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At least 19 recordsLinked to original sources
PubMed2005

Identification of kinetin and kinetin riboside in coconut (Cocos nucifera L.) water using a combined approach of liquid chromatography-tandem mass spectrometry, high performance liquid chromatography and capillary electrophoresis.

Kinetin (free base and riboside), which was assumed by many scientists to be a synthetic cytokinin plant growth hormone, has been detected for the first time in the endosperm liquid of fresh young coconut fruits ("coconut water"). To facilitate the study, we developed a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the identification and quantification of kinetin and kinetin riboside in purified coconut water extract sample. Following a solid-phase extraction of cytokinins in coconut water using C18 columns, the samples were further purified by Oasis MCX columns and analyzed by LC-MS/MS for kinetin and kinetin riboside. Detection by mass spectrometry was carried out using selected reaction monitoring (SRM) mode, by identifying the putative kinetin and kinetin riboside based on their characteristic fragments. Based on a signal-to-noise ratio of 3, the limits of detection in SRM mode were 0.02 microM and 0.005 microM for kinetin and kinetin riboside, respectively. Furthermore, optimal conditions for a baseline chromatographic separation of 18 cytokinin standards by high performance liquid chromatography (HPLC) were developed. The HPLC method had been employed for the confirmation and further fractionation of kinetin in coconut water extracts. The confirmation and fractionation of kinetin riboside was carried out using a further modified HPLC program due to the presence of other interfering material(s) in the sample matrix. Finally, fractions of putative kinetin and kinetin riboside collected from HPLC eluate of coconut water sample were further authenticated by independent capillary zone electrophoresis (CZE) experiment.

Chromatography, High Pressure Liquid↗
PubMed2003

Inhibitory activity of kinetin on free radical formation of activated platelets in vitro and on thrombus formation in vivo.

Kinetin has been shown to have anti-aging effects on several different systems, including plants and human cells. Recently, we demonstrated that kinetin markedly inhibited platelet aggregation in washed human platelets. In the present study, an electron spin resonance (ESR) method was used to further evaluate the scavenging activity of kinetin on the free radicals formed. Kinetin (70 and 150 microM) concentration dependently reduced the ESR signal intensity of hydroxyl radicals in collagen (1 microg/ml)-activated platelets. Furthermore, kinetin was effective in reducing the mortality of ADP-induced acute pulmonary thromboembolism in mice when administered intravenously at doses of 4 and 6 mg/kg. In addition, intravenous injection of kinetin (4 and 6 mg/kg) significantly prolonged the bleeding time by approximately 1.9- and 2.1-fold as compared with normal saline in severed mesenteric arteries of rats. A continuous infusion of kinetin (0.6 mg/kg/min) for 10 min also significantly increased the bleeding time by about 2.3-fold, and the bleeding time returned to baseline within 120 min after cessation of kinetin infusion. Platelet thrombi formation was induced by irradiation of mesenteric venules with filtered light in mice pretreated intravenously with fluorescein sodium. When kinetin was administered at 13 and 14 mg/kg in mice pretreated with fluorescein sodium (5 mg/kg), the occlusion time was significantly prolonged. In conclusion, these results suggest that kinetin has effective free radical-scavenging activity in vitro and antithrombotic activity in vivo. Treatment with kinetin may lower the risk of thromboembolic-related disorders. Therefore, kinetin may be a potential therapeutic agent for arterial thrombosis, but its toxicity must be further assessed.

Adenine↗
PubMed1968

Effect of the kinetin-naphthaleneacetic acid interaction upon total RNA and protein in senescing detached leaves.

The interaction between kinetin and naphthaleneacetic acid in the regulation of senescence of excised tissue of mature broccoli leaves has been used to examine the extent of synchrony between changes in chlorophyll, RNA, and protein. Kinetin increased the net uptake of (14)C-labeled orotic acid and leucine. Naphthaleneacetic acid decreased the effect of kinetin on net uptake after long treatment, but in short-time treatments the auxin increased the effect of kinetin on net uptake. Results of long (24 hr) treatments indicated a general synchrony between the loss of RNA, protein, and chlorophyll. Naphthaleneacetic acid reduced the stabilizing effect of kinetin upon chlorophyll content and upon the content and synthesis of RNA. In short-time experiments, however, RNA content and synthesis were transiently increased by kinetin, and further increased by kinetin plus naphthaleneacetic acid, while chlorophyll content decreased in the presence of kinetin and decreased further in the presence of kinetin plus naphthaleneacetic acid. Actinomycin-D accelerated the loss of chlorophyll, RNA and protein and strongly depressed the rate of RNA synthesis. In the presence of actinomycin-D the stabilizing effect of kinetin upon RNA was substantially reduced. In contrast, the chlorophyll and protein contents remained higher than in the control. Actinomycin-D did not nullify the basal incorporation of orotic acid into RNA, nor did it negate the effect of kinetin upon incorporation. The failure of synchrony between changes in chlorophyll and RNA does not substantiate the proposal that kinetin regulates senescence by a direct effect upon DNA-dependent RNA synthesis.

