Studies On The Chemical Constituents And Bioactivities Of Leaves Of Morus Alba L.

Morus alba is the species belonging to the genus Morus of Moraceae. Its roots, twigs, leaves and fruits as well are used as the folk medicine. The bioactive screening on the 95%ethanol extract and water extract of the leaves of M. alba resulted in:the ethyl acetate fraction from the 95%ethanol extract displayed significant anti-oxidative activity; the acetone fraction and methanol fraction of the 95%ethanol extract and the water extract as well showed remarkable inhibitory activity against a-glucosidase.The 95%ethanol extract and water extract of the leaves of M. alba were investigated respectively on their chemical constituents systematically by various kinds of chromatographic methods. The isolates were elucidated on the basis of spectroscopic analysis and chemical methods as well. Some of them in sufficient amount were assayed for their bioactivities.Among the thirty-five compounds isolated from the leaves of M. alba, ten compounds (1,5-13) are new compounds. Thirty-two compounds were isolated and identified from the 95%ethanol extract of the leaves of M. alba, including four Diels-Alder type adducts, twelve 2-arylbenzofuran derivatives, fourteen flavonoids. These compounds are listed as follows:mulberrofuran F1 (1), mulberrofuran F (2), chalcomoracin (3), kuwanon J (4), moracin V (5), moracin W (6). morancin X (7), morancin Y (8), morancin Z (9), morachalcone B (10), morachalcone C (11), (2R,4S)2',4'-dihydroxy-2H-furan-(3",4" 8,7)-flavan-4-ol (12). (2S)-2',4'-dihydroxy-7-methoxyl-8-butyricflavane (13), moracin P (14). moracin N (15), moracin C (16), moracin I (17), mulberrofuran A (18). wittifuran R (19), mulberrofuran B (20), morachalcone A (21), isobavachalcone (22), norartocarpetin (23). morusin (24), kuwanon C (25),3-(2"-hydroxyl-3"-methyl-3"-butenyl)-morusin (26), mornigrol F (27). mornigrol G (28),6-geranylapigenin (29), kaempferol-3-O-β-D-gluco-side (30),β-sitosterol (31).β-daucosterol (32).Three compounds were obtained and identified from the water extract of the leaves of M. alba, including two polyhydroxyalkalines, and betaine. The corresponding compounds are displayed as I-deoxynojirimycin (33), fagomine (34), betaine (35).Within the compounds isolated from the leaves of M. alba, twenty-one compounds (compounds 1-2,6-8,16-21) inhibited the production of the lipid peroxide induced by Fe2+-Cys system in the liver microsomal obviously, with inhibitory rates more than 50% at a concentration of 10-5 M. On the pharmacological model of release ofβ-glucuronidase from rat PMNs induced by PAF, eleven compounds (compounds 7,12-13.15-16.19.21) displayed antiinflammatory activity with the inhibitory rates more than 50%at a concentration of 10-5 M.Sixteen compounds (compounds 1-4,7-8,10-11,14,16-20,27-29) obtained from the leaves of M. alba displayed moderate inhibitory activity against five human tumor cells (A549, Bel 7402, BGC 823, HCT-8 and A 2780) by MTT method.The inhibition against a-glucosidase was performed for two compounds isolated from water extract of the leaves of M. alba. The resulst showed that two polyhydroxyalkalines (compounds 33-34) possessed significant inhibition agaist a-glucosidase, with inhibitory rates over 80%at a concentration of 40μg/mL. Especially for compound 33, the IC50 values was 0.07μM; which was comparative to the positive control acarbose (IC50= 0.52μM).