Towards eco-friendly crop protection: natural deep eutectic solvents and defensive secondary metabolites

With mounting concerns over health and environmental effects of pesticides, the search for environmentally acceptable substitutes has amplified. Plant secondary metabolites appear in the horizon as an attractive solution for green crop protection. This paper reviews the need for changes in the techniques and compounds that, until recently, have been the mainstay for dealing with pest insects. Here we describe and discuss main strategies for selecting plant-derived metabolites as candidates for sustainable agriculture. The second part surveys ten important insecticidal compounds, with special emphasis on those involved in human health. Many of these insecticidal metabolites, however, are crystalline solids with limited solubility which might potentially hamper commercial formulation. As such, we introduce the concept of natural deep eutectic solvents for enhancing solubility and stability of such compounds. The concept, principles and examples of green pest control discussed here offer a new suite of environmental-friendly tools designed to promote and adopt sustainable agriculture.     

Isolation and characterization of outermost layer deficient mutant spores of Bacillus megaterium

Outermost layer deficient mutant spores of Bacillus megaterium ATCC 12872 were isolated by Urografin density gradient centrifugation after mutagenesis with ethyl methanesulfonate. Although the composition of the cortex peptidoglycan was the same as that of the parent spores, three major proteins (48, 36, and 22 K daltons) were missing, suggesting that these proteins are components of the outermost layer. All mutant spores were also found to have very hydrophobic surface by 'salt aggregation test,' which would facilitate selection of such mutants.     

Single molecule detection of PARP1 and PARP2 interaction with DNA strand breaks and their poly(ADP-ribosyl)ation using high-resolution AFM imaging

PARP1 and PARP2 are implicated in the synthesis of poly(ADP-ribose) (PAR) after detection of DNA damage. The specificity of PARP1 and PARP2 interaction with long DNA fragments containing single- and/or double-strand breaks (SSBs and DSBs) have been studied using atomic force microscopy (AFM) imaging in combination with biochemical approaches. Our data show that PARP1 localizes mainly on DNA breaks and exhibits a slight preference for nicks over DSBs, although the protein has a moderately high affinity for undamaged DNA. In contrast to PARP1, PARP2 is mainly detected at a single DNA nick site, exhibiting a low level of binding to undamaged DNA and DSBs. The enhancement of binding affinity of PARP2 for DNA containing a single nick was also observed using fluorescence titration. AFM studies reveal that activation of both PARPs leads to the synthesis of highly branched PAR whose size depends strongly on the presence of SSBs and DSBs for PARP1 and of SSBs for PARP2. The initial affinity between the PARP1, PARP2 and the DNA damaged site appears to influence both the size of the PAR synthesized and the time of residence of PARylated PARP1 and PARP2 on DNA damages.     

Role of outer coat in resistance of Bacillus megaterium spore

The outer coat fraction (OC-Fr) of Bacillus megaterium ATCC 12872 spore was isolated as a resistant residue after alkali extraction, sonic treatment, and pronase digestion of the spore coat preparation, and its backbone structure was determined by chemical analysis to be composed of galactosamine-6-phosphate (GalN-P) polymers with polypeptides and calcium. OC-Fr was not fully solubilized after ordinary acid hydrolysis. OC-Fr was insensitive to all hexosaminidases tested, and moreover, an isolated fragment, a pentamer of GalN-P, was also resistant to lysozyme and hexosaminidases even after N-acetylation, being sensitive to them to some extent after dephosphorylation. Molecular sieving experiments revealed that the outer coat limited the entry of compounds with a molecular weight of more than 2,000. Exchange of the metal on the spore surface also influenced the heat resistance. Spores of OC-Fr-deficient mutants were less resistant but were still much more resistant than the vegetative cells. These results suggest that the outer coat protects the contents of the spore against chemical, physical and enzymatic treatments owing to the chemical structure itself, composed mainly of GalN-P polymers, and the molecular sieving effect.     

