Solasodine glycosides of Solanum unguiculatum (A.) Rich

Besides solasonine, three new glycosides, namely, 3-O--L-rhamnopyranosyl-(13)-solasodine, 3-O--L-rhamnopyranosyl-(12)--L-rhamnopyranosyl-(14)--D-galactopyranosyl solasodine, and 3-O--L-rhamnopyranosyl-(12)--D-galactopyranosyl solasodine, were isolated fromSolanum unguiculatum (A.) Rich. Their structures were determined on the basis of chemical and spectral methods.     

Studies on the chemical constituents from the roots of <Emphasis Type="Italic">Platycodon grandiflorum</Emphasis>

Three known monodesmosidic saponins: 3-O--d-glucopyranosyl-2,3,16,23,24-pentahydroxyolean-12-ene-28-oic acid, 3-O--d-glucopyranosyl polygalacic acid, and 3-O--d-glucopyranosyl-(13)--d-glucopyranosyl polygalacic acid; and two known nonsaponin compounds: a mixed compound of n-tetracosanoic acid (lignoceric acid), n-hexacosanoic acid (cerotic acid), and n-octacosanoic acid, and -monopalmitin; were isolated for the first time from the root of Platycodon grandiflorum A. DC. together with another seven known compounds: platycoside G₁ (3-O--d-glucopyranosyl-(16)--d-glucopyranosyl-(16)--d-glucopyranosyl-2,3,16,23,24-pentahydroxyolean-12-ene-28-oic acid 28-O--d-xylopyranosyl-(14)--l-rhamnopyranosyl-(12)--l-arabinopyranoside), deapio-platycodin D, Polygalacin D, deapio-platycodin D₃, platycoside A, -spinasterol, and -spinasteryl-3-O--d-glucopyranoside. Alkaline hydrolysis of platycoside G₁ afforded a new monodesmosidic prosaponin: 3-O--d-glucopyranosyl-(16)--d-glucopyranosyl-(16)--d-glucopyranosyl-2,3,16,23,24-pentahydroxyolean-12-ene-28-oic acid. Their chemical structures were elucidated on the basis of their spectral data and chemical evidence.     

Determination of ethinyloestradiol in the presence of norethisterone by derivative-difference spectrophotometry

A simple and direct method for the determination of ethinyloestradiol as a minor component in the presence of norethisterone and in oral contraceptive tablets is presented. The method is based on measuring the signal intensity, dA/d and d²A/d ², of the generated first and second derivative spectra of the -absorbance curves obtained by measuring solutions in methanol and methanol-sodium hydroxide at certain wavelengths. The method has been applied to the determination of ethinyloestradiol in oral contraceptive tablets, with a coefficient of variation of less than 2%.     

Scopolamine effects on go-no go avoidance discriminations: influence of stimulus factors and primacy of training

Rats were trained in a shuttle-box to perform four go-no go avoidance discrimination tasks, with various combinations of active and passive avoidance signals: 1) light go, noise-light no go; 2) light go, noise no go; 3) noise go, light-noise no go; 4) noise go, light no go. The first task was learned with great average difficulty, and showed a large passive avoidance deficit after scopolamine treatment. The other tasks were much easier to learn, and scopolamine exerted little or no effect on their performance. However, relationships between task difficulty and sensitivity to drug were practically absent within groups.After the completion of discrimination tests, active avoidance retraining was carried out with former passive avoidance cues. This was to obtain an indirect measure of possible differences in the amount of response suppression by these cues. Retraining with noise as CS showed identical acquisition rates in the groups which had previously performed with light as active avoidance signal, and either noise or noise-light as passive avoidance signal. Retraining with light as CS showed faster acquisition in the former noise go, light no go group, as compared with the former noise go, light-noise no go group.An additional experiment showed that the elimination of active avoidance pretraining before discrimination training reduced the passive avoidance deficit and enhanced the active avoidance deficit provoked by scopolamine in the light go, noise-light no go task. In spite of such elimination of the primacy of training in favour of active responses, however, the passive avoidance deficit remained greater than the active avoidance deficit.The relative merits of various neuropsychological interpretations of the effects of central antimuscarinic agents (reappearance of responses to biologically irrelevant stimuli, response disinhibition, set perseveration, amnesia, state-dependency) are discussed. The role of built-in hierarchies between stimulus-response relationships, and of response hierarchies (both innate and dependent on training history) are emphasized.On leave from the Department of Pharmacology of the Medical Faculty, Bul. JNA 18, Beograd (Yugoslavia).     

