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111 results on '"Xiao, Shiji"'

1. Contents and antioxidant activities of phenolic compounds in Hawk tea with different maturity levels

Author

LI Zhirong, SHAO Qiju, WU Qimei, LI Ying, LI Wenyang, FANG Cancan, XIAO Shiji, and CHEN Rongxiang

Subjects
hawk tea, phenolic compounds, lc-ms/ms, antioxidant activity, correlation analysis, Botany, QK1-989
Abstract

To study the difference in the contents of phenolics and the antioxidant activities between two kinds of Hawk tea of different maturity levels, and to evaluate their qualities, the contents of 15 phenolic compounds were determined using LC-MS/MS method. Then, the antioxidant activities of two types of tea were evaluated using DPPH radical scavenging rate, ABTS+ radical scavenging rate, and Fe3+ ferric reducing antioxidant power (FRAP). And then, the contents of 15 phenolic compounds and the antioxidant activities between two kinds of Hawk tea of different maturity levels were analyzed by analysis of variance (ANOVA). Based on the contents of 15 phenolic compounds, hierarchical cluster analysis (HCA), principal component analysis (PCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) were used to classify two kinds of Hawk tea. Finally, the contribution of different phenolic compounds in Hawk tea to antioxidation was discussed by partial least square regression analysis (PLSR). The results were as follows: (1) The contents of catechin, p-coumaric acid, isoquercitrin, hyperoside, nicotiflorin, astragalin, kaempferol, quercetin, and afzelin in tender leaf tea were significantly higher than those in old leaf tea, among which the average contents of catechin, isoquercitrin, and astragalin were higher than those in old leaf tea by 1 039.43, 169.12 and 257.35 mg·100 g-1, respectively. The results of HCA, PCA, and OPLS-DA could distinguish two kinds of Hawk tea. (2) The ANOVA showed significant differences in DPPH radical scavenging rate, ABTS+ radical scavenging rate, and FRAP between two kinds of tea, with the tender leaf tea superior to the old leaf tea. (3) The PLSR suggested that isoquercitrin, catechin, astragalin, chlorogenic acid, hyperoside, p-coumaric acid, and kaempferol were the main phenolic compounds those contributed to the antioxidant activity of Hawk tea. This study can provide a reference for Hawk tea's quality control and application promotion.

Published
2024
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12. Calcium-catalyzed dehydrative allylation of P-ylides and sequential Wittig reaction for streamlined access to versatile 1,4-dienes.

Author

Li, Xiaohong, Zhang, Dong, Wang, Yan, Xiao, Shiji, Wu, Ying, Xie, Peizhong, and Loh, Teck-Peng

Subjects
WITTIG reaction, ALLYLATION, YLIDES, ALLYL alcohol, SCISSION (Chemistry)
Abstract

A transition metal-free dehydrative allylation of stabilized P-ylides with activated allylic alcohols has been developed. This protocol utilizes a calcium catalyst to facilitate the cleavage of C–OH bonds and enables smooth dehydrative cross-coupling with P-ylides, resulting in water as the sole by-product. Remarkably, this transformation exhibits excellent tolerance towards a diverse range of allylic alcohols and P-ylides. Furthermore, the subsequent Wittig reaction affords a wide array of highly functionalized 1,4-dienes with high yields. [ABSTRACT FROM AUTHOR]

Published
2023
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35. New phomalone derivatives from the endolichenic fungus Cochliobolus kusanoi in Ny‐Alesund Arctic.

Author

Yang, Cailing, Xiao, Shiji, Yan, Song, Zhang, Maosheng, Cai, Qing, Fu, Shaobin, and Meng, Qingfeng

Subjects
*METABOLITES, *CHEMICAL derivatives, *FILAMENTOUS fungi, *COCHLIOBOLUS, *BIOSYNTHESIS, *NUCLEAR magnetic resonance, *MASS spectrometry
Abstract

