Papers - Suenaga, Kiyotake

Evaluation of phytotoxic potential and identification of phytotoxic substances in Cassia alata Linn. leaves

Das K., Iwasaki A., Suenaga K., Kato-Noguchi H.

Acta Agriculturae Scandinavica Section B: Soil and Plant Science (Acta Agriculturae Scandinavica Section B: Soil and Plant Science)   2019

ISSN  09064710

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© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. Cassia alata (Caesalpiniaceae) is a large perennial shrub native to tropical America. It is an important medicinal and ornamental plant and has been reported to possess several pharmacological properties. However, phytotoxic substances from C. alata have not yet been documented in the literature. Therefore, this study seeks to evaluate the phytotoxic potential of C. alata leaves and to identify inhibitory substances for the purpose of eco-friendly weed management. The effect of aqueous methanol extracts of C. alata on the seedling growth of alfalfa, cress, lettuce, rapeseed, barnyard grass, foxtail fescue, Italian ryegrass, and timothy was examined. The level of inhibition of the extracts corresponded to concentration. Several chromatographic steps were performed to separate the extracts, and through spectroscopic analysis, two active substances were isolated and characterised as rutin and syringone. These two active substances significantly inhibited the seedling growth of cress and foxtail fescue. The range of I 50 values (required concentration for 50% growth inhibition) of rutin and syringone for the seedling growth of cress and foxtail fescue were 129.5–417.8 and 160.1–466.5 µM, respectively. These results indicate that the two identified active phytotoxic substances from C. alata may be responsible for its growth inhibitory properties.

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Isolation and Total Synthesis of Mabuniamide, a Lipopeptide from an Okeania sp. Marine Cyanobacterium

Ozaki K., Iwasaki A., Sezawa D., Fujimura H., Nozaki T., Saito-Nakano Y., Suenaga K., Teruya T.

Journal of Natural Products (Journal of Natural Products)  82 ( 10 ) 2907 - 2915 2019

ISSN  01633864

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Copyright © 2019 American Chemical Society and American Society of Pharmacognosy. The bioassay-guided fractionation of an Okeania sp. marine cyanobacterium collected in Okinawa led to the isolation of the lipopeptide mabuniamide (1). The gross structure of 1 was determined by spectroscopic analyses, and its absolute configuration was determined using Marfey's analysis of the acid hydrolysate of 1. The absolute configuration of 1 was confirmed by total synthesis. Mabuniamide (1) stimulated glucose uptake in cultured rat L6 myotubes. In addition, mabuniamide (1) and its stereoisomer (2) exhibited moderate antimalarial activity.

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Allelopathic property and an allelopathic substance in Eleocharis atropurpurea (Retz.)

Zaman F., Iwasaki A., Suenaga K., Kato-Noguchi H.

Theoretical and Experimental Plant Physiology (Theoretical and Experimental Plant Physiology)  30 ( 4 ) 347 - 355 2018.12

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© 2018, Brazilian Society of Plant Physiology. Plants, which include crops, weeds, and trees, are able to release effective allelochemicals that inhibit the growth and development of other plants. Eleocharis atropurpurea, a small, annual tufted weed, is renowned for being widely found in crop fields, yet there have been no studies on the allelopathy of E. atropurpurea (Cyperaceae). Thus, we explored the allelopathic potential and allelochemicals in E. atropurpurea and found that aqueous methanol extracts of E. atropurpurea inhibited the seedling growth of Lepidium sativum, Medicago sativa, Lolium multiflorum, and Phleum pratense. There was a significant negative correlation between the seedling growth of the test plants and extract concentration. Extracts were purified using several chromatographic steps and one growth inhibitory substance was isolated and identified by spectroscopic analysis as trans-ferulaldehyde. The active substance trans-ferulaldehyde significantly inhibited the shoot and root length of Lepidium sativum at concentrations higher than 1.0 and 3.0 mM, respectively, whereas the seedling length of Echinochloa crus-galli was inhibited by trans-ferulaldehyde at concentrations higher than 3.0 mM. The trans-ferulaldehyde I50 values for the growth of Lepidium sativum and Echinochloa crus-galli were in the range of 0.73–3.68 mM. The growth inhibitory results of this study suggest that trans-ferulaldehyde may be responsible for the inhibitory effects of E. atropurpurea and may contribute to weed allelopathy.

