Acetic acid lignins from Chinese quince fruit (Chaenomeles sinensis): effect of pretreatment on their structural features and antioxidant activities

Unraveling the structural aspects of microwave-assisted OrganoCat-based coconut shell lignins: An eco-friendly route for obtaining bio-based antioxidants

New routes for biomass valorization have been developing by the scientific community. The aim of this work was developing a novel OrganoCat-based protocol and deeply understand the structure of the obtained lignins. Microwave-assisted OrganoCat-based process was performed using a biphasic system (ethyl acetate and oxalic acid or HCl) at mild conditions. OrganoCat-based lignins (OCLs) were characterized by compositional analysis, FTIR, 1H, 13C, 1H13C HSQC, 31P NMR, TGA and GPC. The solubility of OCLs in different organic solvents and their antioxidant capacity against DPPH were investigated. The spectroscopic analyses showed that OCLs have high residual extractives and the lignin motifs were preserved. OCLs have presented lower thermal stability than MWL, but showed great antioxidant activities and high solubility in a wide range of organic solvents. A novel biorefinery protocol yielded coconut shell lignins with peculiar structural and compositional features and several technological applications through an eco-friendly, sustainable and relatively low-cost biphasic pulping process.

Protective effect of mixture of Acanthopanax sessiliflorum and Chaenomeles sinensis against ultraviolet B-induced photodamage in human fibroblast and hairless mouse

Skin photoaging, characterized by collagen degradation and upregulation of matrix metalloproteinases (MMPs), is a major concern caused by UVB irradiation. In this study, we investigated the potential of Acanthopanax sessiliflorum extract (ASE) and Chaenomeles sinensis (CSE) extracts to mitigate the effects of UVB-induced photodamage in human fibroblast and hairless mice. Water extracts of AS (ASE) and CS (CSE) were found to inhibit the expression of MMP-1/-3 in vitro. Furthermore, the extract of mixture of AS and CS (ACE) showed more potent inhibitor effect, as compared to ASE and CSE. In UVB-irradiated hairless mice, oral administration of ACE effectively reduced wrinkle formation, skin roughness, and epidermal thickness while promoting the deposition of collagenous fibers. These results indicate that ACE has the potential to protect against skin photoaging by restoring the impaired skin via downregulation of MMP-1/-3 expression and secretion. Our findings highlight the therapeutic potential of ACE in mitigating skin photoaging.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01462-3.

Phytochemistry and pharmacology of plants in the genus Chaenomeles

Chaenomeles plants belong to the Rosaceae family and include five species, Chaenomeles speciosa (Sweet) Nakai, Chaenomeles sinensis (Thouin) Koehne, Chaenomeles japonica (Thunb.) Lindl, Chaenomeles cathayensis (Hemsl.) Schneid and Chaenomeles thibetica Yu. Chaenomeles plants are found and cultivated in nearly every country worldwide. China serves as both the origin and distribution hub for the plants in the Chaenomeles genus, and all Chaenomeles species except for C. japonica are indigenous to China. Chaenomeles spp. is a type of edible medicinal plant that has been traditionally used in China to treat various ailments, such as rheumatism, cholera, dysentery, enteritis, beriberi, and scurvy. A variety of chemical constituents have been extracted from this genus, including terpenoids, phenolics, flavonoids, phenylpropanoids and their derivatives, benzoic acid derivatives, biphenyls, oxylipins, and alkaloids. The biological activity of some of these constituents has already been evaluated. Pharmacological investigations have demonstrated that the plants in the genus Chaenomeles exhibit anti-inflammatory, analgesic, antioxidant, antihyperglycemic, antihyperlipidemic, gastrointestinal protective, antitumor, immunomodulatory, antibacterial, antiviral, hepatoprotective, neuroprotective and other pharmacological activities. The objective of this review is to provide a comprehensive and up-to-date summary of the available information on the genus Chaenomeles to serve as a valuable reference for further investigations.

Structural variation of lignin-carbohydrate complexes (LCC) in Chinese quince (Chaenomeles sinensis) fruit as it ripens

Chinese quince (Chaenomeles sinensis) fruits are rich in lignin, and too sour, astringent and woody to be eaten raw. More than 50 % of lignin in plant cell walls is covalently associated with carbohydrates to form lignin-carbohydrate complexes (LCC). In this study, LCC preparations were extracted from fruits harvested on the 15th day of the month from May-October 2019. A variety of chemical and instrumental analytical approaches were used to characterize the LCC fractions, including HPAEC, TGA, GPC, FT-IR, and 2D HSQC NMR. Antioxidant activities were evaluated by DPPH radical scavenging assays. Results showed that the LCC fractions from October fruits had better thermal stability and homogeneity. NMR results revealed that the lignin-lignin linkages in LCC-AcOH preparations included β-O-4', β-β' and β-5', but β-5' linkages were not present in LCC preparations. And the NMR signals of carbohydrate confirmed the presence of lignin-pectin complexes, which was consistent with sugar analysis. All LCC preparations showed good antioxidant activity, among which Björkman LCC from October fruits showed best. This study will facilitate understanding the chemical bonds of LCC macromolecules in the plant cell wall. More specifically, it provides information critical for specific industrial applications of quince fruits.

