Effect of elevated glucose concentrations on cellular lipid peroxidation and growth of cultured human kidney proximal tubule cells

This study has examined whether elevated glucose can induce lipid peroxidation and contribute to the inhibition of cell growth in human kidney proximal tubule(HPT) cells. HPT cells were cultured in media containing glucose concentrations of 8 mM (control), 25 mM, and 50 mM. Lipid peroxidation was assessed by the thiobarbituric acid reactivity and cell growth was assessed by ³H-thymidine uptake. Results show decreased (59%, p < 0.01) growth of HPT cells cultured in 50 mM glucose. Cells cultured in 50 mM mannitol did not show any growth inhibition, suggesting that the decreased cell growth associated with glucose is not due to osmolarity changes. There was an increase (108%, p < 0.02) in lipid peroxidation in cells cultured with high levels of glucose (50 mM) compared with controls and cells cultured with 50 mM mannitol. To examine if membrane lipid peroxidation or malondialdehyde (MDA, an end product of lipid peroxidation) has any role in the inhibition of cell growth, we examined the effect of tertiary butylhydroperoxide (TBH, known to cause lipid peroxidation and generate MDA) on the growth of HPT cells. TBH decreased cell growth (49, 17 and 3% of controls at 0.1, 0.25, and 0.5 [mole TBH/ml medium). Similarly, a marked reduction in the growth was observed with exogenous MDA (72, 69 and 34% of controls at 0.1, 0.25, and 0.5 mole MDA/ml medium). This suggests that elevated glucose can induce membrane lipid peroxidation and accumulation of MDA, which in turn can inhibit cellular growth and contribute to the altered structure and function of HPT cells in diabetes.     

Ultrasonic radiation induced lipid peroxidation in liposomal membrane

Summary Ultrasonic radiation produced a dose dependent linear increase in lipid peroxidation (MDA formation) in the liposomal membrane. The yield of MDA was significantly inhibited by butylated hydroxytoluene (BHT), the antioxidant, sodium formate, the OH radical scavenger, and EDTA, the metal ion chelator. Ascorbic acid at low concentration increased the ultrasonic induced MDA formation while high concentrations inhibited lipid peroxidation. A mechanism of ultrasound induced lipid peroxidation is suggested.     

Lipid peroxidation in hepatocyte cell cultures: Modulation by free radical scavengers and iron

Summary Rat hepatocytes were isolated and then maintained in serum-free cell culture medium for 24 h. The amount of malondialdehyde (MDA) accumulated in the medium was assayed and used as a measure of lipid peroxidation. The acivity of lactate dehydrogenase (LDH) and urea were measured in the medium and used as indicators of hepatocellular viability and function. The effects of iron; desferrioxamine mesylate (Desferal), an iron chelator; and mannitol, a hydroxyl free radical scavenger were investigated. The addition of iron, Fe² resulted in a three-fold increase in the levels of MDA. Desferal inhibited the production of MDA and blocked the effect of Fe²⁺. Neither iron nor Desferal had any effect on LDH or urea levels. Mannitol had no effect on MDA or urea production, but caused a 4 to 8-fold increase in the LDH levels in the medium. The results show that iron is involved in the mechanism of lipid peroxidation in hepatocyte cultures but suggest that as a pathologic event lipid peroxidation is not expressed in terms of viability during the first 24 h of hepatocyte culture.     

Lipid peroxidation induced by bolesatine,a toxin ofBoletus satanas: Implication in m5dC variation in Vero cells related to inhibition of cell growth

