Decreased lipolysis in peanuts by a pyridazinone bioregulator

Peanut,Arachis hypogaea, plants were treated in the field with the bioregulator BAS 105 00W, 4-chloro-5-dimethylamino-2-phenylpyridazin-3-one, a substituted pyridazinone, at different times of development. The seeds were harvested, dried, hand-shelled, and analyzed for lipoxygenase activity and conjugated diene hydroperoxide content. Reduced lipoxygenase activity occurred when the bioregulator was applied to the plants at flowering and pegging. The conjugated diene hydroperoxide content decreased the most in peanuts when the bioregulator was applied at pegging. The apparent K_m for lipoxygenase of treated peanuts with linoleic acid as substrate was the same as that for untreated peanuts.     

Reduction of linolenate content in soybean cotyledons by a substituted pyridazinone

The effect of a substituted pyridazinone, 4-chloro-5-(dimethylamino)-2-phenyl-3(2H)-pyridazinone (San 9785), on the reduction of linolenate content was examined in the cotyledons of the soybean cv. Century and a low linolenate mutant of soybeans, C1640, cultured in vitro. No apparent changes in dry matter and total fatty acid accumulation were observed in the cotyledons developing in the presence of San 9785. However, a significant reduction of linolenate content with a corresponding increase in linoleate resulted from growth of the cotyledons in culture medium containing San 9785. San 9785 had a greater effect on decreasing the linolenate content in cotyledons excised in early developmental phases than later stages from both the wild type and mutant soybeans. This result supports other observations that the biosynthesis oflinolenate relative to the other major fatty acids of soybean cotyledons declines in later developmental stages. The compound becomes progressively less effective in reducing the content of linolenate during seed development in the mutant than in the wild type. Both San 9785 and the mutation result in changes in phosphatidylcholine molecular species which indicates the presence of a number oflinolenate desaturation systems in developing soybean cotyledons. The possible biochemical nature of the mutation is discussed.     

Nitric oxide as a bioregulator of apoptosis

Nitric oxide (NO), synthesized from l-arginine by NO synthases, is a small, diffusible, highly reactive molecule with dichotomous regulatory roles under physiological and pathological conditions. NO can promote apoptosis (proapoptosis) in some cells, whereas it inhibits apoptosis (antiapoptosis) in other cells. This complexity is a consequence of the rate of NO production and the interaction with biological molecules such as iron, thiols, proteins, and reactive oxygen species. Long-lasting production of NO acts as a proapoptotic modulator by activating caspase family proteases through the release of mitochondrial cytochrome c into the cytosol, upregulation of p53 expression, activation of JNK/SAPK, and altering the expression of apoptosis-associated proteins including Bcl-2 family proteins. However, low or physiological concentrations of NO prevent cells from apoptosis induced by trophic factor withdrawal, Fas, TNFalpha, and lipopolysaccharide. The antiapoptotic mechanism can be understood via expression of protective genes such as heat shock proteins, Bcl-2 as well as direct inhibition of the apoptotic caspase family proteases by S-nitrosylation of the cysteine thiol. Our current understanding of the mechanisms by which NO exerts both pro- and antiapoptotic actions is discussed in this review article.     

Changes of fatty acids and sterols in apple buds during bud break induced by a plant bioregulator, thidiazuron

The effects of N-phenyl-N'-l,2,3,-thidiazol-5-ylurea (thidiazuron; Dropp; SN 49537) on fatty acids of membrane lipids and sterol content in apple ( Malus domestica Borkh cv. Golden Delicious) buds associated with bud break and bud development were determined. The predominant fatty acids in the membrane lipids of apple buds were palmitic acid (C16:0), linoleic acid (C18:2) and linolenic acid (C18:3). β -Sitosterol and sitosteryl ester were the predominant sterols. An accumulation of unsaturated polar membrane fatty acids started after thidiazuron treatment. A decrease in the percentage of the sitosterol was accompanied by an increase in campesterol and stigmasterol at the beginning of rapid growth. An increase in the ratio of campesterol and stigmasterol to sitosterol and a decrease in the ratio of free sterols to membrane lipids upon breaking of dormancy also occurred in apple buds induced by thidiazuron.     

