n = 4 < n = 5. The 3-carbethoxy substituents of 17a, 18a, and 19a did not support AE activity, but a 3-aroyl group did. Bulky (or hydrophobic) substituents at the meta and para positions of the 3-benzoyl group and also 3-naphthoyl groups greatly enhanced activity. Thus, the hA(1)AR contains an allosteric binding site able to accommodate 3-aroyl substituents that are bulky and/or hydrophobic but not necessarily planar. A second region in the allosteric binding site interacts constructively with alkyl substituents at thiophene C-4 and/or C-5.     

Pharmacological evaluation of the beta-adrenoceptor agonist properties of N-benzyl substituted trimetoquinol analogues

The beta 1- and beta 2-adrenoceptor agonist properties of trimetoquinol (TMQ, I) and N-benzyl ring substituted TMQ analogues (II, 4'-methylbenzylTMQ; III, 4'-chloro-benzylTMQ; IV, 4'-methoxybenzylTMQ; V, 4'-nitrobenzylTMQ; VI, 3',4'-dichlorobenzylTMQ; and VII, 4'-aminobenzylTMQ) were studied in guinea pig atria and trachea. All compounds gave concentration-dependent responses in atria and trachea, and the rank order of beta-adrenoceptor agonist potency was I greater than VII greater than II greater than V greater than IV greater than VI greater than III and I greater than VII greater than IV = VI greater than V greater than III greater than II, respectively. Whereas the N-benzyl substitution reduced potency for beta-agonist activity, the beta 2/beta 1-selectivity ratio was enhanced by addition of groups to the N-benzyl ring, and the rank order of beta 2-selectivity was VI (10-fold) greater than III (8-fold) = IV (8-fold) greater than VII (3-fold) greater than V = I greater than II. The results show that varying the nature of substituents on the N-benzyl ring of TMQ produces compounds which retain greater beta 2-selectivity.     

Properties of benzpyrene hydroxylase from human liver and comparison with the rat, rabbit and guinea-pig enzymes.

1. Benzpyrene hydroxylase of human liver biopsies and of livers from four inbred rat strains and from a non-inbred Sprague-Dawley rat strain, rabbit and guinea-pig was studied. 2. The human liver benzpyrene hydroxylase was similar to that of laboratory animals with respect to cofactor requirements, NADPH and O2, microsomal localization and inhibition by CO and N2. 3. Kinetic analysis of human adult benzpyrene hydroxylase indicated the presence of two enzymes, whereas human foetal liver contained only one enzyme hydroxylating 3,4-benzpyrene. Michaelis constants of human liver benzpyrene hydroxylase were slightly higher than Km values of animal liver enzymes. 4. Benzpyrene hydroxylase activity in human liver showed no sex difference, was enhanced by cigarette smoking and was decreased in patients with liver damage. 5. Variation of benzpyrene hydroxylase activity in human liver samples was about 6-fold in the 'control' group and 16-fold when all patients were considered. Variation of benzpyrene hydroxylase activity in inbred rat strains was less than 60% between different individuals and in the non-inbred rat, rabbit and guinea-pig the variation was 2- to 3-fold or less.