Biochemical Mechanism of Rhododendrol-Induced Leukoderma.

RS-4-(4-hydroxyphenyl)-2-butanol (rhododendrol (RD))-a skin-whitening ingredient-was reported to induce leukoderma in some consumers. We have examined the biochemical basis of the RD-induced leukoderma by elucidating the metabolic fate of RD in the course of tyrosinase-catalyzed oxidation. We found that the oxidation of racemic RD by mushroom tyrosinase rapidly produces RD-quinone, which gives rise to secondary quinone products. Subsequently, we confirmed that human tyrosinase is able to oxidize both enantiomers of RD. We then showed that B16 cells exposed to RD produce high levels of RD-pheomelanin and protein-SH adducts of RD-quinone. Our recent studies showed that RD-eumelanin-an oxidation product of RD-exhibits a potent pro-oxidant activity that is enhanced by ultraviolet-A radiation. In this review, we summarize our biochemical findings on the tyrosinase-dependent metabolism of RD and related studies by other research groups. The results suggest two major mechanisms of cytotoxicity to melanocytes. One is the cytotoxicity of RD-quinone through binding with sulfhydryl proteins that leads to the inactivation of sulfhydryl enzymes and protein denaturation that leads to endoplasmic reticulum stress. The other mechanism is the pro-oxidant activity of RD-derived melanins that leads to oxidative stress resulting from the depletion of antioxidants and the generation of reactive oxygen radicals.

[Drinking study on the pharmacokinetics of the grappa congener 2-butanol].

A drinking study on the pharmacokinetics of the typical grappa congeners 2-butanol and 2-butanone (methyl ethyl ketone) was performed. It was expected that the concentration ratio might provide a means to estimate the time of ingestion of a grappa beverage. Twelve subjects drank a volume of the grappa "Vecchio di Prosecco" (42 vol%) to reach a blood alcohollevel of 1.20 %o. In the congener analyses in serum, a median 2-butanol concentration of 0.79 mg/1 (range 0.45-1.34 mg/1) and of 1.01 mg/I (0.44-1.62 mg/1) for 2-butanone were measured. The concentration-time curve was biphasic starting with a slow and plateau-like elimination. However, considerable inter-individual differences were observed. Only in 3 subjects, a 2-butanol : 2-butanone ratio below 1 suggested ingestion within the last 6 hours. The majority of the subjects exhibited higher concentrations of 2-butanone than of 2-butanol such that the ratio was always smaller than 1. According to the present results the concentrations of 2-butanol and 2-butanone or their ratio do not provide a reliable basis to draw conclusions on the time of grappa ingestion.

Pharmacokinetics of Compound D, the Major Bioactive Component of Zingiber cassumunar, in Rats.

Rhizomes of Zingiber cassumunar have been used for many years in traditional Thai medicine as an anti-inflammatory agent. The major bioactive component of this plant is Compound D [E-4-(3', 4'-dimethoxyphenyl)but-3-en-1-ol], which is a strong smooth muscle relaxant, and has antihistamine and anti-inflammatory actions. There is, however, incomplete information available for the pharmacokinetics of Compound D in mammals. In this study, we examined the pharmacokinetic profiles of Compound D in male Wistar rats. A standardized extract of Z. cassumunar containing 4 % w/w Compound D was administered intravenously at 25 mg/kg or by oral gavage at 25, 75, or 250 mg/kg to Wistar rats. Blood, tissues, urine, and feces were collected from 0 to 48 h after dosing and the level of Compound D was determined by liquid chromatography-tandem mass spectrometry. The concentration of Compound D ranged from 10-100 µg/L, reached a maximum approximately 0.15 h after oral dosing. Compound D exhibited an excellent tissue to plasma ratio, ranging from 1- to 1000 in several organs at 1-4 h after oral dosing. Less than 1 % of unchanged Compound D was excreted in the urine and feces. Further studies on tissue uptake and metabolite identification are required to obtain complete pharmacokinetic information and to develop appropriate dosing strategies of Compound D and the standardized extract of Z. cassumunar.

Improving the permeability of the hydroxyethylamine BACE-1 inhibitors: structure-activity relationship of P2' substituents.

