Antioxidant Metabolism in Plants and Algae

A special issue of Antioxidants (ISSN 2076-3921). This special issue belongs to the section "Natural and Synthetic Antioxidants".

Deadline for manuscript submissions: closed (15 September 2022) | Viewed by 20115

Special Issue Editors

School of Life Sciences, Nanjing University, Nanjing 210023, China
Interests: chloroplast; terpenoids; carotenoid; metabolism; chlorophyll
Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
Interests: plant micronutrient metabolism; maize functional genomics
Special Issues, Collections and Topics in MDPI journals
School of Pharmaceutical Sciences, Shandong University, Jinan 250012, China
Interests: flavonoids; terpenoids; metabolism; phenylpropanoids; liverworts

Special Issue Information

Dear Colleagues,

Antioxidants are small molecular weight compounds that effectively scavenge free radicals, protect cells, delay aging, and prevent diseases. Photosynthetic organisms, including higher plants, algae, and also cyanobacteria, are constantly challenged by the oxidative environment and have thus developed sophisticated metabolic and regulatory networks for the biosynthesis of antioxidants. Moreover, humans are not able to synthesize most of the antioxidants and have to uptake them as essential phytonutrients from our diets. The elucidation of the metabolic reactions and their corresponding regulations, in addition to their evolution and specialization, would expand our understanding of the natural metabolic processes and also facilitate future biofortification research for enhancing the nutritional value of staple crops.

This Special Issue aims to collect papers dealing with all aspects of antioxidants from plants (including algae and cyanobacteria), such as, but not limited to, carotenoids, anthocyanins, vitamin C, vitamin E, and phenolics. Papers describing recent developments in the molecular regulation of these metabolisms and their responses to environmental challenges will be especially welcome, although molecular cloning and functional characterization of specialized enzymes are also within the scope of this Special Issue. Because there has been a large body of reports on the bioactivity of antioxidants to humans, and there are other more suitable Special Issues in this journal opening in parallel, those physiological and/or nutritional studies, and other studies using animal systems, will not be considered.

Prof. Dr. Shan Lu
Prof. Dr. Chunyi Zhang
Prof. Dr. Aixia Cheng
Guest Editors

Manuscript Submission Information

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Keywords

  • phenylpropanoid
  • carotenoid
  • vitamin C
  • vitamin E
  • phenolics
  • metabolism
  • transcription factor
  • isolation and characterization
  • biofortification
  • gene expression
  • stress response

Published Papers (9 papers)