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Hoshinoamides A and B, Acyclic Lipopeptides from the Marine Cyanobacterium Caldora penicillata

Iwasaki A., Tadenuma T., Sumimoto S., Shiota I., Matsubara T., Saito-Nakano Y., Nozaki T., Sato T., Suenaga K.

Journal of Natural Products (Journal of Natural Products)  81 ( 11 ) 2545 - 2552 2018.11

Research paper (scientific journal), Joint Work, Accepted,  ISSN  01633864

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Copyright © 2018 American Chemical Society and American Society of Pharmacognosy. Hoshinoamides A (1) and B (2), new acyclic lipopeptides, were isolated from the marine cyanobacterium Caldora penicillata. Their structures were elucidated by spectroscopic analyses and degradation reactions. Hoshinoamides A (1) and B (2) did not exhibit any cytotoxicity against HeLa cells at 10 μM, but inhibited the in vitro growth of the malarial parasite Plasmodium falciparum (IC50 = 0.52 and 1.0 μM, respectively).

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Isolation and identification of a phytotoxic substance in kiwifruit leaves

Okada S., Iwasaki A., Kataoka I., Suenaga K., Kato-Noguchi H.

Acta Horticulturae (Acta Horticulturae)  1218   207 - 212 2018.10

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© International Society for Horticultural Science. All rights reserved. The yield of kiwifruit [Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson] often decreases after 20 years of cultivation. Replanted young kiwifruit plants cannot grow well in fields where aged trees were previously cultivated. Phytotoxicity is considered one possible reason for this problem. However, allelopathic or phytotoxic substances from kiwifruit have not been reported. This study aimed to isolate and identify potentially allelopathic active substances in kiwifruit leaves. Extracts from kiwifruit leaves inhibited the growth of cress, suggesting that kiwifruit leaf extracts may contain growth-inhibitory substances. The extracts were then purified using a silica-gel column, Sephadex LH-20 column, ODS cartridge, and HPLC. The inhibitory activity of all fractions obtained in each purification step was determined by the cress bioassay. Quercitrin was finally isolated and identified as a growth-inhibitory substance. This substance inhibited cress root growth by more than 50% of control at 3 mM. The aglycone of quercitrin, quercetin, did not significantly inhibit cress growth. Quercitrin may work as an allelopathic substance and cause the kiwifruit replant problem. Further study is in progress to investigate the influence of kiwifruit leaf extracts and these flavonoids on kiwifruit seedlings.

Croissamide, a proline-rich cyclic peptide with an N-prenylated tryptophan from a marine cyanobacterium Symploca sp.

Iwasaki K., Iwasaki A., Sumimoto S., Sano T., Hitomi Y., Ohno O., Suenaga K.

Tetrahedron Letters (Tetrahedron Letters)  59 ( 42 ) 3806 - 3809 2018.10

Research paper (scientific journal), Accepted,  ISSN  00404039

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© 2018 Elsevier Ltd Croissamide, a proline-rich cyclic peptide that contains an N-prenylated tryptophan, was isolated from a marine cyanobacterium Symploca sp. Its gross structure was determined by spectroscopic analyses, and the absolute configuration was established based on chiral HPLC analyses of acid hydrolysates.

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Unified Total Synthesis, Stereostructural Elucidation, and Biological Evaluation of Sarcophytonolides

Takamura, Hiroyoshi, Kikuchi, Takahiro, Iwamoto, Kohei, Nakao, Eiji, Harada, Naoki, Otsu, Taichi, Endo, Noriyuki, Fukuda, Yuji, Ohno, Osamu, Suenaga, Kiyotake, Guo, Yue-Wei, Kadota, Isao

Journal of Organic Chemistry 83 ( 18 ) 11028 - 11056 2018.09

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0022-3263

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Isolation of Jahanene and Jahanane, and Total Synthesis of the Jahanyne Family

Iwasaki, Arihiro, Fujimura, Haruka, Okamoto, Shinichiro, Kudo, Takafumi, Hoshina, Shizuka, Sumimoto, Shimpei, Teruya, Toshiaki, Suenaga, Kiyotake

Journal of Organic Chemistry 83 ( 17 ) 9592 - 9603 2018.09

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0022-3263

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ISOLATION AND IDENTIFICATION OF A GROWTH INHIBITORY SUBSTANCE FROM HELIOTROPIUM INDICUM L.

