Vitamin C protects against defects induced by juglone during porcine oocyte maturation

Juglone, a naphthoquinone isolated from many species of the Juglandaceae family, has been used in traditional Chinese medicine for centuries because of its antiviral, antibacterial, and antitumor activities. However, the toxicity of juglone has also been demonstrated. Here, we used porcine oocytes as a model to explore the effects of juglone on oocyte maturation and studied the impact of vitamin C (VC) administration on juglone exposure-induced meiosis defects. Exposure to juglone significantly restricted cumulus cell expansion and decreased the first polar body extrusion. In addition, juglone exposure disturbed spindle organization, actin assembly, and the distribution of mitochondria during oocyte meiosis, while the acetylation level of α-tubulin was also reduced. These defects were all ameliorated by VC administration. Our findings indicate that juglone exposure induced meiotic failure in porcine oocytes, while VC protected against these defects during porcine oocyte maturation by ameliorating the organization of the cytoskeleton and mitochondrial distribution.     

Pin1 inhibition activates cyclin D and produces neurodegenerative pathology

Abnormal cell cycle events are increasingly becoming important attributes of neurodegenerative pathology. Pin1 is a crucial target of neurodegeneration in relation to its functions regarding these abnormal cell cycle events in neurons. Pin1 is majorly involved in many aspects of cell cycle regulation and it has also been suggested to have a neuroprotective function against neurodegenerative pathologies. Oxidative dysregulation of Pin1 affects not only normal tau regulation, eventually causing tangle formation, but also cell cycle regulation in neurons. Presence of cell cycle proteins has been shown in many neurodegenerative diseases. Importantly, many of these proteins have physical interactions with Pin1. Hence, understanding Pin1's role in abnormal cell cycle re-entry is critical in terms of finding new approaches for the future therapeutic options treating neurodegenerative pathologies. Here, we show that inhibition of Pin1 by its selective inhibitor juglone leads to up-regulation of cyclinD1, phospho-tau, and caspase 3, producing apoptosis in cultured rat hippocampal neurons. We also observed axonal retraction with a change in sub-cellular localizations of cyclins. Therefore, Pin1 dysregulation, in relation to its role in cell cycle regulation in neurons, may have profound effects in the progression of neurodegenerative pathology, making it a possible crucial target behind many neurodegenerative diseases.     

Naphthaquinones in Lomatia species

Lomatiol, juglone, β-hydrojuglone and naphthazarin have been found distributed in various parts of six Lomatia spp. Three others contained no quinonoid pigments but the leaves of L. dentata yielded kaempferol-3-methyl ether and quercetin-3-methyl ether.     

铁核桃根与叶水浸提液对果园间作绿肥植物的化感作用及其生理机制

以西南地区具有代表性的16种绿肥植物为受体材料,采用培养皿药膜法研究了铁核桃(Juglans sigillata)根水浸提液对受体种子发芽率及幼苗鲜重、干重的化感效应;并进一步研究了铁核桃根、叶水浸提液和胡桃醌对化感效应存在明显差异的4种绿肥植物(绿豆、红三叶、白三叶、花生)种子萌发与幼苗生长以及抗氧化酶特性的影响,以筛选适宜中国西南地区核桃园种植的绿肥植物,探讨核桃根和凋落物对绿肥作物的化感作用机制。结果表明:(1)铁核桃根水浸提液对绿豆的发芽率没有影响,但对绿豆幼苗鲜重和干重有显著抑制作用,而对其他15种绿肥的发芽率和鲜重、干重均有抑制作用。(2)胡桃醌显著抑制绿豆种子萌发,而铁核桃根或叶水浸提液对绿豆种子萌发没有影响。(3)铁核桃根或叶水浸提液以及胡桃醌对绿肥植物幼苗生长的化感效应趋势一致,但核桃根或叶水浸提液的化感效应强于胡桃醌。(4)绿豆幼苗在铁核桃根或叶水浸提液以及胡桃醌处理下,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的活性均高于其他3种(红三叶、白三叶、花生)受体幼苗,表明绿豆清除活性氧能力高,细胞受损害程度较低,受化感作用影响最弱。研究认为,绿豆为适宜中国西南地区幼龄核桃园种植的间作绿肥植物。     

Toxicity of plumbagin and juglone to the eggs of the cotton stainer,Dysdercus koenigii

Toxicity of two plumbaginoids viz., plumbagin and juglone to the eggs of the cotton stainer,Dysdercus koenigii was studied by a residual film technique. Of these two, plumbagin showed the higher toxicity against different-age eggs with LC₅₀ ranging from 0.0044 to 0.0066%. Eggs showed low susceptibility in the middle of embryogenesis. The toxicity of plumbaginoids, especially plumbagin, is discussed in relation to mode of action and prospects of its use as an ovicide in control of the insect.     

