The plant metabolite 6-methoxybenzoxazolinone interacts with follicle-stimulating hormone to enhance ovarian growth

6-Methoxybenzoxazolinone (6-MBOA) is a novel plant metabolite that enhances reproductive status in vertebrate consumers while it inhibits insect, fungal, and bacterial infestation of the plant. Ovaries of prepubertal rats show a dose response to increasing amounts of 6-MBOA.administered in Silastic capsule implants. Ovaries increased in size in response to capsules with 0.5-3.0 cm exposed surface area of 6-MBOA, whereas larger capsules (6 cm 6-MBOA) had no effect. Removal of the pituitary in both prepubertal and mature rats eliminated the stimulatory influence of 6-MBOA. In hypophysectomized animals treated with diethylstibestrol implants, 6-MBOA did not affect ovarian weight and no animals ovulated. Administration of follicle-stimulating hormone (FSH) increased ovarian weight and stimulated production of ova, and FSH combined with 6-MBOA resulted in larger ovaries that released more ova. 6-MBOA also enhanced ovarian growth in intact prepubertal animals treated with pregnant mare's serum gonadotropin. These results show that 6-MBOA has the ability to interact with FSH to stimulate follicular development and increase ovulation. Non-steroidal plant compounds may have a significant impact on the reproductive patterns of wild animal populations.

Synthesis of (aryloxy)alkylamines. 1. Novel antisecretory agents with H+K+-ATPase inhibitory activity

A series of heterocyclic (aryloxy)alkylamines of structures II and III were prepared and found to possess gastric antisecretory activity. Of the variety of substituted thiazoles, benzoxazoles, and benzothiazoles prepared, thiazole 18, benzoxazole 32, and benzothiazole 47 exhibited gastric antisecretory potency comparable to that of ranitidine in vivo in the pylorous ligated rat model. In an isolated rabbit parietal system, the series of thiazoles, benzoxazoles, and benzothiazoles also demonstrated similar potency to that of ranitidine toward the inhibition of both histamine-stimulated and dcAMP-stimulated uptake of amino[14C]pyrine. These compounds inhibited the H+K+-sensitive ATPase enzyme in isolated gastric microsomes. A direct correlation existed between inhibition of 14C uptake, in vivo antisecretory activity, and inhibition of the H+K+-ATPase enzyme. The more potent antisecretory compounds 18, 32, and 47 were also the more potent enzyme inhibitors. These data suggest that the mechanism responsible for the observed in vitro and in vivo gastric antisecretory activity, in these series of compounds, is a consequence of the inhibition of the H+K+-sensitive ATPase enzyme.

Kinetics of some benzothiazoles, benzoxazoles, and quinolines as substrates and inhibitors of rabbit liver aldehyde oxidase

1. Twelve oxygen and sulphur azaheterocycles were studied as potential substrates of rabbit liver aldehyde oxidase. Only benzoxazole and 1,2-benzisoxazole were found to be substrates. 2. Nine of the compounds inhibited the oxidation of quinazoline by aldehyde oxidase and in all cases mixed inhibition kinetics were observed. 3. pi-Excessive heterocycles consisting of a single 5- or 6-membered ring (thiazole, oxazole) were neither substrates or inhibitors. Addition of a carbocyclic ring (benzothiazole, benzoxazole, 1,2-benzisoxazole) allowed binding to the enzyme as a substrate and/or inhibitor. 4. The mixed inhibition exhibited by the pi-excessive azaheterocycles benzothiazole, 1,2-benzisoxazole, and 2-substituted benzoxazoles was characterised by a Ki/KI ratio greater than 1.0, where Ki is the inhibitor constant for binding to the free enzyme and KI is the inhibitor constant for binding to the ES complex. In contrast, five pi-deficient methyl-substituted quinolines, which are known substrates for aldehyde oxidase, exhibited a Ki/KI ratio of less than 1.0. 5. The pi-excessive heterocycles 2,3-benzthiophene and 2,3-benzfuran, which do not contain a nitrogen atom, exhibited weak inhibition with a very high Ki/KI ratio. 6. The results of the study indicated that whilst thiazoles and oxazoles are unlikely to be extensively metabolized by aldehyde oxidase, they may inhibit the metabolism of substrates of the enzyme.

Pharmacodynamics of zoxazolamine and chlorzoxazone in rats

Zoxazolamine is used for the pharmacologic assessment of possible changes in oxidative enzyme activity (paralysis time test) in rodents, whereas one of its metabolites, chlorzoxazone, is used clinically as a skeletal muscle relaxant. In this investigation, the pharmacodynamics of the two compounds were characterized in normal adult rats to determine their suitability for studies of the kinetics of drug action in disease states. Upon i.v. infusion 5 min beyond the onset of loss of the righting reflex (LRR) and concomitant blood sampling, serum concentrations of either drug were higher at the onset than at the offset of LRR, suggestive of a distribution disequilibrium. When zoxazolamine was infused at three different rates to onset of LRR, the pharmacologic end point was reached in 10 to 53 min. Drug concentrations in serum and brain at onset of LRR increased with increasing infusion rate, whereas drug concentrations in cerebrospinal fluid (CSF) were infusion rate independent and essentially identical to CSF concentrations at offset of LRR. Similar experiments (five infusion rates) with chlorzoxazone revealed drug infusion rate dependence even of CSF concentrations at the onset of LRR; only at very slow infusion rates (onset of effect in greater than or equal to 50 min) were onset concentrations in CSF essentially equal to offset concentrations. Neither drug produced measurable metabolite concentrations in the CSF. It is concluded that zoxazolamine but not chlorzoxazone distributes rapidly between CSF and the biophase, metabolites of either drug do not contribute measurably to the pharmacologic effect, and neither drug is subject to development of functional tolerance under the experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal consequences of subcutaneous 6-methoxy-2-benzoxazolinone pellets or injections in prepubertal male and female rats

