Special Issue "Special Issue Dedicated to Late Professor Takuo Okuda, “Tannins and Related Polyphenols Revisited: Chemistry, Biochemistry and Biological Activities”"
Deadline for manuscript submissions: 30 June 2018
Prof. Dr. Tsutomu Hatano
Faculty of Pharmaceutical Sciences, Okayama University, Tsushima-naka, Okayama 700-8530, Japan
Interests: tannins; flavonoids; isolation and structure elucidation; biological activity; antibiotic
Emeritus Prof. Dr. Takashi Yoshida
Faculty of Pharmaceutical Sciences, Okayama University, Tsushima-naka, Okayama, 700-8530, Japan
Interests: tannins; flavonoids; terpenoids; isolation and structure elucidation; biological activity; chemoprevention
Molecules is pleased to announce a memorial Special Issue, dedicated to Emeritus Professor Dr. Takuo Okuda at Okayama University, Japan, on the occasion of his passing away in December 2016, for his outstanding contribution in the research field of vegetable tannins and related polyphenols.
Prof. Okuda (born in 1927) was Professor of Medicinal Plants Chemistry at the Okayama University, in Japan, from 1970 to 1993. He was one of the pioneers of the chemistry of hydrolyzable tannins and related polyphenols in traditional medicinal plants in Japan, China, and South-East Asian countries. His prolific scientific activity is documented by more than 300 papers concerning the isolation and characterization of tannins and related polyphenolics in many plant species, including their diverse pharmacological functions beneficial to human health care, particularly to antioxidants, chemoprevention of life-related diseases such as cancers, diabetes, arteriosclerosis, and heart diseases. Prof. Okuda established fruitful collaborations with many pharmacologists, biochemists, and microbiologists. Prof. Okuda received the Tannin Award in the 4th Tannin Conference in 2004 (Philadelphia, USA), Groupe Polyphenol Medal in 2014 (Nagoya), for his achievements in the field of polyphenolic natural products.
This memorial Special Issue welcomes submission of previously unpublished manuscripts (original researches or reviews) on the investigation of tannins and biologically active polyphenolic compounds isolated from plants. We plan to receive submissions from April 2017 to the end of June 2018. Manuscripts will be published on an ongoing basis after being processed.
Prof. Dr. Hideyuki Ito
Prof. Dr. Tsutomu Hatano
Emeritus Prof. Dr. Takashi Yoshida
Manuscript Submission Information
Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access monthly journal published by MDPI.
Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.
- New polyphenolic natural products
- New tannins and flavonoids
- Improved methodology of analysis
- Biological activity
- Bioavailability and metabolites
- Structure elucidation
- Organic synthesis
- Mechanism of action
The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.
Title: Composition and Structural Features of Condensed Tannins from Legumes Exhibiting Methane Abatement Activity during in vitro Rumen Digestion
Authors: Harley D. Naumann 1, Rebecka Sepela 2, Aria Rezaire 2, Laurie A. Reinhardt 3, Jamison T. Robe 3, Wayne Zeller 3, Ann E. Hagerman 2
Affiliations: 1 Division of Plant Sciences, University of Missouri, Columbia, MO, United States.
2 Department of Chemistry and Biochemistry, Miami University, Oxford, OH, United States.
3 U.S. Dairy Forage Research Center, USDA-ARS, Madison, WI, United States.
Abstract: Previous studies showed that a series of purified condensed tannins (CTs) from warm-season perennial legumes exhibited high variability in their modulation of methane production during in vitro rumen digestion. The molecular weight difference of these CTs did not provide correlation with either the in vitro methane production or the ability to precipitate bovine serum albumin. In an effort to delineate other structure-activity relationships from these methane abatement experiments, the structures of purified CTs from legumes representing Papilionoideae (Desmodium paniculatum, Lespedeza stuevei, and Lespedeza cuneata and Mimosoideae (Mimosa strigillosa, Leucaena retusa, Neptunia lutea, Desmanthus illinoensis, and Acacia angustissima var hirta) were assessed through a combination of methanolysis, quantitative thiolysis, ESI-MS, MALDI-TOF MS and high resolution 1H-13C HSQC NMR spectroscopy. The structural composition of these CTs were as follows: D. paniculatum proanthocyanidin to proanthodelphinidin (PC/PD) ratio 55/45, cis/trans ratio 87/13, mDP ~20; L. stuevei, PC/PD ratio, 42/58, cis/trans ratio 31/69 (NMR), 64/36 (thiolysis), mean degree of polymerization mDP (~10) and a trace of galloylated subunits; L. cuneata, PC/PD ratio 5/95, cis/trans ratio 75/25 (NMR), 93/7 (thiolysis), mDP ~14 and a trace of galloylated subunits; M. strigillosa PC/PD ratio 15/85, cis/trans ratio 89/11, mDP ~10 and 43% of the flavan-3-ol subunits galloylated; L. retusa PC/PD ratio 99/1, cis/trans ratio 98/2, mDP ~6 and ~25% of the flavan-3-ol subunits galloylated; N. lutea PC/PD ratio 12/88, cis/trans ratio 94/6, mDP ~12 and 32% of the flavan-3-ol subunits galloylated; and D. illinoensis PC/PD ratio 4/96, cis/trans ratio 99/1, mDP ~6 and 75% of the flavan-3-ol subunits galloylated. The CT isolated from A. angustissima presented an unusual challenge as it was resistant to standard thiolytic degradation conditions and exhibited an atypical set of cross-peak signals in the 2D NMR. Efforts to elucidate the structure of this CT will be discussed.
