Seven pairs of new oxygenated aplysinopsin-type enantiomers, (+)- and (-)-oxoaplysinopsins A‒G (1‒7), two new bromotyrosine-derived alkaloids, subereamollines C and D (18 and 19), together with ten known compounds (8‒17) were isolated from the Xisha Islands sponge Fascaplysinopsis reticulata. The planar structures were determined by extensive NMR and MS spectroscopic data. Each of the optically pure enantiomers was achieved by chiral HPLC separation. The absolute configurations were assigned by the quantum chemical calculation methods. Compound 19 showed cytotoxicity against Jurkat cell lines with IC50 value of 0.88 μM. Compounds 2, 16 and 17 showed tyrosine phosphatase 1B (PTP1B) inhibition activity with IC50 value ranging from 7.67 to 26.5 μM, stronger than the positive control of acarbose and 1-deoxynojirimycin. A structural activity relationship for the aplysinopsin-type enantiomers were observed in PTP1B inhibition activity of 2 and cytotoxicity of 3 that the dextrorotary (+)-2 and (+)-3 showed stronger activity than the levorotary (-)-2 and (-)-3.