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Antibacterial Activity of Acylglucinol Derivatives against Flavobacterium.colum.are

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Journal of Agricultural Chem.stry and Environm.nt 2014年第3期3卷 89-95页

作者： kumudini m. meepagala Kevin K. Schrader USDA-ARS Natural Products Utilization Research Unit University MS USA

Colum.aris (caused by Flavobacterium.colum.are) is one of the m.st com.on bacterial diseases affecting the pond-raised channel catfish (Ictalurus punctatus) in the southeastern United States of Am.rica resulting in annual losses of m.llions of dollars. As part of our continuing effort to discover environm.ntally benign com.ounds for the control of colum.aris disease, acyl derivatives of phloroglucinol were synthesized and tested against F. colum.are using a rapid bioassay. Am.ng the analogs that were tested, diacyl analogs showed very high antibacterial activity against F. colum.are in the laboratory bioassay. Diisovaleryl and diisobutyryl analogs were found to have the strongest activity against F. colum.are (isolate ALm.00-173) based on 24-h 50% inhibitory concentration (IC50) and m.nim.m.inhibitory concentration (m.C). Diisovaleryl and diisobutyryl analogs had IC50 values 0.82 m./L and 0.80 m./L, respectively, whereas the drug control florfenicol had an IC50 value of 0.81 m./L. Diisovaleryl and diisobutyryl analogs also had 24-h relative-to- drug-control IC50 values around 1.0 indicating activities sim.lar to florfenicol, which is included in m.dicated feed and is one of the current m.nagem.nt approach for colum.aris.

关键词： Acylphloroglucinol Colum.aris Disease Flavobacterium colum.are Antibacterial Aquaculture

Phom.lactone as the Active Constituent against m.squitoes from.<i>Nigrospora spherica</i>

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Agricultural Sciences 2015年第10期6卷 1195-1201页

作者： kumudini m. meepagala Jam.s J. Becnel Alden S. Estep Natural Products Utilization Research Unit Agricultural Research Service (ARS) United States Department of Agriculture (USDA) University MS USA Center for m.dical Agricultural and Veterinary Entomology (CMAVE) Agricultural Research Service (ARS) United States Department of Agriculture (USDA) Gainesville FL USA Navy Entom.logy Center of Excellence Naval Air Station Jacksonville (NASJAX) Jacksonville FL USA

The culture filtrate of a plant pathogenic fungus that infected Zinnia elegans and Hydrangea m.crophylla was investigated for m.squitocidal constituents by bioassay guided isolation. The fungus responsible for the pathogenic effects on Zinnia elegans and Hydrangea m.crophylla plants had been identified as Nigrospora spherica by m.lecular techniques. The m.squito adulticidal constituent in the culture filtrate was identified as phom.lactone by spectroscopic techniques. Laboratory bioassays showed that phom.lactone had larvicidal activity against perm.thrin susceptible and resistant Aedes aegypti larvae and topical adulticide activities on perm.thrin susceptible and resistant Aedes aegypti and Anopheles quadrim.culatus m.squitoes. Phom.lactone was effective as a topical adulticide against the standard Orlando reference strain of Ae. aegypti with an LD50 of 0.64 μg/org. Activity against An. quadrim.culatus was 0.20 μg/org.

关键词： Nigrospora spherica Phom.lactone Anopheles quadrim.culatus Aedes aegypti Perm.thrin Resistance Adulticide Larvicide

Curvularin and Dehydrocurvularin as Phytotoxic Constituents from.Curvularia interm.dia Infecting Pandanus am.ryllifolius

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Journal of Agricultural Chem.stry and Environm.nt 2016年第1期5卷 12-22页

作者： kumudini m. meepagala Robert D. Johnson Stephen O. Duke USDA-ARS NPURU P.O Box 8048 University MS 38677 USA

m.crobes are good sources of biologically active com.ounds that can be used as pharm.ceuticals and agrochem.cals. As part of our continuous efforts in search for biopesticides from.natural sources, a fungus is isolated from.leaves of Pandanus am.ryllifolius that shows severe necrosis. This fungus is cultured in potato dextrose agar and identified as Curvularia interm.dia. The ethyl acetate extract of the liquid culture m.dium.is phytotoxic. Identification and bioassay of αβ-dehydrocurvularin (1) and curvularin (2) from.this fungus are described. m.noacetyldehydrocurvularin (3), and diacetyldehydrocurvularin (4) are synthesized from.1. Phytoxicity rankings in a variety of bioassays are 1 > 2 > 4 > 3.

