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2. Polysaccharide and ethanol extracts of Anoectochilus formosanus Hayata: Antioxidant, wound-healing, antibacterial, and cytotoxic activities

Author

Thi-Phuong Nguyen, Han N. Phan, Thang Duc Do, Giap Dang Do, Long Hoang Ngo, Hoang Dang Khoa Do, and Khoa Thi Nguyen

Subjects
Anoectochilus formosanus, Antibacterial, Antioxidant, Cytotoxic, Wound-healing, Science (General), Q1-390, Social sciences (General), H1-99
Abstract

Introduction: Polysaccharide and alcohol extracts of Anoectochilus formosanus Hayata have attracted great attention as they exhibit noteworthy properties such as prebiotic and anti-hyperglycemic effects. However, the antioxidant and wound-healing activities of the polysaccharide extract as well as the antibacterial and cytotoxic effects of the ethanol extracts have not been thoroughly uncovered. Therefore, our study investigated these bioactivities of the two extracts prepared from Anoectochilus formosanus to broaden understandings of medical benefits of the plant. Methods: The monosaccharide composition was analyzed by HPAEC-PAD. The antioxidant and wound-healing activities of the polysaccharide extract were evaluated by ABTS and scratch assays, respectively. The broth dilution method was used to determine the antibacterial ability of the ethanol extract. Additionally, the cytotoxic and mechanistic effects of this extract against hepatocellular carcinoma HUH-7 cells was assessed by MTT assay, qRT-PCR and Western blotting methods. Results: The polysaccharide extract possessed an effective free radical scavenging ability in an ABTS assay (IC50 = 44.92 μg/ml). The extract also ameliorated wound recovery in a fibroblast scratch assay. Meanwhile, the ethanol extract was able to inhibit the growth of Staphylococcus aureus (MIC = 2500 μg/ml), Bacillus cereus (MIC = 2500 μg/ml), Escherichia coli (MIC = 2500 μg/ml), and Pseudomonas aeruginosa (MIC = 1250 μg/ml). Additionally, it repressed the viability of HUH-7 cells (IC50 = 53.44 μg/ml), possibly through upregulating the expression of caspase 3 (CASP3), CASP8, and CASP9 at both mRNA and protein levels. Conclusion: The polysaccharide extract of A. formosanus exhibited the antioxidant and wound-healing properties whereas the ethanol extract showed the antibacterial activity and cytotoxicity against HUH-7 cells. These findings specify notable biological effects of the two extracts which could be of potential use in human healthcare.

Published
2023
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3. Self-sacrificial tyrosine cleavage by an Fe:Mn oxygenase for the biosynthesis of

Author

Olivia M, Manley, Han N, Phan, Allison K, Stewart, Dontae A, Mosley, Shan, Xue, Lide, Cha, Hongxia, Bai, Veda C, Lightfoot, Pierson A, Rucker, Leonard, Collins, Taufika Islam, Williams, Wei-Chen, Chang, Yisong, Guo, and Thomas M, Makris

Subjects
Oxygen, Manganese, Folic Acid, Bacterial Proteins, Iron, Oxygenases, para-Aminobenzoates, Tyrosine, Chlamydia trachomatis
Abstract

Chlamydia protein associating with death domains (CADD) is involved in the biosynthesis of

Published
2023

4. Distal Hydrophobic Loop Modulates the Copper Active Site and Reaction of AA13 Polysaccharide Monooxygenases

Author

Son Tung Ngo, Han N. Phan, Cuong X. Luu, Chinh N. Le, Giap T. Ho, Nhung T. C. Ngo, Loan Q. Le, Binh Khanh Mai, Huong T. T. Phung, Hoang-Dung Nguyen, Khanh B. Vu, and Van V. Vu

Subjects
Oxygen, Polysaccharides, Superoxides, Catalytic Domain, Materials Chemistry, Starch, Physical and Theoretical Chemistry, Ligands, Copper, Surfaces, Coatings and Films, Mixed Function Oxygenases
Abstract

Polysaccharide monooxygenases (PMOs) use a type-2 copper center to activate O

Published
2022

5. Self-sacrificial tyrosine cleavage by an Fe:Mn oxygenase for the biosynthesis of para -aminobenzoate in Chlamydia trachomatis

Author

Olivia M. Manley, Han N. Phan, Allison K. Stewart, Dontae A. Mosley, Shan Xue, Lide Cha, Hongxia Bai, Veda C. Lightfoot, Pierson A. Rucker, Leonard Collins, Taufika Islam Williams, Wei-Chen Chang, Yisong Guo, and Thomas M. Makris

Subjects
Multidisciplinary
Abstract

Chlamydia protein associating with death domains (CADD) is involved in the biosynthesis of para -aminobenzoate (pABA), an essential component of the folate cofactor that is required for the survival and proliferation of the human pathogen Chlamydia trachomatis . The pathway used by Chlamydiae for pABA synthesis differs from the canonical multi-enzyme pathway used by most bacteria that relies on chorismate as a metabolic precursor. Rather, recent work showed pABA formation by CADD derives from l -tyrosine. As a member of the emerging superfamily of heme oxygenase–like diiron oxidases (HDOs), CADD was proposed to use a diiron cofactor for catalysis. However, we report maximal pABA formation by CADD occurs upon the addition of both iron and manganese, which implicates a heterobimetallic Fe:Mn cluster is the catalytically active form. Isotopic labeling experiments and proteomics studies show that CADD generates pABA from a protein-derived tyrosine (Tyr27), a residue that is ∼14 Å from the dimetal site. We propose that this self-sacrificial reaction occurs through O 2 activation by a probable Fe:Mn cluster through a radical relay mechanism that connects to the “substrate” Tyr, followed by amination and direct oxygen insertion. These results provide the molecular basis for pABA formation in C. trachomatis , which will inform the design of novel therapeutics.

Published
2022
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6. Fine Tuning of the Copper Active Site in Polysaccharide Monooxygenases

Author

Son Tung Ngo, Van V. Vu, Han N. Phan, Nguyen Thanh Tung, Nhung C. T. Ngo, Chinh N. Le, Cuong X. Luu, and Khanh B. Vu

Subjects
chemistry.chemical_classification, biology, Stereochemistry, Electron Spin Resonance Spectroscopy, Active site, chemistry.chemical_element, SUPERFAMILY, Monooxygenase, Polysaccharide, Copper, Surfaces, Coatings and Films, Mixed Function Oxygenases, chemistry, Polysaccharides, Cleave, Catalytic Domain, Materials Chemistry, biology.protein, Humans, Physical and Theoretical Chemistry
Abstract

Type 2 copper active sites, one of the several important copper active sites in biology, were recently found in the novel superfamily of polysaccharide monooxygenases (PMOs) that cleave recalcitrant polysaccharides via an unprecedented oxidative mechanism. The copper center in PMOs is ligated by the bidentate N-terminal histidine residue and another conserved histidine residue, forming a unique T-shaped core termed as

Published
2020

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