Ranunculus muricatus L. is a spiny fruit buttercup that is used in various traditional medicinal systems. In the current investigation of R. muricatus, the new chalcone 4-benzyloxylonchocarpin (1), the new anthraquinone muracatanes A (2), the new-to-nature anthraquinone muracatanes B (3), and the
new naphthalene analog muracatanes C (4) were isolated, in addition to the three previously reported
compounds, 4-methoxylonchocarpin (5), β-sitosterol (6), and β-sitosterol β-D-glucopyranoside (7). Their structures were elucidated using 1D (¹H and ¹³C) and 2D (COSY, HSQC, and HMBC) NMR
spectroscopy and HR-ESI-MS. Chalcone 1 showed potent acetylcholinesterase inhibitory effects with
K_i of 5.39 μM and K_i' of 3.54 μM, but none of the isolated compounds showed inhibitory activity
towards butyrylcholinesterase. Anthraquinone 3 illustrated α-glucosidase inhibitory effects with
IC₅₀-values of 164.46 ± 83.04 μM. Compound 5 displayed moderate cytotoxic activity towards ovarian carcinoma (A2780, IC₅₀ = 25.4 μM), colorectal adenocarcinoma (HT29, IC₅₀ = 20.2 μM), breast cancer (MCF7, IC₅₀ = 23.7 μM), and thyroid carcinoma (SW1736, IC₅₀ = 26.2 μM) while it was inactive towards pharynx carcinoma (FaDu: IC⁵⁰ > 30 μM).