Two New Naphthalene Derivatives from the Fermentation Products of an Endophytic Fungus Phomopsis sp.

Two new naphthalene derivatives, 5-methoxy-2-methyl-7-(3-methyl-2-oxobut-3-enyl)-1-naphthaldehyde (1) and 2-(hydroxymethyl)-5-methoxy-7-(3-methyl-2-oxobut-3-enyl)-1-naphthaldehyde (2), together with two known naphthalene derivatives (3 and 4), were isolated from the fermentation products of an endophytic fungus Phomopsis sp. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1 and 2 were evaluated for their anti-methicillin-resistant Staphylococcus aureus (anti-MRSA) activity. The results showed that compounds 1 and 2 showed good inhibition with IZD of 14.5 ± 1.2 and 15.2 ± 1.3 mm, respectively.