Alpha-picolinic acid,a fungal toxin and mammal apoptosis-inducing agent,elicits hypersensitive-like response and enhances disease resistance in rice

Alpha-picolinic acid (PA),a metabolite of tryptophan and an inducer of apoptosis in the animal cell,has been reported to be a toxin produced by some of plant fungal pathogens and used in screening for disease resistant mutants. Here,we report that PA is an efficient apoptosis agent triggering cell death of hypersensitive-like response in planta. Confirmed by Fluorescence Activated Cell Sorter (FACS),rice suspension cells and leaves exhibited programmed cell death induced by PA. The PA-induced cell death was associated with the accumulation of reactive oxygen species that could be blocked by diphenylene iodonium chloride,indicating that the generation of reactive oxygen species was NADPHoxidase dependent. We also demonstrated the induction of rice defense-related genes and subsequent resistant enhancement by PA against the rice blast fungus Magnaporthe grisea. Hence,it was concluded that the PA-stimulated defense response likely involves the onset of the hypersensitive response in rice,which also provides a simple eliciting tool for studying apoptosis in the plant cell.

Synthesis and Structural Characterization of Cu(pic)_2[CO(NH_2)_2]_2 and (picH_2)_2[Cu(pic)_2(SCN)_2]

Two new compounds Cu(pic)2[CO(NH2)2]2 1 and (picH2)2[Cu(pic)2(SCN)2] 2 were prepared from the reaction of picolinic acid and copper(II) per-chlorate by using carbamide to adjust pH = 4 in the preparation of compound 1 and KSCN to adjust pH = 6 in the preparation of 2. Crystal data for 1: monoclinic system, space group P21/n with a = 7.441(1), b = 14.291(2), c = 7.790(1) ? b = 95.855(2), V = 824.0(2) ?, Dc = 1.724 g/cm3, F(000) = 438, C14H16N6O6Cu, Mr = 427.87, m(MoKa) = 1.375 mm-1, Z = 2 and the final R = 0.0365 for 1164 observed reflections. Crystal data for 2: monoclinic system, space group P21/c with a = 9.8237(3), b = 10.0409(3), c = 14.5867(2) ? b = 104.190(2), V = 1394.91(6) ?, Dc = 1.595 g/cm3, F(000) = 686, C26H20N6O8S2Cu, Mr = 672.14, m(MoKa) = 0.994 mm-1, Z = 2 and the final R = 0.0442 for 1651 observed reflections. The Cu(II) atom in both 1 and 2 has a 4+2 elongated octahedral environment with the pic ligands locating on the equatorial plane, and carbamide and SCN occupying the axial sites, respectively. In compound 2, there also exist two protonated picolinate cations for charge balance.

Synthesis and Crystal Structure of Copper(II) Complex with N-Acetoxyl-picolinamide

Using Cu(II) as the template, a complex {[Cu2L2(H2O)2]·4H2O}n (L = N-acetoxyl- picolinamide) has been successfully synthesized and characterized by single-crystal X-ray diffrac- tion. The crystal is of monoclinic, space group C2/c, with a = 24.144(5), b = 7.1622(14), c = 17.283(4) ?, C16H24Cu2N4O12, Mr = 591.47, β = 131.73(3)o, V = 2230.3(8) ?3, Z = 4, Dc = 1.761 g/cm3, F(000) = 1208, μ = 1.978 mm?1, R = 0.0400 and wR = 0.1099. The copper (II) ion is five- coordinated with a distorted square pyramidal geometry. The complex can be viewed as a one- dimensional chain structure by carboxylic bridges among copper atoms. In the complex there exist hydrogen bonding interactions to stabilize the structure.

Copper-catalyzed ortho-Monofluorination of Aniline Derivatives with Selectfluor Directed by Picolinic Acid Amides

A novel and facile method for selective ortho-C--H monofluorination of aniline derivatives was achieved using Selectfluor/Cu（OAc）JHOAc system. The reaction proceeded via electrophilic process with diverse substrates in acceptable moderate to high yields. The position selectivity was controlled by bidentate coordination of picolinic acid amides with copper.

Could zinc dipicolinate be used to“smuggle”zinc into prostate cancer cells?

Although prostate epithelium concentrates zinc for the purpose of promoting citrate secretion,it loses its capacity to import zinc while undergoing malignant transformation.This exclusion of zinc may be necessary for the viability of prostate cancer,as measures which increase the intracellular zinc content of prostate cancers lead to cell death,oxidative stress,and a marked reduction in ATP,suggestive of mitochondrial damage.The anti-fungal drug clioquinol,which can act as a zinc ionophore,can markedly slow the growth of human prostate cancer in nude mice,and has been proposed as a clinical therapy for prostate cancer.However,clioquinol is currently only available as a topical agent,as it was linked to subacute myelo-optic neuropathy with oral use.A more practical option for promoting zinc transport may be offered by the nutraceutical zinc dipicolinate,a stable chelate in which four coordination positions of zinc are occupied by two molecules of the tryptophan metabolite picolinic acid.Zinc dipicolinate is a highly effective supplemental source of zinc that has been shown to be more potent than soluble zinc salts for alleviating the symptoms of acrodermatitis enteropathica,a genetic zinc deficiency disorder reflecting homozygous loss of functional ZIP4 zinc importers in enterocytes.This suggests that the zinc dipicolinate complex is sufficiently stable and lipophilic to transfer zinc across cellular membranes.If so,it may have potential for“smuggling”zinc into prostate cancer cells.Hence,cell culture and rodent studies to evaluate the impact of zinc dipicolinate on human prostate cancer are warranted.