Prepubertal 27-day-old female rats maintained in a 14L:10D cycle (lights on 06:00 h) were injected s.c. at 13:00 h with saline or 2, 20 or 200 micrograms 6-methoxy-2-benzoxazolinone (6-MBOA) and killed 25-27 h later. No significant differences in body, pituitary or ovarian weight were noted. Differences in uterine weight (mg/100 g body weight) and in circulating free thyroxine index fit the pattern of a reduction after the lower doses with reversal of this effect after the highest dose. A dose-related rise in plasma prolactin concentration was accompanied by a significant increase in pituitary prolactin at the lowest (2 micrograms) dose. When 27-day-old prepubertal male and female rats maintained in a 14L:10D cycle were implanted with a beeswax pellet or a wax pellet that contained 100 micrograms or 1 mg 6-MBOA and killed 3 days later between 14:00 and 16:00 h, body and absolute ventral prostate weights (but not weights of other accessory organs, testes or relative ventral prostate weights) in males were lower. Pituitary (but not plasma) prolactin concentrations were higher after the lower dose compared to the controls; pituitary and plasma values of LH and FSH were unchanged. In females, reproductive variables were unchanged except for a reduction of pituitary prolactin after the 1 mg dose. Triiodothyronine and its free index were elevated after the higher dose in males and the lower dose in females. The free thyroxine index appeared raised after the larger dose only in males.(ABSTRACT TRUNCATED AT 250 WORDS)

The plant metabolite, 6-methoxybenzoxazolinone, stimulates an increase in secretion of follicle-stimulating hormone and size of reproductive organs in Microtus pinetorum

The plant metabolite, 6-methoxybenzoxazolinone (6-MBOA), occurring in leaf tissue of rapidly growing monocots, cues reproduction in some mammals. In the pine vole, Microtus pinetorum, peripubertal females respond to this nonestrogenic compound with a 40% increase in serum levels of follicle-stimulating hormone (FSH). In addition, 6-MBOA significantly increases the weight of the ovary and uterus in both peripubertal and mature voles. This study is the first to offer evidence that 6-MBOA interacts with the pituitary to stimulate reproduction in voles.

Pharmacodynamics of chlorzoxazone in rats

Pharmacological effect-time profiles of a centrally acting muscle relaxant, chlorzoxazone, were evaluated by both rotarod and crossed extensor reflex (CER) methods. Drug response was measured by percent change in the remaining time on the rod for the former method and in intensity of isometric contraction of the muscle for the latter method. The drug response was quantitated using the logarithmic-logistic function and then biophase levels were calculated. The results indicated that the maximum response was observed 10 min after drug administration for both methods at every dose studied. However, the values of ED50 indicated that the CER method was more sensitive than the other. Pharmacodynamic analysis offered the results that the dose-normalized biophase levels for each dose obtained from the CER method were coincident with each other and that the logarithmic-logistic function was proven to be of use for the pharmacodynamic modeling which could simply assess the bioavailability. On the other hand, all dose-normalized values obtained from the rotarod method did not scatter around the same line. This evidence indicated a violation of assumption for the pharmacodynamic analysis. From the above data, the CER method proved to be of use for assessing the drug response based on the dose-independent kinetics with high sensitivity.

Uterotropic 6-methoxybenzoxazolinone is an adrenergic agonist and a melatonin analog

6-Methoxybenzoxazolinone (MBOA) is a compound isolated from grasses which has gonadotropic effects in a variety of animals. The weak beta-adrenergic agonist character of MBOA is shown by its in vitro stimulation of adenylate cyclase from several tissues. Tritiated MBOA bound specifically to particulate fractions from uterus is also displaced by alpha- and beta-adrenergic compounds. The adrenergic properties of MBOA suggest it may exert diverse effects including direct actions on gonadotropin synthesis and release. The mixed adrenergic agonist ephedrine and the antidepressant imipramine were also found to be uterotropic in the vole Microtus montanus following injection protocols used with MBOA. MBOA is structurally similar to melatonin (5-methoxy-N-acetyltryptamine); [3H]melatonin which binds to uterine and pineal membranes is displaced by MBOA and by other adrenergic agents. The fact that MBOA is a beta-adrenergic agonist and a melatonin analog can account for stimulatory and inhibitory effects of this compound on sexual development.