Chaipon, Sirinapa, Suwitchayanon, Prapaipit, Iwasaki, Arihiro, Suenaga, Kiyotake, Kato-Noguchi, Hisashi

Acta Biologica Hungarica 69 ( 3 ) 259 - 269 2018.09

Research paper (scientific journal), Accepted,  ISSN  0236-5383

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Izenamides A and B, Statine-Containing Depsipeptides, and an Analogue from a Marine Cyanobacterium

Kanamori Yuki, Iwasaki Arihiro, Sumimoto Shimpei, Matsubara Teruhiko, Sato Toshinori, Suenaga Kiyotake

Journal of Natural Products 81 ( 7 ) 1673 - 1681 2018.07

Accepted,  ISSN  0163-3864

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<p>Izenamides A, B, and C (1-3), new linear depsipeptides, were isolated from a taxonomically distinct marine cyanobacterium. Izenamides A and B contain a statine moiety [(3S,4S)-4-amino-3-hydroxy-6-methylheptanoic acid] and inhibited the activity of cathepsin D, an aspartic peptidase. Meanwhile, izenamides did not show growth-inhibitory activity against HeLa, HL60, or MCF-7 cells at up to 10 μM.</p>

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Plant growth inhibitory activity and active substances with allelopathic potential of cogongrass (Imperata cylindrica) rhizome

Suzuki Masahiko, Tominaga Tohru, Ohno Osamu, Iwasaki Arihiro, Suenaga Kiyotake, Kato-Noguchi Hisashi

Weed Biology and Management 8 ( 2 ) 92 - 98 2018.06

Accepted,  ISSN  1444-6162

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<p>Cogongrass (Imperata cylindrica [L.] Raeusch.) is a perennial rhizomatous grass that belongs to the Poaceae and is widely distributed in tropical, subtropical and temperate regions over the world. The grass is strongly invasive and is suggested to have allelopathic potential. However, limited information is available on allelopathic substances in cogongrass rhizomes. Therefore, the allelopathic potential and substances in cogongrass rhizomes were investigated. The extracts of cogongrass rhizomes inhibited the root and shoot growth of barnyard grass, ryegrass, timothy, cress, lettuce and alfalfa. After bioassay-guided separations of the extracts, four growth inhibitory substances, 5-methoxyflavone, 5,2'-dimethoxyflavone, methyl caffeate and abscisic acid, were isolated. 5-Methoxyflavone, 5,2'-dimethoxyflavone and methyl caffeate significantly inhibited the root and shoot growth of cress at concentrations of ≥0.03-0.3m mol L^-1 and their concentrations required for 50% growth inhibition were 0.079-0.24, 0.23-1.1 and 0.59-0.88m mol L^-1, respectively. The other isolated substance, abscisic acid, has been reported to have strong growth inhibitory activity. Its concentrations required for 50% growth inhibition on cress were 0.31-0.61μ mol L^-1. The present study suggests that cogongrass rhizomes might have allelopathic potential and that those four substances might contribute to that potential.</p>

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Evaluation of phytotoxic activity of leaf and stem extracts and identification of a phytotoxic substance from Caesalpinia mimosoides Lamk.

