Diterpene Constituents of Euphorbia exigua L. and Multidrug Resistance Reversing Activity of the Isolated Diterpenes

Phytochemical investigation of the MeOH extract obtained from the aerial parts of the annual weed Euphorbia exigua L. resulted in the isolation of two novel ( 1, 2 ) and one known ( 3 ) jatrophane diterpenes. Their structures were established by extensive 1D‐ and 2D‐NMR spectroscopy and HR‐ESI‐MS. The isolated compounds were evaluated for multidrug resistance (MDR) reversing activity on human MDR gene‐transfected L5178 mouse lymphoma cells; and all three compounds were found to modulate the intracellular drug accumulation.     

Multiple treatment potentiates the anticonvulsive activity of cholecystokinin octapeptides

The dose-response curves for the anticonvulsive activity of sulfated and nonsulfated cholecystokinin octapeptide (CCK-8-SE and CCK-8-NS) against picrotoxin-induced (6 mg/kg SC) seizures were assessed either following or without pretreatment with a single high dose of CCK-8-SE or CCK-8-NS, to examine acute tolerance to the effect after IP injections in mice. As CCK-8-SE or CCK-8-NS pretreatment, a 1.6 μmole/kg dose was injected 2 hr prior to the second injection. No acute tolerance to the anticonvulsive activity was demonstrated, and CCK-8-NS pretreatment significantly potentiated its own anticonvulsive activity. Chronic (8-day) daily treatment with a 0.16 μmole/kg dose of CCK-8-SE or CCK-8-NS antagonized seizures by picrotoxin, presumably in a cumulative manner. To investigate the interactions of CCK octapeptides with other anticonvulsive agents, picrotoxin-induced seizures were antagonized with several doses of diazepam following or without acute, high-dose pretreatment with CCK-8-SE or CCK-8-NS. The two octapeptides only slightly modified the activity of diazepam: CCK-8-SE pretreatment displayed a tendency to antagonize it, while CCK-8-NS pretreatment to potentiate it. The results suggest that multiple treatment with CCK-8 induces sensitization of CCK receptors mediating anticonvulsive activity.     

Regional effect of monosodium-L-glutamate on the superficial layers of superior colliculus in rat

Summary Systemic administration of monosodium-1-gluta-mate by single injections of 4 mg/g body weight in infant rats (2–10 days of age) results in acute swelling of cytoplasm and nuclear pyknosis of neurons in the stratum zonale and stratum griseum superficiale of the superior colliculus. Multiple daily doses of 4 mg/g body weight monosodium-1-glutamate result in an almost complete loss of neurons in these two superficial layers. The deeper layers appear not to be affected. No pathological effects were observed in the lateral geniculate body or pretectal complex.Light-and electron-microscopic studies reveal that the optic nerves are remarkably shrunken and many myelinated as well as unmyelinated axons are lost. Injection of ³Hproline into the vitreous body of one eye results in limited transport to the suprachiasmatic nucleus, lateral geniculate body and to lateral portions of the superior colliculus.The small percentage of intact axons in the optic nerve, as well as the limited proline transport from the eye, suggest that administration of monosodium-1-glutamate leaves intact some optic fibers, a portion of which belongs to the retinohypothalamic tract.     

Isolation of a full-length mitotic cyclin cDNA clone CycIIIMs from Medicago sativa: Chromosomal mapping and expression

Cyclins in association with the protein kinase p34^cdc2and related cyclin-dependent protein kinases (cdks) are key regulatory elements in controlling the cell division cycle. Here, we describe the identification and characterization of a full-length cDNA clone of alfalfa mitotic cyclin, termed CycIIIMs. Computer analysis of known plant cyclin gene sequences revealed that this cyclin belongs to the same structural group as the other known partial alfalfa cyclin sequences. Genetic segregation analysis based on DNA-DNA hybridization data showed that the CycIIIMs gene(s) locates in a single chromosomal region on linkage group 5 of the alfalfa genetic map between RFLP markers UO89A and CG13. The assignment of this cyclin to the mitotic cyclin class was based on its cDNA-derived sequence and its differential expression during G2/M cell cycle phase transition of a partially synchronized alfalfa cell culture. Sequence analysis indicated common motifs with both the A- and B-types of mitotic cyclins similarly to the newly described B3-type of animal cyclins.     

Biotic and abiotic initiators for rishitin formation and accumulation in tomato

γ-Ray irradiation of pre-sowing seeds of tomato did not trigger the formation of the phytoalexin “rishitin” in either leaves or fruits of tomato plants through different growth seasons. Application of copper sulfate initiated rishitin formation in both leaves and fruits. Increasing of γ-ray dose was accompanied by decreasing rishitin accumulation in the presence of copper sulfate. Rishitin of tomato leaves was found to be reduced significantly, concomitant with increasing the disease incidence for late and early blight, andFusarium wilt disease, after applying γ-irradiation, in the case of biotic initiatorsPhytophthora infestans, Alternaria solani orFusarium oxysporum alone or together with the abiotic inducer copper sulfate. Shelf-extending γ-ray doses of 1.0, 1.5 and 2.0 kGy decreased rishitin amounts in tomato fruits treated with copper sulfate alone or infected withPhytophthora infestans. Also, the amount of formed rishitin was reduced by extending the storage period.     

