Glycopentanolones A-D, four new geranylated quinolone alkaloids from Glycosmis pentaphylla.

•Four new geranylated 2(1H)-quinolone alkaloids and 12 known compounds were isolated from the stem of Glycosmis pentaphylla.•The structures of the compounds were elucidated by NMR and MS data.•Four alkaloids (1, 5, 8, and 11) with N-methyl moiety exhibited potent inhibition activity β-hexosaminidase release.