Chemical Constituents of the Deep-Sea-Derived Penicillium limosum ZEN48 and Their Osteoclasts' Inhibitory Activity

Three previously undescribed compounds (1-3), including an unusual pyridazine derivative, one sesquiterpenoid, and a polyketide with novel stereochemistry, together with 24 known compounds (4-27), were isolated from the deep-sea-derived Penicillium limosum ZEN48. The structures of the new compounds were elucidated by comprehensive analyses of one- and two-dimensional nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, and optical rotation calculation. Compounds 13, 18, and 19 exhibited considerable inhibitory effect in osteoclast formation at 20 µM in bone marrow-derived monocytes, indicating their potential application in anti-osteoporotic therapy.