Antifilarial activities of benzazole derivatives. 1. Macrofilaricidal effects against Litomosoides carinii, Dipetalonema viteae, Brugia malayi, and B. pahangi in Mastomys natalensis

Eighteen 2-tert-butyl-benzazole derivatives were evaluated comparatively as macrofilaricidal agents against L. carinii (L.c.), D. viteae (D.v.), B. malayi (B.m.) and B. pahangi (B.p.). Upon repeated treatment (once daily) for five consecutive days the eight benzoxazole derivatives were invariably less potent than the corresponding benzothiazole derivatives. The minimal curative dose (DCM) of the benzoxazoles varied depending on the species and on the chemical structure between 25 and 100 mg/kg p.o. once daily for five days. In the benzothiazole series the lowest DCMs were observed with compound CGP 20376 which is the 5-methoxy-6-dithiocarbamic-S-(2-carboxy-ethyl)ester derivative. This compound eliminated all macrofilariae of L.c., B.m. and Bp. at 6.25 mg/kg p.o. once a day for five days, whereas 12.5 mg/kg x 5 days were needed against D.v. For all other benzothiazole derivatives the DCMs varied between 6.25 mg/kg p.o. x 5 to 100 mg/kg x 5. Six of the most potent benzothiazoles were tested by single oral treatment. In general doses had to be increased 2-4 times to reach minimum curative effects. CGP 20376 was fully effective against B.m. and B.p. at 12.5 mg/kg p.o., against L.c. at 25 mg/kg p.o. and against D.v. at 50 mg/kg p.o.. This compound has been selected from this series of novel benzazoles as a first candidate for trials against human bancroftian filariasis.

Effects of melatonin and 6-methoxybenzoxazolinone on photoperiodic control of testis size in adult male golden hamsters

Consumption of young plants containing 6-methoxybenzoxazolinone (6-MBOA) appears to play an important role in the initiation of reproduction each spring in wild populations of the montane vole. Following its identification, 6-MBOA has been found to stimulate the reproductive system in a number of rodent species, but the mechanism of action remains unknown. The chemical structure of 6-MBOA is similar to melatonin, which, in addition to its well-known antigonadal effects, can exert a progonadal influence under certain experimental conditions. To determine if 6-MBOA might act as a melatonin agonist, four experiments were conducted to compare the effect of these two compounds on testis size in the golden hamster, a rodent whose responses to melatonin are well characterized. 1) Hamsters exposed to 14 h light per day (14L:10D) received a daily injection of melatonin (25.0 micrograms) or 6-MBOA (17.8 micrograms). 2) Hamsters exposed to 6L:18D received Silastic capsules (50 or 200 mm) containing melatonin or 6-MBOA. 3) Hamsters exposed to 6L:18D received chow containing melatonin (21.1 or 42.2 micrograms/gm chow) or 6-MBOA (15.0 or 30.0 micrograms/gm). 4) Hamsters exposed to 6L:18D received drinking water containing melatonin (15.5 micrograms/ml) or 6-MBOA (11.0 micrograms/ml). Testis widths were determined at 2--3 week intervals, and after 66-73 days testes were removed and weighed. Melatonin significantly influenced testis size in each experiment, but treatment with 6-MBOA had no effect in any of these experimental paradigms, indicating that 6-MBOA does not act as a melatonin agonist in the hamster. However, these results indicate that the consumption of melatonin (and presumably melatonin agonists) could serve as an environmental stimulus for reproductive activity.

Synthesis and evaluation of non-catechol D-1 and D-2 dopamine receptor agonists: benzimidazol-2-one, benzoxazol-2-one, and the highly potent benzothiazol-2-one 7-ethylamines

Our interest in identifying D-1 and D-2 dopamine receptor agonists that are not catechols led us to extend previous studies with oxindoles by investigating analogues of dopamine, N,N-dipropyldopamine, m-tyramine, N,N-dipropyl-m-tyramine, and epinine in which the m-hydroxyl is replaced by the NH portion of a thiazol-2-one, oxazol-2-one, or imidazol-2-one group fused to the 2,3-position. These compounds were evaluated for their affinity and agonist activity at D-1 and D-2 receptors by using in vitro assays. Replacement of the m-hydroxy in N,N-dipropyldopamine with the thiazol-2-one group resulted in a dramatic increase in D-2 receptor affinity and activity compared to that of N,N-dipropyldopamine itself or that of the corresponding oxindole, 1. The resulting compound, 7-hydroxy-4-[2-(di-n-propylamino)ethyl]benzothiazol-2(3H)-one (4), is the most potent D-2 receptor agonist reported to date in the field-stimulated rabbit ear artery (ED50 = 0.028 nM). The benzoxazol-2-one (6), benzimidazol-2-one (5), and isatin (51) analogues showed D-2 receptor agonist potency similar to that of 1. The des-7-hydroxyl analogue of 4 (21) also has enhanced D-2 receptor activity compared to that of the corresponding oxindole, 8. 7-Hydroxy-4-(2-aminoethyl)benzothiazol-2(3H)-one, 27, a non-catechol, has enhanced D-1 and D-2 receptor activity in vitro compared to that of the corresponding oxindole, 7. In vivo, 27 increased renal blood flow and decreased blood pressure in the dog. However, these effects were mediated primarily by D-2 receptor agonist activity. This may be a result of the D-1 partial agonist activity of 27 coupled with its potent D-2 receptor activity.

