Epicoccolides: Antimicrobial and Antifungal Polyketides from an Endophytic Fungus Epicoccum sp. Associated with Theobroma cacao

Abstract

In the search for new compounds to protect plants from fungi, an endophytic fungus, Epicoccum sp. CAFTBO, obtained from Theobroma cacao was found to produce three polyoxygenated polyketides, namely epicolactone (1) and epicoccolides A (2) and B (3), together with seven known metabolites. The structures of these compounds were elucidated by a combination of detailed spectroscopic and spectrometric analyses as well as DFT calculations of the electronic circular dichroism spectra and the single‐crystal X‐ray diffraction analysis of 1. Compounds 1–3 showed potent antimicrobial activities and significant inhibitory effects on the mycelial growth of two peronosporomycete phytopathogens, Pythium ultimum and Aphanomyces cochlioides, and the basidiomycetous fungus Rhizoctonia solani.

Tricyclic and Spirobicyclic Norsesquiterpenes from the Endophytic Fungus Pseudolagarobasidium acaciicola

“…HMBC correlations from H 2 -1, H 2 -2, H 2 -9, H 3 -10, and H 3 -11 to C-3a and from H 2 -1, H 2 -2, and H 2 -4 to C-8a suggested the presence of a five-membered ring attached to a six-membered ring at C-3a (Figure 1). HMBC correlation from the exchangeable 8a-OH proton to C-8a (δc = 90.2 ppm) indicated that C-8a was an oxygenated sp 3 quaternary carbon attached to a hydroxy group. Moreover, the 13 C resonances of C-7 (δc = 86.6 ppm) and C-8 (δc = 82.5 ppm) suggested that both C-7 and C-8 were also oxygenated sp 3 quaternary carbons.…”

“…We propose the name "acaciicolane" for the norsesquiterpene skeleton of 1 (Figure 3). It should be noted that, as revealed by X-ray analysis (Figure 2), a five-membered (middle) ring is perpendicular to a six-membered ring through C-7/C-8 and C-3a/C-8a bonds, and that acaciicolin A (1) possesses three consecutive oxygenated sp 3 quaternary carbons at C-7, C-8, and C-8a.…”

Pictet–Spengler reaction-based biosynthetic machinery in fungi

“…The observation, along with their 1 Hand 13 C-NMR spectra, suggested that the latter was a methyl ester of the former. Scrutiny of the 1 H-1 H COSY, ROESY, HSQC, and HMBC spectra of 3 indicated the presence of a 4,5,6-trihydroxy-7-methylisoindolin-1-one motif (27,28), which was shown to share the nitrogen atom with the 1-MT moiety (SI Appendix, Fig. S9).…”

Antimicrobial and antitumor activity and diversity of endophytic fungi from traditional Chinese medicinal plant Cephalotaxus hainanensis Li

“…While existing in an evolutionary environment such as plant tissues, some endophytic fungi can produce the same or similar secondary metabolites as their hosts as well as other biologically active ingredients simultaneously, including new compounds (Stierle et al, 1993). Recent studies have suggested that novel natural products from endophytes displayed antibiotic effects against plant pathogens (Talontsi et al, 2013) and human tumor cell lines (Wu et al, 2013a). Therefore, they have numerous potential applications in agriculture and modern medicine, and screening for a variety of active substances from endophytic fungi has become the focus of relevant studies.…”