Herein we describe further evolution of hydroxyethylamine inhibitors of BACE-1 with enhanced permeability characteristics necessary for CNS penetration. Variation at the P2' position of the inhibitor with more polar substituents led to compounds 19 and 32, which retained the potency of more lipophilic analog 1 but with much higher observed passive permeability in MDCK cellular assay.

Fragrance material review on alpha-methylcinnamic alcohol.

A toxicologic and dermatologic review of alpha-methylcinnamic alcohol when used as a fragrance ingredient is presented.

Chirality in anesthesia I: minimum alveolar concentration of secondary alcohol enantiomers.

Most studies of chirality in inhaled anesthetic action have used the enantiomers of isoflurane. These enantiomers are expensive and scarce, which limits studies, such as the preliminary identification of molecular targets of anesthetic action, that can be performed with these isomers. We hypothesized that secondary alcohols (i.e., compounds having a -CH2-CHOH-CH3 group) that are experimental anesthetics would show enantioselectivity. To test this hypothesis, we determined the minimum alveolar anesthetic concentration (MAC) of the enantiomers of the homologous series of 2-alcohols from 2-butanol to 2-heptanol in rats. Because these alcohols are partially metabolized to 2-ketones during the course of study (i.e., having a -CH2-CO-CH3 group), we independently measured the MAC of the 2-ketones. Assuming additivity of MAC of the ketones with the alcohols, we corrected for the anesthetic effect of the ketones in rats to determine the MAC of the alcohols. We found that the 2-butanol and 2-pentanol isomers were enantioselective. S-(+)-2-butanol had a MAC that was 17% larger than for the R-(-)-enantiomer, whereas S-(+)-2-pentanol had a MAC that was 38% larger than the R-(-)- enantiomer. No stereoselectivity was observed for 2-hexanol and 2-heptanol. These findings may permit studies of chirality in anesthesia, particularly in in vitro systems where metabolism does not occur, using inexpensive volatile compounds.

Enhancing effect of alpha-hydroxyacids on "in vitro" permeation across the human skin of compounds with different lipophilicity.

The percutaneous penetration-enhancing effects of glycolic acid, lactic acid and sodium lauryl sulphate through the human epidermis was investigated using 5-fluorouracil as a hydrophilic model permeant and three compounds belonging to the phenylalcohols: 2-phenyl-ethanol, 4-phenyl-butanol and 5-phenyl-pentanol. The lipophilicity values of the compounds ranged from log Poct -0.95 to 2.89. The effect of the enhancer concentration was also studied. Skin pretreatment with aqueous solutions of the three enhancers did not increase the permeability coefficient of the most lipophilic compound (log Poct = 2.89). For the other compounds assayed, the increase in the permeability coefficients depended on the concentration used in skin pretreatment, and on the lipophilicity of the compounds tested-and was always greater for the most hydrophilic compound (5-fluorouracil), for which lactic acid exerted a greater enhancer effect than glycolic acid or sodium lauryl sulphate. Primary irritation testing of the three enhancers was also carried out at the two concentrations used in skin pretreatment for diffusional experiments (1% and 5%, w/w). The least irritant capacity corresponded to lactic acid; consequently, this alpha-hydroxyacid could be proposed as a percutaneous penetration enhancer for hydrophilic molecules that are of interest for transdermal administration.

Lifibrol: a novel lipid-lowering drug for the therapy of hypercholesterolemia. Lifibrol Study Group.

