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Catecholic Isoquinolines from Portulaca oleracea and Their Anti-inflammatory and β2-Adrenergic Receptor Agonist Activity

Jin, Tian-Yun, Li, Shao-Qiang, Jin, Cui-Rong, Shan, Hao, Wang, Rui-Min, Zhou, Ming-Xing, Li, Ai-Ling, Li, Ling-Yu, Hu, Shui-Yao, Shen, Tao, Xiang, Lan
Journal of natural products 2018 v.81 no.4 pp. 768-777
Portulaca oleracea, agonists, anti-inflammatory activity, beta-2 adrenergic receptors, calcium, catecholamines, cell lines, chromatography, drugs, isoquinoline alkaloids, isoquinolines, macrophages, median effective concentration, medicinal plants, mice, nitric oxide, polyamides, water solubility
Isoquinoline alkaloids possess a wide range of structural features and pharmaceutical activities and are promising drug candidates. Ten water-soluble catecholic isoquinolines were isolated from the medicinal plant Portulaca oleracea, including three new (1–3) and seven known compounds (4–10), along with the known catecholamines 11 and 12 and four other known compounds (13–16). A method of polyamide column chromatography using EtOAc–MeOH as the mobile phase was developed for the isolation of catecholic isoquinolines. Alkaloids 1–12 exhibited anti-inflammatory activities (EC₅₀ = 18.0–497.7 μM) through inhibition of NO production in lipopolysaccharide-induced murine macrophage RAW 264.7 cells. Among these compounds, 11, 2, 5, 4, and 8 were more potent than was the positive control, 3,4-dihydroxybenzohydroxamic acid (EC₅₀ = 82.4 μM), with EC₅₀ values of 18.0, 18.1, 35.4, 36.3, and 58.7 μM, respectively. Additionally, at 100 μM, compounds 1–12 showed different degrees of β₂-adrenergic receptor (β₂-AR) agonist activity in the CHO-K1/GA15 cell line which stably expressed β₂-AR as detected by a calcium assay. The EC₅₀ values of 2 and 10 were 5.1 μM and 87.9 nM, respectively.