Effect of 6-methoxybenzoxazolinone on sex ratio and breeding performance in Microtus montanus

The plant derivative, 6-mathoxybenzoxazolinone (6-MBOA), which has been demonstrated to initiate reproduction in field populations of the montane meadow vole (Microtus montanus), was administered via feeding or Silastic capsule implants to mated pairs of laboratory bred M. montanus. The animals remained paired for 120 days, and the number, size, and sex ratios of the resulting litters were recorded. Both the size and frequency of litters were significantly greater in 6-MBOA-treated pairs than in controls. By using implants, it was possible to treat one or both sexes in a mated pair. The positive effects of this compound on litter size and number of litters occurred when the females received implants, which indicates that the male has no influence on these parameters. The most unusual result of these experiments was that 6-MBOA has a significant effect on the sex ratio of the litters. Animals receiving 6-MBOA produced significantly more females than did control pairs. This result occurred regardless of the method of administration, and in the case of the implant studies, regardless of which sex received the active implants. These findings are discussed in relation to the ecology and life history strategy of Microtus montanus.

Inhibition of energy metabolism by benzoxazolin-2-one

The effects of the title compound (BOA) on energy-linked reactions in mitochondria were studied. BOA inhibited electron transfer between the flavin and ubiquinone in Complex I, and ATP synthesis at the F1 moiety of the ATPase complex. These results are discussed in relation to the toxicity of BOA towards a wide range of aerobic organisms.

Interference of the new antiinflammatory compound flunoxaprofen with eicosanoid formation in various biological systems

S-(+)-2-(4-Fluorophenyl)-alpha-methyl-5-benzoxazolacetic acid (flunoxaprofen, Priaxim is a new antiinflammatory compound, which in various biological systems interferes with the generation and release of arachidonic acid metabolites of the cyclo-oxygenase pathways without affecting the formation of 5- and 12-lipoxygenase products. Flunoxaprofen reduces the concentration of thromboxane (TX)B2 (ED50 = 35.4 mg/kg p.o.) and prostaglandin (PG)E2-like activity (ED50 = 39.9 mg/kg p.o.) in the inflammatory exudate of rats 8 h after implantation of sponges soaked with carrageenan, whereas the concentration of leukotriene (LT)B4 remains in the range of that of the untreated animals (3.1 ng/ml). Flunoxaprofen inhibits cell infiltration in the exudate and this suggests that LTB4 does not initiate cell recruitment but may represent a mechanism for amplifying the inflammatory response. Using human platelets challenged with collagen, flunoxaprofen only at higher concentration (10(-4) mol/l) reduces TXB2 formation without altering generation of 12-hydroxy-5,8,10,14-eicosatetraenoic acid. This suggests a low capacity of flunoxaprofen of affecting platelet aggregation regulated by arachidonic acid metabolites. Flunoxaprofen prevents pulmonary changes due to secondary release of TXA2 in the guinea-pig. In fact this drug prevents changes due to immunological reaction and antagonizes bronchoconstriction due to exogenous administration of histamine and LTC4.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolactin response in Border-Leicester x merino ewes to administration of melatonin, melatonin analogues, a melatonin metabolite and 6-methoxybenzoxazolinone

The effect of structural modifications of the melatonin molecule on plasma half-life of the analogues and basal prolactin secretion was studied in Border-Leicester x Merino ewes. Halogenation at position 6 and/or unsaturation of the 2,3-double bond of the melatonin molecule slightly lengthened the half-life of the analogues. Melatonin, 6-chloromelatonin, 2,3-dihydromelatonin and 6-chloro-2,3-dihydromelatonin decreased plasma prolactin to 31, 45, 54 and 48% of control levels respectively when administered daily (100 micrograms at 1600 h) for 21 days. The brain metabolite of melatonin, N-acetyl-N'-formyl-5-methoxykynurenamine, and the putative natural melatonin analogue, 6-methoxybenzoxazolinone, failed to affect prolactin levels when administered in a similar manner. These results indicate that certain structural modifications to the melatonin molecule can be tolerated biologically; however, the modifications reported here still did not prevent rapid clearance from the circulation.

[Synthesis and pharmacologic study of 6-(amino-2 ethyl) benzoxazolinones]

Reaction of various amines on 6-(2-bromoethyl)benzoxazolinone or its N-methylated derivative provided eleven new 6-substituted aminoalkyl analogues. In a pharmacological evaluation, several compounds bearing an arylpiperazinic moiety were found to possess significant effects on arterial blood pressure and on the central nervous system; two of them showed interesting analgesic activity.

A naturally occurring plant compound, 6-methoxybenzoxazolinone, stimulates reproductive responses in rats

A nonestrogenic component of young, rapidly growing plants, 6-methoxybenzoxazolinone (6-MBOA), was examined to determine its effect on the reproductive responses of prepubertal and mature female rats. Prepubertal animals treated with a single injection of 6-MBOA or with Silastic capsules implanted for 3 days showed a significant increase in both ovarian and uterine weight. Serum luteinizing hormone was unaffected by 6-MBOA treatment for 3 days in 32-day-old animals, whereas serum follicle-stimulating hormone was elevated. Silastic capsule treatment of mature animals showed the following results. Extended treatment for 6 estrous cycles had no influence on the timing of vaginal cyclicity; despite this, 6-MBOA treatment for 2 cycles caused an increase in ovarian weight resulting from an increase in the number of corpora lutea per ovary. Animals treated for 1 cycle showed a significant increase in the number of ova shed. Uterine weight in mature animals did not increase. This study indicates that 6-MBOA has a stimulatory effect on the reproductive system of young and mature female rats. It is the first attempt to relate the effects of the compound on the endocrine system of any animal. That nonestrogenic plant compounds can trigger reproduction has important ecologic and physiologic significance.