Naphthaleneacetic Acids↗
PubMed2003

Inhibitory mechanisms of kinetin, a plant growth-promoting hormone, in platelet aggregation.

Kinetin has been shown to have anti-aging effects on several different systems including plants and human cells. The aim of this study was to examine the detailed inhibitory mechanisms of kinetin in platelet aggregation. In this study, kinetin concentration-dependently (50-150 microM) inhibited platelet aggregation in human platelets stimulated by agonists. Kinetin (70 and 150 microM) also concentration-dependently inhibited intracellular Ca2+ mobilization and phosphoinositide breakdown in platelets stimulated by collagen (1 microg/ml). Kinetin (70 and 150 microM) significantly inhibited thromboxane A2 formation stimulated by collagen (1 microg/ml) and arachidonic acid (60 microM) in human platelets. In addition, kinetin (70 and 150 microM) significantly increased the formation of cyclic AMP. Intracellular pH values were measured spectrofluorometrically using the fluorescent probe BCECF-AM in platelets. The thrombin-evoked increase in pHi was markedly inhibited in the presence of kinetin (70 and 150 microM). Rapid phosphorylation of a platelet protein of molecular weight (Mr) 47000 (P47), a marker of protein kinase C activation, was triggered by collagen (1 microg/ml). This phosphorylation was inhibited by kinetin (70 and 150 microM). In conclusion, these results indicate that the anti-platelet activity of kinetin may be involved in the following pathways: kinetin's effects may initially be due to inhibition of the activation of phospholipase C and the Na+/H+ exchanger. This leads to lower intracellular Ca2+ mobilization, followed by inhibition of TxA2 formation and then increased cyclic AMP formation, followed by a further inhibition of the Na+/H+ exchanger, ultimately resulting in markedly decreased intracellular Ca2+ mobilization and phosphorylation of P47. These results suggest that kinetin has an effective anti-platelet effect and that it may be a potential therapeutic agent for arterial thrombosis.

Adenine↗
PubMed2003

"Action-at-a distance" of a new DNA oxidative damage product 6-furfuryl-adenine (kinetin) on template properties of modified DNA.

N(6)-furfuryladenine (kinetin, K) was shown to have cytokinin activity and antiageing effects. It also appears to protect DNA against oxidative damage mediated by the Fenton reaction. Kinetin was identified as a natural component of DNA in plant extract, calf thymus DNA, fresh DNA preparations from human cell culture, as well as in human urine. A proposed mechanism of kinetin synthesis includes furfural, the oxidative damage product of a 2-deoxyribose moiety of DNA, which reacts with an adenine residue to form N(6)-furfuryladenine at DNA level. The identification of kinetin in plant cell extracts, as well as human urine, suggests its excision from DNA by repair mechanisms. Since such a bulky modification as kinetin induces conformational changes of DNA, this could lead to mutations. Therefore, it was interesting to analyze an effect of kinetin on coding properties of DNA. Chemically synthesized oligodeoxynucleotide (20-mer) containing kinetin AAAACTGCCGTCCTGAKGAT was used as a primer. It was elongated in a polymerase chain reaction (PCR) on a template plasmid pEW1 harboring a 210-bp fragment of DNA derived from the 5' end of HIV mRNA. The PCR product of that length containing kinetin in position 17 from the 5' end was isolated and sequenced. Interestingly, DNA polymerase correctly incorporates thymine opposite of kinetin (an adenine derivative) on the complementary strand, but the misincorporations occur in a vicinity of the modified base.

Adenine↗
PubMed1976

Stimulation of ethylene production in the mung bean hypocotyls by cupric ion, calcium ion, and kinetin.