Natural products from endolichenic fungi, isolated from different lichen species, have been attracting much attention because of their potential to produce metabolites with activities and/or new structures. The filamentous fungus M227‐2 isolated from lichen in Ny‐Alesund Arctic showed significant anti‐microbial activity and was identified as Cochliobolus kusanoi based on 18S rDNA. Secondary metabolites of M227‐2 were investigated in order to exploit them as lead compounds for new antibiotics. Chemical investigation on M227‐2 led to the isolation of three phomalone derivatives (products 1–3). Their structures were elucidated on the basis of their NMR and MS spectral data. Product 2 was new, whereas products 1 and 3 were isolated for the first time from the species. The biosynthetic pathway is also proposed. The filamentous fungus M227‐2 was isolated from lichen in Ny‐Alesund Arctic, which showed significant anti‐microbial activity and was identified as Cochliobolus kusanoi based on 18S rDNA. Chemical investigation on M227‐2 led to the isolation of three phomalone derivatives (product 1–3). Their structures were elucidated on the basis of their NMR and MS spectral data. [ABSTRACT FROM AUTHOR]

Published
2019
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41. New phomalone derivatives from the endolichenic fungus Cochliobolus kusanoiin Ny‐Alesund Arctic

Author

Yang, Cailing, Xiao, Shiji, Yan, Song, Zhang, Maosheng, Cai, Qing, Fu, Shaobin, and Meng, Qingfeng

Abstract

Natural products from endolichenic fungi, isolated from different lichen species, have been attracting much attention because of their potential to produce metabolites with activities and/or new structures. The filamentous fungus M227‐2 isolated from lichen in Ny‐Alesund Arctic showed significant anti‐microbial activity and was identified as Cochliobolus kusanoibased on 18S rDNA. Secondary metabolites of M227‐2 were investigated in order to exploit them as lead compounds for new antibiotics. Chemical investigation on M227‐2 led to the isolation of three phomalone derivatives (products 1–3). Their structures were elucidated on the basis of their NMR and MS spectral data. Product 2was new, whereas products 1and 3were isolated for the first time from the species. The biosynthetic pathway is also proposed. The filamentous fungus M227‐2 was isolated from lichen in Ny‐Alesund Arctic, which showed significant anti‐microbial activity and was identified as Cochliobolus kusanoibased on 18S rDNA. Chemical investigation on M227‐2 led to the isolation of three phomalone derivatives (product 1–3). Their structures were elucidated on the basis of their NMR and MS spectral data.

Published
2019
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42. Identification and bioinformatic analysis of Aux/IAAfamily based on transcriptome data of Bletilla striata

Author

Liu, Houbo, Li, Lin, Li, Chun, Huang, Ceyin, ShangGuan, Yanni, Chen, Ronghui, Xiao, Shiji, Wen, Weie, and Xu, Delin

Abstract

ABSTRACTAuxin/Indole-3-Acetic Acid (Aux/IAA) genes are involved in auxin signaling pathway and play an important role in plant growth and development. However, many studies focus on Aux/IAAgene families and much less known in Bletilla striata. In this study, a total of 27 Aux/IAAgenes (BsIAA1-27) were cloned from the transcriptome of Bletilla striata. Based on a phylogenetic analysis of the Aux/IAA protein sequences from B. striata, Arabidopsis thalianaand Dendrobium officinale, the Aux/IAAgenes of B. striata(BsIAAs) were categorized into 2 subfamilies and 9 groups. While BsIAAswere more closer to those of D. officinalecompared to A. thaliana. EST-SSR marker mining test showed that 4 markers could be stably amplified with obvious polymorphisms among 4 landraces. Our results suggested that BsIAAswere involved in the process of tuber development and provided insights into functional roles of Aux/IAAgenes in B. striataand other plants.

Published
2019
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43. Biocatalytic Synthesis of a Novel Corosolic Acid Derivative

Author

Xin Qing, Fu Shaobin, Xiao Shiji, and Meng Qingfeng

Subjects
Thesaurus (information retrieval), chemistry.chemical_compound, chemistry, Organic Chemistry, Corosolic acid, Combinatorial chemistry, Derivative (chemistry)
Published
2016

44. A New Biphenylpropanoid from Hawk Tea

Author

Yu Rundong, Xu Delin, Xiao Shiji, and Zhang Maosheng

Subjects
Litsea coreana, biology, Traditional medicine, Chemistry, Organic Chemistry, Lauraceae, biology.organism_classification
Published
2016

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