Allelopathy in black walnut (Juglans nigraL.) alley cropping. II. Effects of juglone on hydroponically grown corn (Zea maysL.) and soybean (Glycine maxL. Merr.) growth and physiology

We conducted an experiment to investigate the effects of juglone (5-hydroxy-1, 4-napthoquinone) on the growth and physiology of hydroponically grown corn (Zea mays L.) and soybean (Glycine max L. Merr.) seedlings. Three different concentrations of juglone (10^-6 M, 10^-5 M, and 10^-4 M) along with a control were applied. Within 3 days, juglone exhibited significant inhibitory effects on all measured variables including shoot and root relative growth rates (RGR_s and RGR_r), leaf photosynthesis (P_net), transpiration (E), stomatal conductance (g_s), and leaf and root respiration. In general, soybean was found to be more sensitive to juglone than corn. RGR_r was the most inhibited variable for both species, and reductions of 86.5 and 99% were observed in corn and soybean, respectively, with 10_-4 M juglone concentrations. Among the physiological variables measured, P_net showed the greatest impact of toxicity though the other physiological parameters were also impacted. We conclude that both corn and soybean are sensitive to juglone and observed growth reductions in corn and soybean in black walnut alley cropping may partly be due to juglone phytotoxicity. Determination of actual phytotoxicity will require quantification of soil solution juglone levels, particularly in areas where soil solid-phase levels are high in close proximity to trees.     

Tolerance of the yeast Yarrowia lipolytica to oxidative stress

The adaptive response of the yeast Yarrowia lipolytica to the oxidative stress induced by the oxidants hydrogen peroxide, menadione, and juglone has been studied. H₂O₂, menadione, and juglone completely inhibited yeast growth at concentrations higher than 120, 0.5, and 0.03 mM, respectively. The stationary-phase yeast cells were found to be more resistant to the oxidants than the exponential-phase cells. The 60-min pretreatment of logarithmic-phase cells with nonlethal concentrations of H₂O₂ (0.3 mM), menadione (0.05 mM), and juglone (0.005 mM) made the cells more resistant to high concentrations of these oxidants. The adaptation of yeast cells to H₂O₂, menadione, and juglone was associated with an increase in the activity of cellular catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, and glutathione reductase, the main enzymes involved in cell defense against oxidative stress.     

Respiratory Activity and Naphthoquinone Synthesis in the Fungus Fusarium decemcellulare Exposed to Oxidative Stress

The effect of oxidants (hydrogen peroxide and juglone) on the growth, respiration, and naphthoquinone synthesis in the fungus Fusarium decemcellulare was studied. The addition of the oxidants to the exponential-phase fungus inhibited cell respiration (either partially or completely, depending on the oxidant concentration), culture growth, and naphthoquinone synthesis. The treatment of fungal cells with nonlethal concentrations of H₂O₂ (below 0.25 mM) and juglone (below 0.1 mM) induced the resistance of cell respiration to cyanide. The residual respiration in the presence of cyanide could be inhibited by benzohydroxamic acid, indicating the occurrence of alternative oxidase. Increased concentrations of oxidants (0.25 mM juglone and 0.5 mM H₂O₂) rapidly and irreversibly inhibited cell respiration. These observations suggest that the mitochondrial respiratory chain of fungal cells exposed to oxidative stress is subject to the action of active oxygen species. The treatment of fungal cells with nonlethal concentrations of H₂O₂ and juglone activated cellular glutathione reductase and glucose-6-phosphate dehydrogenase, which are protective enzymes against oxidative stress.     

Metabolic relation between naphthalene derivatives in Juglans

It has been shown by labelling experiments that 4-oxo-α-tetralone and β-hydrojuglone may be involved in the biosynthesis of naphthoquinols in Juglans regia. Experiments on the metabolic role of aglycones and glucosides are discussed and a hypothetical scheme for these biosynthetic relationships is presented.     

酶法辅助超声波微波仪从胡桃青皮中提取胡桃醌的工艺研究

以胡桃青皮为原料,在优化酶解与超声波微波萃取仪提取条件下,用硅胶层析法制取胡桃醌,并检测其纯度和含量。经过对多种提取条件的优化,确定其最佳酶解条件为:1%纤维素酶和1%果胶酶各400μL等量混合,固液比1∶20,温度55℃,pH 6.2,时间15 h。最佳提取条件是以氯仿作提取剂,固液比1∶20;在超声波恒定条件下,超声波微波萃取仪处理15 min;设置温度分别为55、60、65℃,超声波功率800、900、1 000 W,微波功率200、250、300 W,超声波频率25 kHz,模式15∶10,电机转速900 r·min-1。硅胶柱干法上样,用氯仿和石油醚分阶段洗脱得到较纯的胡桃醌制品。光度计测得胡桃醌平均含量为0.49%,纯度为81.7%。