Antimutagenic and antioxidant activities of cascalote (Caesalpinia cacalaco) phenolics

There is an increasing awareness and interest in the antioxidant behaviour and potential health benefits of phenolic acids. The identification of novel sources of phenolic acids has been also of scientific interest. Cascalote (Caesalpinia cacalaco) pods are known to be a good source of ‘tannins’, the name by which industry in Mexico recognizes phenolic extract. Phenolics were determined as gallic acid equivalents g^?1. The antimutagenic activity against aflatoxin B₁ and the antioxidant activity, using two different methods, of the extract were also evaluated. Gallic acid accounts for almost 90% of the phenolic extract of cascalote, the remaining 10% was tannic acid. Antimutagenic activity of cascalote phenolics was dose‐dependent, showing an inhibition level of 64.42% at the highest dose assayed. Antioxidant and antiradical activities were also dose‐dependent. The highest antioxidant activity showed by cascalote phenolics was 73.5%, higher than that of Trolox. The highest antiradical activity of cascalote phenolics was 75.3%, higher than that of BHT and Trolox. Cascalote pods are an outstanding source of gallic and tannic acids. Copyright © 2004 Society of Chemical Industry     

A Germin-Like Protein Gene (CchGLP) of Capsicum chinense Jacq. Is Induced during Incompatible Interactions and Displays Mn-Superoxide Dismutase Activity

A germin-like gene (CchGLP) cloned from geminivirus-resistant pepper (Capsicum chinense Jacq. Line BG-3821) was characterized and the enzymatic activity of the expressed protein analyzed. The predicted protein consists of 203 amino acids, similar to other germin-like proteins. A highly conserved cupin domain and typical germin boxes, one of them containing three histidines and one glutamate, are also present in CchGLP. A signal peptide was predicted in the first 18 N-terminal amino acids, as well as one putative N-glycosylation site from residues 44-47. CchGLP was expressed in E. coli and the recombinant protein displayed manganese superoxide dismutase (Mn-SOD) activity. Molecular analysis showed that CchGLP is present in one copy in the C. chinense Jacq. genome and was induced in plants by ethylene (Et) and salicylic acid (SA) but not jasmonic acid (JA) applications in the absence of pathogens. Meanwhile, incompatible interactions with either Pepper golden mosaic virus (PepGMV) or Pepper huasteco yellow vein virus (PHYVV) caused local and systemic CchGLP induction in these geminivirus-resistant plants, but not in a susceptible accession. Compatible interactions with PHYVV, PepGMV and oomycete Phytophthora capsici did not induce CchGLP expression. Thus, these results indicate that CchGLP encodes a Mn-SOD, which is induced in the C. chinense geminivirus-resistant line BG-3821, likely using SA and Et signaling pathways during incompatible interactions with geminiviruses PepGMV and PHYVV.     

Oxidative and Molecular Responses in Capsicum annuum L. after Hydrogen Peroxide,Salicylic Acid and Chitosan Foliar Applications

Hydrogen peroxide (H₂O₂) is an important ROS molecule (Reactive oxygen species) that serves as a signal of oxidative stress and activation of signaling cascades as a result of the early response of the plant to biotic stress. This response can also be generated with the application of elicitors, stable molecules that induce the activation of transduction cascades and hormonal pathways, which trigger induced resistance to environmental stress. In this work, we evaluated the endogenous H₂O₂ production caused by salicylic acid (SA), chitosan (QN), and H₂O₂ elicitors in Capsicum annuum L. Hydrogen peroxide production after elicitation, catalase (CAT) and phenylalanine ammonia lyase (PAL) activities, as well as gene expression analysis of cat1, pal, and pathogenesis-related protein 1 (pr1) were determined. Our results displayed that 6.7 and 10 mM SA concentrations, and, 14 and 18 mM H₂O₂ concentrations, induced an endogenous H₂O₂ and gene expression. QN treatments induced the same responses in lesser proportion than the other two elicitors. Endogenous H₂O₂ production monitored during several days, showed results that could be an indicator for determining application opportunity uses in agriculture for maintaining plant alert systems against a stress.