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Research

12 pages, 1538 KiB  
Communication
Transcriptomic Analysis Suggests a Coordinated Regulation of Carotenoid Metabolism in Ripening Chili Pepper (Capsicum annuum var. conoides) Fruits
by Shuyan Song, Shu-Yuan Song, Peiwen Nian, Dexin Lv, Yunhe Jing, Shan Lu, Qiang Wang and Fei Zhou
Antioxidants 2022, 11(11), 2245; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11112245 - 14 Nov 2022
Cited by 2 | Viewed by 1448
Abstract
Carotenoids are not only photosynthetic and photoprotective pigments in plants, but also essential antioxidative nutrients for human health. The fruit is the main plant organ that synthesizes and sequestrates carotenoids. Fruit ripening is a complicated developmental process, during which the rewiring of the [...] Read more.
Carotenoids are not only photosynthetic and photoprotective pigments in plants, but also essential antioxidative nutrients for human health. The fruit is the main plant organ that synthesizes and sequestrates carotenoids. Fruit ripening is a complicated developmental process, during which the rewiring of the metabolic network is tightly coordinated with the re-organization of cellular and organellular structures. Chili pepper (Capsicum annuum) is one of the major crops that accumulates a distinct level of carotenoids, especially capsanthin, in their ripened fruits. To elucidate how different metabolic and developmental scenarios are regulated in ripening chili pepper fruits, we analyzed the carotenoid profiles and transcriptomes of fruits at different ripening stages. Our pigment analysis indicated an opposite correlation between the contents of carotenoid species with β,β-structures (e.g., β-carotene, zeaxanthin, and capsanthin) and of lutein with the β,ε-structure, whereas lutein displayed a high correlation with chlorophylls during ripening. From the chili pepper Zunla-1 genome, a full repertoire of 38 homologous genes encoding enzymes in the carotenoid biosynthetic pathway was identified. The fluctuations in their transcript abundances during ripening suggested different involvement of these genes in the regulation of carotenoid biosynthesis. We further searched genes of which the expression showed high correlations with the accumulation of β-carotene during the ripening process. Moreover, from the transcriptomic analysis, a total of 17 transcription factors that co-expressed with different groups of carotenoid biosynthetic genes were identified. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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12 pages, 4057 KiB  
Article
Spatial Distribution, Antioxidant Capacity, and Spore Germination-Promoting Effect of Bibenzyls from Marchantia polymorpha
by Jiao-Zhen Zhang, Chan Wang, Ting-Ting Zhu, Jie Fu, Hui Tan, Cheng-Min Zhang, Ai-Xia Cheng and Hong-Xiang Lou
Antioxidants 2022, 11(11), 2157; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11112157 - 31 Oct 2022
Cited by 1 | Viewed by 1233
Abstract
Liverworts, considered to be the first plant type to successfully make the transition from water to land, can resist different oxidative stress. As characteristic constituents of liverworts, the bibenzyls are efficient antioxidants. In this study, spatial distributions of the bibenzyls within Marchantia polymorpha [...] Read more.
Liverworts, considered to be the first plant type to successfully make the transition from water to land, can resist different oxidative stress. As characteristic constituents of liverworts, the bibenzyls are efficient antioxidants. In this study, spatial distributions of the bibenzyls within Marchantia polymorpha L., the model species of liverworts, were mapped using airflow-assisted desorption electrospray ionization imaging mass spectrometry. Bibenzyls were found to largely exist in the female receptacle of M. polymorpha, where lunularic acid was found to focus in the central region and bisbibenzyls were enriched in the periphery. The region-specific gene expression and antioxidant activities were characterized. In line with the spatial feature of bibenzyls, higher MpSTCS1A and Mp4CL expression levels and antioxidant ability were exhibited in the archegoniophore. The expression level of MpSTCS1A, and the content of total phenolic acid was increased after UV-B irradiation, suggesting bibenzyls play an important role in UV-B tolerance. Moreover, lunularic acid and extract of archegoniophore at a certain concentration can stimulate the spore germination under normal conditions and UV-B stress. These works broaden our understanding of the significance of bibenzyls in spore propagation and environmental adaptation. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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15 pages, 2904 KiB  
Article
Metabolomics Reveals Nutritional Diversity among Six Coarse Cereals and Antioxidant Activity Analysis of Grain Sorghum and Sweet Sorghum
by Yao Zhao, Guowei Zhai, Xuetong Li, Han Tao, Linying Li, Yuqing He, Xueying Zhang, Fulin Wang, Gaojie Hong and Ying Zhu
Antioxidants 2022, 11(10), 1984; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11101984 - 05 Oct 2022
Cited by 3 | Viewed by 1932
Abstract
