Terretonins P–Y, Meroterpenoids with Distinct 6/6/6/6 and 6/6/6/5 Ring Systems from the Soil-Derived Fungus Aspergillus sp. (Strain TJ403–126)

Ten new 3,5-dimethylorsellinic acid-derived meroterpenoids featuring 6/6/6/6 or 6/6/6/5 ring systems, designated terretonins P-Y (1-10), together with one known analogue, lichtheiterpene A (11), were isolated from the soil-derived fungus Aspergillus sp. (strain TJ403-126). Planar structures incorporating absolute configurations were elucidated via a combination of HRESIMS, NMR spectroscopy, single-crystal X-ray diffraction analyses (Cu Kα), and electronic circular dichroism data analyses. Compounds 1-4 and 6-9 were evaluated for the herbicidal and antibacterial activities. The results revealed that compound 9 exhibited herbicidal activity against Medicago sativa (alfalfa), whereas compound 4 showed only weak inhibition. Compounds 4 and 6 demonstrated weak antibacterial effects against Escherichia coli, with inhibition zone diameters of 24.3 ± 0.3 mm and 25.4 ± 0.1 mm, respectively.