OBJECTIVE: To determine the effects of lifibrol on serum lipids in adult patients with primary hypercholesterolemia. METHODS: These were two double-blind, randomized placebo-controlled studies. Each patient in each study had an 8-week dietary lead-in period on the American Heart Association Step I diet before administration of lifibrol or placebo. The first study consisted of active dosing of 4 weeks, and the second study had 12 weeks of active dosing. The setting for the study involved outpatients in private or university hospitals in the United States. All patients had primary hypercholesterolemia with low-density lipoprotein (LDL) cholesterol levels of > 160 mg/dl after the dietary lead-in period. There were 155 patients in the 4-week study and 336 patients in the 12-week study. In the first study, patients were randomly assigned to receive either 150, 300, 450, 600, or 900 mg lifibrol as a single daily dose for 4 weeks. In the second study, patients were randomized to receive either 150, 300, or 600 mg lifibrol for 12 weeks. Efficacy was determined by serial measurements of serum lipids either on a weekly or biweekly basis during each study. RESULTS: Compared with baseline, lifibrol reduced LDL cholesterol (> 40%, p < 0.0001) and apolipoprotein B (approximately 40%, p < 0.0001) by 4 weeks in both studies. After 6 weeks, high-density lipoprotein (HDL) cholesterol levels increased in the placebo and 150 and 300 mg lifibrol groups. In the 600 mg lifibrol group, triglycerides (approximately 25%, p < 0.001), lipoprotein (a) (approximately 30%, p < 0.001), and HDL cholesterol (approximately 5%, p < 0.002) decreased. Lifibrol reduced key sterol intermediates (e.g., lanosterol, lathosterol, beta-sitosterol, and campesterol) and increased serum bile acids, but it had no effect on urinary mevalonic acid excretion. The pharmacokinetics of lifibrol are independent of dose and are similar in men and women. Lifibrol was well tolerated. The most frequent medical event in both studies was skin rash. CONCLUSIONS: Lifibrol is a potent lipid-lowering drug in patients with hypercholesterolemia.

Effect of methotrexate on perfusion and nitrogen-13 glutamate uptake in the Walker-256 carcinosarcoma.

The tissue uptake of [13N]glutamate (glu) was related to that of [11C]butanol (but), a highly diffusible perfusion tracer. In 25 rats bearing Walker-256 carcinomas tumor-to-muscle glu uptake averaged 6.34 +/- 2.84 (s.d.) prior to interventions and the respective uptake of but was 6.79 +/- 3.08 (y = 0.03 + 0.94x). One hour after selective intraarterial administration of methotrexate (mtx), glu uptake fell by 47%, whereas blood flow remained within the pretreatment range (N = 9). Four hours after mtx, perfusion was reduced by approximately 40%, and 2 days later both perfusion and glu uptake reached extremely low levels. No significant difference in the effect of 10 and 50 mg/kg mtx was observed. Regional tissue mtx uptake estimations using 77Br-labeled bromomethotrexate did not reveal any significant uptake in muscle. The relationship between tumor-to-muscle uptake of glu and but (13N/11C-index) was 0.94 +/- 0.015 (s.e.m., N = 25) before intervention. After methotrexate (1 hr, 4 hr, and 2 days) this index was 0.58 +/- 0.06 (N = 9), and 0.85 +/- 0.04 (N = 11) and 1.03 +/- 0.05 (N = 5), respectively. These values demonstrate an early mtx-induced uncoupling of glu uptake with respect to perfusion.

PET quantification of specific binding of carbon-11-nicotine in human brain.

UNLABELLED: Previous work on the PET measured uptake of (S)-[11C]nicotine presents conflicting findings as to whether it reflects specific binding. METHODS: We studied the uptake of (R)-[11C]nicotine and (S)-[11C]nicotine in normal volunteers at baseline conditions and after a challenge with unlabeled (S)-nicotine to decrease the concentration of free binding sites or with CO2 to increase perfusion. We analyzed the data using two- and three-compartment models. RESULTS: We found tissue pharmacokinetics of (R)- and (S)-[11C]nicotine are adequately described by the two-compartment model. (S)-nicotine challenge induced small but statistically significant reductions in distribution volume (DV) of both (R)- and (S)-[11C]nicotine. The changes in DV could not be attributed to perfusion changes because DV was not affected by CO2 challenge. Although the reduction in DV indicates sensitivity of [11C]nicotine to status of nicotinic binding sites, the small magnitude of the reduction suggests that most nicotine uptake is nonspecific. CONCLUSION: Although differences in DV attributable to specific binding were detected, (R)- and (S)-[11C]nicotine are relatively poor tracers for studying nicotinic binding sites using PET.

Pyrene butanol--an efficient, selective and non-metabolized photosensitizing agent for human myeloid leukemia cells.

