Showing papers on "Mimosine published in 1999"

Mimosine induces apoptosis in the HL60 human tumor cell line.

Abstract: Mimosine, a plant amino acid not found in proteins, has been widely used as a synchronizing agent, blocking the progression of cell cycle on the G1/S phase border. The mechanism by which this block is achieved is still unclear. We report that in HL60 cells the synchronization is related to an increase in apoptosis. Another human tumor cell line, K562, is insensitive to both phenomena thereby demonstrating that apoptosis observed in HL60 is line-specific. We hypothesize that the mimosine-induced apoptosis and alteration of the cell cycle is due to the inhibition of hypusine generation.

Oxidative stress during selenium deficiency in seedlings of Trigonella foenum-graecum and mitigation by mimosine. Part I. Hydroperoxide metabolism.

Abstract: Actaptive alterations in glutathione (GSH) metabolism were studied during oxidative stress induced by selenium (Se) deficiency in germinating seedlings ofTrigonella foenum- graecum grown for 72 h and the response to supplementation individually of Se or mimosine was explored. Growth enhancement with improved mitochondrial efficiency was elicited by supplementation of Se at 0.5-0.75 ppm or mimosine at 0.1-0.2 mM. Total thiol and protein levels of mitochondrial and soluble fractions, in general, did not vary significantly with supplementation of either Se or mimosine except that the mitochondrial protein levels in mimosine groups (0.1-0.2 mM) decreased by 20–30%. Mitochondrial glutathione peroxidase (GSH-Px) increased by twofold in activity toward H2O2, cumene hydroperoxide (CHP), and t-butyl hydroperoxide (tBHP) in Se groups, and by 50–60% increase toward H2O2 and CHP but by a twofold enhancement in enzyme activity with tBHP in mimosine groups. Soluble GSH-Px activity increased by 30–40% only in mimosine groups and remained unaltered in Se groups. Glutathione S-transferase activity (GST) in the soluble fraction of both Se and mimosine groups increased dramatically by fivefold to sixfold. Distinct differences were noted in the response of the stressed seedlings toward exposure to Se or mimosine and included a decline in glutathione reductase (GR) activity by 50–60% in both mitochondria and soluble fractions of Se groups and an increase in GR activity of the mitochondria by twofold and of the soluble enzyme activity by 30% in the mimosine groups. Mimosine exposure resulted in a dose-dependent decrease in the γ-glutamyl transpeptidase levels, but, in contrast, a significant enhancement by 50% was noted in the Se group at 0.75 ppm. The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of mimosine.

Oxidative stress during selenium deficiency in seedlings oftrigonella foenum-graecum and mitigation by mimosine

Abstract: Oxidative stress during selenium (Se) deficiency in the seedlings ofTrigonella foenum-graecum grown for 72 h was investigated and the response to supplemented levels of Se (0.5-1 ppm) and mimosine (0.05-1 mM) was evaluated. Beneficial effects of Se was maximal at 0.75 ppm. Mimosine, a toxic amino acid, was also found to be beneficial to the growth of the seedlings exposed up to 0.2 mM. When compared to the stressed seedlings, mitochondrial oxygen uptake from seedlings of Se (0.75 ppm) group and mimosine (0.2 mM) group exhibited threefold enhancement in state 3 respiration rate and a controlled state 4 rate, with respiratory control ratios of 5–8. Upon supplementation at the optimal levels, Superoxide dismutase (SOD) activities were enhanced fourfold with Se and eightfold with mimosine in the mitochondria. The soluble activity in mimosine groups increased twofold, but only by 75% in Se groups. Peroxidase activity registered a significant increase by threefold in mitochondria and fourfold in soluble fraction in both Se and mimosine groups. Exposure to Se or mimosine exhibited a differential response in the mitochondrial catalase and ascorbate peroxidase (Asc-Px) activities. In the Se groups, both catalase and Asc-Px in mitochondria decreased by 50–60%, which was contrasted by 60% increase in Asc-Px activity and 40% in catalase activity in mimosine groups. Supplementation with either Se or mimosine evoked similar responses of increases with respect to soluble catalase by twofold to threefold and Asc-Px by 90%. The results of the present study reveal (1) the Prevalence of oxidative stress inT. foenum-graecum during Se deficiency, (2) enhanced mitochondrial functional efficiency mediated by Se and mimosine independently, and (3) an antitoxidative role for mimosine during Se deficiency. The study demonstrates for the first time that mimosine, a naturally occuring toxic amino acid, could be a beneficial growth factor in concentrations between 0.1 and 0.2 mM.

Establishment of synchronization in carrot cell suspension culture and studies on stage specific activation of glyoxalase I.