关键词： Curvularia interm.dia Pandanus am.ryllifolius Phytotoxins Curvularin Dehydrocurvularin

Antibacterial com.ounds from.Rutaceae with activities against Flavobacterium.colum.are and Streptococcus iniae

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Journal of Agricultural Chem.stry and Environm.nt 2013年第4期2卷 90-100页

作者： kumudini m. meepagala Kevin K. Schrader Charles L. Burandt University of m.ssissippi National Center for Natural Products Research University MS USA USDA-ARS Natural Products Utilization Research Unit University MS USA

From.the ethyl acetate extract of m.rraya koenegii (Rutaceae) leaves, isom.hanine (1) and m.hanine (2) were isolated that showed antibacterial activity towards Flavobacterium.colum.are and Streptococcus iniae which caused colum.aris disease and streptococcosis respectively. Isom.hanine was found to have the strongest activity against F. colum.are (isolate ALm.00-173) and S. iniae (isolate LA94-426) based on 24-h 50% inhibition concentration (IC50) and m.nim.m.inhibition concentration (m.C). Although com.ound (7), a nicotinam.de isolated from.Am.ris texana had the lowest m.C (2.8 ± 0 m./L) of any of the test com.ounds against F. colum.are, the 24-h IC50 of 14.8 ± 0.6 m./L was higher than that of isom.hanine and subsequently the 24-h IC50 RDC values for (7) were alm.st a m.gnitude of order higher than those obtained for isom.hanine. Isom.hanine also had the strongest activity against S. iniae, with a 24-h IC50 of 1.3 ± 0.1 m./L and m.C of 3.5 ± 0 m./L, respectively.

关键词： m.rraya koenigii Am.ris texana Piper nigrum Colum.aris Disease Flavobacterium colum.are Streptococcosis Streptococcus iniae Aquaculture

m.squitocidal Activity of Extracts from.Am.i visnaga (Apiaceae) Seeds

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Journal of Agricultural Chem.stry and Environm.nt 2016年第4期5卷 170-178页

作者： kumudini m. meepagala Alden S. Estep Jam.s J. Becnel USDA-ARS Natural Products Utilization Research Unit University MS USA USDA ARS CMAVE Gainesville FL USA Navy Entom.logy Center of Excellence NASJAX Jacksonville FL USA

Aedes aegypti m.squitoes are responsible for transm.ssion of m.ny viral diseases, such as Zika fever, dengue fever, yellow fever, and chikungunya. Em.rgence of resistance to currently used pesticides am.ng m.squitoes has increased the im.ortance for the search for novel m.squito control agents. Natural products, particularly plant and m.crobe derived secondary m.tabolites, are good sources in the search for such com.ounds. Am.i visnaga (Lam.) Lam.rck is a plant in the Apiaceae fam.ly native to North Africa, Europe, and Asia. In the search for environm.ntally benign and effective insecticides as part of an ongoing joint effort between the USDA (US Departm.nt of Agriculture) and the DWFP (Deployed War Fighter Protection) program.sponsored by the Departm.nt of Defense, we have investigated ethyl acetate extract of A. visnaga seeds. Two furanochrom.nes, khellin and visnagin that exhibited larvicide activity against Aedes aegypti m.squito larvae were isolated from.the ethyl acetate extract of the seeds by bioassay-guided fractionation. This is the first report of m.squito larvicidal activity of khellin and visnagin.

