Onychomycosis is a common nail infection mainly caused by species belonging to the F. oxysporum, F. solani, and F. fujikuroi species complexes. The aim of this study was to evaluate the in vitro susceptibility of six representative strains of clinically relevant Fusarium spp. toward a set of natural-occurring hydroxycinnamic acids and their derivatives with the purpose to develop naturally occurring products in order to cope with emerging resistance phenomena. By introducing a prenylated chain at one of the hydroxy groups of trans-cinnamic acids 1–3, ten prenylated derivatives (coded 4–13) were preliminarily investigated in solid Fusarium minimal medium (FMM). Minimal inhibitory concentration (MIC) and lethal dose 50 (LD50) values were then determined in liquid FMM for the most active selected antifungal p-coumaric acid 3,3′-dimethyl allyl ester 13, in comparison with the conventional fungicides terbinafine (TRB) and amphotericin B (AmB), through the quantification of the fungal growth. Significant growth inhibition was observed for prenylated derivatives 4–13, evidencing ester 13 as the most active. This compound presented MIC and LD50 values (62–250 µM and 7.8–125 µM, respectively) comparable to those determined for TRB and AmB in the majority of the tested pathogenic strains. The position and size of the prenylated chain and the presence of a free phenol OH group appear crucial for the antifungal activity. This work represents the first report on the activity of prenylated cinnamic esters and ethers against clinical Fusarium spp. and opens new avenues in the development of alternative antifungal compounds based on a drug repositioning strategy.
Onychomycosis是一种常见的指甲感染,主要由属于F. oxysporum、F. solani和F. fujikuroi物种复合体的物种引起。本研究旨在评估临床相关的六株代表性Fusarium spp.菌株对一组天然存在的羟基肉桂酸及其衍生物的体外敏感性,以开发天然产物,以应对新兴的耐药现象。通过在对固体Fusarium最小培养基(FMM)中引入一种烯丙基链到反式肉桂酸1-3的羟基中的十种烯丙基衍生物(编码为4-13),对其进行了初步研究。然后,在液体FMM中确定了对最活性的选定抗真菌p-香豆酸3,3'-二甲基烯丙酯13的最小抑制浓度(MIC)和半数致死量50(LD50)值,与常规杀菌剂特比萘啶(TRB)和两性霉素B(AmB)进行比较,通过对真菌生长的定量化。对于烯丙基衍生物4-13观察到显著的生长抑制,表明酯13是最活性的。该化合物的MIC和LD50值(分别为62-250 µM和7.8-125 µM)与大多数测试的致病菌株中确定的TRB和AmB的值相当。烯丙基链的位置和大小以及自由酚羟基的存在似乎对抗真菌活性至关重要。这项工作是关于烯丙基肉桂酸酯和醚对临床Fusarium spp.的活性的首次报告,并为基于药物再定位策略开发替代抗真菌化合物开辟了新途径。