A 50% aqueous EtOH extract of Aglaonema treubii found to potently inhibit α-glucosidase was subjected to various ion-exchange column chromatographic steps to give 2(R),5(R)-bis(hydroxymethyl)-3(R),4(R)-dihydroxypyrrolidine (1), α-homonojirimycin (2), β-homonojirimycin (3), α-homomannojirimycin (4), β-homomannojirimycin (5), α-3,4-di-epi-homonojirimycin (6), 7-O-β-D-glucopyranosyl-α-homonojirimycin (7), and 5-O-α-D-galactopyranosyl-α-homonojirimycin (8). Compounds 1 and 2 are known inhibitors of various α-glucosidases. Compounds 6 and 8 are new natural products. Compounds 3-5 and 7 have been chemically synthesized previously, but this is the first report of their natural occurrence.