Characterization and Antimicrobial Activity of Protease and α-Amylase Inhibitors from Immature Fruits of Capsicum chinense Jacq.

Abstract

Antimicrobial peptides (AMPs) are small groups of proteins obtained from plants and animals. AMPs participate in the immune response, as they provide a quick line of defense against infections, while others may be related to the plant's defense against certain pests and pathogens. The objective of the present study was to evaluate an inhibitory activity of fractions obtained from immature fruits of Capsicum chinense Jacq. (accession UENF 1755) on trypsin, chymotrypsin and α-amylase families and on yeast growth. The peptides were obtained from the immature fruits using saline extraction. The extract was semi-purified by DEAE-Sepharose chromatography into two fractions: D1 (non-retained fraction) and D2 (retained fraction), and analyzed using SDS-tricine-gel electrophoresis. The antifungal activity of these fractions was tested on Candida albicans, Candida buinensis, Candida parapsilosis and Candida tropicalis. To elucidate the antimicrobial mechanism of these fractions, membrane permeabilization and endogenous reactive oxygen species (ROS) induction assays were performed. The fractions were also tested for inhibition of trypsin, chymotrypsin and α-amylase enzymes. The two fractions, D1 and D2, inhibited yeast growth at a concentration of 100 μg.mL^-1, promoted membrane permeabilization and caused an increase in the induction of endogenous ROS in C. albicans and C. tropicalis. Both these fractions were able to inhibit trypsin and α-amylase enzyme, while only D1 inhibited chymotrypsin activity. Thus, D1 was found to possess a greater antifungal and enzymatic inhibition activity on trypsin, chymotrypsin and α-amylase.

Keywords:
Capsicum ; plant antimicrobial peptides; antifungal activity; protease inhibitors

HIGHLIGHTS

Immature fruits of C. chinense presents AMPs with antifungal activity against yeasts.

D1 fraction has greater antifungal activity.

D1 fraction shows activity against C. albicans and C. tropicalis, two yeasts of medical interest.