Kumudini Meepagala

• Research Chemist at Agricultural Research Service

Green propolis, particularly from the unique flora of the Brazilian Caatinga biome, has gained significant interest due to its diverse chemical composition and biological activities. This study focuses on the chemical characterization and antimicrobial evaluation of Caatinga green propolis. Twelve compounds were isolated through different chromatog...

Edwardsiella ictaluri and Flavobacterium covae are two bacteria species that cause diseases in farm‐raised channel catfish ( Ictalurus punctatus ) that cause heavy economic damage to the aquaculture industry, particularly to the channel catfish farming. In search for environmentally benign antibacterial compounds active against E. ictaluri and F. c...

In search of environmentally benign and mammalian-friendly mosquito-mitigating compounds, we conducted an investigation into the constituents isolated from Brazilian red, brown, and green propolis. Additionally, we synthetically modified active constituents to explore the role of lipophilicity in enhancing their larvicidal activity. Honeybees colle...

A bacterium growing on infected leaves of Hydrocotyle umbellata, commonly known as dollarweed, was isolated and identified as Pantoea ananatis. An ethyl acetate extract of tryptic soy broth (TSB) liquid culture filtrate of the bacterium was subjected to silica gel chromatography to isolate bioactive molecules. Indole was isolated as the major compo...

Natural product (NP)-based pesticides have emerged as a compelling alternative to traditional chemical fungicides, attracting substantial attention within the agrochemical industry as the world is pushing toward sustainable and environmentally friendly approaches to safeguard crops. Microbes, both bacteria and fungi, are a huge source of diverse se...

The identification of natural and environmentally friendly pesticides is a key area of interest for the agrochemical industry, with many potentially active compounds being sourced from numerous plant species. In this study, we report the bioassay-guided isolation and identification of phytotoxic and antifungal compounds from the ethyl acetate extra...

In the search for effective and environmentally friendly mosquito control agents, we have examined natural sources, such as microbes and plants, and the synthetic analogs of natural products. These plants and microbes have evolved in their ecological niches to produce defensive compounds against other competing organisms in their surroundings such...

The metabolism of papaverine, the opium benzylisoquinoline alkaloid, with Aspergillus niger NRRL 322, Beauveria bassiana NRRL 22864, Cunninghamella echinulate ATCC 18968 and Cunninghamella echinulate ATCC 1382 has resulted in O-demethylation, O-methylglucosylation and N-oxidation products. Two new metabolites (4″-O-methyl-β-D-glucopyranosyl) 4′-dem...

Bioassay-guided fractionation of the ethyl acetate extract of Amyris elemifera leaves was carried out to identify phytotoxic and antifungal constituents. A novel phytotoxic furanocoumarin 8-(3-methylbut-2-enyloxy)-marmesin acetate (1) and its deacyl analog 8-(3-methylbut-2-enyloxy)-marmesin (2) were isolated. The X-ray crystal structure determinati...

Five sesquiterpene-α-amino acid quaternary ammonium hybrids and the sesquiterpene core with no amino acid moiety linked were isolated from the n-butanol partition of the Stereum complicatum fungal culture grown on potato dextrose broth. Chemical structures were unambiguously elucidated by high resolution electrospray ionization mass spectrometry (H...

Herein, we describe the isolation and identification of four new and three known sesquiterpenes from the culture broth of the fungus Stereum complicatum. Chemical structures were elucidated based on HR-DART-MS, 1D and 2D NMR experiments. Compounds were identified as sterostrein X (1), sterostrein Y (2), hirsutenol G (3), sterpurol C (4), sterostrei...

The discovery of potent natural and ecofriendly pesticides is one of the focuses of the agrochemical industry, and plant species are a source of many potentially active compounds. We describe the bioassay-guided isolation of antifungal and phytotoxic compounds from the ethyl acetate extract of Ambrosia salsola twigs and leaves. With this methodolog...

Bacterial diseases cause major financial damage to the producers of channel catfish (Ictalurus punctatus) in the southeastern US. The two most common bacterial diseases among pond raised channel catfish are enteric septicemia (ESC), caused by the gram negative bacterium Edwardsiella ictaluri, and columnaris disease, caused by the rod‐shaped gram‐ne...

The culture filtrate of a plant pathogenic fungus that infects English ivy (Hedera helix L., Araliaceae) was investigated for mosquitocidal constituents by bioassay-guided isolation. The fungus responsible for pathogenic effects on the plant H. helix has been identified as Diaporthe eres Nitschke by molecular techniques. The mosquito adulticidal co...

Background: The fungus Diaporthe eres was isolated from a fungal pathogen-infected leaf of Hedera helix (English Ivy) exhibiting necrosis. It is hypothesized that the causative fungus produces phytotoxins as evidenced by necrotic lesions on the leaves. Results: The fungus was isolated and grown in Czapek Dox broth culture medium and potato dextr...