Delay of onset of oviposition in pullets promoted by 6-methoxybenzoxazolinone

Single Comb White Leghorn pullets were used to determine the effects of 6-methoxy-2-benzoxazolinone (6-MBOA) and photoperiod on sexual maturity and egg production. Pullets were maintained on a constant 11L:13D photoperiod until 18 weeks of age and then were divided into two light-controlled chambers. Half the pullets in each chamber received a standard layer mash and the other half received the same diet supplemented with 6-MBOA (MB). Over the ensuing 21 days, the photoperiods were increased to 15L:9D in one chamber and 12L:12D in the other. Consumption of MB resulted in delayed sexual maturity and lower average egg production of those pullets when compared with pullets in the 15L:9D chamber. No significant difference between MB and C pullets was noted in the 12L:12D chamber. These results are similar to those obtained with pinealectomized quail and chickens.

Effects of 6-methoxy-2-benzoxazolinone on the pineal melatonin generating system

6-Methoxy-2-benzoxazolinone (6-MBOA) at concentrations greater than 20 microM stimulates serotonin N-acetyltransferase (NAT) activity of rat pineal glands in 48-hr organ culture as well as of glands freshly cultured, indicating that 6-MBOA acts postsynaptically. The effects of 6-MBOA on NAT activity can be blocked by propranolol but not by prazosin, suggesting that 6-MBOA acts on the beta receptor. At the doses used 6-MBOA stimulation does not block or enhance NAT stimulation by norepinephrine, but is additive with vasoactive intestinal polypeptide which stimulates NAT activity at a site different than the beta receptor. This study demonstrates that 6-MBOA stimulates rather than inhibits melatonin biosynthesis and does not prevent stimulation of melatonin synthesis by norepinephrine. The progonadal association with eating plants containing 6-MBOA in the Montane vole may be due to over stimulation of melatonin receptor sites. Other possible explanations include an extrapineal action such as a blockade of melatonin receptors in the central nervous system, a blockade of receptors on the gonads or to a direct action of this agent on the gonads.

The discovery, fermentation, isolation, and structure of antibiotic A33853 and its tetraacetyl derivative

The structure of antibiotic A33853, isolated from the culture broth of Streptomyces sp., NRRL 12068, is reported. The structure was deduced from an X-ray crystallographic study of its tetraacetyl derivative. Tetraacetyl A33853 is unique because it contains an anhydride moiety, an unexpected product from the reaction of A33853 with acetic anhydride and pyridine.

The antibacterial action of Tinopal AN

The bactericidal activity of Tinopal AN [1,1-bis(3,N-5-dimethyl-benzoxazol-2-yl)-methine p-toluene sulphonate] was shown to be due to a mechanism entirely independent of its inhibitory effects upon NADH dehydrogenase which were reported previously. Whereas the compound had no significant effect upon DNA synthesis in Escherichia coli D22, RNA and protein synthesis were immediately and markedly inhibited. In confirmation, Tinopal AN caused an immediate cessation in inducible beta-galactosidase synthesis in the same organism. An in vitro assay of the transcription of calf-thymus DNA by purified E. coli RNA polymerase showed that this process was inhibited by Tinopal AN.

The nature of the reaction of an essential tyrosine residue of bovine heart mitochondrial ATPase with 4-chloro-7-nitrobenzofurazan and related compounds

Bovine heart mitochondrial ATPase is inhibited after covalent modification with 4-chloro-7-nitrobenzofuroxan. The kinetics of the reaction are indistinguishable from those for the reaction of an essential tyrosine residue of the ATPase with 4-chloro-7-nitrobenzofurazan that have been described previously [Ferguson et al. (1975) Eur. J. Biochem. 54, 117-126]. 4-Fluoro-7-nitrobenzofurazan inhibits the ATPase with a pseudo-first-order rate constant that is tenfold greater than that for 4-chloro-7-nitrobenzofurazan. These data indicate that the rate-limiting step for reaction of the enzyme with these reagents is formation of a Meisenheimer complex at the C-4 position and that the modified tyrosine is probably on the surface of the protein. No evidence was found for more complex patterns of reactivity of 4-chloro-7-nitrobenzofurazan and its analogues. Both ammonium 4-chloro-7-sulphobenzofurazan and ammonium 4-fluoro-7-sulphobenzofurazan fail to react with the ATPase. The utility of these reagents as alternatives to the nitro derivatives may be limited owing to their slow reaction rates. After modification on tyrosine by 4-chloro-7-nitrobenzofurazan, the nitrobenzofurazan group can be transferred by an intramolecular process to lysine [Ferguson et al. (1975) Eur. J. Biochem. 54, 127-133]. ATPase with the lysine thus modified is shown to be reactive towards 4-chloro-7-nitrobenzofurazan in a manner indistinguishable from the native enzyme. This indicates that the intramolecular transfer occurs at sufficient distance to avoid steric hindrance to the second reaction, and that the lysine does not participate in a neighbouring group effect to enhance the reactivity of the tyrosine.

