Abstract Common bean ( Phaseolus vulgaris ), a key component of human nutrition, is highly susceptible to infection by Colletotrichum lindemuthianum , a fungus that rapidly develops fungicide resistance. Since this phytopathogen represents a challenge to common bean crops, new fungicides are needed to control it. Thus, curcuminoids have emerged as potential antifungal candidates. In this study, we synthesised 18 monoketone curcuminoids (MKCs) and evaluated their antifungal activity against C. lindemuthianum . We also employed in silico methods to identify the C. lindemuthianum protein targeted by the most active MKC. MKCs were synthesised via aldol condensations (yield = 38%–97%). Compound 9 (curcumin A or (1 E ,4 E )-1,5-bis(4-hydroxy-3-methoxyphenyl)penta-1,4-dien-3-one) was the most active curcuminoid against C. lindemuthianum in vitro , with a minimum inhibitory concentration of 62.5 μ g/mL, which was similar to that of the commercial fungicide thiophanate-methyl (60.9 μ g/mL) under the same conditions. In experiments conducted on P. vulgaris inoculated with C. lindemuthianum , curcumin A ( 9 ) reduced anthracnose severity from 7.31 to 2.13, similar to the severity with thiophanate-methyl application (2.59). In silico analysis showed that curcumin A and protein kinase inhibitors had similar three-dimensional structures and affinities for protein kinase, suggesting that curcumin A inhibits this type of enzyme in the fungus. These results show that compound 9 is a potentially useful lead compound for developing new fungicides to control C. lindemuthianum in common bean.
Oliveira et al. (Thu,) studied this question.