Boonmee Sutjaritpan, Iwasaki Arihiro, Suenaga Kiyotake, Kato-Noguchi Hisashi

Theoretical and Experimental Plant Physiology 30 ( 2 ) 129 - 139 2018.06

Accepted

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<p>Caesalpinia mimosoides (Fabaceae) has been used as a folk medicine and reported to have pharmacological properties. However, the phytotoxicity of C. mimosoides has not yet been studied. Therefore, the phytotoxic activity of C. mimosoides leaf and stem extracts was evaluated against the growth of dicotyledonous and monocotyledonous plants. Aqueous methanol extracts of C. mimosoides leaves and stems exhibited inhibitory effects on the growth of all the test plants. The growth of the test plants decreased with the increase of concentrations of the extracts. Comparison of the concentrations required for 50% growth inhibition (I₅₀ values) indicates that the leaf extracts had more inhibitory effects than the stem extracts. Thus, the active substances in the leaf extracts were purified using column chromatographic separations and a growth inhibitory substance was isolated and identified as methyl gallate by using spectral analysis. This study reports the first isolation of methyl gallate in C. mimosoides leaves. Methyl gallate at 10 mM completely inhibited the growth of cress shoots and inhibited its roots by 4.7% of control growth. At the same concentration, the shoots and roots of barnyard grass were inhibited by 84.2 and 1.7% of control growth, respectively. I₅₀ values of methyl gallate for the growth of cress and barnyard grass ranged from 2.3 to 2.9 and 0.3 to 30.5 mM, respectively. The results suggest that methyl gallate may be responsible for the phytotoxic effects of C. mimosoides.</p>

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Ypaoamides B and C, Linear Lipopeptides from an Okeania sp. Marine Cyanobacterium

Sueyoshi Kosuke, Yamada Miki, Yamano Aki, Ozaki Kaori, Sumimoto Shimpei, Iwasaki Arihiro, Suenaga Kiyotake, Teruya Toshiaki

Journal of Natural Products 81 ( 4 ) 1103 - 1107 2018.04

Accepted,  ISSN  0163-3864

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<p>Two new pyrrolinone-containing lipopeptides, ypaoamides B (1) and C (2), were isolated from an Okeania sp. marine cyanobacterium collected in Okinawa. Their structures were determined by spectroscopic analysis and Marfey's analysis of acid hydrolysates. Ypaoamides B (1) and C (2) stimulated glucose uptake in cultured rat L6 myotubes. In particular, ypaoamide B (1) showed potent activity and activated AMP-activated protein kinase.</p>

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Total synthesis of janadolide

Ojima Daisuke, Mine Hitomi, Iwasaki Arihiro, Suenaga Kiyotake

Tetrahedron Letters 59 ( 14 ) 1360 - 1362 2018.04

Accepted,  ISSN  0040-4039

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<p>The first total synthesis of janadolide, a new cyclic polyketide-peptide hybrid possessing a tert-butyl group, is described. The synthesis of an unsaturated hydroxycarboxylic acid was effected via the lithiation of vinyl iodide followed by addition to a Weinreb amide with a tert-butyl group and stereoselective 1,2-reduction. The cyclic structure was constructed by macrolactamization at the amide bond between the proline moiety and fatty acid moiety.</p>

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Caldorin, a new polyketide from the marine cyanobacterium Caldora penicillata

Shiota Ikuma, Iwasaki Arihiro, Sumimoto Shimpei, Tomoda Hiroshi, Suenaga Kiyotake

Tetrahedron Letters 59 ( 13 ) 1261 - 1263 2018.03

Accepted,  ISSN  0040-4039

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<p>A new polyketide with a cis-fused decalin ring scaffold, caldorin, was isolated from the marine cyanobacterium Caldora penicillata. The gross structure and relative configuration were elucidated by spectroscopic analyses. We also clarified that caldorin is a weak SOAT inhibitor and moderate osteoblast differentiation inhibitor. On the other hand, caldorin did not exhibit cytotoxicity against either HeLa or HL60 cells.</p>

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Design, synthesis and anti-malarial activities of synthetic analogs of biselyngbyolide B, a Ca²⁺ pump inhibitor from marine cyanobacteria

Sato E., Morita M., Ogawa H., Iwatsuki M., Hokari R., Ishiyama A., Ōmura S., Iwasaki A., Suenaga K.

Bioorganic and Medicinal Chemistry Letters (Bioorganic and Medicinal Chemistry Letters)  28 ( 3 ) 298 - 301 2018.02

ISSN  0960894X

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© 2017 Elsevier Ltd Biselyngbyaside, an 18-membered macrolide glycoside from marine cyanobacteria, and its derivatives are known to be sarco/endoplasmic reticulum Ca2+ ATPase (SERCA) inhibitors. Recently, a SERCA orthologue of the malaria parasite, PfATP6, has attracted attention as a malarial drug target. To provide a novel drug lead, we designed new synthetic analogs of biselyngbyolide B, the aglycone of biselyngbyaside, based on the co-crystal structure of SERCA with biselyngbyolide B, and synthesized them using the established synthetic route for biselyngbyolide B. Their biological activities against malarial parasites were evaluated.