Abstract: The present report summarizes and compares the effects of three cell cycle inhibitors, viz. aphidicolin, hydroxyurea and mimosine, in inducing synchronization of a rapidly proliferating suspension culture of carrot. These treatments efficiently synchronized the cell cycle as the doubling time of the cell population was roughly equal to the total length of one cell cycle. Protoplasts derived from mimosine treated cell suspension culture were resolved via flow cytometry to get an idea of the temporal organization of the cell cycle events. The biochemical analysis showed a rise in stage specific activity of glyoxalase I, an auxin inducible marker enzyme activated at G2-M. This activity peak could be shifted to an early phase of interphase in response to auxin treatment.

Effects of mimosine and 2,3-dihydroxypyridine on fiber shedding in Angora goats.

Abstract: The effects of intravenous infusion of mimosine or 2,3-dihydroxypyridine (2,3-DHP) and the effects of oral dose level of mimosine on fiber shedding in Angora goats were determined. In one experiment, 20 mature Angora wethers (36 ± 1.9 kg BW) were infused for 2 d with 79, 102, or 135 mg/(kg BW.d) of mimosine, 90 mg/(kg BW.d) of 2,3-DHP, or saline. At 7 d after infusion began, fiber shedding was observed in all goats receiving mimosine but not in any goats infused with 2,3-DHP or saline. Fiber shedding varied among goats; in some goats, fiber shedding was complete and occurred without hand-plucking, whereas in others fiber was retained by nonshed fibers but could be removed by hand-plucking. Nonshed fibers were larger in diameter and more likely to be medullated ( P <.05) compared with hand-plucked fibers. Mean plasma mimosine concentration at 24 and 48 h after infusion began was 79 and 98 μmol/L (P <.05), respectively, and greater (P < .05) for mimosine infused at 135 than at 102 mg/(kg BW.d) (89, 68, and 108 μmol/L for mimosine infused at 79, 102, and 135 mg/[kg BW.d], respectively; SE 9.5). In another experiment, oral dosing of eight Angora bucks (23 ±.5 kg BW) with 400 or 600 mg/kg BW of mimosine rapidly increased plasma mimosine concentration, which reached approximately 100 and 160 μmol/L at 5 h after dosing; however, periods of time during which plasma mimosine concentrations were comparable to those in the first experiment were considerably shorter. Oral mimosine dosing did not induce fiber shedding in 7 d. After 31 d, fiber was retained by nonshed fibers but could be removed by hand-plucking or could only be partially removed with difficulty by hand-plucking. There were no toxic effects of mimosine or 2,3-DHP administration; only minor, short-term inhibitions of feed intake by mimosine were noted in some goats. In conclusion, mimosine holds promise as a safe means to remove fiber of Angora goats; further research is necessary to characterize the seasonality of follicle activity and to develop convenient means of mimosine delivery.

Isolation and Characterization of a DNA Fragment Containing Genes for Mimosine Degradation from Rhizobium Sp. Strain TAL1145

Abstract: The rhizosphere of plants is a highly complex and dynamic ecosystem due to the continuous supply of organic material from the plants as root exudates. We found that mimosine, a toxic free amino acid, is present in the root exudates of the tree legumes of genus Leucaena. Mimosine is found in large quantities in the seeds, foliage and roots of Leucaena spp. It has general antimitotic activity that inhibits the growth of certain microorganisms but it also enhances the growth of others that can utilize it as a putriept source Some Rhizobium strains isolated from the podules of leucaena trees.

Enhancement of β-Glucosidase and β-Galactosidase of Trigonella foenum-graecum by Exposure to the Allelochemical Mimosine

Abstract: Glycohydrolases assume significance in the metabolism of biological systems and have important industrial applications in the areas of pharmaceuticals, food, and medicine. Glycosidases were screened in germinating seeds, and attempts were made to enhance their levels. Screening of glycosidases in the seedlings during a 72 h germination period revealed higher levels of β-glucosidase and β-galactosidase in Trigonella foenum-graecum compared to Cicer arietinum and Vigna radiata. Activity of β-galactosidase was in general higher than that of β-glucosidase in all the seedlings tested. During growth, exposure of the seedlings to an allelochemical, mimosine, at 0.1 mM resulted in the enhancement of enzyme levels by 50% in the seedlings of T. foenum-graecum, whereas the addition of mimosine to the assay medium in vitro did not affect the enzyme activities. Hydrolytic activity was enhanced by addition of glycerol in the medium up to 0.1 M in the case of β-glucosidase and with 0.05 M in the case of β-galactosidase. In general, the hydrolytic rate was higher by about 30% in the seedlings exposed to mimosine compared to that of the control. Concomitant enhancement in the rates of transgalactosidation by 51% and transglucosidation by 23% was also noted, underscoring the relevance of plant glycohydrolases for appropriate applications.

