Special Issue "Marine Chitin and Chitosan"

Guest Editor
Prof. Dr. Riccardo A.A. Muzzarelli
Via Volterra, 7, Ancona, Ancona, 60123, Italy
Website: www.chitin.it
E-Mail:

Dear Colleagues,

Chitin can be interpreted as the most abundant organic compound of nitrogen. Current sources are the crustacean shells isolated as by-products of canning / freezing operations in marine food factories. Mechanical peeling and enzyme inactivation are pre-requisites for treating the chitin-bearing biomass. Immediately after isolation, chitin is transformed into chitosans of various grades. Chemical, physical and enzymatic deacetylation methods are available for the production of chitosan, the sole abundantly accessible cationic polysaccharide. Manipulation of the molecular weight leads to water-soluble chitosans: the randomly 50 % deacetylated, and the partially depolymerized chitosans are water-soluble. Advanced water-soluble modified chitosans are also available, as well as new solvent systems. Purification methods from proteins, carotenoids and inorganics enable to produce chitosans of technical, food, pharmaceutical and medical grades, that are officially recognized as safe in a large number of countries. The industrial production of N-acetylglucosamine and glucosamine is based on the depolymerization of chitosan from marine crustaceans. Due to different crystallinity, chitosan obtained from squid chitin is more prone to chemical modification because the nanofibrillar structure of chitin and chitosan has a certain technical significance. Chitosans in novel physico-chemical forms include composites, electrospun nanofibers, polyelectrolyte complexes, blends with neutral polysaccharides (cellulose, starch...), silylated and otherwise cross-linked chitosans, metal ion chelates, and films for marine food protection. Chitin and chitosan are not drugs sensu stricto, but exhibit peculiar characteristics that recently qualified them in the biomedical field, for example as carriers for drug delivery, chitosan being the best DNA vector for gene therapy. Chitosan exerts immuno-stimulating effects, and it is not seen as a foreign body by human cells. The antimicrobial activity of chitosans has been elucidated for numerous bacteria and some fungi. This special issue is expected to encourage a wider exploitation of the marine chitin resources, and the scaling-up of certain applications, particularly in the pharmaceutical area.

Prof. Dr. Riccardo A.A. Muzzarelli
Guest Editor

Submission

All manuscripts should be submitted to marinedrugs@mdpi.org with a copy to the Guest Editor. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Marine Drugs is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this Open Access journal is 1400 CHF per accepted paper.

• Chitin
• chitosan
• crustaceans
• squid
• quality assessment
• N-acetylglucosamine
• glucosamine
• pharmaceuticals
• antimicrobials
• drug carriers

Type of Paper: Review
Title: The Immunoadjuvant Activity of Chitins and Chitosans and Their Use as Non-Allergenic Wound Dressings, Drug Carriers and Gene Vectors
Author: Riccardo A.A. Muzzarelli
Affiliation: Via Volterra, 7, Ancona, 60123, Italy; Website: www.chitin.it; E- mail: muzzarelli.raa@gmail.com
Abstract: Nearly 3 decades ago, Japanese authors demonstrated that chitin and chitin derivatives stimulate macrophages to produce cytokines that confer anti-tumor activity and non-specific host resistance against bacterial and viral infections. Since then, more specific immunologic activities of phagocytosable chitin particles demonstrated significant priming effects in murine alveolar macrophages and NK cells. In fact, the intravenous administration of chitin particles into the lung activates alveolar macrophages to express cytokines such as interleukin-12, interleukin-18 and tumor necrosis factor-α leading to interferon-γ production mainly by NK cells.
Direct intranasal application of chitin microparticles into the lung also significantly down-regulated allergic response to Dermatophagoids pteronyssinus and Aspergillus fumigatus in a murine model of allergy. The chitin treatment substantially reduced the allergen-induced serum IgE levels, peripheral eosinophilia, airway hyper-responsiveness and lung inflammation. The data obtained over the most recent years confirm that the administration of chitin is beneficial because it promotes immunoadjuvant effect, and depresses the insurgence of Th2 inflammation and allergy.
Nevertheless, the exposure to chitin has been associated with allergy and asthma by a small number of scientists, who claimed the involvement of chitin in asthma insurgence in workers exposed to crustaceans in canning factories. They did not care about the possible presence of NAGase in those hypothetically inhaled aerosols where they pretend that insoluble chitin particles are present (not demonstrated), nor they paid attention to the real allergens, tropomyosin in primis, a soluble compound coming from crustacean flesh. They published certain rudimentary illustrations that translate the images of chitin-bearing animals and microbes into the chitin chemical formula, so that the reader perceives chitin as the organism itself. Those illustrations transmit the erroneous concept that the human organism detects a pathogen by virtue of its chitin.
The correct notion instead is that chitin in vivo is orderly combined with other macromolecules: in arthropods it is covalently linked to proteins and tanned by quinone. Therefore, at the nano level, chitin is a highly associated structure that has been recently refined in terms of chemical regularity, nature of bonds, crystallinity degree, etc. In vivo, the chitin is periodically depolymerized under the enzymatic action of chitinases.
For example, the effect of Streptomyces griseus chitinase on Ca²⁺ signaling in human airway epithelial cells has been investigated: the exogenous chitinase was found to cleave a peptide representing the cleavage site of protease-activated receptor-2 (PAR-2) and enhanced IL-8 production. Therefore, the exogenous chitinase is a potent proteolytic activator of PAR-2 that can directly induce Ca²⁺ signaling in human airway epithelial cells. The meaning of this is that the mammalian organism recognizes the secreted water-soluble chitinase produced by a pathogen like S. griseus, rather than the insoluble and well protected chitin.
The present review identifies the sources of errors present in some articles, and re-confirms the immunostimulating activity of chitin / chitosan, in the light of the most advanced applications in controlled drug delivery and in drug targeting to cancer and metastases, particularly via the nasal and pulmonary routes.
As a matter of fact, the use of nanocrystalline chitin (in conjunction with chitosan) in wound healing on a large number of patients did not reveal any detrimental effect. Most importantly, medical grade chitins and chitosans are considered today the best gene and DNA vectors, because they are endowed with ancillary beneficial activities compared to other non-viral vectors.