Bolesatine, a glycoprotein fromBoletus satanas Lenz, has previously been shown to be mitogenic in rat and human lymphocytes at very low concentrations, whereas higher concentrations inhibited protein synthesisin vitro and in severalin vivo systems. The low concentrations (1–10 ng/ml) of bolesatine were shown to activate protein kinase C (PKC)in vitro (cell-free system) and in Vero cells. In the same time, Vero cells significantly proliferated when incubated with bolesatine concentrations ranging from 1 to 10 ng/ml; the DNA synthesis increased by 27–59% as referred to the control, and InsP3 release increased in a concentration-dependent manner, up to 142%. At higher concentrations, 1–10 g in cell-free systems, bolesatine inhibits protein synthesis by hydrolyzing the nucleoside triphosphates GTP and ATP.In the present work, the implication of other toxic mechanisms, such as lipid peroxidation and active radical production, was investigated in relation to inhibition of cell growth, whereas possible modifications of the ratio m⁵dC/dC+m⁵dC were determined in order to correlate with the biphasic action of bolesatine in Vero cells.Low concentrations of bolesatine up to 10 ng/ml do not increase malonaldehyde (MDA) production, while they induce hypomethylation (5.2% as compared to 7.1%). Higher concentrations (above 20 ng/ml) increase MDA production, from 58 ng/mg of cellular proteins to 113 ng/mg at a concentration of 50 ng/ml, for example, and induce hypermethylation in Vero cell DNA. It is concluded that low concentrations of bolesatine that are proliferative induce hypomethylation, which could be one of the pathways whereby bolesatine induces cell proliferation. Higher concentrations which enhance lipid peroxidation also induce hypermethylation. These mechanisms could be at least partly implicated in the pathway whereby bolesatine induces cell death.Abbreviations MDA malonaldehyde - TBA thiobarbituric acid     

Measurement of doxorubicin-induced lipid peroxidation under the conditions that determine cytotoxicity in cultured tumor cells.

We have investigated doxorubicin-induced lipid peroxidation by the measure of malondialdehyde (MDA) formation in rat glioblastoma cells and human breast carcinoma cells in culture. There was a significant production of MDA when the cells were incubated with pharmacologically relevant doxorubicin concentrations, i.e., concentrations that produce a significant cytotoxicity (0.1 micrograms/ml). At equitoxic doses, vincristine provided no lipid peroxidation, indicating that MDA formation is not a consequence of cell death. Doxorubicin-induced lipid peroxidation was maximal 24 h after incubation of the cells with doxorubicin, indicating that a delay was necessary for the free radical-mediated membrane damage induced by doxorubicin. In the presence of alpha-tocopherol in the culture medium, the doxorubicin-induced MDA formation was inhibited. The development of this method will help in defining the role of free radicals and lipid peroxidation in the cytotoxicity of doxorubicin.     

The effect of radiotherapy and chemotherapy on osmotic fragility of red blood cells and plasma levels of malondialdehyde in patients with breast cancer

BackgroundGamma radiation effects on the erythrocyte membrane from three different functional parts, lipid bilayer, cytoskeleton and protein components. When the red cell membrane is exposed to radiation, it loses its integrity and hemoglobin leaks out. In addition, irradiation leads to lipid peroxidation and the products of this process, leading to hemolysis. The aim of the present study was to measure osmotic fragility (OF) of red blood cells and malondialdehyde (MDA) levels as a marker of oxidative injury in breast cancer patients treated with radiation and chemotherapy.Materials and MethodsThe OF test was performed using different concentrations of a salt solution. The measurement of MDA was done with chemical methods.¹¹ The sampling was taken during three stages of treatment: first sample was taken before starting chemotherapy, the second sample was taken before radiation therapy and the third sample was taken after radiotherapy.ResultsNo statistically significant differences between levels of MDA in these three stages of treatment were observed. However, the comparison of mean levels of MDA showed an increase after radiotherapy. The OF rate did not show significant difference (P > 0.05) during the stages of treatment.ConclusionIn a standard treatment program of radiotherapy and chemotherapy lipid peroxidation level and OF do not significantly increase.     

Bactericidal Activity of Photocatalytic TiO2 Reaction: toward an Understanding of Its Killing Mechanism

When titanium dioxide (TiO₂) is irradiated with near-UV light, this semiconductor exhibits strong bactericidal activity. In this paper, we present the first evidence that the lipid peroxidation reaction is the underlying mechanism of death of Escherichia coli K-12 cells that are irradiated in the presence of the TiO₂ photocatalyst. Using production of malondialdehyde (MDA) as an index to assess cell membrane damage by lipid peroxidation, we observed that there was an exponential increase in the production of MDA, whose concentration reached 1.1 to 2.4 nmol · mg (dry weight) of cells⁻¹ after 30 min of illumination, and that the kinetics of this process paralleled cell death. Under these conditions, concomitant losses of 77 to 93% of the cell respiratory activity were also detected, as measured by both oxygen uptake and reduction of 2,3,5-triphenyltetrazolium chloride from succinate as the electron donor. The occurrence of lipid peroxidation and the simultaneous losses of both membrane-dependent respiratory activity and cell viability depended strictly on the presence of both light and TiO₂. We concluded that TiO₂ photocatalysis promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced major disorder in the E. coli cell membrane. Subsequently, essential functions that rely on intact cell membrane architecture, such as respiratory activity, were lost, and cell death was inevitable.     