Breaking bud dormancy in apple with a plant bioregulator,thidiazuron

The effects of N-phenyl-N′-1,2,3,-thidiazol-5-ylurea (thidiazuron; Dropp; SN49537; TDZ) on metabolic changes in apple buds during dormancy break were determined. The data showed that thidiazuron has the capacity to release lateral buds from dormancy. Decreasing degree of bud break and bud growth with thidiazuron treatment occurred in a basipetal direction, suggesting a gradient of increasingly deep rest from shoot apex to base. The breaking of dormancy by thidiazuron is correlated with increase in DNA, RNA, protein, 1-aminocyclopropane-1-carboxylic acid (ACC), 1-(malonylamino) cyclopropane-1-carboxylic acid (MACC), S-adenosylmethionine (SAM) as well as with greater polyamine formation. Polyamine and ethylene biosynthesis did not seem to be competing for SAM, their common substrate, during bud break and bud development. The release of dormancy in apple bud by thidiazuron was inhibited by cordycepine, 5-fluorouracil, 6-methylpurine and cycloheximide. Inhibition of bud break and bud growth also resulted from treatment with α-difluoromethylarginine (DFMA) and α-difluoromethylornithine (DFMO). DFMO was more inhibitory than DFMA.     

Substrate-dependent lipolysis induced by isoproterenol

The relationship between isoproterenol-induced lipolysis and the phosphorylation of perilipin and hormone-sensitive lipase (HSL) was examined using cell-free systems consisting of lipid droplets isolated from rat fat cells and HSL, and/or trioleoylglycerol emulsified with gum arabic and HSL. Isoproterenol was found to stimulate lipolysis in the cell-free system with the lipid droplets without an increase in the phosphorylation of either perilipin or HSL. On the other hand, no stimulation of lipolysis was found in the cell-free system containing lipid droplets despite increases in the phosphorylation of perilipin and HSL. In the cell-free system consisting of trioleoylglycerol emulsified with gum arabic and HSL, neither isoproterenol nor increases in the phosphorylation of perilipin and HSL accelerated lipolysis. These results suggest that isoproterenol-induced lipolysis may not be mediated through the phosphorylation of perilipin and HSL, and may rather be dependent on the substrate of HSL.     

A novel pyridazinone derivative as a nonprostanoid PGI2 agonist

A novel optically pure pyridazinone derivative was synthesized and identified as a nonprostanoid PGI₂ agonist. It inhibited ADP-induced aggregation of human platelets with an IC₅₀ value of 0.081 μM and has high oral bioavailability (56%) with a long half-life (4.3 h) in rats.     

Essential oil variation in dwarf plants of Pelargonium sp. capitatum,induced by a new plant growth bioregulator

Dwarf plants derived from tissue cultures of Pelargonium capitatum, gave an essential oil of quite different composition from that produced by normal plants. This difference persisted for as long as the plant demonstrated the effect of the growth retardant. The chemical composition of the essential oil derived from growth-retarded plants is presented.     

Structural-functional characteristics of a new bioregulator isolated from bovine pigmented epithelium tissue

A new bioregulator operating in ultralow doses corresponding to 10^?17 mg/ml has been isolated from tissue of pigmented epithelium of bovine eyes. It has been established that the functional basis of this bioregulator is a complex of a low molecular weight regulatory peptide (4372 Da) and a modulator consisting of a mixture of proteins with molecular weights of 14.980–66.283 kDa. It has been shown that the regulatory peptide is responsible for membranotropic activity of the bioregulator, and the modulator proteins are responsible for biological action in ultralow doses. The data demonstrate an interrelation between nanocondition of the bioregulator and its ability to show activity in ultralow doses.     

Interactions of lipoidal materials and a pyridazinone inhibitor of chloroplast development

Formation of chloroplast pigments was inhibited, and free fatty acids accumulated in mustard (Brassica juncea [L.] Coss.) cotyledons and in barley (Hordeum vulgare L.) first leaves developed after treatment with 4-chloro-5- (dimethylamino)-2- (α, α, α-trifluoro-m-tolyl) -3 (2H) -pyridazinone. The inhibitor reduced the amount of fatty acids found in polar lipids (galactolipids) of barley chloroplasts and increased the amount in nonpolar lipids while having little effect on total content of bound fatty acids. The inhibition of chlorophyll formation was circumvented by D-α-tocopherol acetate, phytol, farnesol, and squalene, and by unsaturated fatty acids and their methyl esters. The protective action can be explained partially by an interaction external to the plant whereby 4-chloro-5- (dimethylamino) -2- (α, α, α-trifluoro-m-tolyl) -3 (2H) -pyridazinone partitioned out of the aqueous phase and into the lipid phase, thus limiting availability of the inhibitor to plants. However, the amount of inhibitor reaching the cotyledons of tocopherol-protected mustard seedlngs was still in excess of the amount necessary to cause white foliage, but it failed to produce the effect. Tocopherol treatment did not prevent the 4-chloro-5- (dimethylamino) -2- (α, α, α-trifluoro-m-tolyl) -3 (2H) -pyridazinone-induced buildup of fatty acids in mustard cotyledons but did partially circumvent the effect in barley leaves. The amount of linolenic acid relative to linoleic acid was reduced in barley leaves and chloroplasts by 4-chloro-5- (dimethylamino) -2- (α, α, α-trifluoro-m-tolyl) -3 (2H) -pyridazinone action and this effect was circumvented by tocopherol.     

