Structural characterization, antiproliferative and anti-inflammatory activities of alkaloids from the roots of Zanthoxylum austrosinense

Three new carbazole alkaloids, zanthoaustrones A-C (1-3), as well as nine known compounds 4-12, were isolated and characterized from the roots of Zanthoxylum austrosinense Huang (Rutaceae). Their chemical structures were elucidated on the basis of extensive and comprehensive spectroscopic methods, while the known alkaloids were identified by the comparison of their observed spectroscopic data including NMR data, MS data and optical rotation values with the data described in the literature. Furthermore, the antiproliferative activities as well as the anti-inflammatory effects of all isolated alkaloids in vitro were evaluated. All obtained alkaloids 1-12 displayed notable antiproliferative activities against diverse human cancer cell lines exhibiting IC₅₀ values in range of 0.85 ± 0.06 to 29.56 ± 0.17 µM, which is equivalent to the positive control (cisplatin) showing IC₅₀ values ranging from 1.58 ± 0.09 to 28.69 ± 0.21 µM. Moreover, compounds 1-12 exhibited pronounced inhibitory activities on nitric oxide (NO) production with IC₅₀ values displaying IC₅₀ values in range of 0.89 ± 0.05 to 9.62 ± 0.15 µM, which is comparable to the positive control (hydrocortisone) holding an IC₅₀ value of 4.06 ± 0.11 µM. These findings indicate that the separation and characterization of these alkaloids displaying significant antiproliferative activities together with anti-inflammatory effects from the roots of Z. austrosinense could be meaningful to the research and development of new anti-cancer drugs as well as anti-inflammatory agents.

Keywords: Anti-inflammatory effects; Antiproliferative activities; Carbazole alkaloids; Rutaceae; Zanthoaustrones; Zanthoxylum austrosinense.