Investigation of the catalytic site of actinidin by using benzofuroxan as a reactivity probe with selectivity for the thiolate-imidazolium ion-pair systems of cysteine proteinases. Evidence that the reaction of the ion-pair of actinidin (pKI 3.0, pKII 9.6) is modulated by the state of ionization of a group associated with a molecular pKa of 5.5

Benzofuroxan reacts with the catalytic-site thiol group of actinidin (EC 3.4.22.14, the cysteine proteinase from Actinidia chinensis) to produce stoicheiometric amounts of the chromophoric reduction product, o-benzoquinone dioxime, and of a catalytically inactive derivative of actinidin that is devoid of thiol and that is assumed to contain, initially at least, the sulphenic acid of cysteine-25. A similar result applies also to papain (EC 3.4.22.2). The rate of o-benzoquinone dioxime formation is neither increased by inclusion of 2-mercaptoethanol or hydroxylamine in the reaction mixture nor decreased by changing the solvent from H2O to 2H2O. The change of solvent was shown to be without effect also on the rate of reaction of benzofuroxan with papain. These results suggest that the reactions of benzofuroxan with both actinidin and papain involve rate-determining attack of the catalytic-site thiol group to produce an intermediate adduct that then reacts rapidly with water to form enzyme sulphenic acid and o-benzoquinone dioxime. The pH-dependence of the second-order rate constant for the reaction of benzofuroxan with actinidin was determined in the pH range 4.3-10.2. In marked contrast with the analogous reaction of papain (reported by Shipton & Brocklehurst [(1977) Biochem. J. 167, 799-810] ) the pH-k profile for the actinidin reaction clearly contains a sigmoidal component with pKa 5.5, in which k increases with decreasing pH. These data together with the molecular pKa values for S-/ImH+ ion-pair formation and decomposition (3.0 and 9.6) suggest that the combined nucleophilic-electrophilic reactivity of the ion-pair of actinidin might be controlled by the state of ionization of another ionizing group, associated with the molecular pKa of 5.5. The pH-dependence of k for the reaction of actinidin with benzofuroxan at 25 degrees C at I 0.1 in aqueous buffers containing 6.7% (v/v) ethanol is probably adequately described by: k = k1/(1 + [H+]/KI + KII/[H+]) + k2/(1 + [H+]/KII + KIII/ [H+] + k3/(1 + [H+]/KIII) in which kI = 2.55 M -1 X s -1, k2 = 1.35 M -1, k3 = 0.93 M -1 X s -1, pKI = 3.0, pKII = 5.5 and pKIII = 9.6. By contrast, the analogous reaction of papain may be described by the same equation but with kI = 0, k2 = 2.2 M -1 X s -1, k3 = 1.3 M -1 X s -1, pKII = 3.6 and pKIII = 9.0.

Effects of 4-nitro- and 4-sulpho-7-substituted benzofurazans on nucleic acid and protein synthesis of a malignant fibrosarcoma cell line in combination with mild hyperthermia

The inhibitory effects of substituted nitro- and sulphobenzofurazans on DNA, RNA and protein synthesis were compared in a new malignant fibrosarcoma cell line at 37 degrees C and 41 degrees C. The effects of these drugs with and without mild hyperthermia were evaluated by determining the % inhibition of incorporation of 3H-precursors into DNA, RNA and protein. None of the sulphobenzofurazan derivatives (Sbf) were effective inhibitors of nucleic acid and protein synthesis at 37 degrees C nor did they enhance the inhibitory effect of hyperthermia alone. The nitrobenzofurazan derivatives (Nbf) at concentrations 10% that used for the Sbf derivatives strongly inhibited biopolymer synthesis in a dose related manner; 4-chloro-7-nitrobenzofurazan (Nbf-Cl) being the most potent inhibitor. Hyperthermia amplified the effect of all the Nbf compounds tested on RNA and protein synthesis but did not further affect DNA synthesis. This selective synergistic effect was most pronounced when the lowest concentrations of Nbf compounds were studied. The synergism however, did not follow a uniform pattern. 6-Mercaptopurine and 6-(1-methyl-4-nitro-5-imidazoyl)thiopurine (Azathioprine) (100 microM) had marginal effects on nucleic acid and protein synthesis when the cells were exposed to these two thiopurines for 1 h at both 37 degrees C and 41 degrees C and they had only a moderate inhibitory effect after exposure for 15 h.

Antiparasitic agents. 5. Synthesis and anthelmintic activities of novel 2-heteroaromatic-substituted isothiocyanatobenzoxazoles and benzothiazoles

The synthesis and antiparasitic properties of 22 isothiocyanato-2-pyridinylbenzoxazoles and benzothiazoles are described; the preparation and anthelmintic activities of 14 isothiocyanato-2-thienyl-, -furyl-, and -pyrrolylbenzoxazoles are outlined. In mice experimentally infected with Nematospiroides dubius (nematode) and Hymenolepis nana (tapeworm), three derivatives, i.e., 5-isothiocyanato-2-(2-furyl)benzoxazole (34), 5-isothiocyanato-2-(5-methyl-2-furyl)benzoxazole (35), and 5-isothiocyanato-2-(1-methyl-1H-2-pyrroly)benzoxazole (37), show 100% nematocidal activity and two, i.e., 5- and 6-isothiocyanato-2-(3-pyridinyl)benzoxazole (5) and 5- and 6-isothiocyanato-2-(3-pyridinyl)benzthiazole (21), show 10% taeniacidal activity at 0.2% in the diet. Two derivatives (5 and 21) show good nematocidal activity in sheep. Maximum activity requires 3-pyridinyl derivatives for both the benzoxazole and benzothiazole series.

