Abstract
Natural and bioactive products have been of great interest due to their benefit as health foods and drugs to prevent various diseases. The aim of this study is to efficiently reuse marine chitinous materials (CMs), abundant and low-cost fishery by-products, for the bio-synthesis, isolation, and identification of antioxidant compounds possessing some other beneficial bioactivities. Paenibacillus sp. was used to convert CMs to antioxidants. Among various tested CMs, squid pen powder (SPP) gave the best results when used as the sole carbon/nitrogen source. Fermented SPP (FSPP) had comparable antioxidant activity (IC50 = 124 µg/mL) to that of α-tocopherol (IC50 = 30 µg/mL). The antioxidant productivity increased 1.83-fold after culture optimization. The use of multiple techniques, including Diaion, silica, and preparative HPLC columns coupled with a bioassay resulted in the isolation of two major antioxidants characterized as exopolysaccharides and homogentisic acid. These isolated compounds showed great maximum activity and low IC50 values (96%, 30 µg/mL and 99%, 5.4 µg/mL, respectively) which were comparable to that of α-tocopherol (95%, 24 µg/mL). The crude sample, fractions, and isolated compounds also demonstrated α-glucosidase inhibition and anti–inflammatory activity. Notably, homogentisic acid was found as a non-sugar-based moiety α-glucosidase inhibitor which show much higher inhibition (IC50 = 215 µg/mL) than that of acarbose (IC50 = 1324 µg/mL) and also possessed acceptable anti–inflammatory activity (IC50 = 9.8 µg/mL). The results highlighted the value of using seafood processing by-products, like squid pens, for the production of several compounds possessing multi-benefit bioactivities and no cytotoxicity.
Highlights
Living organisms are negatively affected by free radicals [1]
TKU042, a bacterium previously found to produce antioxidants when cultured in nutrient broth (NB) [21]
Antioxidant activity was dramatically increased by purification
Summary
Living organisms are negatively affected by free radicals [1]. Synthetic and natural antioxidants have been used to prevent damage, but synthetic antioxidants may result in liver damage and Molecules 2018, 23, 1124; doi:10.3390/molecules23051124 www.mdpi.com/journal/moleculesMolecules 2018, 23, 1124 carcinogenesis [2]. The discovery of new, abundant, low-cost, active and green production methods for natural antioxidant compounds is needed. Antioxidants can be obtained from many sources, such as microbial conversion [3], higher plants [4,5,6], marine products [7] or synthesis [8]. Microbial conversion has provided a very large number of novel active products and is of great interest due to the valuable characteristics of the microbes, such as fast growth and synthesis of various bioactive compounds under different conditions, as well as the advantages of its green production process, such as low-cost materials, mild fermentation, and no environmental pollution [9,10,11]. There are few reports on EPS production with antioxidant properties from marine chitinous materials via bacterial conversion [3]. Similar to EPS antioxidants, there are few reports on homogentisic acid induced via bacterial conversion [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