5-methoxytryptophol preserves hepatic microsomal membrane fluidity during oxidative stress

Lipid peroxidation is a degenerative chain reaction in biological membranes that may be initiated by exposure to free radicals. This process is associated with changes in the membrane fluidity and loss of several cell membrane-dependent functions. 5-methoxytryptophol (ML) is an indole isolated from the mammalian pineal gland. The purpose of this study was to investigate the effects of ML (0. 01mM-10mM) on membrane fluidity modulated by lipid peroxidation. Hepatic microsomes obtained from rats were incubated with or without ML (0.01-10 mM). Then lipid peroxidation was induced by FeCl(3), ADP, and NADPH. Membrane fluidity was determined using fluorescence spectroscopy. Malonaldehyde (MDA) +4-hydroxyalkenals (4-HDA) concentrations were estimated as an indicator of the degree of lipid peroxidation. With oxidative stress, membrane fluidity decreased and MDA+4-HDA levels increased. ML (0.01-3 mM) reduced membrane rigidity and the rise in MDA+4-HDA formation in a concentration-dependent manner. 10 mM ML protected against lipid peroxidation but failed to prevent the membrane rigidity. In the absence of oxidative reagents, ML (0.3-10 mM) decreased membrane fluidity whereas MDA+4-HDA levels remained unchanged. This indicates that ML may interact with membrane lipids. The results presented here suggest that ML may be another pineal indoleamine (in addition to melatonin) that resists membrane rigidity due to lipid peroxidation.     

Toxicity of 1,2-dibromoethane in isolated hepatocytes: Role of lipid peroxidation

Treatment of isolated hepatocytes with 1,2-dibromoethane (DBE) caused a concentration dependent depletion of cellular glutathione (GSH) content and a parallel increase in the covalent binding of reactive intermediates to cell proteins, as a consequence of the haloalkane activation. The reduction of the hepatocyte GSH content, induced by DBE, stimulated the onset of lipid peroxidation, as measured by malondialdehyde (MDA) accumulation. N-Acetylcysteine (1 mM) was found to partially prevent GSH loss and to inhibit MDA formation, whereas equal concentrations of cysteine and methionine were ineffective on these respects. The stimulation of the peroxidative reactions appeared to be also associated with an increase in the leakage of lactate dehydrogenase (LDH) from the cells, indicative of a severe hepatocyte injury. Antioxidants such as -tocopherol, N,N′-phenyl-phenylenediamine (DPPD) and promethazine, as well as N-acetylcysteine reduced MDA formation to various extents and also protect against LDH release, yet without interfering with the covalent binding of DBE reactive intermediates to hepatocyte proteins. These results suggest the involvement of lipid peroxidation, consequent to GSH depletion, in the pathogenesis of liver cell necrosis due to DBE.     

The role of lipid peroxidation in aluminium toxicity in soybean cell suspension cultures

The primary reactions leading to Al toxicity in plant cells have not yet been elucidated. We used soybean (Glycine max [L.] Merr.) cell suspension cultures to address the question whether lipid peroxidation plays an important role in Al toxicity. Upon transfer to an Al-containing culture medium with a calculated Al3+ activity of 15 microM soybean cells showed a distinct and longtime increase in lipid peroxidation within 4 h. At the same time a drastic loss of cell viability was observed. Butylated hydroxyanisole (BHA) and N,N'-diphenyl-p-phenylenediamine (DPPD), two lipophilic antioxidants, were able to almost completely suppress lipid peroxidation in Al-treated cells at a concentration of 20 microM. This effect was dose-dependent for DPPD and was observed at minimum concentrations of 1-2 microM. When lipid peroxidation was suppressed by DPPD or BHA cell viability remained high even in the presence of toxic Al concentrations. These results suggest that Al-induced enhancement of lipid peroxidation is a decisive factor for Al toxicity in suspension cultured soybean cells.     