Methods for ex vivo purging of neoplastic cells from harvested marrow are being developed to increase the efficacy of autologous transplantation. One approach is selective photosensitization, using sensitizing compounds and light radiation. Pyrene-containing fatty acids and lipids are potent photosensitizers, e.g. 12-(1-pyrene)dodecanoic acid (P12), is taken up preferentially by leukemic cells and undergo photoexcitation when exposed to long wave ultra-violet light, resulting in selective killing of leukemic cells. These compounds are incorporated into the neutral- and phospho-lipids of the cells. The presence of intracellular pyrene-linked lipids might present a potential hazard in applying these agents for clinical use. We have, therefore, studied a series of other pyrene-linked compounds with the objective of finding a non-metabolizable photosensitizing agent that can be easily removed from the cells. In the present paper we report the results with pyrene butanol (P4-OH), a pyrene linked short-chain alcohol. When compared to P12, P4-OH was found to be taken up by cells most rapidly and reached saturation within minutes. It did not undergo any metabolism and washing the cells with serum-containing salt solutions removed practically all the P4-OH. This compound was found to be an efficient photosensitizer (in terms of concentrations and time of incubation with the cells) and selective to leukemic cells--it caused a 99% reduction in leukemic clonogenic cells under conditions that normal hemopoietic progenitors remained almost intact. These properties make P4-OH a potential photosensitizer for clinical application.

Comparison of the blood-brain barrier and liver penetration of acridine antitumor drugs.

The blood-brain barrier penetration of amsacrine and its analogs 9-([2-methoxy-4-[(methylsulfonyl)-amino]phenyl]amino)-,5-dimethyl- 4-acridine carboxamide (CI-921) and M-[2-(dimethylamino)ethyl]-acridine-4-carboxamide (AC) was measured in the barbiturate-anesthetized mouse. After intracarotid administration, AC was almost completely extracted (90%) in a single transit through the brain capillaries, whereas CI-921 (20%) and amsacrine (15%) were moderately extracted. AC is retained in the brain; no loss of AC from the brain was apparent at 1, 2, 4, or 8 min after injection. In contrast, after intraportal administration, 75% of the AC, 94% of the CI-921, and 57% of the amsacrine was extracted in a single transit through the hepatic vasculature. Rather than being retained in the mouse liver, these acridine antitumor agents show time-dependent loss (t1/2 = 10 min for amsacrine and AC, 24 min for CI-921). We conclude that unlike most antitumor agents, these acridine drugs appear to penetrate the blood-brain barrier readily.

The motion aftereffect: more than area V5/MT? Evidence from 15O-butanol PET studies.

The motion aftereffect is a perceptual phenomenon which has been extensively investigated both psychologically and physiologically. Neuroimaging techniques have recently demonstrated that area V5/MT is activated during the perception of this illusion. The aim of this study was to test the hypothesis if a more broadly distributed network of brain regions subserves the motion aftereffect. To identify the neuronal structures involved in the perception of the motion aftereffect, regional cerebral blood flow (rCBF) measurements with positron emission tomography were performed in six normal volunteers. Data were analysed using SPM96. The motion-sensitive visual areas including area V5/MT were activated in both hemispheres. Additionally, the lateral parietal cortex bilaterally, the right dorsolateral prefrontal cortex, the anterior cingulate cortex and the left cerebellum showed significant increases in rCBF values during the experience of the waterfall illusion. In a further reference condition with identical attentional demand but no perception of a motion aftereffect elevated rCBF were found in these regions as well. In conclusion, our findings support the notion that the perceptual illusion of motion arises exclusively in the motion-sensitive visual area V5/MT. In addition, a more widespread network of brain regions including the prefrontal and parietal cortex is activated during the waterfall illusion which represents a non-motion aftereffect-specific subset of brain areas but is involved in more basic attentional processing and cognition.

The effects of prenatal tertiary butanol administration in CBA/J and C57BL/6J mice.

