Preparation, characterization, antioxidant, and antifungal activity of phenyl/indolyl-acyl chitooligosaccharides.

In this study, carboxylic acids compounds were grafted onto chitooligosaccharides to prepare seven phenyl/indolyl-acyl chitooligosaccharides derivatives. The structures of the derivatives were characterized by IR spectroscopy, 13C NMR and elemental analysis. Meanwhile, antioxidant activities in vitro of the novel derivatives were analyzed. Compared to COS and carboxylic acid, the derivatives showed higher scavenging capacity for superoxide anion and DPPH radicals, with scavenging rates of 59.39% and 94.86%, respectively. The hydroxyl radical scavenging ability of the derivatives was only 18.89%. The antifungal activities of chitooligosaccharide derivatives against Diaporthe batatas and Phytophthora capsici were studied by the growth rate method. Compared with chitooligosaccharide itself, derivatives were inhibited by 97.77% and 100%. The above results showed that chitooligosaccharide derivatives have good biocompatibility and can be used in food, agriculture and medicine.

Preparation, characterization, antioxidant and antifungal activities of benzoic acid compounds grafted onto chitosan.

The current study created three novel chitosan derivatives named BACS, PIBACS, and MHBACS by grafting benzoic acid (BA), p-isopropyl benzoic acid (PIBA), and m-hydroxybenzoic acid (MHBA) onto chitosan (CS). The structures of the derivatives were investigated using infrared spectroscopy (FT-IR) and nuclear magnetic resonance (13C NMR). The derivatives were discovered to be 45.06 %-60.49 % substituted using elemental analysis (EA). Based on the findings of in vitro antioxidant experiments (hydroxyl radical scavenging activity, superoxide anion radical scavenging activity, and DPPH radical scavenging activity), all of the derivatives had a higher hydroxyl radical scavenging activity than the chitosan raw material. MHBACS scavenged (31.02 ± 0.90)% of hydroxyl radicals at 0.5 mg/mL, 28.69 % more than chitosan raw. The derivatives scavenged more superoxide anion radicals than the chitosan feedstock at a particular concentration. For instance, at a test dose of 0.2 mg/mL, the scavenging rate of MHBACS on superoxide anion radicals was 7.75 % greater than that of chitosan raw materials. DPPH radical scavenging activity, on the other hand, was not as competent as chitosan feedstock. The growth rate approach was used to assess the potential of the three derivatives to inhibit the development of four phytopathogenic fungi. Chitosan derivatives have better antifungal efficacy than chitosan raw materials. PIBACS, MHBACS, BACS, and Wuyiencin inhibited Phytophthora capsici by (98.03 ± 1.95)%, (81.73 ± 1.63)%, (66.38 ± 1.81)%, and (93.01 ± 2.69)%, respectively, at 1.0 mg/mL. PIBACS had a higher inhibitory impact on Phytophthora capsici than the positive control. Based on the evidence presented above, it is reasonable to conclude that the addition of benzoic acid molecules increased the antioxidant and antifungal capabilities of chitosan.

Chitooligosaccharide-induced plant stress resistance.

In nature, the production of plant stress resistance traits is often induced by extreme environmental conditions. Under extreme conditions, plants can be irreversibly damaged. Intervention with phytostimulants, however, can improve plant stress resistance without causing damage to the plants themselves, hence maintaining the production. For example, exogenous substances such as proteins and polysaccharides can be used effectively as phytostimulants. Chitooligosaccharide, a plant stimulant, can promote seed germination and plant growth and development, and improve plant photosynthesis. In this review, we summarize progress in the research of chitooligosaccharide-induced plant stress resistance. The mechanism and related experiments of chitooligosaccharide-induced resistance to pathogen, drought, low-temperature, saline-alkali, and other stresses are classified and discussed. In addition, we put forward the challenges confronted by chitooligosaccharide-induced plant stress resistance and the future research concept that requires multidisciplinary cooperation, which could provide data for the in-depth study of the effect of chitooligosaccharide on plants.

The preparation and antioxidant activities of four 2-aminoacyl-chitooligosaccharides.

Chitooligosaccharides (COS) with two different molecular weights are acylated with four nonpolar amino acids: glycine (Gly), alanine (Ala), valine (Val) and leucine (Leu) to obtain 2-aminoacetyl-chitooligosaccharide (2-GlyCOS), 2-aminopropionyl-chitooligosaccharide (2-AlaCOS), 2-amino-3-methylbutyryl-chitooligosaccharide (2-ValCOS), and 2-amino-4-methylpentanoyl-chitooligosaccharide (2-LeuCOS). The structure of the derivatives was characterized by FT-IR spectroscopy, 13C NMR spectroscopy, and elemental analysis. The antioxidant activities of the derivatives, such as hydroxyl radical (·OH) scavenging ability, superoxide anion (O2·-) scavenging ability, reducing ability, and DPPH radical scavenging ability, were investigated using various established systems. Compared with chitooligosaccharide and nonpolar amino acids, all derivatives have strong scavenging ability toward hydroxyl radicals and superoxide anions, and the clearance rate was 19.05% and 67.70% separately. The reducing ability and DPPH free radical scavenging ability of the derivatives are only 0.021Abs and 32.97%. Among them, only 2-AlaLCOS has significant reducing ability, and the value can reach 0.143Abs. The above results showed that the antioxidant activity of some derivatives was higher than that of chitooligosaccharide. The water solubility of the new derivatives was also greatly improved compared to that of nonpolar amino acids. Therefore, the application of 2-aminoacyl-chitooligosaccharides (2-AACOS) in antioxidants has laid a foundation and has certain potential application value in the fields of medicine, agriculture, and animal husbandry.

The preparation and antioxidant activities of three phenyl-acylchitooligosaccharides.

Chitooligosaccharides with two different molecular weights are acylated with three containing benzene carboxylic acids: salicylic acid (BHA), α-naphthylacetic acid (NAA) and indole-3-butyric acid (IBA) to obtain o-hydroxybenzoyl-chitooligosaccharide, α-naphthylacetyl-chitooligosaccharide, and 3-Indolebutyryl-chitooligosaccharide. The structure of the derivatives was characterized by FT-IR spectroscopy, 13C NMR spectroscopy and elemental analysis. According to several amide characteristic absorption peaks between 1750 cm-1-1500 cm-1 in the FT-IR spectrum, it can be determined that the target group has been successfully grafted. And there are obvious characteristic absorption peaks of aromatic ring at 900-650 cm-1. The six chemical shifts of 98.02, 76.42, 74.83, 72.00, 60.39, 55.37 ppm in 13C NMR proved that the chitooligosaccharide did not destroy its own sugar ring structure during the reaction. The antioxidant activities of the derivatives, such as hydroxyl radical (·OH) scavenging ability, superoxide anion (O2·-) scavenging ability, reducing ability, and DPPH radical scavenging ability were investigated using various established systems. Comparing with chitooligosaccharide and containing benzene carboxylic acids, most derivatives have strong scavenging ability toward superoxide anions and DPPH radicals, and the clearance rate up to 47.44% and 80.27% separately. The reducing ability and hydroxyl free radical scavenging ability of the derivatives are only 0.032 Abs and 11.43%. The above results showed that the antioxidant activity of some derivatives was higher than that of chitooligosaccharide. The water solubility of the new derivatives was also greatly improved than that of containing benzene carboxylic acids. Therefore, the application of phenyl-acyl-chitooligosaccharide in antioxidants has laid a foundation, and has certain potential application value in the fields of medicine and agriculture and animal husbandry.