Relative efficacies of indole antioxidants in reducing autoxidation and iron-induced lipid peroxidation in hamster testes

Increased iron stores are associated with free radical generation and carcinogenesis. Lipid peroxidation is involved in DNA damage, thus indirectly participating in the early steps of tumor initiation. Melatonin and structurally related indoles are effective in protecting against oxidative stress. The aim of the study was to compare the relative efficacies of melatonin, N-acetylserotonin (NAS), indole-3-propionic acid (IPA), and 5-hydroxy-indole-3-acetic acid (5HIAA) in altering basal and iron-induced lipid peroxidation in homogenates of hamster testes. To determine the effect of the indoles on the autoxidation of lipids, homogenates were incubated in the presence of each agent in concentrations of 0.0, 0.01, 0.05, 0.1, 0.25, 0.5, 0.75, 1.0, 2.0, 2.5, or 5.0 mM. To study their effects on induced lipid peroxidation, homogenates were incubated with FeSO(4) (30 microM + H(2)O(2) (0.1 mM) + each of the indoles in the same concentrations as above. The degree of lipid peroxidation was expressed as concentrations of malondialdehyde + 4-hydroxyalkenals (MDA + 4-HDA) per mg protein. The indoles decreased both basal and iron-related lipid peroxidation in a concentration-dependent manner. Melatonin reduced basal MDA + 4-HDA levels when used at the concentrations of 0.25 mM or higher, and prevented iron-induced lipid peroxidation at concentrations of 1.0, 2.0, 2.5, or 5.0 mM. The lowest effective concentrations of NAS required to lower basal and iron-related lipid peroxidation were 0.05 mM and 0.25 mM, respectively. IPA, only when used in the highest concentrations of 2.5 mM or 5 mM inhibited basal lipid peroxidation levels and it was ineffective on the levels of MDA + 4-HDA due to iron damage. 5HIAA reduced basal lipid peroxidation when used at concentrations of 0.25 mM or higher, and it prevented iron-induced lipid peroxidation only at the highest applied concentration (5 mM). In conclusion, melatonin and related indoles at pharmacological concentrations protect against both the autoxidation of lipids as well as induced peroxidation of lipids in testes. In doing so, these agents would be expected to reduce testicular cancer that is initiated by products of lipid peroxidation.     

Carbonyl stress: malondialdehyde induces damage on rat hippocampal neurons by disturbance of Ca<Superscript>2+</Superscript> homeostasis

The objective of this study was to investigate the influences of carbonyl stress induced by malondialdehyde (MDA), a typical intermediate of lipid peroxidation, on intracellular free Ca²⁺ concentration ([Ca²⁺]_i) alterations in cultured hippocampal neurons of rat. The microphotographic study clearly demonstrated that the hippocampal neurons became gradually damaged following exposure to different concentrations of MDA. Further study indicated that the plasma membrane Ca²⁺-ATPase (PMCA) activity was inhibited by MDA in a concentration- and time-dependent manner. The supplementation of 100 μM MDA was found to cause a notable early phase increase of [Ca²⁺]_i in hippocampal neuron cultures followed by a more pronounced late-phase elevation of [Ca²⁺]_i. Such effect of MDA was prevented by the addition of nimodipine, an inhibitor of L-type calcium channel or by an extracellular Ca²⁺ chelator EGTA. The identification of the calcium signalling pathways were studied by applying U73122, an inhibitor of PL-C, and H-89, an inhibitor of protein kinase A (PKA), showing the involvement of PL-C/IP3 pathway but not the PKA/cAMP pathway. These results suggested that MDA-related carbonyl stress caused damages of rat hippocampal neurons by triggering Ca²⁺ influx and influencing Ca²⁺ homeostasis in cultured neurons, and also MDA may act as a signalling molecule regulating Ca²⁺ release from intracellular stores.     