Is Stability Prediction Possible for Protein Drugs? Denaturation Kinetics of β- Galactosidase in Solution

Denaturation and aggregation kinetics of Aspergillus oryzae -galactosidase in solution were studied in order to determine whether the stability of protein drugs can be predicted. Denaturation of -galactosidase, monitored by measuring enzyme activity, conformed to first-order kinetics, whereas aggregation of the denatured form, monitored by high performance size exclusion chromatography, showed a reaction order higher than 1. Denaturation of -galactosidase was irreversible and exhibited a biphasic kinetic pattern which could be explained by assuming that two isoenzymes denatured irreversibly at different rates. Linear Arrhenius plots were obtained for the estimated rate constants, and H and S were estimated according to the Eyring equation. The estimated H was much larger than H observed in usual chemical reactions. The present study suggests that the denaturation of protein drugs can be analyzed by the Eyring equation in the same manner as chemical degradation, contradicting the general consensus that accelerated testing can not be used to predict the stability of protein formulations.     

An aid to decision-making in bioequivalence assessment

A new approach particularly appropriate in bioequivalence studies is outlined. Two formulations of a drug are considered as bioequivalent if the ratio =_N/_s of the expected values of the formulation means lies between specified limits r₁ and r₂.We use the posterior probability P,which provides, in histogram form, interpretational flexibility in bioequivalence assessment.     

Cytotoxic Effects of Topotecan Combined with Various Active G2/M-Phase Anticancer Drugs in Human Tumor-Derived Cell Lines

Topotecan (TPT) is a DNA-Topoisomerase I poison that exhibitsantitumor activity. TPT, like other DNA-damaging agents, arrests ordelays cell cycle progression during S- and G2-phase in a widevariety of tumor-derived cell lines. Particularly, the G2-arrest gives time for the cell to repair its DNA lesions prior tostarting a new cell cycle. Based on these observations, we assessedthe interaction between TPT and G2/M-active agents in p53–mutatedcell lines of diverse origin in order to achieve cell toxicity. Two short-term sequential schedules were administered(TPT G2/M-active drug at the interval of greatest TPT-inducedG2/M-phase cell arrest, and G2/M-active drug TPT), in threehuman tumor-derived cell lines with proven sensitivity to the following drugs: Bleomycin in HEp-2 (squamous larynx carcinoma);Docetaxel in SKBr-3 (breast adenocarcinoma); Etoposide in NCI-H23(non-small-cell lung cancer). Our results show that: 1) SequentialTPT G2/M-active drugs are synergistic when administrationoverlapped the maximum percentage of TPT-induced G2/M–phase cellarrest interval in all three mutated p53 cell lines; 2) the reversesequential schedule (G2/M-active drug TPT) was antagonistic,and being only additive for Etoposide TPT association. Inconclusion, our findings further support the potential cytotoxicrole of TPT in combination with other active drugs when the correctschedule of administration is applied. In addition, they provide arationale for new applications in clinical trials using short-termsequential TPT G2/M-active drugs.     

Effect of α-hexachlorocyclohexane on metabolism and excretion of pentetrazol (Cardiazol®) in the rat