The synergistic stimulation of ethylene production by kinetin and Ca(2+) in hypocotyl segments of mung bean (Phaseolus aureus Roxb.) seedling was further studied. The requirement for Ca(2+) in this system was specific. Except for Sr(2+), which mimicked the effect of Ca(2+), none of the following divalent cations, including Ba(2+), Mg(6+), Cu(2+), Hg(2+), Co(2+), Ni(2+), Sn(2+), and Zn(2+), showed synergism with kinetin on ethylene production. Fe(2+), however, showed a slight synergism with kinetin. Some of them (Hg(2+), Co(2+), and Ni(2+)) had a strong inhibitory effect, while others (Zn(2+), Mg(2+), Sn(2+), and Ba(2+)) had a slight or no inhibitory effect on ethylene production in the absence or presence of kinetin.Cu(2+) alone, depending on the concentration applied, stimulated ethylene production with a lag period of about 2 hours and had no synergism with kinetin on ethylene production. When Cu(2+) was applied with Ca(2+), a remarkable synergistic stimulation of ethylene production was observed. Tracer experiments indicated that Cu(2+) enhanced the uptake of (45)Ca(2+) into the tissues during the first few hours of incubation, and this increase of (45)Ca(2+) uptake paralleled the enhancement of ethylene production. When Ca(2+) was applied together with kinetin plus Cu(2+), both the ethylene production and the (45)Ca(2+) uptake were greatly increased over those from the segments treated with Cu(2+) or kinetin alone. The increase in ethylene production as a result of kinetin plus Ca(2+) plus Cu(2+) treatment is equal to the combined increases caused by kinetin plus Ca(2+) and Cu(2+) plus Ca(2+). A possible mechanism accounting for such cooperative effects of Cu(2+), Ca(2+), and kinetin on ethylene production is discussed.

Journal Article↗
PubMed1975

Effect of kinetin on the formation of chromosome aberrations during irradiation of Crepis capillaris L. seeds and its radioprotective effect.

The object of this investigation was the mutagenic effect of kinetin (6-phurphuryl-aminopurine) on chromosomes of Crepis capillaris L. Dry seeds were soaked in the 0.05% kinetin solution for 4, 6 and 8 hours before the irradiation with X-rays. It is observed that soaking of dry seeds in kinetin solution stimulates the appearance of chromatid aberrations for almost two hours earlier, than in the control (soaking seeds in water). A regular increase of the chromatid-type rearrangements with increasing the duration of soaking in the kinetin solution was observed (3.3%, 16-20% and almost 50% at 4 hours; 6 hours' and 8 hours' soaking respectively). This increase is indicative for the effect of kinetin on the processes taking place in the cell before the irradiation. Apparently kinetin stimulates the onset of the stage S for a certain proportion of cells, and thus at the moment of irradiation the cell population is at the asynchronous state. A considerable radioprotective effect of kinetin was observed in all the variants of the experiment, which is not associated with the capacity of stimulating the initiation of chromatid aberrations inherent in kinetin. Kinetin alone (without irradiation) exerts no mutagenic effect on the cells of Crepis capillaris.

Chromosome Aberrations↗
PubMed2000

Effect of kinetin concentration and methods of application on seed germination, yield components, yield and fiber properties of the Egyptian cotton (Gossypium barbadense).

Two field experiments in 1993 and 1994 as well as a laboratory germination experiment were conducted on the Egyptian cotton cultivar Giza 75 (Gossypium barbadense) to determine the effect of six concentrations of kinetin (6-furfurylaminopurine) ranging from 0 to 10.0 mg l(-1) and three different methods of application: (A) seeds were soaked for 24 h before germination (laboratory experiment) or sowing (field experiment) in solutions of different kinetin concentration, (B) cotton plants were sprayed twice with different kinetin concentrations at 60 and 75 days after sowing (DAS) during the square initiation and the beginning of bolling stages, at volume solution of 480 l ha(-1). (C) Seeds were soaked in kinetin solutions before sowing as method A. In addition cotton plants were sprayed twice as method B with the same kinetin concentrations. Kinetin application improved seed viability and seedling vigour as shown by lengths of the hypocotyl, radicle and the entire seedling, as well as seedling fresh weight. Moreover, significant increases were recorded in the number of open bolls/plant, boll weight, lint and seed indices, seed cotton yield/plant, and seed cotton and lint yields/plot. The highest means were obtained at 5 mg kinetin l(-1) concentration and under method C of application. Treatments generally, had no significant effects on lint percentage, yield earliness and fiber properties. These results show that, the use of kinetin at 5 mg l(-1) for pre-soaking seeds before planting and spraying cotton plants at 60 and 75 DAS with the same concentration could improve cotton germination, seed cotton and lint yields.

Journal Article↗
PubMed1966

Interaction of naphthaleneacetic Acid and kinetin in the senescence of detached leaves.

