SOME NATURAL AND SYNTHETIC COMPOUNDS INHIBITING THE BIOSYNTHESIS OF AFLATOXIN B1 AND MELANIN IN Aspergillus flavus

Dzhavakhiya, V. G.; Voinova, T. M.; Popletaeva, Sofya B.; Statsyuk, N. V.; Mikityuk, O. D.; Nazarova, T. A.; Щербакова, Л. А.

doi:10.15389/agrobiology.2016.4.533eng

Cited by 3 publications

(5 citation statements)

References 21 publications

(16 reference statements)

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“…We found that other phosphate-containing compounds inhibited melanization in a similar manner including phosphoserine, phosphoacetic acid, pyrophosphate, and phosphoric acid. This is in line with literature reports that other aminophosphonic acids inhibit fungal eumelanin in the human pathogen Aspergilius flavus [ 118 ]. Incidentally, this class of compounds is patented for use in human cosmetics and is marketed as solutions to inhibit melanogenesis in the skin [ 119 , 120 ].…”

Section: Discussionsupporting

confidence: 93%

Glyphosate inhibits melanization and increases susceptibility to infection in insects

et al. 2021

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Melanin, a black-brown pigment found throughout all kingdoms of life, has diverse biological functions including UV protection, thermoregulation, oxidant scavenging, arthropod immunity, and microbial virulence. Given melanin’s broad roles in the biosphere, particularly in insect immune defenses, it is important to understand how exposure to ubiquitous environmental contaminants affects melanization. Glyphosate—the most widely used herbicide globally—inhibits melanin production, which could have wide-ranging implications in the health of many organisms, including insects. Here, we demonstrate that glyphosate has deleterious effects on insect health in 2 evolutionary distant species, Galleria mellonella (Lepidoptera: Pyralidae) and Anopheles gambiae (Diptera: Culicidae), suggesting a broad effect in insects. Glyphosate reduced survival of G. mellonella caterpillars following infection with the fungus Cryptococcus neoformans and decreased the size of melanized nodules formed in hemolymph, which normally help eliminate infection. Glyphosate also increased the burden of the malaria-causing parasite Plasmodium falciparum in A. gambiae mosquitoes, altered uninfected mosquito survival, and perturbed the microbial composition of adult mosquito midguts. Our results show that glyphosate’s mechanism of melanin inhibition involves antioxidant synergy and disruption of the reaction oxidation–reduction balance. Overall, these findings suggest that glyphosate’s environmental accumulation could render insects more susceptible to microbial pathogens due to melanin inhibition, immune impairment, and perturbations in microbiota composition, potentially contributing to declines in insect populations.

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Section: Discussionsupporting

confidence: 93%

Glyphosate inhibits melanization and increases susceptibility to infection in insects

et al. 2021

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“…An increased AFB1 production was also observed in the case of thymol and 3-HBA. Thus, the effect of these three compounds was similar to that observed earlier for N -hydroxyputrescine and (1-aminoethyl)phosphonic acid [24]. …”

Section: Resultssupporting

confidence: 85%

“…We also revealed several such compounds in our previous studies [14,24]. This effect can be explained by the common initial biosynthetic stages of both metabolites first hypothesized by Brown and Salvo [13].…”

Section: Discussionsupporting

confidence: 80%

“…Among the planned theoretical tasks, we can mention the determination of the exact point of compactin action in the polyketide biosynthetic pathway using known intermediates and the study of the compactin effect on other mycotoxins of the polyketide origin, such as zearalenone. The authors also plan to continue the study of other statins for their potential as AFB1 inhibitors and have already obtained promising results for lovastatin [24]. Note that, according to the obtained data, compactin is able to inhibit the toxinogenesis at very low concentrations.…”

Section: Discussionmentioning

confidence: 83%

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Effect of Various Compounds Blocking the Colony Pigmentation on the Aflatoxin B1 Production by Aspergillus flavus

Dzhavakhiya

Voinova

Popletaeva

et al. 2016

Toxins

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Aflatoxins and melanins are the products of a polyketide biosynthesis. In this study, the search of potential inhibitors of the aflatoxin B1 (AFB1) biosynthesis was performed among compounds blocking the pigmentation in fungi. Four compounds—three natural (thymol, 3-hydroxybenzaldehyde, compactin) and one synthetic (fluconazole)—were examined for their ability to block the pigmentation and AFB1 production in Aspergillus flavus. All compounds inhibited the mycelium pigmentation of a fungus growing on solid medium. At the same time, thymol, fluconazole, and 3-hydroxybenzaldehyde stimulated AFB1 accumulation in culture broth of A. flavus under submerged fermentation, whereas the addition of 2.5 μg/mL of compactin resulted in a 50× reduction in AFB1 production. Moreover, compactin also suppressed the sporulation of A. flavus on solid medium. In vivo treatment of corn and wheat grain with compactin (50 μg/g of grain) reduced the level of AFB1 accumulation 14 and 15 times, respectively. Further prospects of the compactin study as potential AFB1 inhibitor are discussed.

