Are the reductions in nematode attack on plants treated with seaweed extracts the result of stimulation of the formaldehyde cycle?

Soil application to the roots of tomato plants (Lycopersicon esculentum) of a commercially-available alkaline extract of the brown alga, Ascophyllum nodosum, resulted in a significant reduction in the number of second-stage juveniles of both Meloidogynejavanica and M. incognita invading the roots, compared to those of plants treated with water alone. Egg recovery from the seaweed extract treated plants was also significantly lower. The three major betaines found in the seaweed extract (gamma-aminobutyric acid betaine, delta-aminovaleric acid betaine and glycinebetaine) also led to significant reductions in both the nematode invasion profile and egg recovery when applied at concentrations equivalent to those present in the extract. This led to the conclusion that the betaines present in the seaweed extract play a major role in bringing about the observed effects. Treatment of Arabidopsis thaliana plants with seaweed extract also resulted in a significant decrease in the number of females of M. javanica which developed in the roots. Significant reductions in egg recovery were also achieved from plants treated with the seaweed extract and similar effects were produced with the betaines found in the seaweed extract. As the experiments were conducted under monoxenic conditions, it can be concluded that the results obtained with the application of either the seaweed extract or betaines are not dependent on microorganisms associated with the rhizosphere.

Antiviral (RNA) activity of selected Amaryllidaceae isoquinoline constituents and synthesis of related substances.

A series of 23 Amaryllidaceae isoquinoline alkaloids and related synthetic analogues were isolated or synthesized and subsequently evaluated in cell culture against the RNA-containing flaviviruses (Japanese encephalitis, yellow fever, and dengue viruses), bunyaviruses (Punta Toro, sandfly fever, and Rift Valley fever viruses), alphavirus (Venezuelan equine encephalomyelitis virus), lentivirus (human immunodeficiency virus-type 1) and the DNA-containing vaccinia virus. Narciclasine [1], lycoricidine [2], pancratistatin [4], 7-deoxypancratistatin [5], and acetates 6-8, isonarciclasine [13a], cis-dihydronarciclasine [14a], trans-dihydronarciclasine [15a], their 7-deoxy analogues 13b-15b, lycorines 16 and 17, and pretazettine [18] exhibited consistent in vitro activity against all three flaviviruses and against the bunyaviruses, Punta Toro and Rift Valley fever virus. Activity against sandfly fever virus was only observed with 7-deoxy analogues. In most cases, however, selectivity of the active compounds was low, with toxicity in uninfected cells (TC50) occurring at concentrations within 10-fold that of the viral inhibitory concentrations (IC50). No activity was observed against human immunodeficiency virus-type 1, Venezuelan equine encephalomyelitis virus, or vaccinia viruses. Pancratistatin [4] and its 7-deoxy analogue 5 were evaluated in two murine Japanese encephalitis mouse models (differing in viral dose challenge, among other factors). In two experiments (low LD50 viral challenge, variant I), prophylactic administration of 4 at 4 and 6 mg/kg/day (2% EtOH/saline, sc, once daily for 7 days, day -1 to +5) increased survival of Japanese-encephalitis-virus-infected mice to 100% and 90%, respectively. In the same model, prophylactic administration of 5 at 40 mg/kg/day in hydroxypropylcellulose (sc, once daily for 7 days, day -1 to +5) increased survival of Japanese-encephalitis-virus-infected mice to 80%. In a second variant (high LD50 viral challenge), administration of 4 at 6 mg/kg/day (ip, twice daily for 9 days, day -1 to +7) resulted in a 50% survival rate. In all cases, there was no survival in the diluent-treated control mice. Thus, 4 and 5 demonstrated activity in mice infected with Japanese encephalitis virus but only at near toxic concentrations. To our knowledge, however, this represents a rare demonstration of chemotherapeutic efficacy (by a substance other than an interferon inducer) in a Japanese-encephalitis-virus-infected mouse model.

Structures of the 4-cyano and 4-methylamidate analogs of tiazofurin.

4-Cyanotiazofurin [2-(beta-D-ribofuranosyl)thiazole-4-carbonitrile, (1)], C9H10N2O4S, M(r) = 242.3, monoclinic, P2(1), a = 7.329(1), b = 8.295 (1), c = 8.697(1) A, beta = 90.90 (1) degree, V = 528.7(1) A3, Z = 2, Dx = 1.52 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 27.2 cm-1, F(000) = 252, T = 293 K, R = 0.0487 for all 1171 unique reflections. 4-Methylamidatetiazofurin [methyl 2-(beta-D-ribofuranosyl)thiazole-4-carboximidate, (2)], C10H14N2O5S, M(r) = 274.3, orthorhombic, P2(1)2(1)2(1), a = 8.596(1), b = 11.060(1), c = 26.064(1) A, V = 2478.1(2) A3, Z = 8, Dx = 1.47 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 24.5 cm-1, F(000) = 1152, T = 293 K, R = 0.0374 for all 2902 unique reflections. Compound (2) crystallizes with two crystallographic unique structures in the asymmetric unit [(2a) and (2b)]. All three structures show a close contact between the thiazole sulfur and the pentose oxygen O(1'). S...O(1') distances are 2.936 (3) A in (1), 2.773 (2) A in (2a) and 2.878 (2) A in (2b), resulting from C-glycosidic torsion angles of 34.5 (4), 15.6 (3) and 27.2 (3) degrees respectively. This interesting feature is conserved in the crystal structures of other thiazole nucleosides [Burling & Goldstein (1992).

