Botanical Control of Citrus Green Mold and Peach Brown Rot on Fruits Assays Using a Persicaria acuminata Phytochemically Characterized Extract.

Persicaria acuminata (Polygonaceae) is a perennial herb that grows in the central area of Argentina and it is commonly used by native populations to heal infected wounds and other conditions related to fungal infections. In this article, we explored the in vitro antifungal activity of its ethyl acetate extract against a panel of three fruit phytopathogenic fungi including: Penicillium digitatum, P. italicum, and Monilinia fructicola. The sesquiterpenes isolated from the extract were also evaluated against these strains, demonstrating that the dialdehyde polygodial was the responsible for this activity. In order to encourage the use of the extract rather than the pure compound, we displayed ex vivo assays using fresh oranges and peaches inoculated with P. digitatum and M. fructicola, respectively, and subsequently treated by immersion with an extract solution of 250 and 62.5 µg/mL, respectively. There were no statistically significant differences between the treatments with commercial fungicides and the extract over the control of both fruit rots. The concentration of the active compound present in the extract used on fruit experiments was determined by Gas Chromatography-Mass Spectroscopy. Finally, cytotoxicity evaluation against Huh7 cells showed that P. acuminata extract was less cytotoxic than the commercial fungicides at the assayed concentrations. After these findings we could conclude that a chemically characterized extract of P. acuminata should be further developed to treat fungal diseases in fruits from an agro-ecological model.

Synthesis and evaluation of aromatic methoxime derivatives against five postharvest phytopathogenic fungi of fruits. Main structure-activity relationships.

The antifungal activity of a library of twenty-four aromatic methoximes was examined against five representative postharvest phytopathogenic fungi. The panel included Penicillium digitatum, Penicillium italicum, Rhizopus stolonifer, Botrytis cinerea and Monilinia fructicola, all of which cause relevant economic losses worldwide as a result of affecting harvested fruits. The minimum inhibitory concentrations and minimum fungicidal concentrations of each compound were defined and the main structure-activity relationships were determined. Although other congeners were more potent, drug likeliness considerations pointed to the methoxime derived from 2,4-dihydroxypropiophenone as the compound with the most suitable profile. The morphology of the colonies of the fungal strains treated with the methoxime was examined microscopically and the compound was also tested in freshly harvested peaches and oranges, exhibiting promising control profiles in both fruits, similar to those of the commercial agents Imazalil and Carbendazim.

Zanthosimuline and Related Pyranoquinolines as Antifungal Agents for Postharvest Fruit Disease Control.

The natural product zanthosimuline and its 18 analogues were easily prepared from simple starting materials and evaluated in vitro against postharvest fruit fungal pathogens. The panel included Penicillium digitatum, Botrytis cinerea, Monilinia fructicola, and Rhizopus stolonifer; all of them causing relevant economic losses worldwide. The minimum inhibitory concentrations and minimum fungicidal concentrations of each compound were determined, and the main structure-activity relationships were established. The biological activity observed was strongly increased by maintaining the prenyl side chain of zanthosimuline in an N-demethylated derivative. In addition, the compound that is the most active in the in vitro evaluation was tested in freshly harvested peaches exhibiting a promising brown rot control profile, comparable to the commercial agent carbendazim but demonstrating less toxicity against human liver cell lines.

Evaluation of Argentinean medicinal plants and isolation of their bioactive compounds as an alternative for the control of postharvest fruits phytopathogenic fungi

Abstract One of the main problems that fruit health goes through in recent years is the difficult eradication of their fungal pathogens after harvesting. This concern to the whole world because it represents huge losses of production, fruit export restrictions and consumers distrust. One of the alternatives to solve this problem could be the exploration of plants and their active compounds, which have proven to be antifungal against human pathogens, but now applied to the treatment of fruits health. In this work, eighteen plant species that grow in Argentina were evaluated against four phytopathogenic fungi that greatly affect the postharvest stage of fruits commercially important to our country. All the species studied were at least active against one fungus of the panel, while three of them displayed high antifungal properties inhibiting the growth of selected pathogens. In addition, bio-guided fractionation of these most active extracts, led to the isolation of some compounds which proved to be responsible for their antifungal activity. Although they are known compounds and were previously isolated from other natural sources, this is the first time that they are evaluated for their phytopathogenic activities against this panel of fungi.

Activity of the pterophyllins 2 and 4 against postharvest fruit pathogenic fungi. Comparison with a synthetic analog and related intermediates.

The antifungal activity of pterophyllin 2, pterophyllin 4, a 5-desmethyl analog of the latter and some of their synthetic intermediates, against three postharvest phytopathogenic fungi, was evaluated. The target fungi were Rhizopus stolonifer, Botrytis cinerea and Monilinia fructicola, which affect fruits worldwide, causing important economic losses. The tests were carried out with imazalil and carbendazim as positive controls. Minimum inhibitory concentrations and minimum fungicidal concentrations were determined, and the morphology of the colonies was examined microscopically. In liquid medium, it was found that pterophyllin 4 exhibited selective fungicidal activity toward M. fructicola, whereas its congener pterophyllin 2 proved to be less potent and not selective and the 5-desmethyl analog of pterophyllin 4 displayed a different activity profile. Morphological changes were observed in the colonies exposed to pterophyllin 4. The results highlighted the importance of small structural features for the antifungal behavior and also suggested that, in Nature, the pterophyllins may act as plant defenses against pathogens.

Synthesis and antifungal activity of diverse C-2 pyridinyl and pyridinylvinyl substituted quinolines.

Diverse 2-pyridinyl quinolines 6-12 and 2-pyridinilvinyl quinolines 13-17 were prepared using a straightforward synthesis based on the BiCl(3)-catalyzed multicomponent imino Diels-Alder (imino DA) reaction or a novel tandem imino DA/catalytic tetrahydroquinoline ring oxidation/Perkin condensation sequential process. All members of the series showed activities against dermatophytes and some of them possessed a broad spectrum of action. 2-(Pyridin-4-yl)quinoline 9 and 2-(2-pyridin-4-yl)vinyl)quinoline 16 showed the best MIC(80) and MIC(50) against the clinically important fungi Candida albicans and non-albicans Candida species. In turn, 6-ethyl-2-(pyridin-2-yl)quinoline 6 showed the best properties against standardized as well as clinical strains of Cryptococcus neoformans.

Synthesis of steroidal quinones and hydroquinones from bile acids by Barton radical decarboxylation and benzoquinone addition. Studies on their cytotoxic and antifungal activities.

Twelve new hydroquinones and quinones (4a-c to 7a-c) derived from free or peracetylated bile acids were prepared by a Barton decarboxylation reaction, with subsequent trapping of the resulting free radical by benzoquinone. All new compounds were completely characterized by 2D NMR techniques and screened for antifungal and cytotoxic activity. One of the new hydroquinones (7b) showed promising results against the human pancreatic ductal carcinoma cell line PANC1, with similar cytotoxic activity as the commercial chemotherapy drug doxorubicin.