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“…We found that other phosphate-containing compounds inhibited melanization in a similar manner including phosphoserine, phosphoacetic acid, pyrophosphate and phosphoric acid. This is in line with literature reports that other aminophosphonic acids inhibit fungal eumelanin in the human pathogen Aspergilius flavus (117). Incidentally, this class of compounds is patented for use in human cosmetics, and are marketed as solutions to inhibit melanogenesis in the skin (118,119).…”

Section: Discussionsupporting

confidence: 81%

Glyphosate Inhibits Melanization and Increases Susceptibility to Infection in Insects

Smith

Camacho

Thakur

et al. 2020

Preprint

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13Melanin is a black-brown pigment found throughout all kingdoms of life playing diverse 14 roles including: UV protection, thermoregulation, oxidant scavenging, arthropod immunity, and 15 microbial virulence. Given melanin's broad functions in the biosphere, particularly in insect 16 immune defenses, it is important to understand how environmental conditions affect 17 melanization. Glyphosate, the most widely used herbicide, inhibits melanin production. Here we 18 elucidate the mechanism underlying glyphosate's inhibition of melanization demonstrate the 19 herbicide's multifactorial effects on insects. Glyphosate acts as an antioxidant and disrupts the 20 oxidation-reduction balance of melanization. The drug reduced wax moth larvae survival after 21 infection, increased parasite burden in malaria-transmitting mosquitoes, and altered midgut 22 microbiome composition in adult mosquitoes. These findings suggest that glyphosate's 23 environmental accumulation could contribute to the so called insect apocalypse, characterized 24 by species declines, by rendering them more susceptible to microbial pathogens due to 25 melanization inhibition, immune impairment, and perturbations in microbiota composition. 26 27 29 30 2Melanin is produced through a series of oxidation and reduction reactions, which are 32 typically catalyzed by two distinct classes of enzymes: laccases (EC. 1.10.3.2) and phenol 33 oxidases, the latter is divided into tyrosinases (EC. 1.14.18.1) and catechol oxidases (EC. 34 1.10.3.1) (Whitten and Coates, 2017). Tyrosinases are copper metalloenzymes found 35 throughout nature in fungi, protists, arthropods, birds, and mammals, and are responsible for 36 two catalytic roles: 1) hydroxylation of monophenols into ortho-diphenols, followed by 2) two-37 electron oxidation of ortho-catechols into ortho-quinones (Ramsden and Riley, 2014). In melanin 38 biosynthesis, tyrosinase first converts 3,4-dihydroxyphenylalanine (L-DOPA) into dopaquinone 93 mushroom tyrosinase model, and validate GLYPH as an inhibitor of insect melanogenesis using 94 Galleria mellonella and Anopheles gambiae. We further characterize the effects of GLYPH on 95 G. mellonella susceptibility to C. neoformans infection, and A. gambiae susceptibility to 96 Plasmodium falciparum infection. Our results indicate that GLYPH can be a major immune 97 modulator of insects through its effect on melanization. 98 99 4 RESULTS 100 GLYPH Inhibits Dopaquinone Production 101To investigate how glyphosate (GLYPH) inhibited melanization, we evaluated the 102 formation of melanin intermediates in a step-wise manner using a commercially available fungal 103 tyrosinase. Although this tyrosinase differs from insect PO, the melanization reaction in these 104 systems follows the same Mason-Raper pathway (Mason, 1948;Raper, 1927). First, L-DOPA is 105 oxidized into dopaquinone (DQ) enzymatically or spontaneously (García-Borrón and Sánchez, 106 2011). Using L-DOPA with and without tyrosinase, we monitored the initial step of melanin 107 production in a controlled syste...

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SOME NATURAL AND SYNTHETIC COMPOUNDS INHIBITING THE BIOSYNTHESIS OF AFLATOXIN B1 AND MELANIN IN Aspergillus flavus

Cited by 3 publications

References 21 publications

Glyphosate inhibits melanization and increases susceptibility to infection in insects

Glyphosate inhibits melanization and increases susceptibility to infection in insects

Effect of Various Compounds Blocking the Colony Pigmentation on the Aflatoxin B1 Production by Aspergillus flavus

Glyphosate Inhibits Melanization and Increases Susceptibility to Infection in Insects

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