Amino acid composition and biological action of a peptide bioregulator from bovine k-casein

Peptide material has been first isolated from k-casein pepsin hydrolysate. Its subcutaneous injection to hungry animals induced high amplitude (250-350 mV) and high frequency (16-20 Hz) oscillations of electrical potentials usually observed in food satiety and cholecystokinin administration. The peptide reduced respiratory and to a lesser extent heart rate. Its effect is temporary eliminated by naloxone. According to an aminogram, the peptide is a fragment of para-k-casein. A neurotropic peptide effect is connected with satiety regulation and milk consumption in the postnatal period.     

Continuous lipolysis in a reversed micellar membrane bioreactor

The enzymatic hydrolysis of olive oil using Chromobacterium viscosum lipase B encapsulated in reversed micelles of AOT in isooctane was carried out in a continous reversed micellar membrane bioreactor. A tubular ceramic membrane installed in an ultrafiltration module was used to retain the lipase and separate the products from the reaction media. Water filled micelles were supplemented to the reactor together with the substrate/solvent solution to compensate for the permeation of reversed micelles. The influence of substrate concentration, residence time and water content in the productivity and conversion of the system were investigated. A linear relationship between productivity and conversion degree was found for each substrate concentration tested. Operational stability of the bioreactor was tested in a long term operation confirming the high stability of this catalytic system.List of Symbols a(S ₀ ), b(S ₀ ) parameters of Eq. (3) - [AOT] mM AOT concentration - C _c mM concentration in the concentrate - C _p mM concentration in the permeate - E _t mg total amount of lipase - [lipase] mg/cm³ overall lipase concentration - [OIL] mM olive oil concentration - [OLEIC] mM oleic acid concentration in the permeate - P mol/(min · mg) oleic acid productivity - Q _in cm³/min inlet flow rate - Q _out cm³/min outlet flow rate (equal to permeate flow rate) - Q _r cm³/min recirculation flow rate - W _o ratio of water to AOT molar concentrations - X steady state conversion degree in the permeate stream - T °C temperature - rejection coefficient     

Correction of lipid peroxidation in stress with the peptide bioregulator thymopentin

Experiments on rats subjected to acute stress have revealed protective effect of thymopentin pentapeptide on somatic disorders and the state of the antioxidation system and the processes of lipid peroxidation in blood and brain.     

Lead optimization of a sulfonylurea-based piperazine pyridazinone series of glucan synthase inhibitors

The structure-activity relationship studies of a novel sulfonylurea series of piperazine pyridazine-based small molecule glucan synthase inhibitors is described. The optimization of PK profiles within the series led to the discovery of several compounds with improved pharmacokinetic profiles which demonstrated in vitro potency against clinically relevant strains. However, the advancement of compounds from this series into a non-lethal systemic fungal infection model failed to show in vivo efficacy.     

Evidence for a dual mechanism of lipolysis activation by epinephrine in rat adipose tissue

Whole homogenates prepared from tissue previously exposed to epinephrine displayed a 3-fold increased rate of lipolysis of endogenous substrate. When the aqueous infranatant phase of such homogenates was collected by centrifugation and assayed against exogenous triolein emulsions, no hormone effect could be demonstrated. Treatment of such infranatants with cAMP-dependent protein kinase prepared from muscle increased their lipase activity against exogenous triolein by 80%. Employing [3H]triolein emulsions as exogenous substrate, rates of lipolysis of both endogenous and exogenous glycerides were measured simultaneously in whole tissue homogenates. Prior treatment of the tissue with epinephrine increased the rate of lipolysis of endogenous glycerides an average of 3-fold but had no effect on the hydrolysis of exogenous triolein. By contrast, treatment of whole homogenates with protein kinase accelerated lipolysis of exogenous triolein without altering the rate of hydrolysis of endogenous glycerides. The data suggest that a second pathway of lipolysis activation occurs in response to epinephrine in addition to that involving a cAMP-mediated increase in the state of phosphorylation of the hormone-sensitive lipase.