Summary -Hexachlorocyclohexan (-HCH) has been shown to be a potent anticonvulsant when tested with pentetrazol. In the experiments reported here the question was examined whether or not the anticonvulsant properties of -HCH are based on an acceleration of pentetrazol breakdown in the rat.In this study the rat has been shown to metabolize pentetrazol extensively. The enzymatic activity is located in the microsomal fraction of the liver and requires NADPH and oxygen. It is inhibited by SKF-525 A and carbon monoxide. This is taken as evidence that P-450 containing mixed function oxidases are involved in the breakdown of pentetrazol.-HCH pretreatment leads to an acceleration of pentetrazol break-down by microsome preparations of about 140%. In vivo -HCH pretreated rats eliminate pentetrazol from brain and serum with a half life of 1.3 h, while this is 3.8 h in untreated rats.The earliest point in time at which -HCH pretreatment causes diminished brain levels of pentetrazol has been found 60 min after pentetrazol injection. Prior to this brain levels of pentetrazol were identically in untreated and -HCH-treated rats.As pentetrazol elicits convulsions within the first 30 min following oral or subcutaneous administration of a convulsive dose and -HCH is clearly active as an anticonvulsant under these conditions, the accelerated breakdown of pentetrazol cannot be the cause of the anticonvulsive action of -HCH.Supported by Deutsche Forschungsgemeinschaft.H. W. V. was the holder of a grant from Deutsche Forschungsgemeinschaft.     

Synergistic anticonvulsant effects of GABA-T inhibitors and glycine

Summary The anticonvulsant effect of inhibitors of GABA-T (R/S--vinyl-GABA, ethanolamine-O-sulfate, gabaculine, aminooxyacetic acid) was enhanced by 10 mmol/kg glycine in animal seizure models which are based on a functional GABA deficit. Similar to glycine in their action, although less effective, were its close structural analogues (sarcosine, N,N-dimethylglycine) and homologous -aminoacids (-alanine, taurine, -aminobutyric acid, -aminovaleric acid). It is assumed that glycine and its structural analogues act on supraspinal glycine receptors as glycine agonists. Our observation is the first example of the synergistic interaction of two inhibitory neuronal systems resulting in the amplification of the anticonvulsant effect. Combined treatment with GABA-T inhibitors and glycine may turn out to be of practical importance in the therapy of seizure disorders and other diseases, for which treatment with GABA-T inhibitors is considered a potentially useful therapeutic approach.     

Effect of α2-adrenoceptor agonists on the expression of morphine-withdrawal in rats

Summary Previous studies using clonidine indicate that ₂-adrenoceptors are involved in suppressing opiate-withdrawal symptoms. However, clonidine may act as a partial agonist at ₂-adrenoceptors and it also possesses significant ₁-receptor agonist activity.The aim of this study was to determine the role of ₂-adrenoceptors in the expression of opiate withdrawal signs using morphine-dependent rats. A range of agonists were selected for study on the basis of their differential preferences for -adrenoceptors.Hooded Wistar rats were made physically dependent on morphine (s.c. injection of an emulsion releasing a total of 250 mg/kg of morphine base over 48 h). Test drugs were injected s.c. followed by naloxone (10 mg/kg i.p.) 20 min later. The incidence of 5 selected withdrawal signs was recorded during the following 20 min. The ₂-adrenoceptor agonists displayed different profiles of activity. Azepexole (1–10 mg/kg) reduced all signs. Clonidine (80–800 g/kg) reduced all signs except paw shakes while guanfacine (25–250 g/kg) reduced all except jumping and diarrhoea. Talipexole (0.1–1 mg/kg) reduced all signs except diarrhoea which was not affected and jumping which was markedly enhanced. UK 14,304 (80–800 g/kg) reduced jumps, potentiated paw shakes but did not affect body shakes, teeth chattering or diarrhoea. The results suggest that there are subpopulations of ₂-adrenoceptors that modulate the expression of opiate withdrawal signs and/or that some of the drugs used affect receptors other than ₂-adrenoceptors.     