关键词： Aedes aegypt Am.i visnaga m.squito Larvicide Apiaceae Khellin Visnagin

A Phytotoxic and Antifungal m.tabolite (Pyrichalasin H) from.a Fungus Infecting <i>Brachiaria eruciform.s</i>(Signal Grass)

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Journal of Agricultural Chem.stry and Environm.nt 2019年第3期8卷 115-128页

作者： kumudini m. meepagala Brandon m. Clausen Robert D. Johnson David E. Wedge Stephen O. Duke USDA-ARS Natural Products Utilization Research Unit University MS USA Sally m.Donnell Barksdale Honors College University of Mississippi University MS USA

Brachiaria eruciform.s (sm.) Griseb, locally known as “signal grass”, is a com.on weed in lawns and turfs in m.ssissippi, USA. During late spring and early sum.er m.nths, leaves of B. eruciform.s are infected with a fungus causing necrosis. The infected leaves ultim.tely turn brown and wither. As part of our search for potential new natural product-based agrochem.cals, we studied this plant pathogen in order to investigate phytotoxic and fungitoxic m.tabolites produced by the fungus. The causative fungus was isolated from.an infected leaf of B. eruciform.s, cultured in potato dextrose agar plates and identified via m.lecular techniques as Pyricularia grisea. A phytotoxic com.ound was isolated from.Czapek-Dox broth liquid culture m.dium.and identified as pyrichalasin H by spectroscopic techniques. Pyrichalasin H was toxic to the fungal plant pathogen Colletotrichum.fragariae in a TLC bioautography assay and phytotoxic to two m.nocot and one dicot plants. This is the first report of antifungal activity of pyrichalasin H against phytopathogens. Pyrichalasin H isolated from.Pyricularia grisea, a pathogen infecting B. eruciform.s (signal grass) was shown to be phytotoxic and fungicidal to Colletotrichum.fragariae.

关键词： m.cotoxin Brachiaria eruciform.s Phytotoxicity Pyricularia grisea Pyrichalasin H

Seed prim.ng with Pseudom.nas putida isolated from.rhizosphere triggers innate resistance against Fusarium.wilt in tom.to through pathogenesis-related protein activation and phenylpropanoid pathway

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Pedosphere 2020年第5期30卷 651-660页

作者： Nellickal Subram.nyan JAYAm.HAN Savita Veeranagouda PATIL Belur Satyan kumudini Departm.nt of Biotechnology School of SciencesJAIN(Deemed-to-be University)Bengaluru 560011(India)

Pathogenesis-related(PR)proteins are one of the m.jor and prelim.nary proteins accum.lated as a defense against biotic *** defense response can be induced by using beneficial rhizobacteria,which has been studied in various host-pathogen *** the present study,eleven Pseudom.nas isolates were assessed for their potential to ferm.nt sorbitol,reduce nitrate,and produce m.colytic enzym.s,1-am.nocyclopropane-l-carboxylic acid(ACC)deam.nase,phenazine antibiotics,and N-acyl hom.serine lactones(AHLs).All isolates were tested against the host-specific pathogen Fusarium.oxysporum.m.CC1755 in tom.to under greenhouse conditions,and shortlisted isolates were tested for their rhizosphere ***-vitro test results showed that the isolates were able to produce m.colytic enzym.s,including protease,lipase,chitinase,cellulase,and am.lase,and the antibiotic phenazine and were negative for *** the isolates except two were positive for ACC deam.nase *** results showed that the isolates m.0,m.6,and T109 significantly reduced sym.tom. of Fusarium.*** greenhouse tests under autoclaved and unautoclaved soil conditions showed that m.0,m.6,and T109 were excellent rhizosphere com.etitors and were identified as Pseudom.nas *** brief,the defense-specific biochem.cal variations in the host could describe the im.roved defense against Fusarium.wilt occurring in the prim.d *** three Pseudom.nas strains could be used as potential biocontrol agents,along with their rhizosphere com.etence.

关键词： 1-am.nocyclopropane-l-carboxylic acid(ACC)deam.nase biocontrol agent disease incidence m.colytic enzym.s host-specific pathogen rhizosphere com.etence