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Design, synthesis and anti-malarial activities of synthetic analogs of biselyngbyolide B, a Ca²⁺ pump inhibitor from marine cyanobacteria

Sato Eisuke, Morita Maho, Ogawa Haruo, Iwatsuki Masato, Hokari Rei, Ishiyama Aki, Omura Satoshi, Iwasaki Arihiro, Suenaga Kiyotake

Bioorganic and Medicinal Chemistry Letters 28 ( 3 ) 298 - 301 2018.01

Accepted,  ISSN  0960-894X

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<p>Biselyngbyaside, an 18-membered macrolide glycoside from marine cyanobacteria, and its derivatives are known to be sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA) inhibitors. Recently, a SERCA orthologue of the malaria parasite, PfATP6, has attracted attention as a malarial drug target. To provide a novel drug lead, we designed new synthetic analogs of biselyngbyolide B, the aglycone of biselyngbyaside, based on the co-crystal structure of SERCA with biselyngbyolide B, and synthesized them using the established synthetic route for biselyngbyolide B. Their biological activities against malarial parasites were evaluated.</p>

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Identification of 6,7-dimethoxychromone as a potent allelochemical from jatropha podagrica

Boonmee S., Iwasaki A., Suenaga K., Kato-Noguchi H.

Natural Product Communications (Natural Product Communications)  13 ( 11 ) 1515 - 1518 2018

ISSN  1934578X

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© 2018 Natural Product Incorporation. Jatropha podagrica Hook. is cultivated as an ornamental plant and is also used in traditional medicine. The species has various pharmacological properties, but it has not yet been investigated for any potential allelopathic activity and allelopathic substances. In this study, an allelopathic active substance was isolated from an aqueous methanol extract of J. podagrica leaves through chromatography and reverse-phase HPLC. The substance was characterized as 6,7- dimethoxychromone by spectral analysis. 6,7-Dimethoxychromone significantly inhibited the shoots and roots of cress at concentrations greater than 0.3 mM. The concentrations required of 6,7-dimethoxychromone for 50% growth inhibition of cress shoots and roots were 0.95 and 0.83 mM, respectively. The inhibitory activity against the seedling growth of cress indicates that 6,7-dimethoxychromone may contribute to the allelopathic effects and may be responsible for the allelopathic activity in J. podagrica. This report is the first on the allelopathic activity of 6,7-dimethoxychromone as an allelopathic substance from J. podagrica.

Total Synthesis of Kanamienamide and Clarification of Biological Activity

Ojima Daisuke, Iwasaki Arihiro, Suenaga Kiyotake

Journal of Organic Chemistry 82 ( 23 ) 12503 - 12510 2017.12

Accepted,  ISSN  0022-3263

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<p>The total synthesis of kanamienamide, an enamide with an enol ether and an 11-membered macrolactone of marine origin, was achieved. The synthesis features the construction of an enamide adjacent to an enol ether by Buchwald amidation and an 11-membered ring by Mitsunobu lactonization. In addition, on the basis of the biological assay of synthetic 1, we clarified that kanamienamide (1) was not an apoptosis-like cell death inducer, as reported in the isolation paper, and revealed its real biological activity as a necrosis-like cell death inducer.</p>

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Total Synthesis of Kanamienamide and Clarification of Biological Activity

Ojima Daisuke, Iwasaki Arihiro, Suenaga Kiyotake

Journal of Organic Chemistry 82 ( 23 ) 12503 - 12510 2017.12

Accepted,  ISSN  0022-3263

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<p>The total synthesis of kanamienamide, an enamide with an enol ether and an 11-membered macrolactone of marine origin, was achieved. The synthesis features the construction of an enamide adjacent to an enol ether by Buchwald amidation and an 11-membered ring by Mitsunobu lactonization. In addition, on the basis of the biological assay of synthetic 1, we clarified that kanamienamide (1) was not an apoptosis-like cell death inducer, as reported in the isolation paper, and revealed its real biological activity as a necrosis-like cell death inducer.</p>

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