Publications in July and August 2013

In the summer months July and August, 222 publications about chitosan and chitosan derivatives have been released. Most of these reports examined chitosan-based pharmaceutical preparations and nanoparticles and analysed the effectiveness in animal and human studies. The leading countries in chitosan research are: China (70 articles), India (23) and Taiwan (16).

Table: List of the leading journals, which published most chitosan-based articles in July and August 2013.
Source: GoPubMed

Chitosan and chitosan derivatives are intensively studied for their antioxidative activity. The radical scavenging ability of chitosan is attributed to its hydroxyl (OH) and amino (NH2) groups. However, the semi-crystalline structure and strong hydrogen bonds of chitosan restrict its full antioxidant potential. Hence, several chitosan derivatives have been developed to improve the antioxidative capacity of the polymer. Below, we present two novel formulations, which might be of interest for pharmaceutical and food industries.

Development of tea extracts and chitosan composite films for active packaging materials.

Peng Y1, Wu Y, Li Y. Int J Biol Macromol. Vol.: 59:282-9. August 2013

The objective of the present study was to investigate the antioxidant properties of chitosan films, which were modified with green tea (GTE) or black tea (BTE) extracts. The films were prepared from chitosan solutions (2%, w/v), glacial acetic acid (1%, w/w), 30% glycerol and different concentrations of tea extract (0.5%, 1% and 2%). The antioxidant capacity of the chitosan-based films was measured by their DPPH scavenging ability and in the presents of food simulating liquids (aqueous solutions with 0%, 20%, 75% and 95% ethanol).

Results for tea extract incorporated chitosan films:

• Increased solubility and swelling degree in water
• Decreased water content and vapour permeability
• Decreased tensile strength and elongation at break
• Increased antioxidant ability (DPPH radical scavenging) GTE-chitosan films > BTE-chitosan films

Conclusion:  The antioxidant capacity is a crucial parameter for active packaging films, which are used for the food industry. Chitosan-based films are biodegradable and non-toxic, however, their DPPH radical scavenging activity of is low. The incorporation of green or black tea extracts significantly improved the antioxidant ability of the film matrix. The radical scavenging time was accelerated by higher concentrations of tea extracts (2%).

Source: http://www.ncbi.nlm.nih.gov/pubmed/23603075

Preparation, characterization and antioxidant property of water-soluble ferulic acid grafted chitosan.

Woranuch S., Yoksan R. Carbohydr Polym. Vol.: 96(2):495-502. July  2013

The authors of the present study modified chitosan with ferulic acid (FA-chitosan) to improve water solubility and antioxidant capacity of the biopolymer. Ferulic acid is a natural phenolic acid, which possesses antioxidative, antimicrobial and anti-inflammatory properties, making it attractive for food and pharmaceutical industries. To preserve the functional properties of FA-chitosan, ferulic acid was grafted via its carboxyl group to the amino group of chitosan.

Results for FA-chitosan:

Conditions for highest degree of FA substitution: mole ratio 1:1, chitosan to FA 60°C reaction temperature 3h reaction time Reduced crystallinity by ∼10% Decreased decomposition temperature to 55°C Enhanced DPPH radical scavenging activity to ∼55% Improved water solubility up to 1.3 mg/ml

Conclusion: The antioxidant activity of chitosan was significantly improved by grafting it with ferulic acid and increased the radical scavenging form 41% to 96%. The binding of free radicals is presumably performed by OH group of ferulic acid and NH2 group of chitosan. According to the authors, FA-grafted chitosan might be a suitable antioxidant for medicine, food and cosmetic industries.

Source: http://www.ncbi.nlm.nih.gov/pubmed/23768592