Plants constitute a source of novel phytotoxic compounds to be explored in searching for effective and environmentally safe herbicides. From a previous screening of plant extracts for their phytotoxicity, a dichloromethane extract of Ammi visnaga (L.) Lam. was selected for further study. Phytotoxicity-guided fractionation of this extract yielded tw...

Mosquitoes play a major role as vectors that transmit parasitic and viral diseases worldwide, especially in tropical and subtropical countries. Mosquito borne diseases not only affect humans, but they also affect livestock in many parts of the world. They carry diseases that are lethal to dogs and horses, such as dog heartworm (Dirofilaria immitis)...

Microbes are good sources of biologically active compounds that can be used as pharmaceuticals and agrochemicals. As part of our continuous efforts in search for biopesticides from natural sources, a fungus is isolated from leaves of Pandanus amaryllifolius that shows severe necrosis. This fungus is cultured in potato dextrose agar and identified a...

Aedes aegypti mosquitoes are responsible for transmission of many viral diseases, such as Zika fever, dengue fever, yellow fever, and chikungunya. Emergence of resistance to currently used pesticides among mosquitoes has increased the importance for the search for novel mosquito control agents. Natural products, particularly plant and microbe deriv...

Zinnia elegans Jacq. plants are infected by a fungus that causes dark red spots with necrosis on leaves, particularly in late spring to the middle of summer in the Mid-South of the United States. This fungal disease causes the leaves to wilt and eventually kills the plant. The fungus was isolated, cultured in potato dextrose broth, and identified a...

Microbes are good sources of biologically active compounds that can be used as pharmaceuticals and agrochemicals. As part of our continuous efforts in search for biopesticides from natural sources, a fungus is isolated from leaves of Pandanus amaryllifolius that shows severe necrosis. This fungus is cultured in potato dextrose agar and identified a...

The culture filtrate of a plant pathogenic fungus that infected Zinnia elegans and Hydrangea macrophylla was investigated for mosquitocidal constituents by bioassay guided isolation. The fungus responsible for the pathogenic effects on Zinnia elegans and Hydrangea macrophylla plants had been identified as Nigrospora spherica by molecular techniques...

As with pharmaceuticals, a significant proportion of commercial pesticides are natural molecules or are derived from natural compounds. This review describes some of the past commercial successes of phytochemicals as pesticides by pesticide class as well as current work and future prospects for development of pesticides from plant-derived natural c...

Aedes aegypti (L.) is a primary vector that transmits pathogens that cause yellow and dengue fevers. Better products are needed to prevent bites from these insects and therefore reduce the risk of disease transmission to humans and other animals. Mosquito repellents play a major role in reducing bites and therefore mitigating transmission of mosqui...

Among the termite infestations in the United States, the Formosan subterranean termite, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), is considered to be the most devastating termite pest. This pest most likely invaded North America as a result of the disembarkation of wooden military cargo at the port of New Orleans that arrived from...

A chromene amide, N-[2-(2,2-dimethyl-2H-1-benzopyran-6-yl)ethyl]-N,3-dimethylbutanamide, was isolated from the EtOAc extract of the leaves of Amyris texana and found to have moderate antifungal activity against Colletotrichum spp. and selective algicidal activity against Planktothrix perornata, a cyanobacterium (blue-green alga) that causes musty o...

Natural toxins are a source of new chemical classes of pesticides, as well as environmentally and toxicologically safer molecules than many of the currently used pesticides. Furthermore, they often have molecular target sites that are not exploited by currently marketed pesticides. There are highly successful products based on natural compounds in...

Mosquito-borne pathogens are among the most important sources of human disease that cause morbidity and mortality worldwide. They include the viruses responsible for deadly outbreaks of yellow fever, Rift Valley fever, eastern equine encephalitis, Japanese encephalitis and dengue, and an assortment of other serious illnesses caused by the etiologic...

Earthworm casts are a worldwide problem on golf courses and sports fields when they disrupt the playability, aesthetics and maintenance of closely mowed playing surfaces. Currently, no pesticides are labeled for earthworms in the United States. Tea seed pellets (TSPs), a saponin-rich byproduct of Camellia oleifera Abel oil manufacture, were tested...

Oscillatoria perornata, a cyanobacterium (blue-green alga), common in catfish production ponds in the southeastern United States, produces the monoterpene 2-methylisoborneol (MIB), which is absorbed into catfish flesh and imparts a "musty" taste, rendering them unpalatable and unmarketable. Algicides that are currently in the commercial market to c...

Proving allelopathic chemical interference is a daunting endeavor, in that production and movement of a phytotoxin from a donor plant to a receiving plant must be demonstrated in the substrate in which the plants grow, which is usually a complex soil matrix. The soil levels or soil flux levels of the compound generated by the donor must be proven t...

The novel weapons hypothesis states that some invasive weed species owe part of their success as invaders to allelopathy mediated by allelochemicals that are new to the native species. Presumably, no resistance has evolved among the native species to this new allelochemical (i.e., the novel weapon). In their native habitat, however, the plants that...