Kinetin and naphthaleneacetic acid were applied separately and in combination to excised leaf disks, localized areas of laminae, and petioles of detached leaves of broccoli (Brassica oleracea L., var. italica) and Xanthium (Xanthium pensylvanicum Wallr.). Senscence (measured as loss of chlorophyll) was strongly retarded by kinetin, but very slightly influenced by naphthaleneacetic acid. When the 2 substances were applied concurrently, the effect of kinetin was markedly reduced by naphthalene acetic acid. Neither interference with uptake nor transport of kinetin appeared to cause the reduction.In broccoli, the response to kinetin was as great in young leaves as in old leaves, and the reduction of the kinetin effect by naphthaleneacetic acid was greater in young leaves than in old leaves. Results indicate that the prevention of loss of critical material may be more significantly related to the delay of senescence by kinetin than is directed transport and accumulation (mobilization). Kinetin may control 2 or more events which contribute independently to the delay of senescence in detached leaves, and naphthaleneacetic acid may possibly interfere with only 1 of them.

Journal Article↗
PubMed1971

Kinetin and carbohydrate metabolism in chinese cabbage.

The effects of kinetin on starch and sugar levels and on (14)CO(2) and (32)P-orthophosphate labeling patterns of floated Chinese cabbage (Brassica pekinensis) leaf discs were investigated. Kinetin caused gross starch degradation. Neutral sugars were depressed by 30 to 40% in leaf tissue treated with kinetin for 24 hours. (14)CO(2) labeling of leaf discs pretreated with kinetin for 24 hours showed increased radioactivity in chloroform-soluble material and most sugar phosphates, and a 35 to 40% decrease in radioactivity in the neutral sugars, glucose, sucrose, and fructose. Incorporation into ATP was increased by 40% by kinetin. (32)P-Orthophosphate uptake was inhibited 30% by kinetin. When corrected for uptake, kinetin stimulated incorporation into chloroform-soluble material but had little effect on other cell fractions. These results indicate that kinetin mobilizes starch reserves and increases the flow of sugars required for the synthesis of lipids and structural materials in floated discs.

Journal Article↗
PubMed1974

Internal Water Status of Kinetin-treated, Salt-stressed Plants.

Stomatal resistances and turgor pressures were measured during a 12-day period on leaves of bean (Phaseolus vulgaris L. cv. Contender) which were treated with kinetin, were salinized or were treated with kinetin and salinized. Stomatal resistances were highest in salt-stressed plants, and progressively lower in salt-stressed and kinetin-treated plants, control plants, and kinetin-treated plants. Turgor pressures were highest in salt-stressed plants, and progressively lower in control plants, kinetin-treated plants, and salt-stressed and kinetin-treated plants. Stomata appeared to be kept open more widely under kinetin treatment than under control conditions, even when turgor pressures were lower in kinetin-treated plants than in control plants.

Journal Article↗
PubMed1975

Interaction of kinetin and calcium in relation to their effect on stimulation of ethylene production.

Application of kinetin and Ca(2+) caused a striking synergistic increase in ethylene production by mung bean (Phaseolus aureus Roxb) hypocotyl segments. The effect of kinetin on Ca(2+) uptake and of Ca(2+) on the uptake and metabolism of kinetin in relation to their effect on ethylene production was studied. Tracer experiments showed that kinetin greatly increased the uptake of (45)Ca(2+) after 6 hours of incubation. Reciprocally, Ca(2+) stimulated the uptake of kinetin-8-(14)C and remarkably enhanced the metabolism of kinetin-8-(14)C into several polar metabolites. Consequently, the quantity of free kinetin-8-(14)C remaining in Ca(2+)-treated segments was much less than in control segments. A possible mechanism accounting for the synergism between kinetin and calcium on ethylene production is discussed.

Journal Article↗
PubMed2007

Therapeutic potential and mechanism of kinetin as a treatment for the human splicing disease familial dysautonomia.

Mutations that affect the splicing of pre-mRNA are a major cause of human disease. Familial dysautonomia (FD) is a recessive neurodegenerative disease caused by a T to C transition at base pair 6 of IKBKAP intron 20. This mutation results in variable tissue-specific skipping of exon 20. Previously, we reported that the plant cytokinin kinetin dramatically increases exon 20 inclusion in RNA isolated from cultured FD cells. The goal of the current study was to investigate the nature of the FD splicing defect and the mechanism by which kinetin improves exon inclusion, as such knowledge will facilitate the development of future therapeutics aimed at regulating mRNA splicing. In this study, we demonstrate that treatment of FD lymphoblast cell lines with kinetin increases IKBKAP mRNA and IKAP protein to normal levels. Using a series of minigene constructs, we show that deletion of a region at the end of IKBKAP exon 20 disrupts the ability of kinetin to improve exon inclusion, pinpointing a kinetin responsive sequence element. We next performed a screen of endogenously expressed genes with multiple isoforms resulting from exon skipping events and show that kinetin's ability to improve exon inclusion is not limited to IKBKAP. Lastly, we highlight the potential of kinetin for the treatment of other human splicing disorders by showing correction of a splicing defect in neurofibromatosis.