Synthesis, structure and biological activity of a new and efficient Cd(II)–uracil derivative complex system for cleavage of DNA

The new complex formed by Cd(II) and the 1:2 Schiff-base-type ligand 2,6-bis[1-(4-amino-1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxopyrimidin-5-yl)imino]ethylpyridine (DAPDAAU) has been chemically and structurally characterized by X-ray diffraction: the ion Cd(II) is surrounded by six nitrogen atoms from two DAPDAAU ligands which coordinates each one in a tridentate fashion through the pyridine ring (N1) and both azomethine nitrogen atoms (N5). The interaction of the Cd(II) complex (compound I) with calf-thymus DNA as observed by circular dichroism spectroscopy suggests the initial unwinding of the DNA double helix strongly depends on increasing incubation times and metal-to-nucleic acid molar ratios. Electrophoretic experiments indicate that the cadmium complex induces cleavage of the plasmid pBR322 DNA to give ulterior nicking and shortening of this molecule, as a result of the complex binding to DNA, resulting in the conclusion that compound I behaves as a chemical nuclease. Cytotoxic activity of the Cd(II) complex against selected different human cancer cell lines is specific and increases with increasing concentration of the metal compound; this fact indicates the potential antitumor character of the complex. When the culture medium is supplemented with compound I, a remarkable inhibition of the growing cell is observed, important cell degeneration appears before 48 h and abundant precipitates are formed that correspond to cell residues and denatured proteins. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Classification of acute non-lymphocytic leukemia according to the distribution picture of peroxidase activity and cell size: correlation between the classification and therapeutic response

A distribution picture was prepared on the basis of the correlation between peroxidase activity and cell size in leukemic cells using an automated leukocyte differential counter (Hemalog-D). From this, acute nonlymphocytic leukemia was classified into three groups in which the therapeutic response was examined. The leukemic cells of Group I were medium or large and were negative or weakly positive to peroxidase. These cells were characterized by their location in the upper part of the normal lymphocyte distribution. The leukocyte differential count, measured by a computer on the basis of the distribution picture, showed an increase in large unstained cells (LUC) and lymphocytes. The leukemic cells of Group II were large and positive to peroxidase and were characterized by their location in the right upper part, across the region of LUC, monocytes, basophil and neutrophil leukocytes as seen in the distribution picture. The findings of Hemalog-D showed an increase in LUC, remainder and neutrophil leukocytes. The leukemic cells of Group III were medium-sized and moderately or strongly positive to peroxidase. This group was characterized by their location in the lower part of normal neutrophil leukocytes and Hemalog-D showed an increase in neutrophil leukocytes. A total of 71 patients with acute nonlymphocytic leukemia were assessed according to this classification. Group I (14 patients): 11 with acute myelogenous leukemia (AML), 2 with acute monocytic leukemia (AMoL) and 1 with acute myelomonocytic leukemia ( AMMoL ); Group II (17 patients): 7 with AML and 10 with AMoL; Group III (40 patients): 28 with AML, 4 with AMoL, 1 with AMMoL and 7 with acute promyelocytic leukemia (APL). These groups were treated with the protocol (DCMP two step, BH-AC DMP, BH-AC AMP) established by the Yamada Leukemia Study Group of the Japan Welfare Ministry Cancer Research Project (chairman Yamada, K). The complete remission rate was 35.7% in Group I, 58.8% in Group II and 85.0% in Group III. The difference between Groups I and III was statistically significant (P less than 0.005), as was the difference between Groups II and III (P less than 0.1), while that between Groups I and II was not significant. The median survival was 12 months in Group I, 9 months in Group II and 15 months in the Group III and the difference between Groups I and III was statistically significant (P less than 0.05). Group III included a small number of AMoL and APL patients in addition to AML, while Groups I and II consisted mainly of patients with AMoL and AML.(ABSTRACT TRUNCATED AT 400 WORDS)