Title: Structural revisions in natural ellagitannins
Author: Hidetoshi Yamada
Abstract: In this manuscript, we summarized structural revision of 28 natural ellagitannins. Major focuses in the account are the outline of the initial structural determination, the processes to find the errors in the structure, and methods for revision of the structure. Ellagitannins adopted here are alnusiin, alnusnins A and B, castalagin, cercidinins A and B, chebulinic acid, chebulagic acid, corilagin, geraniin, isoterchebin, nobotanins B, C, E, G, H, I, J, and K, punicalin, punicalagin, punigluconin, roxbin B, sanguiins H-2, H-3, and H-6, terchebin, and vescalagin.
Type of paper: Article
Title: Characterization of condensed tannins from freeze-dried, silage or hay purple prairie clover (Dalea purpurea Vent.): structure composition, protein precipitation and anti-Escherichia coli properties
Authors: K. Peng1, 2, Q. Q. Huang3, Z. Xu2, T. A. McAllister2, S. Acharya2, S. Wang1, C. Drake4, I. Mueller-Harvey4, Y. Wang2
1 College of Engineering, China Agricultural University, Beijing, 100083, China
2 Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Albert, T1J 4B1, Canada
3 College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China.
4Chemistry and Biochemistry Laboratory, Food Production and Quality Division, School of Agriculture, Policy and Development, University of Reading, P.O. Box 236, 1 Earley Gate, Reading RG6 6AT, UK
Abstract: Conservation methods have been shown to affect forage nutrient composition and value, but little information is available about the effect of forage conservation on plant condensed tannins (CT). The objective of this study was to assess the effects of conservation method on the concentration, chemical composition and biological activity of CT. Whole plant purple prairie clover (PPC, Dalea purpurea Vent.) was harvested at the full-flower stage and conserved as freeze-dried forage (FD), silage (SIL) or hay (HAY). Concentration of CT in conserved PPC was determined by the butanol-HCl-acetone method. Structural composition, protein-precipitation capacity and anti-bacterial activity of CT isolated from conserved forage were determined by in situ thiolytic degradation followed by LC-MS analysis, a protein precipitation assay using bovine serum albumin (BSA) and ribulose 1,5-disphosphate carboxylase (Rubisco) as model proteins and an Escherichia coli growth test, respectively. Conservation method had no effect on concentration of total CT, but ensiling decreased (P < 0.001) extractable CT and increased (P < 0.001) fiber-bound and protein-bound CT. In contrast, hay only increased (P < 0.01) protein-bound CT. Regardless of conservation method, epigallocatechin (EGC), catechin (C) and epicatechin (EC) were the major flavan-3-ol subunits, and gallocatechin (GC) was absent from both terminal and extension units of PPC CT. The SIL CT had the lowest (P < 0.001) EGC but the highest (P <0.01) EC in the extension units. Similarly, SIL CT exhibited a lower (P < 0.001) mean degree of polymerization (mPD), but a higher (P < 0.001) procyanidin/prodelphinidin ratio (PC/PD) than FD or HAY CT. The protein-precipitating capacity of CT in conserved PPC ranked (P < 0.001) as FD > HAY > SIL. Growth of E. coli in M9 medium was inhibited by 25-100 µg/ml of CT isolated from FD, SIL and HAY (P < 0.05), but preservation method had no effect on the ability of CT to inhibit bacterial growth. The results demonstrated that ensiling decreased the extractability and protein-precipitating capacity of CT by increasing the PC/PD ratio. Purple prairie clover conserved as hay retained more biologically active CT than if it was conserved as silage.
Keywords: Purple prairie clover, forage conservation, condensed tannins, protein-precipitation capacity, antimicrobial activity
Type of paper: Review
Authors: L. Falcão and MEM Araújo
CQB and Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Portugal
Title: Vegetable tannins used in the manufacture of historic leathers
Abstract: In this review a brief description of how in Europe animal skins were transformed in leathers using different kinds of vegetable tannins will be described. Special attention will be dedicated to the description of the kind of tannin and the characteristics of the most important type of historic leathers thus obtained. The text will also focus on de description of the techniques used in the identification of these tannins in historic objects: colorimetric tests and spectroscopic analysis.