Paecilins Q and R: Antifungal Chromanones Produced by the Endophytic Fungus Pseudofusicoccum stromaticum CMRP4328

Abstract

Chemical investigation of the endophyte Pseudofusicoccum stromaticum CMRP4328 isolated from the medicinal plant Stryphnodendron adstringens yielded ten compounds, including two new dihydrochromones, paecilins Q (1) and R (2). The antifungal activity of the isolated metabolites was assessed against an important citrus pathogen, Phyllosticta citricarpa. Cytochalasin H (6) (78.3 %), phomoxanthone A (3) (70.2%), phomoxanthone B (4) (63.1 %) and paecilin Q (1) (50.5 %) decreased in vitro the number of pycnidia produced by P. citricarpa, which are responsible for the disease dissemination in orchards. In addition, compounds 3 and 6 inhibited the development of citrus black spot (CBS) symptoms in citrus fruits. Cytochalasin H (6) and one of the new compounds, paecilin Q (1) appear particularly promising, as they showed strong activity against this citrus pathogen, and low or no cytotoxic activity. The strain CMRP4328 of P. stromaticum and its metabolites deserve further investigation for the control of citrus black spot disease.

Biological and Medicinal Properties of Natural Chromones and Chromanones

“…As part of their screening for natural products with antifungal potential, Iantas and co-workers have isolated two new chromanones, paecilins Q ( 123 , Figure 15 ) and R ( 124 , Figure 15 ) from the endophyte fungus Pseudofusicoccum stromaticum CMRP4328 obtained from the medicinal plant Stryphnodendron adstringens . 80 The chemical structures of the new compounds were determined by HR-ESI-MS analysis and spectroscopic data, and their antifungal activity was assessed against an important citrus pathogen, Phyllosticta citricarpa , the causal agent of citrus black spot disease. At a concentration of 10 mg/mL, paecilin Q ( 123 ) had moderate antifungal activity inhibiting the mycelial growth of P. citricarpa by 48.6%.…”