Secondary Metabolites from Phomopsis amygdali, an Endophytic Fungus Isolated from Hazelnut (Corylus avellana)

Endophytes are microbial entities that live within living tissues of plants. In most cases their relationship with the host plant is symbiotic and probably mutualistic. Many are capable of synthesizing bioactive compounds that have been proven useful for novel drug discovery. The early literature reports that species of Phomopsis isolated from plants produce different bioactive metabolites.

The main aim of the study was to isolate endophytes from different parts of hazelnut, to extract bioactive secondary metabolites and then to elucidate their structures. Different plant materials including the roots, branches and leaves were collected from BlackSea region of Turkey and surface sterilized with 3% sodium hypochlorite (NaOCl). The outer layers removed with a sharp, sterilized blade and cut into pieces. Small pieces of the inner tissue were placed on the surface of potato/dextrose/agar (PDA) medium and incubated at 28°C. Subsequently 7 fungal species was isolated and grown in 1 L flask containing 250ml of Malt Extract Broth medium and cultured at 150 rpm at 28°C for 21 days in a rotary shaker. Then the fermentation broths were extracted with chloroform. The chloroform extracts were screened for their cytotoxic activities by MTT method. Based on the activity results, the isolate L1, identified as Phomopsis amygdali, was selected for further studies. After large scale fermentation and purification studies, a new metabolite (L1F3) together with a known compound, named (-)pestalotin (L1F2) were obtained. The structure of the new metabolite was elucidated as (R)-4-butoxy-6-((S)-1-hydroxybutyl)-5,6-dihydro-2H-pyran-2-one by the extensive use of 1D- and 2D NMR.

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References: 1. Nithya K, Muthumary J (2011) Recent Research in Science and Technology 3(3): 44–48

2. Strobel G, Daisy B (2003) Microbiology and Molecular Biology Reviews: MMBR 67(4): 491–502