Pregnant mice of the CBA/J and C57BL/6J strains were given either tertiary butanol (10.5 mmoles/kg, p.o.) or an equivalent volume of tap water twice daily from day 6 through day 18 of gestation. Examination on day 18 revealed significantly more resorptions per litter in the t-butanol-treated animals but no interstrain difference. Tertiary butanol did not significantly affect the body weight of the survivors nor produce significant abnormalities in either strain. Subsequent blood concentration profiles in female C57BL/6J mice indicated that the treatment regimen produced blood levels equivalent to teratogenic ethanol treatment. Mice receiving 3 days of t-butanol treatment did not eliminate the drug more rapidly than control animals, indicating that tolerance was not a factor in the treatment regimen. Since t-butanol shares membrane disordering effects with ethanol but is not metabolized by the same pathway, a role for acetaldehyde or the process of ethanol metabolism is suggested in ethanol teratogenicity.

Polymorphism and preformulation studies of lifibrol.

Three polymorphic modifications of lifibrol, a novel cholesterol-lowering drug substance, were detected and thoroughly investigated and characterized by thermomicroscopy, DSC, IR-spectroscopy and X-ray powder diffractometry. Mod. I (m.p. 142 degrees C) and mod. II (m.p. 135 degrees C) are stable. Furthermore, true densities, solubilities as function of temperature and pH-value as well as the behavior of the crystal forms under the influence of humid air were determined. The three modifications show distinct differences by IR-spectroscopy, through which a distinction even is possible. The density of mod. I is lower than that of mod. II. The transition of mod. II into mod. I corresponds to an endothermic reaction; from this it follows, that between mod. I and mod. II enantiotropism exists. Mod. II is at 20 degrees C by about 44% less soluble as mod. I. Mod. III, which only can be produced by crystallizing the glassy solidified melt, has a negative heat of transition. That means that mod. III behaves monotropic with regard to both enantiotropic modifications I and II. Mod. I exists in form of small lamellae, mostly of irregular forms. Mod. II consists of rhombohedron grains. Because of this difference in habit, for mod. II one can predict the best properties in case of pressing tablets.

[O-15-butanol Pet activation study on the cerebral representation of declarative memory]. / O-15-Butanol-PET-Aktivierungsstudie zur zerebralen Repräsentation deklarativer Gedächtnisvorgänge.

AIM: In this study, neuroanatomical correlates of encoding and retrieval in paired associate learning were evaluated with positron emission tomography using auditorily presented highly imaginable words. METHODS: Six right-handed normal male volunteers took part in the study. Each subject underwent six O-15-butanol PET scans. On each of the six trials the memory task began with the injection of a bolus of O-15-butanol. The subjects had to learn and retrieve twelve word pairs (highly imaginable words, not semantically related). The presentation of nonsense words served as reference condition. RESULTS: Recall accuracy after 2-4 presentations was high during the PET measurement. In both encoding and retrieval we found anterior cingulate activation. We show bilateral dorsolateral prefrontal activation during the encoding of auditorily presented word pair associates, whereas retrieval led to left frontal activation. Furthermore, we demonstrate the importance of the precuneus in the retrieval of highly imaginable word-pair associates. CONCLUSION: Our results support the hypothesis of the presence of distributed widespread brain structures subserving episodic declarative memory.

Postmortem diffusion of ingested and aspirated paint thinner.

Post mortem diffusion of paint thinner (toluene/ethyl acetate/isobutanol 8:1:1 v/v) from gastric residue (25 ml or 100 ml) and airways contamination (25 ml) was assessed in a human cadaver model, with sampling after 24 h at room temperature. Four torso blood samples showed less toluene diffusion after gastric instillation (0.5-3.8 micrograms/ml) than after tracheal instillation (10.5-421 micrograms/ml). Isobutanol diffused more readily than toluene with four torso blood samples 1.8-256 micrograms/ml after gastric instillation and 26-576 micrograms/ml after tracheal instillation. Following 25 ml gastric instillation, toluene concentrations (microgram/ml or microgram/mg) were: pericardial fluid 0.7-4.0; bile 0.5-0.6; urine 0-0.6; brainstem 1.1; lung 0.4-4.4; liver 0-162; spleen 0.6-0.7; kidneys 0.4-0.6; peri-renal fat 0.3-30.3; psoas muscle 0.3-0.8; concentrations of toluene and isobutanol were markedly higher in the left lobe of the liver than the right. Ethyl acetate was mostly undetectable in tissue samples but variably present in five blood samples: 0-21.2 micrograms/ml following 25 ml or 100 ml gastric instillation and 0-198 micrograms/ml following 25 ml tracheal instillation. Ethyl acetate was always detectable in pericardial fluid but not always detectable in gastric contents. We conclude that post mortem diffusion of toluene from gastric residue or airways contamination is unlikely to compromise the analytical validity of femoral venous blood samples, brain, or liver from deep within the right lobe. Analysis of pericardial fluid and gastric contents allows identification of ethyl acetate and isobutanol thus implicating thinner solution.