Ferrous-iron induces lipid peroxidation with little damage to energy transduction in mitochondria

Addition of ferrous sulfate, but not ferric chloride, in micromolar concentrations to rat liver mitochondria induced high rates of consumption of oxygen. The oxygen consumed was several times in excess of the reducing capacity of ferrous-iron (O: Fe ratios 5–8). This occurred in the absence of NADPH or any exogenous oxidizable substrate. The reaction terminated on oxidation of ferrous ions. Malondialdehyde (MDA), measured as thiobarbituric acid-reacting material, was produced indicating peroxidation of lipids. The ratio of O₂: MDA was about 4: 1. Pretreatment of mitochondria with ferrous sulfate decreased the rate of oxidation (state 3) with glutamate (+malate) as the substrate by about 40% but caused little damage to energy tranduction process as represented by ratios of ADP: O and respiratory control, as well as calcium-stimulated oxygen uptake and energy-dependent uptake of [⁴⁵Ca]-calcium. Addition of succinate or ubiquinone decreased ferrous iron-induced lipid peroxidation in intact mitochondria. In frozen-thawed mitochondria, addition of succinate enhanced lipid peroxidation whereas ubiquinone had little effect. These results suggest that ferrous-iron can cause peroxidation of mitochondrial lipids without affecting the energy transduction systems, and that succinate and ubiquinone can offer protection from damage due to such ferrous-iron released from the stores within the cells.     

翅果油树幼苗对NaCl胁迫的生理生化反应

研究了不同浓度NaCl处理对翅果油树幼苗高度、叶绿素含量、膜脂过氧化和保护酶活性的影响.结果表明,随着NaCl浓度的升高和胁迫时间的延长,幼苗高度明显受到抑制,叶绿素含量呈下降趋势.整个处理过程中,丙二醛(MDA)含量逐渐增加,但增加幅度不大,表明脂质过氧化反应水平不高.各处理浓度的叶片相对电导率、超氧化物歧化酶(SOD)、过氧化物酶(POD)活性均呈上升趋势.研究表明,翅果油树幼苗在NaCl胁迫下有活性较高的膜保护酶系统,具有一定的抗盐能力.     

Membrane lipid peroxidation by UV-A: mechanism and implications

UV-A produced a dose-dependent linear increase of lipid peroxidation in liposomal membrane, as detected by the assay of (i) conjugated dienes, (ii) lipid hydroperoxides, (iii) malondialdehydes (MDA), and (iv) the fluorescent adducts formed by the reaction of MDA with glycine and also a linear dose-dependent increase of [14C]glucose efflux from the liposomes. UV-A-induced MDA production could not be inhibited by any significant degree by sodium formate, dimethyl sulfoxide, EDTA, or superoxide dismutase but was very significantly inhibited by butylated hydroxytoluene, alpha-tocopherol, sodium azide, L-histidine, dimethylfuran, and beta-carotene. MDA formation increased with an increase in the D2O content in water, leading to a maximal amount of nearly 50% enhancement of lipid peroxidation in 100% D2O vis-à-vis water used as dispersion medium. The experimental findings indicate the involvement of singlet oxygen as the initiator of the UV-A-induced lipid peroxidation.     

Melatonin and pinoline prevent aluminium-induced lipid peroxidation in rat synaptosomes.

The serum concentrations of aluminum, a metal potentially involved in the pathogenesis of Alzheimer's disease, increase with age. Also, intense and prolonged exposure to aluminum may result in dementia. Melatonin and pinoline are two well known antioxidants that efficiently reduce lipid peroxidation due to oxidative stress. Herein, we investigated the effects of melatonin and pinoline in preventing aluminum promotion of lipid peroxidation when the metal was combined with FeCl3 and ascorbic acid in rat synaptosomal membranes. Lipid peroxidation was estimated by quantifying malondialdehyde (MDA) and 4-hydroxyalkenal (4-HDA) concentrations in the membrane suspension. Under the experimental conditions used herein, the addition of aluminum (0.0001 to 1 mmol/L) enhanced MDA + 4-HDA formation in the synaptosomes. Melatonin and pinoline reduced, in a concentration-dependent manner, lipid peroxidation due to aluminum, FeCl3 and ascorbic acid in the synaptosomal membranes. These results suggest that the indoleamine melatonin and the beta-carboline pinoline may potentially act as neuroprotectant agents in the therapy of those diseases with elevated aluminum concentrations in the tissues.     

