Abstract
Chemical investigation of the EtOAc extract of the endophytic fungus Bionectria ochroleuca, isolated from the inner leaf tissues of the plant Sonneratia caseolaris (Sonneratiaceae) from Hainan island (China), yielded two new peptides, pullularins E and F (1 and 2) together with three known compounds (3–5). The structures of the new compounds were unambiguously determined on the basis of one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. The absolute configurations of amino acids were determined by HPLC analysis of acid hydrolysates using Marfey’s method. The isolated compounds exhibited pronounced to moderate cytotoxic activity against the mouse lymphoma cells (L5178Y) with EC50 values ranging between 0.1 and 6.7 µg/mL.
Highlights
Endophytic fungi are a fascinating source of new natural products which are of great potential for medicinal and agricultural applications [1,2,3,4]
During our ongoing search for new bioactive metabolites from plant-derived endophytes [9,10,11], we isolated an endophytic Bionectria ochroleuca strain from leaf tissues of the mangrove plant Sonneratia caseolaris (Sonneratiaceae), collected at Hainan Island in caseolaris (Sonneratiaceae) from Hainan island (China)
In the present study we provide a comprehensive analysis of natural products produced by Bionectria ochroleuca and report on two new peptides designated pullularins E (1) and F (2), and two known congeners pullularins A (3) and C (4) [17], in addition to the fungal epipolythiodioxopiperazine metabolite verticillin D (5) [18]
Summary
Endophytic fungi are a fascinating source of new natural products which are of great potential for medicinal and agricultural applications [1,2,3,4]. Mangrove-derived endophytes are attracting significant attention due to their potential of producing novel metabolites. Examples of those bioactive metabolites are the depsidone-type compound paeciloxocin. During our ongoing search for new bioactive metabolites from plant-derived endophytes [9,10,11], we isolated an endophytic Bionectria ochroleuca strain from leaf tissues of the mangrove plant Sonneratia caseolaris (Sonneratiaceae), collected at Hainan Island in China. In the present study we provide a comprehensive analysis of natural products produced by Bionectria ochroleuca and report on two new peptides designated pullularins E (1) and F (2), and two known congeners pullularins A (3) and C (4) [17], in addition to the fungal epipolythiodioxopiperazine metabolite verticillin D (5) [18]
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