Chemical lonization-mass spectrometric approach to structure determination of an intermediate in bile acid biosynthesis

In the course of a study on the details of the biosynthesis of cholic acid from cholesterol, 5β-[26,27-¹⁴C]cholestan-3α,7α,12α,24S,25-pentol, an intermediate in the 25-hydroxylation pathway of cholic acid, was incubated for 2 min with the cytosolic fraction of rat liver homogenate in the presence of NAD. A precursor to cholic acid which appeared to be a ketone was isolate from the reaction mixture by thin-layer chromatography. This material proved to be of inadequate volatility for electron impact mass spectrometry and was therefore studied, without further purification, by techniques of chemical ionization mass spectrometry using ammonia as the reagent gas. The spectrum was rerecorded using argon mixed with ammonia to induce additional fragmentation. One of these fragments corresponded to a McLafferty rearrangement of a 24-keto-25-hydroxycholestane derivative. To obtain additional evidence for this structure the following sequence of reactions was conducted on about 20 μg of the intermediate: (1) periodic acid oxidation, (2) diazomethane treatment, and (3) chromic acid oxidation. The change in molecular weight after each reaction agreed with the presence of a 25-hydroxy-24-keto side chain and three secondary hydroxyl groups in the molecule. Therefore, it could be deduced that the intermediate was 3α,7α,12α,25-tetrahydroxy-5β-cholestan-24-one. This work demonstrates that chemical ionization-mass spectrometic techniques can be a labor-saving alternative to other methods of structure determination and that 3α,7α,12α,25-tetrahydroxy-5β-cholestan-24-one is probably an intermediate in the 25-hydroxylation pathway of cholic acid from cholesterol.     

Dose-dependent dual effect of corticosterone on cerebral 5-HT metabolism

The action of 1.0 and 10.0 mg/kg (i.p.) of corticosterone on serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) contents and on serotonin turnover, measured by an MAO-inhibitor method, was studied at 30 and 120 min after administration. A 1.0 mg/kg dose of corticosterone increased the serotonin content and turnover in the hypothalamus and mesencephalon 30 min after administration; however, it was ineffective on dorsal hippocampus and frontal and parietal cortex. 5-HIAA content did not change significantly in any of the brain areas studied. A 10.0 mg/kg dose of corticosterone decreased the serotonin content and turnover in the hypothalamus and mesencephalon; it was ineffective in other brain areas investigated. 5-HIAA content significantly decreased in the hypothalamus while it increased in the mesencephalon and dorsal hippocampus. In the parietal and frontal cortex, 5-HIAA content did not change following administration of 10.0 mg/kg of corticosterone. At 120 min after corticosterone administration, neither 5-HT content and turnover nor 5-HIAA content showed any change in the brain areas investigated. The results suggest that corticosteroids might change the activity of the brain serotoninergic system in a dose- and time-dependent manner, and in this way the serotoninergic system might play an important role in mediation of the corticosteroid effect exerted on brain function.     

Influence of the estrous cycle and prostaglandins on utero-ovarian vein blood flow in the rat

The blood flow rate in the utero-ovarian vein (UOV) has been measured in adult female rats during the different phases of the estrous cycle. It was observed that the blood flow rate in the UOV is high at proestrus and at estrus and low during diestrus days 1 and 2. The intravenous injection of 10 μg PGF_2α or PGE₂ diminishes the blood flow rate in the UOV. The efficacy of the two PGs in reducing blood flow is different in the various phases of the estrous cycle, being maximal during the day of estrus.     

Identification of 5α-stanols in patients with sitosterolemia and xanthomatosis: stereochemistry of the protonolysis of steroidal organoboranes.

Plasma and fecal sterols of patients who exhibited tendon xanthomas with normal plasma cholesterol levels were studied. Plasma levels were mg/dl mean ± SD) : cholesterol 232 ± 36; cholestanol 5.9 ± 2.1 (normal <0.6); sitosterol 18 ± 5.6 (normal <1.0); campesterol 11 ± 3.3 (normal <1.0). Other sterols such as sitostanol and campestanol (the 5α-dihydro derivatives of sitosterol and campesterol) were also present in large amounts. Examination of the feces from these subjects showed cholesterol, sitosterol, campesterol and their 5β-saturated derivatives. Presence of 5α-stanols in the plasma, and their absence in the feces indicates that the 5α-stanols are synthesized endogenously within the body rather than in the intestine by colonic bacteria. The absolute identification of the structures of these 5α-stanols was elucidated via hydroboration of their corresponding unsaturated sterols coupled with protonolysis of the resultant organoboranes.     

The effect of hydroxyurea and mitomycin C on sperm motility in mice

The mutagen, mitomycin C, and the teratogen, hydroxyurea, were found to decrease sperm motility in mice in a dose-dependent manner. Positive results with these compounds suggest that sperm motility may have been decreased through either mutations or developmental disturbances. Sperm motility can be determined quickly and may be done in conjunction with a sperm-morphology assay.