Carrier Proteins↗
PubMed2006

Kinetin-induced differentiation of normal human keratinocytes undergoing aging in vitro.

Kinetin (N(6)-furfuryladenine) is a cytokinin growth factor having several anti-aging effects reported for human cells and fruit flies. We have observed that short-term culturing of human keratinocytes in the presence of 40 to 200 microM kinetin results in a significant inhibition of cell growth. Studies were undertaken to analyze the process of differentiation as a reason for growth inhibition. Keratinocytes at different passage levels were treated with fetal calf serum (FCS) and calcium as differentiation-inducing positive controls, with different concentrations of kinetin, and with a combination of kinetin and calcium. The induction and progression of differentiation was monitored by morphological observations and by using several differentiation markers, including keratins (K10 and K14), involucrin, epidermal transglutaminase, and some new keratinocyte-specific antibodies isolated by the phage display method. In young keratinocytes, two days of calcium treatment reduced the K14 level by 78%, and increased the levels of K10 and involucrin by 40% and 29%, respectively. In comparison, 40 microM kinetin had no effect on the K14 level, but increased the K10 level by 28% and that of involucrin by four-fold. The combination of calcium and 40 microM kinetin led to a decrease by 23% in the K14 level, to an increase in the level of K10 by 55%, and to a two-fold rise in the involucrin level. These results suggest that the rate, extent, and quality of differentiation depend on the inducing agent, and that kinetin may be useful in promoting the differentiation of human keratinocytes, especially in the presence of calcium.

Adult↗
PubMed1967

Senescence: action of auxin and kinetin in control of RNA and protein synthesis in subcellular fractions of bean endocarp.

A comparative study was made of the effects of auxin (alpha-naphthalene acetic acid), kinetin (6-furfurylaminopurine) and a mixture of auxin and kinetin applied in vivo on synthesis of RNA and protein and the distribution of such synthesis amongst the subcellular fractions of sections of endocarp from Kentucky Wonder pole beans (Phaseolus vulgaris, L.). Auxin caused considerable enhancement of incorporation of labeled precursors into RNA and protein of all subcellular fractions, and induced net synthesis of RNA and protein. That auxin-induced net synthesis of protein is repressed by actinomycin D indicates that auxin acts primarily to stimulate synthesis of RNA, as a result of which synthesis of protein is enhanced. The effect of kinetin alone on synthesis of RNA, or of kinetin on auxin-induced synthesis of RNA was variable, with either stimulation or inhibition observed in different experiments. Kinetin-enhancement of synthesis of both RNA and protein in subcellular fractions also varied, with enhancement of synthesis in 1 or all subcellular fractions among different experiments. The variable effect of kinetin did not seem to be related to the amount of endogenous or added auxin. The mode of action of kinetin is discussed.

Journal Article↗
PubMed1969

Movement and metabolism of kinetin-C and of adenine-C in coleus petiole segments of increasing age.

To see if polar movement was typical of growth-regulators other than auxins, the movement of adenine-8-(14)C and of kinetin-8-(14)C was studied in segments cut from petioles of increasing age. No polarity was found. In time-course experiments lasting 24 hr, kinetin showed a progressive increase of radioactivity in receiver blocks, while adenine showed a maximum at 8 hr with a decline thereafter. More kinetin moved through older segments than through younger ones. There was no difference in net loss as far as the position of the donor block is concerned. However, the loss of radioactivity from adenine donor blocks was much higher than the loss of radioactivity from kinetin donor blocks.The radioactivity in receiver blocks after 24 hr treatment with kinetin-(14)C was still with kinetin, judging by location on chromatograms. By the same criterion, adenine and a smaller amount of some other compound were in receiver blocks after a 6 hr transport with adenine-(14)C in the donors. By contrast, more zones of radioactivity were extracted from petiole segments to which kinetin or adenine had been added. For both purine derivatives the original compound represented no more than 20% of the total radioactivity extracted from the tissue after a transport period of 24 hr.

Journal Article↗