Synthesis and antiviral evaluation of N-carboxamidine-substituted analogues of 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamidine hydrochloride.

Ten, hitherto unreported, analogues of 1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamidine hydrochloride (2a, ribamidine) and methyl carboximidate 5 have been synthesized. These include the N-cyano (2b), N-alkyl (2c-e), N-amino acid (2f-h), N,N'-disubstituted (6, 7a,b), and the N-methylated carboxamide (1f) analogues of ribavirin. In addition, a new facile synthesis of carboxamidine 2a was also developed. All compounds were evaluated for biological activity against the following RNA viruses: Punta Toro (PT) and sandfly fever (SF) viruses (bunyaviruses); Japanese encephalitis (JE), yellow fever (YF), and dengue-4 viruses (flaviviruses); parainfluenza type 3 (PIV3), respiratory syncytial virus (RSV), and measles viruses (paramyxoviruses); influenza A and influenza B viruses (orthomyxoviruses); Venezuelan equine encephalomyelitis virus (VEE, alphavirus); human immunodeficiency virus type-1 (HIV-1, lentivirus); the DNA-containing vaccinia (VV) virus (poxvirus); and adeno type 5 (Ad5) viruses. All of the compounds except for 2b and 7a,b exhibited activity against the bunyaviruses such as that observed with 2a; however, higher IC50 values were generally observed. Glycine analogue 2f showed activity in PT-virus-infected mice in terms of increased survivors and decreased markers of viral pathogenicity. Carboxamidine 2a, carboximidate 5, and dimethyl amidine 6 exhibited activity against dengue type-4 virus. Monomethyl amidine 2c demonstrated activity against RSV, PIV3, and, to a lesser extent, influenza A and B. Activity of 2c generally required higher IC50 values than unsubstituted 2a. The latter exhibited hitherto unreported activity against RSV; therapeutic indices for 2a against RSV and PIV3 were greater than 64 and greater than 21. No substantial in vitro activity was observed for any of the compounds tested against Ad5, measles, JE, YF, VEE, or HIV-1. In addition, evidence is presented which argues in favor of a distinct antiviral mechanism of action for carboxamidines, e.g. 6, in contrast to a role as a carboxamide precursor.

Structures of the 2',3'-dideoxy and 2',3'-didehydro-2',3'-dideoxy analogs of tiazofurin.

2',3'-Dideoxytiazofurin [2-(2',3'-dideoxy-beta-D-glycero-pentafuranosyl)thiazole-4- carboxamide]hemihydrate (1), C9H12N2O3S.1/2H2O, Mr = 237.3, monoclinic, C2, a = 23.141 (2), b = 5.912 (1), c = 8.252 (1) A, beta = 90.71 (1) degrees, V = 1128.9 (4) A3, Z = 4, Dx = 1.396 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 25.0 cm-1, F(000) = 500, T = 295 K, R = 0.0319 for all 1316 unique reflections. 2',3'-Didehydro-2',3'-dideoxytiazofurin [2-(2',3'-dideoxy-beta-D-glyceropent-2-enofuranosyl)thiazole -4-carboxamide] (2), C9H10N2O3S, Mr = 226.3, orthorhombic, P2(1)2(1)2(1), a = 22.172 (2), b = 8.019 (1), c = 5.991 (1) A, V = 1065.2 (4) A3, Z = 4, Dx = 1.411 g cm-3, Cu K alpha, lambda = 1.54178 A, mu = 25.9 cm-1, F(000) = 472, T = 295 K, R = 0.0344 for all 957 unique reflections. Both structures show a close contact between the thiazole S and the pentose O(1') atoms. S...O(1') distances are 2.834 (2) A in (1) and 2.835 (1) A in (2), resulting from C-glycosidic torsion angles of 14.1 (2) and 5.2 (3) degrees respectively. This unusual feature is conserved in the crystal structures of other thiazole nucleosides [Goldstein, Mao & Marquez (1988). J. Med. Chem. 31, 1026-1031].

[Acyclovir creme in recurrent herpes genitalis]. / Acyklovirkrem ved residiverende herpes genitalis.