Type of Paper: Review
Title: Application of Spectroscopic Methods for Structural Analysis of Chitin and Chitosan
Authors: Jolanta Kumirska ¹, Małgorzata Czerwicka ¹, Zbigniew Kaczyński ¹, Monika Paszkiewicz ¹, Krzysztof Brzozowski ¹, Jorg Thöming ² and Piotr Stepnowski ¹
Affiliations: ¹ Faculty of Chemistry, University of Gdansk, Sobieskiego 18/19, PL-80-952 Gdansk, Poland; E-Mails: kumirska@chem.univ.gda.pl (J.K.), sox@chem.univ.gda.pl (P.S.)
² UFT - Centre for Environmental Research and Sustainable Technology, University of Bremen, Leobener Straße UFT, D-28359 Bremen, Germany
Abstract: Chitin (the second most important natural polymer in the world) and its N-deacetylated derivative chitosan have been identified as versatile biopolymers for a broad range of medical, agriculture and food applications. Two of the main reasons for this are the unique chemical, physicochemical, and biological properties of chitin and chitosan; and an unlimited source of raw materials for their production. Depending on the source of chitin and process conditions of chitosan’s production, these polymers show largely varying physicochemical properties. The polysaccharide nature of these biopolymers and the presence of reactive functional groups ensure the ability to undergo diverse chemical modifications. A complete chemical and physicochemical characterization of chitin and chitosan, as well as their derivatives is impossible without using spectroscopic techniques. This review focuses on the application of spectroscopic methods for structural analysis of mentioned compounds.
Keywords: chitin; chitosan; chemical modification; physicochemical parameters; structural analysis using spectroscopic techniques

Type of Paper: Review
Title: The Recovery of Chitin from Crustacean Shells by Fermentative Way
Authors: Wassila Arbia ¹, Leila Arbia ¹, Lydia Adour ^1,2 and Abdeltif Amrane ^3,4
Affiliations: ¹ Laboratoire des Biotechnologies Environnementales et Génie des Procédés (BIOGEP), Ecole Nationale Polytechnique, El Harrach, Algérie
² Département de Chimie, Faculté des Sciences, Université Mouloud Mammeri, Tizi-Ouzou, Algérie
³ Ecole Nationale Supérieure de Chimie de Rennes, Université de Rennes 1, CNRS, UMR 6226, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7, France; E-Mail: abdeltif.amrane@univ-rennes1.fr
⁴ Université européenne de Bretagne, France
Abstract: The recovery of chitin by chemical method (acid or alkaline solutions) in order to deproteinize and to demineralize crustacean shells (the most industrially exploited) at high temperatures can deteriorate the physico-chemical properties of this biopolymer and consequently its biological properties. Biotechnology offers opportunity to preserve the exceptional qualities of chitin and its derivatives. Nowadays, a method based on the use of lactic bacteria and/or proteolytic bacteria can be used for the extraction of chitin.
This inexpensive and nonpolluting method allows the production a chitin of good quality. However, the major disadvantage of this method is a low yield of demineralization and deproteinization compared to chemical methods. The physico-chemical conditions which influence fermentation are the key-factors of this bioprocess. So, the determination of the optimal conditions of bio-deproteinization and bio- demineralization of shells using an effective bacterium and cheap carbon sources are the major parameters to be considered to optimize chitin recovery from crustacean shells by fermentation.

Type of Paper: Review
Title: Biocontrol of Plant Diseases Using Chitosan
Authors: Abdelbasset El Hadrami ¹, Ismail El Hadrami ², and Fouad Daayf ¹
Affiliations: ¹ University of Manitoba, Department of Plant Science, 222, Agriculture Building, Winnipeg, Manitoba, R3T 2N2, Canada. E-mail: daayff@cc.umanitoba.ca
² Laboratoire de Biotechnologies, Protection et Valorisation des Ressources Végétales (Biotec-VRV), Faculté des Sciences Semlalia, B.P. 2390, 40 000, Marrakech, Morocco
Abstract: Chitin, chitosan, and several of their derivatives are naturally-occurring compounds that have potential in agriculture with regard to controlling plant diseases. When applied at high concentrations, these molecules display toxicity and inhibit fungal growth and development. They were also reported to be active against viruses, bacteria and other pests. In addition, fragments from chitin and chitosan are known to have an elicitor activity, and induce a variety of defense responses in host plants in response to microbial infections, i.e., accumulation of phytoalexins, pathogen-related (PR) proteins and proteinase inhibitors, stimulation of lignin synthesis as well as callose formation. Based on these and other proprieties that help strengthen host plants, there has been a growing interest in using them in agricultural systems to reduce the negative impact of diseases on yield and quality of crops. This review will shed some light on the proprieties and uses of chitin and chitin oligosaccharides, and will focus on their applications and mechanisms of action during plant-pathogen interactions.
Keywords: Chitin, Chitosan, biocidal activity, plant defenses, resistance, biological control.