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61.
A novel flavone glycoside was isolated from the methanolic extract of Cynotis axillaris Schult. Various analysis and characterization techniques were used to determine its structure and properties. The compound exhibited a melting point range of 231–232 °C and had a molecular formula of C27H30O14. Several spectral characterization techniques were employed to establish the isolated compound's structure. These included UV-visible spectroscopy, FT-IR, LC-ESI-MS, and NMR spectroscopy. Based on these analyses, the structure of the isolated compound was determined to be 5,7,4’-trihydroxyflavone-8-α-L-rhamnopyranoside-4’-O-β-D-galactopyranosyl. This structure indicates that it is a flavone glycoside consisting of a flavone (5,7,4’-trihydroxyflavone) moiety attached to a sugar molecule (galactopyranosyl) at position 4’, which further bears a rhamnose group at position 8 of the flavone. In addition, to the structural characterization, the compound also demonstrated significant antibacterial efficacy against various bacterial pathogens, including Gram-positive bacteria such as Bacillus subtilis MTCC441 and Gram-negative bacteria such as Escherichia coli MTCC1098, Proteus vulgarize MTCC426, and Salmonella Typhimurium MTCC3224. The antimicrobial activity was evaluated by measuring the zone of inhibition in millimetres, which provides an indication of the compound's ability to inhibit bacterial growth. The study successfully identified and characterized a novel flavone glycoside from Cynotis axillaris Schult. and its antimicrobial activity. 相似文献
62.
63.
Germinating pigeonpea seeds were found to release factor(s), which dramatically altered the growth pattern of rice seedlings. This included an increased sensitivity of roots to gravity, an increase in seminal root length, and increased density of branch roots on the seminal root and suppression of root hair formation. Furthermore, the known characteristic responses of rice to ethylene (namely, coleoptile growth promotion and induction of senescence) were inhibited by the presence of these factor(s). This altered growth pattern of rice seedlings was similar to that brought about by the ethylene-antagonist, silver nitrate. Further, the change in growth pattern in rice was specifically reversed by ethrel. In addition, in wild-type Arabidopsis thaliana these factors suppressed formation of root hair, the development of which is known to be promoted by ethylene. In contrast, in a mutant A. thaliana which shows constitutive ethylene response ( ctr1-1 ), the factors failed to inhibit root hair formation. These observations indicated that germinating pigeonpea seeds secrete factor(s), which have antiethylene-like effects. 相似文献
64.
Prakash Y. S.; Gosselin L. E.; Zhan W. Z.; Sieck G. C. 《Journal of applied physiology》1996,81(3):1240-1248
65.
66.
Protein phosphorylation was investigated in [32P]-labeled cardiomyocytes isolated from adult rat heart ventricles. The -adrenergic stimulation (by isoproterenol, ISO) increased the phosphorylation of inhibitory subunit of troponin (TN-I), C-protein and phospholamban (PLN). Such stimulation was largely mediated by increased adenylyl cyclase (AC) activity, increased myoplasmic cyclic AMP and increased cyclic AMP dependent protein kinase (A-kinase)-catalyzed phosphorylation of these proteins in view of the following observations: (a) dibutyryl-and bromo-derivatives of cyclic AMP mimicked the stimulatory effect of ISO on protein phosphorylation while (b) Rp-cyclic AMP was found to attenuate ISO-dependent stimulation. Unexpectedly, 8-bromo cyclic GMP was found to markedly increase TN-I and PLN phosphorylation. Both 1- and 2-adrenoceptors were present and ISO binding to either receptor was found to stimulate myocyte AC. However, the stimulation of the 2-AR only marginally increased while the stimulation of 1-AR markedly increased PLN phosphorylation. Other stimuli that increase tissue cyclic AMP levels also increased PLN and TN-I phosphorylation and these included isobutylmethylxanthine (non-specific phosphodiesterase inhibitor), milrinone (inhibits cardiotonic inhibitable phosphodiesterase, sometimes called type III or IV) and forskolin (which directly stimulates adenylyl cyclase). Cholinergic agonists acting on cardiomyocyte M2-muscarinic receptors that are coupled to AC via pertussis toxin(PT)-sensitive G proteins inhibited AC and attenuated ISO-dependent increases in PLN and TN-I phosphorylation. Thein vivo PT treatment, which ADP-ribosylated Gi-like protein(s) in the myocytes, markedly attenuated muscarinic inhibitory effect on PLN and TN-I phosphorylation on one hand and, increased the -adrenergic stimulation, on the other. Controlled exposure of isolated myocytes to N-ethyl maleimide, also led to the findings similar to those seen following the PT treatment. Exposure of myocytes to phorbol, 12-myristate, 13-acetate (PMA) increased the protein phosphorylation, augmenting the stimulation by ISO, and such augmentation was antagonized by propranolol suggesting modulation of the -adrenoceptor coupled AC pathway by PMA. Okadaic acid (OA) exposure of myocytes also increased protein phosphorylation with the results supporting the roles for type 1 and 2A protein phosphatases in the dephosphorylation of PLN and TN-I. Interestingly OA treatment attenuated the muscarinic inhibitory effect which was restored by subsequent brief