Coarse cereals are rich in dietary fiber, B vitamins, minerals, secondary metabolites, and other bioactive components, which exert numerous health benefits. To better understand the diversity of metabolites in different coarse cereals, we performed widely targeted metabolic profiling analyses of six popular coarse [...] Read more.
Coarse cereals are rich in dietary fiber, B vitamins, minerals, secondary metabolites, and other bioactive components, which exert numerous health benefits. To better understand the diversity of metabolites in different coarse cereals, we performed widely targeted metabolic profiling analyses of six popular coarse cereals, millet, coix, buckwheat, quinoa, oat, and grain sorghum, of which 768 metabolites are identified. Moreover, quinoa and buckwheat showed significantly different metabolomic profiles compared with other coarse cereals. Analysis of the accumulation patterns of common nutritional metabolites among six coarse cereals, we found that the accumulation of carbohydrates follows a conserved pattern in the six coarse cereals, while those of amino acids, vitamins, flavonoids, and lipids were complementary. Furthermore, the species-specific metabolites in each coarse cereal were identified, and the neighbor-joining tree for the six coarse cereals was constructed based on the metabolome data. Since sorghum contains more species-specific metabolites and occupies a unique position on the neighbor-joining tree, the metabolite differences between grain sorghum 654 and sweet sorghum LTR108 were finally compared specifically, revealing that LTR108 contained more flavonoids and had higher antioxidant activity than 654. Our work supports an overview understanding of nutrient value in different coarse cereals, which provides the metabolomic evidence for the healthy diet. Additionally, the superior antioxidant activity of sweet sorghum provides clues for its targeted uses. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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22 pages, 4897 KiB  
Article
Insight into the Mechanism of Salt-Induced Oxidative Stress Tolerance in Soybean by the Application of Bacillus subtilis: Coordinated Actions of Osmoregulation, Ion Homeostasis, Antioxidant Defense, and Methylglyoxal Detoxification
by Mirza Hasanuzzaman, Md. Rakib Hossain Raihan, Farzana Nowroz and Masayuki Fujita
Antioxidants 2022, 11(10), 1856; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11101856 - 20 Sep 2022
Cited by 9 | Viewed by 2096
Abstract
Considering the growth-promoting potential and other regulatory roles of bacteria, we investigated the possible mechanism of the role of Bacillus subtilis in conferring salt tolerance in soybean. Soybean (Glycine max cv. BARI Soybean-5) seeds were inoculated with B. subtilis, either through [...] Read more.
Considering the growth-promoting potential and other regulatory roles of bacteria, we investigated the possible mechanism of the role of Bacillus subtilis in conferring salt tolerance in soybean. Soybean (Glycine max cv. BARI Soybean-5) seeds were inoculated with B. subtilis, either through a presoaking with seeds or a direct application with pot soil. After 20 days of sowing, both the seed- and soil-inoculated plants were exposed to 50, 100, and 150 mM of NaCl for 30 days. A clear sign of oxidative stress was evident through a remarkable increase in lipid peroxidation, hydrogen peroxide, methylglyoxal, and electrolyte leakage in the salt treated plants. Moreover, the efficiency of the ascorbate (AsA)–glutathione (GSH) pathways was declined. Consequently, the plant growth, biomass accumulation, water relations, and content of the photosynthetic pigments were decreased. Salt stress also caused an increased Na+/K+ ratio and decreased Ca2+. On the contrary, the B. subtilis inoculated plants showed increased levels of AsA and GSH, their redox balance, and the activities of the AsA–GSH pathway enzymes, superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, and peroxidase. The B. subtilis inoculated plants also enhanced the activities of glyoxalase enzymes, which mitigated methylglyoxal toxicity in coordination with ROS homeostasis. Besides this, the accumulation of K+ and Ca2+ was increased to maintain the ion homeostasis in the B. subtilis inoculated plants under salinity. Furthermore, the plant water status was uplifted in the salt treated soybean plants with B. subtilis inoculation. This investigation reveals the potential of B. subtilis in mitigating salt-induced oxidative stress in soybean plants through modulating the antioxidant defense and glyoxalase systems along with maintaining ion homeostasis and osmotic adjustments. In addition, it was evident that the soil inoculation performed better than the seed inoculation in mitigating salt-induced oxidative damages in soybean. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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11 pages, 2456 KiB  
Article
Rice Nudix Hydrolase OsNUDX2 Sanitizes Oxidized Nucleotides
by Yuki Kondo, Kazuhide Rikiishi and Manabu Sugimoto
Antioxidants 2022, 11(9), 1805; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11091805 - 13 Sep 2022
Cited by 2 | Viewed by 1798
Abstract
