Taxonomy Driven Discovery of Polyketides from .

Five new polyketides were isolated from the rare filamentous fungus IBT 16748 including calidiol A (); three phthalide derivatives califuranones A, A, and B (-); and a pair of enantiomers (-)-calitetralintriol A (-) and (+)-calitetralintriol A (+) together with four known metabolites (-). The structures of the new products were established by extensive spectroscopic analyses including HRMS and 1D and 2D NMR. The absolute configurations of two diastereomers and and the enantiomers (-) and (+) were assigned by comparing their experimental and calculated ECD data, whereas the absolute configuration of was proposed by analogy. Compound showed moderate activity against methicillin-resistant .