exposure of myocytes to PMA. While the stimulation of alpha adrenoceptors exerted little effect on the phosphorylation of PLN and TN-I, inactivation of alpha adrenoceptors by chloroethylclonidine (CEC), augmented -adrenergically stimulated phosphorylation. KCl-dependent depolarization of myocytes was observed to potentiate ISO-dependent increase in phosphorylation (incubation period 15 sec to 1 min) as well as to accelerate the time-dependent decline in this phosphorylation seen upon longer incubation. Verapamil decreased ISO-stimulated protein phosphorylation in the depolarized myocytes. Depolarization was found to have little effect on the muscarinic inhibitory action on phosphorylation. Prior treatment of myocytes with PMA, was found to augment ISO-stimulated protein phosphorylation in the depolarized myocytes. Such augmented increases were completely blocked by propranolol. Forskolin also stimulated PLN and TN-I phosphorylation. Prior exposure of myocytes to forskolin followed by incubation in the depolarized and polarized media showed that PLN was dephosphorylated more rapidly in the depolarized myocytes. The results support the view that both cyclic AMP and calcium signals cooperatively increase the rates of phosphorylation of TN-I and PLN in the depolarized cardiomyocytes during -adrenergic stimulation. The results raise the additional possibility that the calcium signal may regulate the dephosphorylation of PLN in the depolarized cell. While muscarinic attenuation of -adrenergic action on protein phosphorylation was mediated, in part, by decreased AC activity, and muscarinic inhibition of AC and protein phosphorylation was not detectably influenced by the depolarization, the evidence was seen that muscarinic stimulation of dephosphorylation mechanisms are intimately involved. The postulate that the simultaneous stimulation of 1-adrenoceptors inhibits -adrenergic stimulation of PLN and TN-I phosphorylation is supported. 相似文献
67.
Urease from seeds of water melon was purified to apparent homogeniety upto a sp act of 3750 units/mg protein with 31% recovery. Enzyme showed single protein band on native PAGE by urease specific staining. The mol wt of the enzyme was 4,70,000 and the preparation was free from bound nucleotides (A280/A260=1.14). The enzyme exhibited maximum activity in 50 mM Tris-acetate buffer (pH 8.5). The Km for urease was 8 mM. The enzyme was not inhibited by 25 mM of EDTA in 50 mM Tris-acetate buffer (pH 8.0 and 8.5). 相似文献
68.
Summary A two-step procedure was used for plant regeneration from in vitro grown leaf strips (2–3 mm wide) of cv. Bintje. Step I medium was designed with 2,4-dichlorophenoxycetic acid (2,4-D) at 0.0 or 9.0 M, in combination with 2.28 M kinetin (K), benzyl adenine (BA), zeatin (Z) or zeatin riboside (ZR). Step II media were 2,4-D-free media containing 5.78 M gibberellic acid (GA3) and growth regulators similar to those of step I media. Leaf explants cultured in medium I containing zeatin riboside or zeatin for 6 days and then subcultured in medium II containing zeatin riboside produced numerous shoots without callus formation. Zeatin riboside containing step I and II media caused shoot regeneration in a high number (97.5±2.2) of explants. Approximately, 33.7±8.4 shoots were regenerated from each leaf explant.Abbreviations BA
benzyladenine
- Z
zeatin
- ZR
zeatin riboside (trans isomer)
- 2,4-D
2,4-dichlorophenoxyacetic acid 相似文献
69.
Prakash C. Misra Theodore A. Craig Frederick L. Crane 《Journal of bioenergetics and biomembranes》1984,16(2):143-152
Carrot (Daucus carota L.) cells grown in suspension culture oxidized exogeneous NADH. The NADH oxidation was able to stimulate K+ (86Rb+) transport into cells, but it did not affect sucrose transport.N,N'-Dicyclohexyl-carbodiimide, diethylstilbestrol, and oligomycin, which only partially inhibited NADH oxidation, almost completely collapsed the K+ (86Rb+) transport. Vanadate, which is less effective as an ion transport inhibitor, was less effective in inhibiting the NADH-driven transport of K+ (86Rb+).p-Fluormethoxycarbonylcyanide phenylhydrazone inhibits the K+ transport over 90% including that induced by NADH. The results are interpreted as evidence that a plasma membrane redox system in root cells is closely associated with the ATPase which can drive K+ transport. Because of the inhibitor effects, it appears that membrane components common to the redox system and ATPase function in the transport of K+. 相似文献
70.
Changes in the concentration of cortisol were observed in the jugular venous plasma of pregnant buffaloes on days 30, 15, 5, 2 and 1 prepartum, at partum, at regular 6-hr intervals up to 72 hr postpartum and on days 4, 6, 10, 18, 34 and 50 postpartum. A radioimmunoassay (RIA) procedure for cortisol standardized in the laboratory was used. Mean plasma cortisol levels showed little fluctuation (P<0.05) between days 30 and 2 prepartum with the values ranging from 1.28 +/- 0.23 to 1.46 +/- 0.13ng/ml. A small (but nonsignificant) rise in the hormone level was observed one day prepartum followed by a sharp increase to a high mean value of 3.78+/-0.36 ng/ml (P<0.05) at parturition. A sharp decline (P<0.05) to a low mean value was recorded within 6 hr postpartum followed by marked fluctuations in the hormone level up to 72 hr postpartum. The hormone levels subsequently varied narrowly between 1.74+/-0.39 and 2.01+/-0.27 ng/ml up to 50 days postpartum. 相似文献