Nudix hydrolase (NUDX) hydrolyzes 8-oxo-(d)GTP to reduce the levels of oxidized nucleotides in the cells. 8-oxo-(d)GTP produced by reactive oxygen species (ROS) is incorporated into DNA/RNA and mispaired with adenine, causing replicational and transcriptional errors. Here, we identified a rice OsNUDX2 gene, whose [...] Read more.
Nudix hydrolase (NUDX) hydrolyzes 8-oxo-(d)GTP to reduce the levels of oxidized nucleotides in the cells. 8-oxo-(d)GTP produced by reactive oxygen species (ROS) is incorporated into DNA/RNA and mispaired with adenine, causing replicational and transcriptional errors. Here, we identified a rice OsNUDX2 gene, whose expression level was increased 15-fold under UV-C irradiation. The open reading frame of the OsNUDX2 gene, which encodes 776 amino acid residues, was cloned into Escherichia coli cells to produce the protein of 100 kDa. The recombinant protein hydrolyzed 8-oxo-dGTP, in addition to dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP), as did Arabidopsis AtNUDX1; whereas the amino acid sequence of OsNUDX2 had 18% identity with AtNUDX1. OsNUDX2 had 14% identity with barley HvNUDX12, which hydrolyzes 8-oxo-dGTP and diadenosine tetraphosphates. Suppression of the lacZ amber mutation caused by the incorporation of 8-oxo-GTP into mRNA was prevented to a significant degree when the OsNUDX2 gene was expressed in mutT-deficient E. coli cells. These results suggest that the different substrate specificity and identity among plant 8-oxo-dGTP-hydrolyzing NUDXs and OsNUDX2 reduces UV stress by sanitizing the oxidized nucleotides. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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13 pages, 4844 KiB  
Article
Molecular Regulation of Antioxidant Melatonin Biosynthesis by Brassinosteroid Acting as an Endogenous Elicitor of Melatonin Induction in Rice Seedlings
by Ok Jin Hwang and Kyoungwhan Back
Antioxidants 2022, 11(5), 918; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11050918 - 06 May 2022
Cited by 6 | Viewed by 1514
Abstract
Gibberellic acid (GA) was recently shown to induce melatonin synthesis in rice. Here, we examined whether brassinosteroids (BRs) also induce melatonin synthesis because BRs and GA show redundancy in many functions. Among several plant hormones, exogenous BR treatment induced melatonin synthesis by twofold [...] Read more.
Gibberellic acid (GA) was recently shown to induce melatonin synthesis in rice. Here, we examined whether brassinosteroids (BRs) also induce melatonin synthesis because BRs and GA show redundancy in many functions. Among several plant hormones, exogenous BR treatment induced melatonin synthesis by twofold compared to control treatment, whereas ethylene, 6-benzylaminopurine (BA), and indole-3-acetic acid (IAA) showed negligible effects on melatonin synthesis. Correspondingly, BR treatment also induced a number of melatonin biosynthetic genes in conjunction with the suppression of melatonin catabolic gene expression. Several transgenic rice plants with downregulated BR biosynthesis-related genes, such as DWARF4, DWARF11, and RAV-Like1 (RAVL1), were generated and exhibited decreased melatonin synthesis, indicating that BRs act as endogenous elicitors of melatonin synthesis. Notably, treatment with either GA or BR fully restored melatonin synthesis in the presence of paclobutrazol, a GA biosynthesis inhibitor. Moreover, exogenous BR treatment partially restored melatonin synthesis in both RAVL1 and RNAi transgenic rice plants, whereas GA treatment fully restored melatonin synthesis comparable to wild type in RAVL1 RNAi plants. Taken together, our results highlight a role of BR as an endogenous elicitor of melatonin synthesis in a GA-independent manner in rice plants. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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15 pages, 1586 KiB  
Article
Identification and Characterization of Two Bibenzyl Glycosyltransferases from the Liverwort Marchantia polymorpha
by Rui-Lin Xiong, Jiao-Zhen Zhang, Xin-Yan Liu, Jian-Qun Deng, Ting-Ting Zhu, Rong Ni, Hui Tan, Ju-Zheng Sheng, Hong-Xiang Lou and Ai-Xia Cheng
Antioxidants 2022, 11(4), 735; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11040735 - 08 Apr 2022
Cited by 4 | Viewed by 2077
Abstract
Liverworts are rich in bibenzyls and related O-glycosides, which show antioxidant activity. However, glycosyltransferases that catalyze the glycosylation of bibenzyls have not yet been characterized. Here, we identified two bibenzyl UDP-glucosyltransferases named MpUGT737B1 and MpUGT741A1 from the model liverwort Marchantia [...] Read more.