A review on lignin antioxidants: Their sources, isolations, antioxidant activities and various applications

Lignin, a biopolymer obtained from agricultural/forestry residues or paper pulping wastewater, is rich in aromatic structure, which is central to its adoption as a candidate to natural antioxidants. Through insight into its structural features from biomass, different functional groups would influence lignin antioxidant activity, wherein phenolic content is the most important factor, hence massive studies have focused on its improvement via different pretreatments and post-processing methods. Besides, lignin nanoparticles and chemical modifications are also efficient methods to improve antioxidant activity via increasing free content and decreasing bond dissociation enthalpy of phenolic hydroxyl. Lignin samples exhibit comparable radicals scavenging ability to commercial ones, showing their potential as renewable alternatives of synthesized antioxidants. Besides, their applications have also been discussed, which demonstrates lignin potential as an inexpensive antioxidant additive and consequent improvements on multiple functionalities. This review is dedicated to summarize lignin antioxidants extracted from biomass resources, methods to improve their antioxidant activity and their applications, which is beneficial for realizing lignin valorization.

Sequential aqueous acetone fractionation and characterization of Brauns native lignin separated from Chinese quince fruit

Lignin, especially Brauns native lignin (BNL), from Chinese quince (Chaenomeles sinensis) fruit represents a potential source of natural antioxidants. However, the highly inhomogeneous structure and the carbohydrate impurity reduce the antioxidant properties of BNL. Accordingly, a sequential aqueous acetone fractionation was used to prepare pure lignin fractions with homogeneous molecular structures; these fractions showed strong antioxidant properties. Analytical results showed that the yields of F_50% and F_60% exceeded 20% (i.e., 20.6% and 24.1%, respectively). The sugar impurities in BNL were mainly retained in the F_30% and F_40% fractions. For all fractions, molecular weight increased as the acetone concentration increased. The results from 2D HSQC NMR and ³¹P NMR indicated that the number of lignin linkages (β-O-4', β-β' and β-5') and functional groups (S-OH, G-OH, H-OH, and COOH) of these fractions varied with their molecular weights. Antioxidant assays showed that F_40%, F_50% and F_60% had higher antioxidant properties than BNL. Overall, the study provides a simple, environmentally friendly fractionation method to prepare lignin with various structural features and strong antioxidant properties from Chinese quince fruit. These lignin fractions have promising application in some fields with high value, such as antioxidants production, biomaterials, packaging materials, and drug delivery and so on.

Hydrothermal oxidative valorisation of lignin into functional chemicals: A review

Lignin is a waste by-product of bio-refineries and paper-pulp industries. It has an attractive potential to produce numerous valuable chemicals due to its highly aromatic character. At present, large amount of lignin is burnt as a source of energy due to lack of suitable efficient lignin valorisation processes. The challenge exists in handling its complex heterogeneous structure and bond breaking at selective locations. The production of high value chemicals/petrochemical feedstocks will improve the economic viability of a bio-refinery. Oxidative depolymerization is a promising way to produce functional compounds from lignin. The aim of the current review is to present the novel methodologies currently used in the area of lignin oxidative depolymerization including effect of temperature, residence time, solvent, oxidizing agents, homogeneous and heterogeneous catalysis etc. It aims to present an insight into the structure of lignin and its breakdown mechanism.