Plasma and erythrocyte lipid peroxidation levels in patients with testis tumor after orchiectomy

Plasma and erythrocyte lipid peroxidation levels of 20 patients with histopathologically confirmed testis cancer and 20 healthy control individuals were studied between November 1995 and June 1997. The group with testis cancer had a mean age of 24.8±8.2 yr and the control group’s mean age was 28.3±6.9 yr. Stage distribution of the testis cancer cases were 4 of stage A, 10 of stage B, and 6 of stage C. Blood samples of the patients were drawn after orchiectomy and after 12 h fasting before chemotherapy. Mean plasma and erythrocyte lipid peroxidation levels were detected to be 14.51±5.30 nmol malondialdehide (MDA)/mL and 9.30±2.06 nmol MDA/g hemoglobin (Hb), respectively, in the testis cancer group, whereas the healthy control group had mean plasma and erythrocyte lipid peroxidation levels of 10.7±1.82 nmol MDA/mL and 6.18±1.68 nmol MDA/g Hb, respectively. Plasma and erythrocyte lipid peroxidation values of the testis cancer patients were determined to be statistically significantly higher than that of the health control group (p<0.001, p<0.001). No significant correlation was determined between plasma, erythrocyte lipid peroxidation levels and tumor markers. In conclusion, it can be said that an increase in the lipid peroxidation may play a role in the pathogenesis of testis carcinomas in addition to the other causes.     

Melatonin, lipid peroxidation, and age in heterophils from the ring dove (Streptopelia risoria)

Numerous recent studies have shown the ability of physiological as well as all pharmacological concentrations of melatonin to prevent oxidative stress. We have found that incubating avian heterophils from young birds with a pharmacological concentration of 100 μM (23 × 10⁶ pg/ml) melatonin reduced superoxide anion levels by modulating the activity of superoxide dismutase while also enhancing phagocytosis. There was also a decline in lipid peroxidation levels with both physiological and pharmacological concentrations of this indolamine.

In the present work, we evaluated malonaldehyde (MDA) levels as an indicator of lipid peroxidation (both basal and antigen-induced) in young and old animals (ring doves) at different times of day (16:00 and 00:00) and with two incubation times (15 and 60 min). The lipid peroxidation was also measured in heterophils from old animals, incubated with the physiological concentrations of melatonin measured in young animals (50 and 300 pg/ml, diurnal and nocturnal, respectively). The results, expressed as nmol MDA/mg protein, show that MDA levels were higher in heterophils of old animals than in the young birds in all the experimental groups studied at both 16:00 and 00:00 (00:00 is the time at which the lowest peroxidation levels were obtained). Incubation with melatonin was found to reduce MDA levels, with the maximum reduction being after the 60 min incubation time and the nocturnal melatonin concentration. At both concentrations (diurnal and nocturnal), melatonin also counteracted the enhancement of MDA levels caused by latex beads, with the effect being greater at the longer incubation time. In conclusion, the results are further evidence of the antioxidant effect of melatonin even at physiological concentrations, and suggest its utility as a therapeutic agent in some pathological processes associated with age.     

Antioxidant enzyme activities, malondialdehyde, and total phenolic content of PEG-induced hyperhydric leaves in sugar beet tissue culture

Hyperhydricity is a physiological abnormality that frequently affects shoots that are vegetatively propagated in vitro. In this study, sugar beet (Beta vulgaris L. cv. Felicita) shoot tip explants were cultured on Murashige and Skoog medium supplemented with different concentrations of polyethylene glycol (PEG) 6000. We observed that higher concentrations of PEG 6000 and longer exposure (up to 4 wk) resulted in increasing levels of hyperhydration as well as browning and/or blackening of tissues in culture. A comparison of hyperhydric shoots with controls on the 28th day showed a marked increase in the content of water, phenolics, and malondialdehyde (MDA), which was positively correlated with an increase in the accumulation of PEG 6000. Selected antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POX), and polyphenol oxidase (PPO) also increased in hyperhydric shoots, especially at lower concentrations of PEG 6000. Regression analysis indicated that strong linear relationships exist between SOD–APX (R ²?=?0.932), SOD–CAT (R ²?=?0.753), SOD–total phenolic content (R ²?=?0.966), APX–PPO (R ²?=?0.842), APX–total phenolic content (R ²?=?0.904), POX–CAT (R ²?=?0.751), and CAT–total phenolic content (R ²?=?0.806). Despite the correlation between different antioxidant enzymes and between the antioxidant enzymes and antioxidant compounds, was not able to prevent ROS damage in hyperhydric shoots. The negative correlation between SOD–MDA, POX–MDA, CAT–MDA, and MDA–total phenolics also indicated an increase in antioxidant enzyme activities, yet the increase in these antioxidant compound contents did not prevent lipid peroxidation of in vitro propagated beet shoots.