Liverworts are rich in bibenzyls and related O-glycosides, which show antioxidant activity. However, glycosyltransferases that catalyze the glycosylation of bibenzyls have not yet been characterized. Here, we identified two bibenzyl UDP-glucosyltransferases named MpUGT737B1 and MpUGT741A1 from the model liverwort Marchantia polymorpha. The in vitro enzymatic assay revealed that MpUGT741A1 specifically accepted the bibenzyl lunularin as substrate. MpUGT737B1 could accept bibenzyls, dihydrochalcone and phenylpropanoids as substrates, and could convert phloretin to phloretin-4-O-glucoside and phloridzin, which showed inhibitory activity against tyrosinase and antioxidant activity. The results of sugar donor selectivity showed that MpUGT737B1 and MpUGT741A1 could only accept UDP-glucose as a substrate. The expression levels of these MpUGTs were considerably increased after UV irradiation, which generally caused oxidative damage. This result indicates that MpUGT737B1 and MpUGT741A1 may play a role in plant stress adaption. Subcellular localization indicates that MpUGT737B1 and MpUGT741A1 were expressed in the cytoplasm and nucleus. These enzymes should provide candidate genes for the synthesis of bioactive bibenzyl O-glucosides and the improvement of plant antioxidant capacity. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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12 pages, 3594 KiB  
Article
Plant Response to Cold Stress: Cold Stress Changes Antioxidant Metabolism in Heading Type Kimchi Cabbage (Brassica rapa L. ssp. Pekinensis)
by Seung Hee Eom, Min-A Ahn, Eunhui Kim, Hee Ju Lee, Jin Hyoung Lee, Seung Hwan Wi, Sung Kyeom Kim, Heung Bin Lim and Tae Kyung Hyun
Antioxidants 2022, 11(4), 700; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11040700 - 01 Apr 2022
Cited by 24 | Viewed by 4166
Abstract
Cold stress is known as the important yield-limiting factor of heading type Kimchi cabbage (HtKc, Brassica rapa L. ssp. pekinensis), which is an economically important crop worldwide. However, the biochemical and molecular responses to cold stress in HtKc are largely unknown. In this [...] Read more.
Cold stress is known as the important yield-limiting factor of heading type Kimchi cabbage (HtKc, Brassica rapa L. ssp. pekinensis), which is an economically important crop worldwide. However, the biochemical and molecular responses to cold stress in HtKc are largely unknown. In this study, we conducted transcriptome analyses on HtKc grown under normal versus cold conditions to investigate the molecular mechanism underlying HtKc responses to cold stress. A total of 2131 genes (936 up-regulated and 1195 down-regulated) were identified as differentially expressed genes and were significantly annotated in the category of “response to stimulus”. In addition, cold stress caused the accumulation of polyphenolic compounds, including p-coumaric, ferulic, and sinapic acids, in HtKc by inducing the phenylpropanoid pathway. The results of the chemical-based antioxidant assay indicated that the cold-induced polyphenolic compounds improved the free-radical scavenging activity and antioxidant capacity, suggesting that the phenylpropanoid pathway induced by cold stress contributes to resistance to cold-induced reactive oxygen species in HtKc. Taken together, our results will serve as an important base to improve the cold tolerance in plants via enhancing the antioxidant machinery. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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17 pages, 2386 KiB  
Article
Culture Conditions Affect Antioxidant Production, Metabolism and Related Biomarkers of the Microalgae Phaeodactylum tricornutum
by Eleonora Curcuraci, Simona Manuguerra, Concetta Maria Messina, Rosaria Arena, Giuseppe Renda, Theodora Ioannou, Vito Amato, Claire Hellio, Francisco J. Barba and Andrea Santulli
Antioxidants 2022, 11(2), 411; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11020411 - 17 Feb 2022
Cited by 10 | Viewed by 2435
Abstract
Phaeodactylum tricornutum (Bacillariophyta) is a worldwide-distributed diatom with the ability to adapt and survive in different environmental habitats and nutrient-limited conditions. In this research, we investigated the growth performance, the total lipids productivity, the major categories of fatty acids, and the antioxidant content [...] Read more.
Phaeodactylum tricornutum (Bacillariophyta) is a worldwide-distributed diatom with the ability to adapt and survive in different environmental habitats and nutrient-limited conditions. In this research, we investigated the growth performance, the total lipids productivity, the major categories of fatty acids, and the antioxidant content in P. tricornutum subjected for 15 days to nitrogen deprivation (N−) compared to standard culture conditions (N+). Furthermore, genes and pathways related to lipid biosynthesis (i.e., glucose-6-phosphate dehydrogenase, acetyl-coenzyme A carboxylase, citrate synthase, and isocitrate dehydrogenase) and photosynthetic activity (i.e., ribulose-1,5-bisphospate carboxylase/oxygenase and fucoxanthin-chlorophyll a/c binding protein B) were investigated through molecular approaches. P. tricornutum grown under starvation condition (N−) increased lipids production (42.5 ± 0.19 g/100 g) and decreased secondary metabolites productivity (phenolic content: 3.071 ± 0.17 mg GAE g−1; carotenoids: 0.35 ± 0.01 mg g−1) when compared to standard culture conditions (N+). Moreover, N deprivation led to an increase in the expression of genes involved in fatty acid biosynthesis and a decrease in genes related to photosynthesis. These results could be used as indicators of nitrogen limitation for environmental or industrial monitoring of P. tricornutum. Full article
(This article belongs to the Special Issue Antioxidant Metabolism in Plants and Algae)
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