Tailored organosolv banana peels lignins: Improved thermal, antioxidant and antimicrobial performances by controlling process parameters

There is a growing environmental concern in the world for replacing the traditional petroleum-based products. The aim of this work was to evaluate the structure - property relationship of banana peel lignins (BPLs) as antioxidant and antimicrobial agents by controlling the parameters of organosolv process. The milled banana peel was hydrolyzed using an aqueous acetic acid solution (70, 80 and 90% v/v) and 2.0% v/v HCl at 110 °C for 1, 2 and 3 h. BPLs were characterized by FTIR, ¹H NMR, ¹H¹³C HSQC, ³¹P NMR, GPC and TGA. The antioxidant capacity of BPLs was evaluated by DPPH, ABTS and H₂O₂ assays, comparing their performance with that of ascorbic and gallic acid. The antimicrobial activity of BPLs was evaluated against E. coli. The reaction time and acetic acid/water ratio had significant effects on the yield and purity of BPLs. The composition of organosolv solution also affected their total amount of hydroxyls (0.71-0.82 mmol g^-1), M_w (2759-3954 g mol^-1), T_onset (232-254 °C), antioxidant and antimicrobial activities. It can be concluded that the control of organosolv parameters can be a useful tool for tuning the structural features of lignins and to maximize their performance.

Structural Changes in Milled Wood Lignin (MWL) of Chinese Quince (Chaenomeles sinensis) Fruit Subjected to Subcritical Water Treatment

Subcritical water treatment has received considerable attention due to its cost effectiveness and environmentally friendly properties. In this investigation, Chinese quince fruits were submitted to subcritical water treatment (130, 150, and 170 °C), and the influence of treatments on the structure of milled wood lignin (MWL) was evaluated. Structural properties of these lignin samples (UL, L130, L150, and L170) were investigated by high-performance anion exchange chromatography (HPAEC), FT-IR, gel permeation chromatography (GPC), TGA, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), 2D-Heteronculear Single Quantum Coherence (HSQC) -NMR, and 31P-NMR. The carbohydrate analysis showed that xylose in the samples increased significantly with higher temperature, and according to molecular weight and thermal analysis, the MWLs of the pretreated residues have higher thermal stability with increased molecular weight. The spectra of 2D-NMR and 31P-NMR demonstrated that the chemical linkages in the MWLs were mainly β-O-4' ether bonds, β-5' and β-β', and the units were principally G- S- H- type with small amounts of ferulic acids; these results are consistent with the results of Py-GC/MS analysis. It is believed that understanding the structural changes in MWL caused by subcritical water treatment will contribute to understanding the mechanism of subcritical water extraction, which in turn will provide a theoretical basis for developing the technology of subcritical water extraction.

Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment

Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4' linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.

Natural Sources and Bioactivities of 2,4-Di-Tert-Butylphenol and Its Analogs

2,4-Di-tert-butylphenol or 2,4-bis(1,1-dimethylethyl)-phenol (2,4-DTBP) is a common toxic secondary metabolite produced by various groups of organisms. The biosources and bioactivities of 2,4-DTBP have been well investigated, but the phenol has not been systematically reviewed. This article provides a comprehensive review of 2,4-DTBP and its analogs with emphasis on natural sources and bioactivities. 2,4-DTBP has been found in at least 169 species of bacteria (16 species, 10 families), fungi (11 species, eight families), diatom (one species, one family), liverwort (one species, one family), pteridiphyta (two species, two families), gymnosperms (four species, one family), dicots (107 species, 58 families), monocots (22 species, eight families), and animals (five species, five families). 2,4-DTBP is often a major component of violate or essential oils and it exhibits potent toxicity against almost all testing organisms, including the producers; however, it is not clear why organisms produce autotoxic 2,4-DTBP and its analogs. The accumulating evidence indicates that the endocidal regulation seems to be the primary function of the phenols in the producing organisms.

Synthesis of anti-photolysis lignin-based dispersant and its application in pesticide suspension concentrate

In the formulation of pesticide Suspension Concentrate (SC), some photosensitive pesticides are easily decomposed in the preparation. In this study, a hindered amine modified lignosulfonate (SL-Temp) with anti-photolysis function was synthesized using 4-amino-2,2,6,6-tetramethylpiperidine (Temp) and Sodium Lignosulfonate (SL) to solve this problem. The obtained SL-Temp was used as a dispersant to prepare 5% SC of avermectin, which shows good physical stability. The decomposition rate of the avermectin in SC after accelerating hot storage is 0%, which is much lower than 6.1% when SL was used as the dispersant. After being exposed to UV irradiation for 60 hours, the highest retention rate of avermectin is 87.1% when SL-Temp was used as the dispersant, which is much higher than 73.6% when SL was used as the dispersant, and also higher than 76.3% when a small molecule antioxidant (BHT) was added to the formulation. QCM-D studies revealed that the SL-Temp adsorption layer on avermectin particles can compete to absorb partial ultraviolet rays, hinder the penetration of ultraviolet light, and scavenge the free radicals produced by photooxidation, so as to protect avermectin from degradation.

Hindered amine grafted lignosulfonate was synthesized and used as functional dispersant in suspension concentrate of photosensitive pesticide avermectin.