Lipid Transfer Proteins (LTPs) Partially Purified from Capsicum chinense Jacq. Seeds: Antifungal Properties and α-amylase Inhibitory Activity.

Abstract

In this study, we identified and partially purified antimicrobial peptides belonging to the family of lipid transfer proteins (LTPs) from Capsicum chinense seeds (UENF 1751 accession). Fractions rich in LTPs were obtained via ion exchange chromatography and subsequently purified via reverse-phase chromatography in an HPLC system. Therefore, two fractions were revealed: C1 (the nonretained fraction) and C2 (the retained fraction in ion-exchange chromatography). Fraction C1 was subjected to reverse-phase chromatography via a C18 column on an HPLC system, and ten fractions were obtained (P1-P10), all of which significantly inhibited the growth of Candida albicans, except for P4 and P9. The viability analysis of the active fractions at a concentration of 100 µg.mL^-1 against C. albicans revealed that they did not exhibit fungicidal activity but rather exhibited fungistatic activity. The peptide is considered fungicidal when it results in the total loss of viable yeast cells, that is, when it causes the complete death of the fungi. When the substance only inhibits cell growth, but does not eliminate them completely, the effect is classified as fungistatic. Fractions P3, P4, P7, and P10 inhibited Tenebrio molitor larvae α-amylase. The P10 fraction presented protein bands in its electrophoretic profile with a molecular mass between 6.5 kDa and 14.2 kDa and reacted positively to an antibody produced against a protein from the LTP family bywestern blotting. The results of the analysis of amino acid residues from the P10 fraction revealed similarity between type I LTPs and type II LTPs. The ultrastructural aspects of C. albicans cells exposed to the P10 fraction were evaluated via transmission electron microscopy (TEM), with significant differences in their morphology being evident compared with those of the control. In summary, our results demonstrated the presence of LTPs in C. chinense seeds with inhibitory effects on the growth of yeasts of the genus Candida, which exhibited fungistatic effects and structural changes in C. albicans cells, in addition to exhibiting inhibitory effects on the larval insect T. molitor α-amylase.