Aedes aegypti (L.) (Diptera: Culicidae) is the primary vector of both dengue and yellow fever. Use of insecticides is one of the primary ways to control this medically important insect pest. However, few new insecticides have been developed for mosquito control in recent years. As a part of our collaborative effort to search for new insecticides to...

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is among the most devastating termite pests. Natural products derived from plant extracts were tested in a discovery programme for effective, environmentally friendly termite control agents. Among the natural products tested, vulgarone B (isolated from Artemisia douglasiana Besser),...

Bioassay-guided fractionation of the ethyl acetate extract of Ruta graveolens roots yielded rutacridone epoxide with potent selective algicidal activity towards the 2-methyl-isoborneol (MIB)-producing blue-green alga Oscillatoria perornata, with relatively little effect on the green alga Selenastrum capricornutum. The diol-analog of rutacridone epo...

Golden apple snail (GAS), Pomacea canaliculata (Lamarck) is a pest in rice fields in Southeast Asia. Vulgarone B, a sesquiterpene from Artemisia douglasiana Besser, has been shown to have molluscicidal activity against ram's horn snail ( Planorbella trivolvis ), and, in this study, it was tested against GAS. Laboratory bioassays indicated that vulg...

The seeds of two Apiaceae species, Ligusticum hultenii and Lomatium californicum, were investigated. Preliminary bioassays indicated that methylene chloride extracts of seeds of both species contained selective phytotoxic activity against monocots and antifungal activity against Colletotrichum fragariae. Active constituents were isolated by bioassa...

Researchers of the Agricultural Research Service (ARS) of the USDA extracted three compounds from wild celery and two weed species that can potentially kill Captotermes formosanus termites. Apiol was isolated from the wild celery Ligusticum hultenii, cnicin from spotted knapweed (Centaurea maculosa), and vulgarone B from variant of mugwort Artemisi...

Bioassay-guided fractionation of the ethyl acetate extract of Ruta graveolens (common rue) leaves led to the isolation of the furanocoumarins 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP), and the quinolone alkaloid graveoline as phytotoxic constituents. Graveoline and 8-MOP substantially inhibited growth of Lactuca sativa (lettuce) seedling...

The ram's horn snail (Planorbella trivolvis (Say)) is an intermediate host for a digenetic trematode (Bolbophorus confusus (Krause) Dubois) that has recently been discovered to be a significant problem in commercial channel catfish (Ictalurus punctatus Raf) production ponds in the Mississippi Delta region in the USA. In these catfish ponds, the dig...

Plants are proven sources of useful anti-tumor and chemopreventative compounds. Hence, identification of phytochemicals useful in dietary prevention and intervention of cancer is of paramount importance. The initial step in the formation of cancer is damage to the genome of a somatic cell producing a mutation in an oncogene or a tumor-suppressor ge...

Antifungal activity of the steam distilled essential oil fraction of Artemisia douglasiana was detected by bioautography on silica gel TLC plates against three Colletotrichum spp. The active principle was isolated by bioassay-directed fractionation using column chromatography followed by crystallization and was characterized as vulgarone B by 1H an...

Bioassay-directed isolation of antifungal compounds from an ethyl acetate extract of Ruta graveolens leaves yielded two furanocoumarins, one quinoline alkaloid, and four quinolone alkaloids, including a novel compound, 1-methyl-2-[6'-(3' ',4' '-methylenedioxyphenyl)hexyl]-4-quinolone. The (1)H and (13)C NMR assignments of the new compound are repor...

The isolation and structure elucidation of antifungal constituents of the steam-distilled essential oil fraction of Artemisia dracunculus are described. Antifungal activities of 5-phenyl-1,3-pentadiyne and capillarin against Colletrotichum fragariae, Colletrotichum gloeosporioides, and Colletrotichum acutatum are reported for the first time. The re...

The steam‐distilled fraction of the aerial parts of Erigeron speciosus (Lindl) DC was tested for activity against strawberry plant pathogenic fungi Botrytis cinerea Pers ex Fr, Colletotrichum acutatum Simmonds, C fragariae Brooks, C gloeosporioides (Penz) Penz & Sacc, and the intermediate host snail Planobdella trivolvis that harbors the trematode,...

Freeze-dried fruits of two strawberry cultivars, Sweet Charlie and Carlsbad, and two blueberry cultivars, Tifblue and Premier were sequentially extracted with hexane, 50% hexane/ethyl acetate, ethyl acetate, ethanol, and 70% acetone/water at ambient temperature. Each extract was tested separately for in vitro anticancer activity on cervical and bre...

Plumbagin, 3,3′-biplumbagin, 8,8′-biplumbagin, neoisoshinanolone and sitosterol were isolated from the leaves and rhizomes of Aristea ecklonii. The rhizomes also contained α-spinasterol. This is the first report of plumbagin, previously found in several dicotyledonous families, in a monocotyledon.