Role of dopamine receptors in the modulation of acetylcholine release in the rabbit hippocampus

Summary Modulation of acetylcholine release was studied in slices of the rabbit hippocampus preincubated with ³H-choline and then continuously superfused with a medium containing 10 mol/l hemicholinium-3. Electrical field stimulation of the superfused slices elicited an increase in tritium outflow, which was tetrodotoxin-sensitive and largely calcium-dependent. Stimulus-evoked acetylcholine release in the rabbit hippocampal slices was modulated by presynaptic muscarinic autoreceptors, as has been shown previously for the rat hippocampus. Drugs with affinity for - and or -adrenoceptors did not affect the evoked overflow of tritium from rabbit hippocampal slices. In contrast, the dopamine receptor agonist apomorphine (0.1 or 1 mol/l) and exogenous dopamine (1 or 10 mol/l) significantly reduced the evoked outflow by about 10 or 20%, respectively. This effect was antagonized by haloperidol (0.01 mol/l) but not by phentolamine (1 mol/l). Attempts to enhance (using nomifensine 10 mol/l) or reduce (using haloperidol, up to 1 mol/l; or bretylium, 1 mmol/l for 5 min) endogenous dopaminergic transmission in the hippocampal slices did not affect stimulation evoked acetylcholine release. In conclusion, presynaptic dopamine receptors modulating acetylcholine release are present in the rabbit hippocampus, but they seem not to be of physiological significance.     

Bioavailability of two hydrochlorothiazide preparations

Summary Eight healthy volunteers received hydrochlorothiazide 75 mg as Dichlotride and Esidrex. Maximal plasma levels were significantly (p<0.05) higher after Dichlotride than Esidrex, 512±189 and 376±70 ng/ml, respectively. However, the bioavailability of the two brands of hydrochlorothiazide did not differ significantly as judged by comparison of the AUC_09h and AUC₀, and the urinary recovery of hydrochlorothiazide during 48 hrs.Supported by the Swedish Medical Research Council (Grant No. B 75-04X-227-12 C) and Hässle-Ciba-Geigy AB, Gothenburg, Sweden     

Effect of erythromycin on the oro-caecal transit time in man

Summary Erythromycins often cause gastrointestinal side-effects due to an increase in motility or to change in the intestinal bacterial flora. In order to evaluate the effect of erythromycin on gastrointestinal motility, 11 healthy volunteers were given placebo, erythromycin stearate (ES) 1000 mg or a therapeutically equivalent single dose of erythromycin acistrate (EA, 2-acetyl erythromycin stearate) 800 mg in a double-blind trial. The orocaecal transit time was measured using the hydrogen breath test with lactulose as the substrate. The transit time was estimated from the H₂-peak (ppm) in end-expiratory breath by two methods, t₁ representing the front and t₂ the bulk of lactulose reaching the colon.t₁ was 51 min in the placebo group, 38 min in the EA and 31 min in the ES group (p < 0.05, ES vs placebo). t₂ was 74 min, 64 min, and 46 min, respectively (p < 0.05, ES vs placebo). The difference between EA and ES was also significant. Six subjects in the ES group but none in the EA group recorded adverse gastrointestinal effects attributable to medication.It was concluded that erythromycin shortens the orocaecal transit time in man and that EA affects the transit time slightly less than ES.     

Über den Einfluß induzierender Substanzen auf Fremdstoff-Oxydasen und andere Redoxenzyme der Leber

Zusammenfassung Die Aktivität einiger Redoxenzyme der Rattenleber wurde nach Behandlung mit folgenden induzierenden Substanzen untersucht: Phenobarbital, -Hexachlorcyclohexan (-HCH), CFT 1201 (Phenyldiallylessigsäure-diäthylaminoäthylester) sowie 3,4-Benzpyren. Der zeitliche Ablauf der Aktivitätsänderungen wurde verfolgt.1. -HCH und CFT 1201 erhöhen ebenso wie Phenobarbital die Cytochrom-P₄₅₀-Konzentration und die NADPH-abhängige Reduktion von Cytochrom c. Die Aktivität der NADH-Cytochrom c-Reduktase wird durch die drei Substanzen gesenkt. Die Aktivität der Aldehyd-Oxydase aus Hyaloplasma wird nur durch -HCH beschleunigt.2. Phenobarbital und -HCH steigern die Demethylierungsrate von Aminopyrin wesentlich mehr als die Konzentration des Cytochroms P₄₅₀. Benzpyren erhöht die Hydroxylierungsgeschwindigkeit von Acetanilid stärker als die Konzentration des P₄₅₀.3. CFT 1201 hemmt die Acetanilid-Oxydation nur in vivo, nicht aber in vitro.4. Phenobarbital induziert die mikrosomalen Enzyme stärker als -HCH, während dieses — wie frühere Befunde zeigten — zu einer stärkeren Proliferation der Leberzellen führt.Wir danken für Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Thermophysical Properties of Pharmaceutically Compatible Buffers at Sub-Zero Temperatures: Implications for Freeze-Drying

