Naphthalene Derivatives and Quinones from Ventilago denticulata and Their Nitric Oxide Radical Scavenging, Antioxidant, Cytotoxic, Antibacterial, and Phosphodiesterase Inhibitory Activities.

New naphthalene derivatives (1 and 2) and a new isomer (3) of ventilagolin, together with known anthraquinones, chrysophanol (4), physcion or emodin 3-methyl ether (5), and emodin (6), were isolated from vines of Ventilago denticulata. The isolated compounds exhibited cytotoxic activity with IC50 values of 1.15 - 40.54 μg/ml. Compounds 1 - 3 selectively exhibited weak antibacterial activity (MIC values of 200.0 - 400.0 μg/ml), while emodin (6) displayed moderate antibacterial activity with MIC value of 25.0 μg/ml. The isolated compounds showed nitric oxide and DPPH radical scavenging activities. Compounds 1 - 3 and 6 exhibited weak xanthine oxidase inhibitory activity, while emodin (6) acted as an aromatase inhibitor with the IC50 value of 10.1 μm. Compounds 1 and 2 exhibited phosphodiesterase 5 inhibitory activity with IC50 values of 8.28 μm and 6.48 μm, respectively.