Oligochitosan Synthesized by Cunninghamella elegans, a Fungus from Caatinga (The Brazilian Savanna) Is a Better Antioxidant than Animal Chitosan.

Lucas Alighieri Neves Costa Batista,Anabelle Camarotti de Lima Batista,Hugo Alexandre Oliveira Rocha,Moacir Fernandes Queiroz,Francisco Ernesto de Souza Neto,Weslley Souza Paiva

doi:10.3390/molecules27010171

Abstract

Animal chitosan (Chit-A) is gaining more acceptance in daily activities. It is used in a range of products from food supplements for weight loss to even raw materials for producing nanoparticles and hydrogel drug carriers; however, it has low antioxidant activity. Fungal oligochitosan (OChit-F) was identified as a potential substitute for Chit-A. Cunninghamella elegans is a fungus found in the Brazilian savanna (Caatinga) that produces OligoChit-F, which is a relatively poorly studied compound. In this study, 4 kDa OChit-F with a 76% deacetylation degree was extracted from C. elegans. OChit-F showed antioxidant activity similar to that of Chit-A in only one in vitro test (copper chelation) but exhibited higher activity than that of Chit-A in three other tests (reducing power, hydroxyl radical scavenging, and iron chelation). These results indicate that OChit-F is a better antioxidant than Chit-A. In addition, Chit-A significantly increased the formation of calcium oxalate crystals in vitro, particularly those of the monohydrate (COM) type; however, OChit-F had no effect on this process in vitro. In summary, OChit-F had higher antioxidant activity than Chit-A and did not induce the formation of CaOx crystals. Thus, OChit-F can be used as a Chit-A substitute in applications affected by oxidative stress.

Highlights

Oxidative stress can be divided into three stages: (1) initiation, when the formation of the first reactive species occurs; (2) propagation, when these species, once formed, cause a series of sequential reactions of propagation and production of new reactive species; (3) termination, when the reactive species are converted into stable molecules [1]
A study by Queiroz et al [16] confirmed this inference by their report on chitosan with a DD of approximately 76%, similar to that found in C. elegans oligochitosan, but with a molecular weight about 10 times greater, which showed more than 80% copper chelation
Structural analyses by Fourier Transform Infrared Spectra (FT-IR) and DRX indicated that the biomaterial extracted from C

Summary

Introduction

Oxidative stress can be divided into three stages: (1) initiation, when the formation of the first reactive species occurs; (2) propagation, when these species, once formed, cause a series of sequential reactions of propagation and production of new reactive species; (3) termination, when the reactive species are converted into stable molecules [1]. Regardless of the stage, humans synthesize or ingest molecules called antioxidants through food that neutralize reactive species and their harmful effects to combat oxidative stress [1]. The amounts of these endogenous antioxidants are often insufficient to elicit effective responses against reactive species. In humans, this is compensated by the absorption of exogenous antioxidants by the cells [2]. Since none of the commercial antioxidants show ideal antioxidant properties, there is a need to find new antioxidants that can adapt to new situations and replace the existing ones [3]

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