Anti-oxidant activities of Acanthopanax senticosus stems and their lignan components.

The antioxidant activities of Acanthopanax senticosus stems were evaluated in CCl4-intoxicated rats. The n-butanol fraction from the water extract of the stems, when pretreated orally at 200 mg/kg/day for 7 consecutive days in rats, was demonstrated to exhibit significant increases in antioxidant enzyme activities such as hepatic cytosolic superoxide dismutase, catalase and glutathione peroxidase by 30.31, 19.82 and 155%, respectively. The n-butanol fraction whereas showed a significant inhibition of serum GPT activity (65.79% inhibition) elevated with hepatic damage induced by CCl4-intoxication. Eleutheroside B, a lignan component, isolated from the n-butanol fraction was found to cause a moderate free radical scavenging effect on DPPH, its scavenging potency as indicated in IC50 value, being 58.5 microM. These results suggested that the stems of A. senticosus possess not only antioxidant but also hepatoprotective activities.

Subchronic toxicity studies of 3-methyl-1-butanol and 2-methyl-1-propanol in rats.

1. 90-day subchronic toxicity studies with 3-methyl-1-butanol (MEB) and 2-methyl-1-propanol (MEP) were performed on rats to evaluate the toxicological profile of the compounds under conditions of drinking water studies, to identify the potential target organs, and to determine no-observable-adverse-effect-levels (NOAELs) respective of the substances. The test substances were administered to groups of 10 male and 10 female Wistar rats in drinking water at concentrations of 0, 1000 p.p.m. (about 80 mg/kg/d), 4000 p.p.m. (about 340 mg/kg/d) and 16,000 p.p.m. (about 1250 and 1450 mg/kg/d of MEB and MEP respectively). 2. 16,000 p.p.m. was found to be the maximal concentration for both alcohols applicable to rats in drinking water. Higher concentrations had an influence on palatability and could thus not be tested in drinking water studies. 3. At 16,000 p.p.m. MEB a marginal increase in the red blood cell count as well as a slight decrease in the mean corpuscular volume and the mean corpuscular hemoglobin content was observed in males only. These changes are considered to be treatment-related, although the toxicological significance of these findings is unclear. No other substance-related effects were found on body weight (b.w.), mortality, various parameters of clinical chemistry, organ weights, gross pathology and histopathology. 4000 p.p.m. MEB did not cause any substance-induced changes. Therefore, the NOAEL of MEB was defined as 4000 p.p.m. for male and 16,000 p.p.m. for female rats under conditions of oral application via drinking water. 4. MEP concentrations up to and including 16,000 p.p.m. did not induce any signs of toxicity and were therefore defined as the NOAEL respective of this substance for rats under conditions of drinking water application.

Kinetics of n-butyl alcohol and m-xylene in blood during single and combined inhalation exposure in rats.

The levels of m-xylene and n-butyl alcohol in blood of rats during single and combined inhalation exposure to m-xylene and n-butyl alcohol at the concentrations of 100 + 100 ppm were investigated. We found that levels of n-butyl alcohol and m-xylene in blood of animals during single exposure did not differ as compared to coexposure. It has been shown that less than additive neurotoxic and irritating respiratory tract effects of m-xylene and n-butyl alcohol mixture, observed earlier under acute and subchronic inhalation study, cannot be explained by their metabolic interaction.