The anti-allergic activity of Benoxaprofen [2-(4-chlorophenyl)-alpha-methyl-5-benzoxazole acetic acid]--a lipoxygenase inhibitor

Benoxaprofen [2-(4-chlorophenyl)-alpha-methyl-5-benzoxazole acetic acid], a novel anti-inflammatory compound, is also an orally-active anti-allergic compound in animals. It reduced the anaphylactic release of mediators, particularly slow-reacting substance of anaphylaxis (SRS-A), from both in vitro and in vivo animal models. Benoxaprofen marginally antagonized the activity of histamine on the guinea pig ileum, but not of SRS-A, at concentrations which inhibited the release of SRS-A.

Chemical triggering of reproduction in Microtus montanus

In a replicated experiment, nonbreeding winter populations of Microtus montanus were given supplements of rolled oats coated with 6-methoxybenzoxazolinone, a naturally occurring plant derivative. After 3 weeks of this feeding regime, samples from the populations demonstrated a high incidence of pregnancy in females and testicular hypertrophy in males. Control populations receiving rolled oats coated only with the solvent showed no reproductive activity. These results demonstrate that the presence of 6-methoxybenzoxazolinone in the plant food resource acts as the ultimate cue to trigger reproductive effort in Microtus montanus.

Benzoxazolone-5-sulphonanilides, 1-(benzoxazolone-5'-sulphonyl)-benzotriazoles and 4-hydroxy-3,2'-diaminobenzenesulphonanilides with antiviral activity

benzoxazolone-5-(2'-nitro)-sulphonanilides were synthesized by acylation of o-nitroanilines with benzoxazolone-5-sulphochloride or 3-methylbenzoxazolone-5-sulphochloride. The nitro group in these compounds was subjected to reduction and the resulting amino derivatives were cyclysed to yield the corresponding 1-(benzoxazolone-5'-sulphonyl)-benzotriazoles. Decyclization of the oxazolone cycle of benzoxazolone-5-(2'-amino)-sulphonanilides resulted in 4-hydroxy-3,2'-diaminobenzenesulphonanilides. In vitro testing of the antiviral activity of the compounds obtained during successive synthetic steps revealed that some of them exhibited marked antiviral effect against toga, orthomixo, oncorna and herpes viruses.

Differential sensitivity of mouse hematopoietic stem cells to merocyanine 540

In vivo and in vitro clonal assays of immature mouse blood cells showed that different populations of hematopoietic progenitor cells differ considerably with respect to their sensitivity to photodynamic damages caused by the fluorescent dye Merocyanine 540. Late erythroid progenitors were the most sensitive cells followed in order of decreasing sensitivity by pluripotent stem cells, early erythroid progenitors, and granulocyte/macrophage progenitors. Only about 2%-4% of all nucleated marrow cells were stained with Merocyanine 540 which correlated well with current frequency estimates of progenitor cells in mouse bone marrow. Our findings indicate that the expression of Merocyanine binding sites is developmentally regulated and might, therefore, provide a useful molecular marker for blood cell differentiation and a basis for an effective purification of hematopoietic progenitor cells.

[Behavioral and EEG effects of coixol (6-methoxybenzoxazolone), one of the components in Coix Lachryma-Jobi L. var. ma-yuen Stapf]

Coixol (6-methoxybenzoxazolone) contained in Coix Lachryma-Jobi L. var. ma-yuen Stapf was compared with chlorzoxazone with respect to behavioral and EEG effects in mice and rats. Coixol 50-100 mg/kg, i.p. decreased locomotor activities of both species and produced hypothermia in rats. These effects of coixol were the same in potency as chlorzoxazone given in the same dose. Coixol was approximately twice as potent as chlorzoxazone in potentiating thiopental-induced sleep. This compound attenuated the writhing syndrome induced by 1% acetic acid and increased the threshold to jumping response induced by foot shock, to the same degree as seen with chlorzoxazone. Coixol was equipotent to chlorzoxazone in preventing convulsions induced by maximal electro-shock, while it was about 1.5 times more potent than chlorzoxazone in suppressing pentylenetetrazol-induced convulsion. Coixol 20-100 mg/kg inhibited the lever pressing response of hypothalamic self-stimulation in rats. In rats with chronically implanted electrodes, coixol 50-100 mg/kg induced drowsy patterns on the spontaneous EEG. The EEG arousal response to the external auditory stimulation was inhibited by the same doses of coixol, whereas it failed to suppress the arousal response to the midbrain reticular stimulation. These results indicate that coixol has pharmacological properties qualitatively similar to chlorzoxazone and acts as a central muscle relaxant with an anti-convulsant effect.