Purpose. To evaluate crystallization behavior and collapse temperature (Tg') of buffers in the frozen state, in view of its importance in the development of lyophilized formulations. Methods. Sodium tartrate, sodium malate, potassium citrate, and sodium citrate buffers were prepared with a pH range within their individual buffering capacities. Crystallization and the Tg were detected during heating of the frozen solutions using standard DSC and modulated DSC. Results. Citrate and malate did not exhibit crystallization, while succinate and tartrate crystallized during heating of the frozen solutions. The citrate buffer had a higher Tg than malate and tartrate buffers at the same pH. Tg vs. pH graphs for citrate and malate buffers studied had a similar shape, with a maximum in Tg at pH ranging from 3 to 4. The Tg maximum was explained as a result of a competition between two opposing trends: an increase in the viscosity of the amorphous phase because of an increase in electrostatic interaction, and a decrease in the Tg because of an increase in a water concentration of the freeze-concentrated solution. Conclusion. Citrate buffer was identified as the preferred buffer for lyophilized pharmaceuticals because of its higher Tg and a lower crystallization tendency.     

Relationship between the ocular and systemic disposition of flurbiprofen: The effect of altered protein dynamics at steady state

The differences in flurbiprofen disposition in the aqueous humor and the plasma were examined after systemic doses. Steady state plasma concentrations of flurbiprofen (20–60 g/mL) were achieved via intravenous infusion to albino rabbits. Flurbiprofen demonstrated linear systemic kinetics throughout the dosing range, with constant body clearance and unbound fraction in plasma. At steady state, aqueous humor drug concentrations depended on the corresponding plasma drug concentration. Two clearance terms—CL_so, the systemic clearance to ocular tissues, and CL_os, the ocular clearance to systemic circulation—were used. After systemic doses, the drug concentration in the aqueous humor was related to that in the plasma as well as to the ratio of these two clearances. Flurbiprofen was extensively bound to plasma proteins and showed limited ocular distribution; its CL_so to CL_so tratio was very small. Thus, the concentration of flurbiprofen in the aqueous humor after systemic doses was lower than that obtained after ophthalmic doses. A plasmapheresis technique was utilized to lower the plasma protein concentrations to 60% of normal levels. As a consequence, flurbiprofen demonstrated reduced aqueous humor protein concentrations, increased unbound fractions in the plasma and the aqueous humor, elevated aqueous humor drug concentrations, and elevated total body clearance. The unbound body clearance stayed unchanged. Our study indicated that a drug should present a significant CL_so/CL_os ratio in order to achieve therapeutic concentrations in the eye via systemic doses. The drug-protein binding kinetics can be different between the plasma and the aqueous humor circulations. Because the ocular compariment is very small compared to the overall systemic distribution of flurbiprofen, it has little effect on the steady state systemic concentrations.     

Synthesis and transformations of furan derivatives

By the reactions of 2-phenyl-4-(2-furfuryliden)-, 2-phenyl-4-(5-nitro-2-furfuryliden)-, and 2-methyl-4-(5-nitro-2-furfuryliden)-5-oxazolones with primary and secondary amines, a series of N-mono- and N,N-disubstituted amides of the corresponding-benzamido--(2-furyl)-acrylic and-benzamido- and-acetamido--(5-nitro-2-furyl)acrylic acids was synthesized. 1-Alkyl(aryl) substituted 2-phenyl-4-(5-nitro-2-furfuryliden)-5-imidazolones were synthesized from the reaction of phosphorus oxychloride and the monosubstituted amides of-benzamido--(5-nitro-2-furyl)acrylic acid.Translated from Khimiko-Farmatsevticheskii Zhurnal, No. 2, pp. 21–27, February, 1967.     