A multicenter clinical, double-blind crossover trial was conducted in 65 men and 31 women experiencing recurrent episodes of genital herpes in order to compare the effect of acyclovir in propylenglycol (40% cream) with that of cream alone (placebo). 59.4 of the patients on acyclovir experienced a beneficial effect in relation to the usual clinical course of their herpetic eruptions. The corresponding figure for placebo was 34.4%. These percentages were 76.6 and 33.3 respectively if the treatment started within four hours after appearance of symptoms or skin lesions. Pain and burning lasted less than four days in 70.8% of the patients on acyclovir and in 36.4% of those on placebo cream (p less than 0.001). The average duration until complete healing of all skin lesions was 32 hours shorter for patients on acyclovir. In 42 patients on acyclovir and 31 patients on placebo (p less than 0.001) it was less than four days. As regards duration of symptoms and skin lesions, the effect was significantly better if treatment was started early (e.g. less than 4 h). Slight to moderate side-effects were reported in 13.5% of the patients on both treatment regimens.

Preservation of potential fermentables in sweet sorghum by ensiling.

Pressed and wilted samples of sweet sorghum [Sorghum bicolor (L.) Moench var. Rio] were ensiled for periods up to 155 days. A kinetic study of the biochemical changes which occurred during ensiling showed that in wilted sorghum ensilage invert sugars and mannitol levels collectively were maintained at 65% of the original ferment able sugar content of the sorghum. The acidic environment produced by ensiling also served as a pretreatment that resulted in enhanced yields of reducing sugar when the sorghum was contacted with cellulolytic enzymes. The quantity of sugar obtained from enzymatic hydrolysis more than compensated for carbohydrate used by organisms during the ensiling process. Both Saccharomyces uvarum and Clostridium acetobutylicum were able to ferment a medium constituted from pressed sorghum juice and the solution resulting from enzymatic hydrolysis of sweet sorghum ensilage.

Oral acyclovir suppression of recurrent genital herpes: a double-blind, placebo-controlled, crossover study.

A randomised, double-blind, placebo-controlled, crossover study was conducted in 31 male patients with a history of frequently recurrent genital herpes who received consecutively 200 mg acyclovir and matching placebo by mouth four times a day for 12 weeks each. During acyclovir therapy recurrences were completely prevented in 24 (77%) and were reduced in both frequency and duration in the remainder compared with those occurring during treatment with placebo. The incidence and nature of adverse events reported during each treatment period was virtually identical. No long-term effects on recurrence rates were discernible but chronic suppressive therapy can be considered to offer the means of controlling the severe forms of disease experienced by some patients.

A biological assay for determination of availability of selenium for restoring blood plasma gluthathione peroxidase activity in selenium-depleted chicks.

This study was undertaken to develop an assay for the determination of biological availability of selenium. In a preliminary experiment, commercial male, White Leghorn chicks had significantly reduced glutathione peroxidase activity in blood plasma after 7 days of depletion on a selenium-deficient (0.04 ppm of Se) diet. Selenium-depleted chicks fed graded levels of selenium (0.02--0.10 ppm in steps of 0.02 ppm) for 9 days had glutathione peroxidase activity in blood plasma which was linearly, highly correlated with dietary selenium content. In three subsequent experiments, chicks were fed a selenium-deficient diet for 7 days and were then distributed into groups of five chicks each. The standard diets, which contained 0.02, 0.04, 0.06, 0.08 and 0.10 ppm of selenium added as NaHSeO3, and the test diets, which contained three levels of each test substance and provided selenium supplements within the standard range, were each fed to three groups of chicks for 9 days. The dose parameter was selenium, in the standard groups added as NaHSeO3 and in the test groups provided by the selenium present in the test substance. The response parameter was blood plasma glutathione peroxidase activity. Statistical analyses of the results utilizing four fish meals as test substances revealed that the assay complied with the requirements for statistical and fundamental validity.

Availability of selenium in fish meal in comparison with soybean meal, corn gluten meal and selenomethionine relative to selenium in sodiumselenite for restoring glutathione peroxidase activity in selenium-depleted chicks.

We assayed the availability of selenium in feeds and selenomethionine relative to selenium in sodium selenite for restoring blood serum glutathione peroxidase activity in selenium-depleted chicks. The contents of total selenium (determined by neutron activation analyses) were for eight samples of capelin fish meal, 1.34, two samples of mackerel fish meal, 6.17, one sample of solvent-extracted soybean meal, 0.42, and one sample of corn gluten meal, 0.54 ppm in dry matter. The availability of the selenium (relative to selenium in selenite=100%) in capelin fish meal was 48.0 (38.5--60.0), mackerel fish meal, 34.1 (32.3--35.8), soybean meal, 17.5, corn gluten meal, 25.7, and in selenomethionine, 78.3%.