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Proteins extracted from Capsicum annuum L. fruits were initially subjected to reversed-phase chromatography on HPLC, resulting in eight peptide-rich fractions. All the fractions obtained were tested for their ability to inhibit porcine trypsin and amylase from both human saliva and from larval insect in vitro. All fractions were also tested for their ability to inhibit growth of the phytopathogenic fungi. Several fractions inhibited the activity of human salivary amylase and larval insect amylase, especially fraction Fa5. No fraction tested was found to inhibit trypsin activity, being Fa2 fraction an exception. Interestingly fraction Fa5 also displayed high antimicrobial activity against the species of the Fusarium genus. Fraction Fa5 was found to have two major protein bands of 17 and 6.5 kDa, and these were sequenced by mass spectrometry. Two peptides were obtained from the 6.5-kDa band, which showed similarity to antimicrobial peptides. Fraction Fa5 was also tested for its ability to permeabilize membranes and induce ROS. Fraction Fa5 was able to permeabilize the membranes of all the fungi tested. Fungi belonging to the genus Fusarium also showed an increase in the endogenous production of ROS when treated with this fraction. Antimicrobial peptides were also identified in the fruits from other Capsicum species., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Antimicrobial peptides (AMPs) are produced by a range of organisms as a first line of defense against invaders or competitors. Owing to their broad antimicrobial activity, AMPs have attracted attention as a potential source of chemotherapeutic drugs. The increasing prevalence of infections caused by Candida species as opportunistic pathogens in immunocompromised patients requires new drugs. Lecythis pisonis is a Lecythydaceae tree that grows in Brazil. The AMPs produced by this tree have not been described previously. We describe the isolation of 12 fractions enriched in peptides from L. pisonis seeds. Of the 12 fractions, at 10 μg/ml, the F4 fraction had the strongest growth inhibitory effect (53.7%) in Candida albicans, in addition to a loss of viability of 94.9%. The F4 fraction was separated into seven sub-fractions by reversed-phase chromatography. The F4.7' fraction had the strongest activity at 10 μg/ml, inhibiting C. albicans growth by 38.5% and a 69.3% loss of viability. The peptide in F4.7' was sequenced and was found to be similar to plant defensins. For this reason, the peptide was named L. pisonis defensin 1 (Lp-Def1). The mechanism of action that is responsible for C. albicans inhibition by Lp-Def1 includes a slight increase of reactive oxygen species induction and a significant loss of mitochondrial function. The results described here support the future development of plant defensins, specifically Lp-Def1, as new therapeutic substances against fungi, especially C. albicans., (© The Author 2015. Published by ABBS Editorial Office in association with Oxford University Press on behalf of the Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences.)

Lipid transfer proteins (LTPs) are soluble plant peptides endowed with biological activities applicable in agronomy, industry, and medicine. We assessed in this work the inhibition of human and intestinal insect α-amylases by r Vu -LTP. The native Vu -LTP coding sequence was inserted into pET-32 EK/LIC and produced in Escherichia coli fused with Trx and His tags (r Vu -LTP-Trx-His). r Vu -LTP-Trx-His was purified by Ni + -chromatography and cleaved with enterokinase to remove the tags. r Vu -LTP was purified on a C 18 reversed-phase column. The natural Vu -LTP was purified by chromatography steps from seeds extract. r Vu -LTP translation and folding were analysed by Western blotting with antibodies against Vu -LTP and circular dichroism by comparing the spectra of Vu -LTP and r Vu -LTP. Human salivary and beetles Callosobruchus maculatus and Tribolium castaneum gut α-amylases were tested for inhibition by r Vu -LTP. r Vu -LTP was correctly produced, translated, and folded in bacterial cytoplasm. r Vu -LTP inhibited 78.1% of human salivary amylase activity at 20 μM, at 40 μM inhibited 65.7% of intestinal α-amylases activity from C. maculatus and was unable to inhibit the T. castaneum gut α-amylases. The results presented by this work suggest biotechnological application of r Vu -LTP in medicine to treat obese patients and in agriculture to improve grain quality protecting plants from insect attack. [ABSTRACT FROM AUTHOR]