Secondary Metabolites by Chemical Screening. 30. Helmidiol, a New Macrodiolide from Alternaria alternata

Abstract

Chemical screening of Fungi imperfecti strains resulted in the detection, isolation, and structure elucidation of a new symmetric 16-membered macrodiolide, named helmidiol (1). This secondary metabolite from Alternaria alternata (strain FH-A 6965) shows anthelmintic properties.

Diversity of Antimicrobial Pyrenophorol Derivatives from an Endophytic Fungus, Phoma sp.

“…Pyrenophorol (1) was previously isolated from the fungus Byssochlamys nivea, [2] and subsequently found in Stemphylium radicinum, [3] Alternaria alternata, [4] Drechslera avenae, [5] Byssochlamys nivea, [6] and Phoma sp. [7] The relative stereo- Table 1.…”

“…Many of these diolides show strong antifungal, [2,7,22] antihelmintic, [4,6,25] or phytotoxic activity. [5,23,24] This broad spectrum of bioactivity and the unique structure of pyrenophorol (1) and its analogues have also attracted great attention from synthetic chemists.…”

An alternative stereoselective synthesis of (-)-1-tetrahydropyrenophorol

“…After the addition was complete, the mixture was stirred for 6 h and then quenched with aq. NH 4 Cl solution (30 mL) dropwise. The residue was filtered using through celite and the filtrate was extracted with EtOAc (2 × 30 mL).…”

“…After stirring at room temperature for 6 h, the reaction mixture was quenched with sat. NH 4 Cl solution (15 mL) and extracted with ethyl acetate (2 × 50 mL). The organic layers were washed with water (2 × 30 mL), brine (30 mL) and dried (Na 2 SO 4 ).…”

“…In nature, macrodiolides are found as both homodimers [1][2][3][4] , consisting of two identical units and showing C 2 symmetry, and heterodimers 5 , consisting of two different units. Many of these macrodiolides (both homo and hetero) exhibit potent biological activities, such as antibacterial, antifungal, cytotoxic, and phytotoxic activity.…”