Synthesis and antimicrobial action of α-(5-nitrofuryl-2)quinoxaline and its derivatives

Conclusions -(5-Nitrofuryl-2) quinoxaline, and its -cyano- and -oxyderivative were synthesized by nitration of the respective furylquinoxalines with a nitrating mixture. When 2-oxy-3-(furyl-2) quinoxaline is subjected to nitration with excess of nitric acid a dinitro-derivative is formed which is presumably 6-nitro-3-(5-nitrofuryl-2)-2-oxyquinoxaline. The antibacterial, tuberculostatic, and fungistatic activities of the -(furyl-2)- and -(5-nitrofuryl-2) quinoxalines and their derivatives were studied in vitro.Translated from Khimiko-Farmatsevticheskii Zhurnal, No. 10, pp. 14–17, October, 1968.     

Alteration of ethanol-induced changes in locomotor activity by adrenergic blockers in mice

The effects of various doses of ethanol (ETOH) on spontaneous locomotor activity (SLMA) in mice were measured using photocell activity chambers. Of the 4 i.p. doses injected, the 2 lowest doses (0.5 and 1.0 g/kg) stimulated SLMA, the next higher dose (2.0 g/kg) produced a biphasic effect of depression followed by stimulation, and the highest dose (4.0 g/kg) depressed SLMA. The mechanism of the biphasic effect of the 2.0 g/kg dose was studied in tests with central catecholamine antagonists at various doses 30 min before ETOH. Doses of 5, 10, and 20 mg/kg of propranolol, a -receptor blocker, significantly antagonized the depressant effect of ETOH but had no influence on the stimulant effect. High doses (10 and 20 mg/kg) of phentolamine, an -receptor blocker, significantly antagonized the stimulant phase of ETOH action but had no significant effect on the depressant phase. All doses (0.062–0.250 mg/kg) of spiroperidol, a dopaminergic blocking drug, significantly enhanced the SLMA depression produced by ETOH. These results indicate that the SLMA-depressant effect of ETOH may be mediated by central beta-type receptors, that the SLMA-stimulant effect of ETOH may be mediated by central alpha-type receptors, and that at least part of ETOH's action may be due to dopaminergic mechanisms.     

In the ventral tegmental area picrotoxin blocks FGIN 1-27-induced increases in sexual behavior of rats and hamsters

Rationale and objectives There are two types of benzodiazepine receptors, mitochondrial benzodiazepine receptors (MBRs), and -aminobutyric acid (GABA_A)/benzodiazepine receptor complexes (GBRs). MBR activation increases neurosteroidogenesis. Ventral tegmental area (VTA) infusions of the MBR agonist, FGIN 1-27, increase midbrain levels of the progesterone metabolite 5-pregnan-3-ol-20-one (3,5-THP) and lordosis of rats and hamsters. Activation of GBRs leads to membrane hyperpolarization. In the VTA, infusions of GBR agonists enhance 3,5-THP-facilitated lordosis. Thus, if, in the VTA, MBR-mediated increases in 3,5-THP enhance sexual responses via actions at GBRs, then blocking GBRs with picrotoxin will reduce FGIN 1-27-induced increases in sexual behavior of female rodents.Methods Ovariectomized rats and hamsters, with unilateral guide cannula to the VTA, received estradiol benzoate (10 g; EB) at hour 0. Hamsters also received progesterone (100 g) at hour 44. At hour 47.5, all animals were infused first with 10 ng or 20 ng picrotoxin or saline, vehicle to the VTA and, 30 min later, with 5 g/11.4 nM FGIN 1-27 or saline, vehicle. Ten minutes later, animals were tested for sex and motor behavior.Results Picrotoxin, but not vehicle, infusions blocked FGIN 1-27-mediated increases in lordosis of rats and hamsters, proceptivity of rats, and sexual responsiveness of hamsters. In addition, midbrain 3,5-THP levels were higher in animals that received VTA infusions of FGIN 1-27, compared to those infused with saline, vehicle.Conclusion In the VTA, GBRs are required for MBR-enhanced sexual behavior of EB-primed rats and EB- and progesterone-primed hamsters.