Short communication Influence of feeding increasing levels of leucaena leaf meal on the performance of milch goats and metabolism of mimosine and 3-hydroxy-4 (1H) pyridone

Abstract: Four crossbred (Alpine Beetal) milch goats (24 months; 30 kg live weight) in early lactation received during 31 days increasing levels of Leucaena leucocephala leaf meal (LLM): 25, 50, 75 and 100% of dietary DM during first, second, third and fourth week onwards, respectively. Remaining dietary DM was supplied through green berseem and a concentrate mixture which constituted the whole diet after the 31 days feeding on LLM. Mimosine and 3-hydroxy-4 (1H) pyridone (3,4 DHP) contents of the LLM were 1.88 and 0.78% respectively. Daily average mimosine, 3,4 DHP and total toxin intake was 196, 82 and 278; 339, 141 and 480; 553, 230 and 783; and 648, 269 and 971 g kg ˇ1 live weight (W) during first, second, third and from fourth week onwards, respectively. DM intake on sole feeding of LLM was 65.9 g kg ˇ1 W 0.75 .N o clinical toxicity symptoms were noted. Milk yield started declining from Day 27 onwards and reached the lowest level on Day 33 though LLM was discontinued from Day 31 onwards. Milk yield started improving from Day 37 and reached a peak by Day 49. The milk samples were free of mimosine and DHP, possibly due to some kind of barrier between blood and udder. Mimosine was not detectable in blood serum samples. The 3,4 DHP concentration in the blood serum, however, ranged from 97 on Day 8 to 402 m gm l ˇ1 on Day 29 and disappeared completely by Day 36 when animals were on conventional diet. During metabolism trial faecal excretion of mimosine and 3,4 DHP was 4.43 and 17.9% of total toxin intake, respectively. Urinary excretion of mimosine was 1.59% while that of 3,4 DHP and 2,3 DHP through faeces and urine was 52.17% of total toxin consumed. DCP and TDN values of LLM in goats were 16.03 and 61.58%, respectively. Goats were in positive N balance. The T3 and T4 levels declined but DM intake was not affected.

Nonprotein amino acids : preparation of 5-substituted-2-aminoadipic acid derivatives

Abstract: The number and structural types of nonprotein amino acids2 have increased dramatically over the past few decades. Some of the synthetic amino acids and nonprotein amino acids found in several plants exhibit interesting biological activities. For instance, methionine sulfoxamine (1)3 and phosphinothricin (2)4 serve as herbicides, fluorine containing amino acids as suicide enzyme inhibitor, β-cyanoalanine as neurotoxicant,5 mimosine (3) as rat liver crystathionine synthetase inhibitor,6 selenium containing amino acids7 and pipecolic acids as insect feeding deterrent, etc..

In Vitro Degradation of'Mimosine and Dihydmoxypyridine in Cattle on Transinoculation of Rumen Liquor from Leucaena Leucocephala Fed Goats

Abstract: Rumen liquor from goats (showing 84.92 to 92.88% DHP degradation on 4 months adaptation toleucaena diet) was transimoculated in two Karats Fries cattle which were thereafter switched over from non-Jeucaeua diet to 60% Jeucaena based ration. From 16 to 24 and 25 to 33 day of experiment, they received 80 and 90% of dry matter through leucaena, respectively. Average mimosine intake varied from 0.36 to 0.56 g/kg body weight, yet there was no toxicity symptom. There was gain in body weight throughout the experimental period. On in vitro incubation For 24 h with rumen liquor from these cattle, 7.88, 62.57, 47.59, 37.77, 34.52 and 50.46 percent of total incubated toxin (mimosine -+- 3.4 DHP + 2.3 DHP) was degraded on zero, 6th, 11th, 16th, 23rd and 34th day of transinoculation, respectively. In vitro ruminal fermentation pattern was normal. It is concluded that cattte can acquire extensive DHPdegradability within 6 days of transinoculation of rumen liquor from leucaena adapted goats.

Indigenous Rhizobium strains from Guam contain a mimosine degrading gene

Abstract: Indigenous Rhizobium strains were isolated from nodules of Leucaena leucocephala(Lam.) de Wit on Guam. The bioassay of grow- ing strains in Rhizobium-mimosine (RM) medium showed that the majority of isolates from the Barrigada site catabolized mimosine, a toxin which was produced by the plant, as a nutrient source, while only a few strains from Yigo site had this ability. The polymerase chain reac- tion (PCR) analysis was used to reveal the presence of a mimosine degrading gene (midA). The PCR products of several Rhizobium strains isolated from Guam revealed that some isolates contained a mimosine degrading gene (midA), the 1055-bp DNA fragment present in Rhizobium TAL1145, a strain from Hawaii.

Direct competition Between mimosine and deoxythymidine triphosphate at the site of DNA replication

Abstract: Mimosine, a plant amino acid, is a reversible cell cycle inhibitor. Biochemical studies have indicated that mimosine may act at multiple levels near the G1/S interface. By using microinjection technique, it is shown that mimosine can also inhibit the replication ofXenopus ribosome DNA (rDNA) plasmid reversibly. The high structure similarity between mimosine and thymine of deoxythymidine triphosphate (dTTP) indicates that a direct competition may occur at the origin of DNA replication to prevent the chain elongation.