Antibacterial and antifungal activities of benzimidazole and benzoxazole derivatives

The in vitro antibacterial and antifungal activities of six benzimidazole and benzoxazole derivatives were tested against standard strains and 59 clinical isolates. Of the six compounds, only compounds II and III (both benzoxazoles) were active, whereas the rest were devoid of any activity. Considerable growth inhibition of all of the standard strains, including fungi and gram-positive and gram-negative bacteria, resulted when they were treated with these compounds. Fifty-nine clinical isolates of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were tested for susceptibility to the two compounds. The most susceptible were the S. aureus isolates. The two compounds were of comparable activity against all of the isolates, with compound III showing a slightly higher activity than compound II. Their respective minimal inhibitory concentrations for 90% inhibition of S. aureus were 25 and 50 microgram/ml. The gram-negative bacteria were resistant to the two compounds and required minimal inhibitory concentrations of 200 microgram/ml for a similar degree of inhibition.

Effects of the non-steroidal anti-inflammatory drug benoxaprofen on leucocyte migration

Possible modes of action of the anti-inflammatory drug, benoxaprofen, have been explored. The drug caused inhibition of leucocyte migration, principally of mononuclear cells into the pleural cavity of rats undergoing carrageenan-induced pleurisy. Evidence was obtained from in vitro leucocyte migration and chemotaxis models that the drug acted directly on the mononuclear cells rather than by inhibition of chemotactic factors.

Studies on 3-substituted 1,2-benzisoxazole derivatives. 6. Syntheses of 3-(sulfamoylmethyl)-1,2-benzisoxazole derivatives and their anticonvulsant activities

Several 3-(sulfamoylmethyl)-1,2-benzisoxazole derivatives were synthesized from 3-(bromomethyl)-1,2-benzisoxazole by the reaction with sodium bisulfite followed by chlorination and amination. Some of them displayed marked anticonvulsant activity in mice. The introduction of a halogen atom to the 5 position of the benzisoxazole ring caused increased activity and neurotoxicity; the substitution of a sulfamoyl group caused decreased activity. The activity of monoalkylated compounds might be the result of biotransformation. Among these compounds, 3-(sulfamoylmethyl)-1,2-benzisoxazole (1a) was thought to be the most promising as an anticonvulsant from the ratio of NTD50 and ED50.

Benoxaprofen: a clinical trial with an unusual design

Benoxaprofen is a new nonsteroidal analgesic anti-inflammatory drug with a long half-life. Preliminary studies showed that steady-state blood levels could be achieved within 24 hours of treatment using a dose of 300 mg on the first day followed by 100 mg twice daily. A double-blind cross-over trial showed that benoxaprofen was effective and well tolerated in rheumatoid arthritis. Its analgesic effect was not apparent until the sixth day of treatment. An unusual trial design was used with treatment periods of unequal duration. This design has the advantage of allowing a new drug to be given for long enough to determine the time course of its action, while sparing patients prolonged treatment with placebo.

A comparative trial of benoxaprofen and naproxen

A double-blind within-patient trial in rheumatoid arthritis comparing the new anti-inflammatory drug benoxaprofen with naproxen is reported. Patients received naproxen 250 mg b.d. for two weeks and benoxaprofen 200 mg b.d. for three weeks. Both drugs demonstrated efficacy. There was no statistically significant difference between them, except for grip strength which favoured naproxen. Side-effects were mild, infrequent and similar for both drugs. Evidence is presented which confirms the long duration of action of benoxaprofen, a fact which may be of clinical significance.

Acylation of benzoxazolin-2-ones and 3-hydroxy-1,2-benzisoxazoles

The acylation courses of 5-bromo and 5,7-dibromo derivatives of benzoxazolin-2--one (BO) and isomeric 3-hydroxy-1,2-benzisoxazoles (BIO) with acetic anhydride, benzoyl chlorides and alkyl chloroformates were investigated. In view of principal course of N-acylation in BO-and O-acylation in BIO-group some of the newly obtained compounds, namely 5,7-Br2-2-(o-chlorobenzoyloxy)-BO (5a) and N-alkoxycarbonyl BIO (22a--27a) make the exceptions. Compounds 25a and 26a were found to possess relatively the most intensive depressant action on the CNS.

Effects of fenoprofen and benoxaprofen on human lymphocytes: inhibition of tritiated thymidine uptake

The effects of the related nonsteroidal anti-inflammatory agents, fenoprofen and benoxaprofen, on in vitro responses of normal human peripheral blood lymphocytes were examined. Drugs caused dose-related inhibition of stimulated cell responses. Fifty percent inhibition occurred at 400 microgram/ml calcium fenoprofen and 250 microgram/ml sodium benoxaprofen. Drugs affected not only responses to soluble phytomitogens but also responses to specific antigens and allogeneic lymphocytes. Numbers of viable cells in cultures with and without mitogens and drugs were similar at beginnings and ends of experiments, excluding drug-related cytotoxicity. Inhibition by drugs was greater when cells were cultured in medium alone than in medium with plasma. Cells that were exposed overnight to drugs and then washed and stimulated did not respond as well as did cells not exposed to drugs. These data indicated that fenoprofen and benoxaprofen exhibited noncytotoxic, incompletely reversible inhibition of nonspecific, specific, soluble and insoluble, mitogen-stimulated lymphocyte responses. These findings may pertain to the anti-inflammatory efficacy of these drugs.