Study On The Inhibitory Activity Of Glucosidase Of Water-soluble Components Of Noni Fruit And Juice

Morinda citrifolia L.（Rubiaceae）,commonly known as noni,is native to certain countries bordering the Indian Ocean and cultivated in tropical areas such as Hainan Island,Taiwan Island and Xisha Islands.Noni is famous to use as food and health product for more than two thousand years.Noni fruit fermented fruit juice（known as Noni juice）is currently used to solve the taste problem of Noni fresh fruit.We found that the water-soluble components of Noni fruit and Noni Juice showed potent inhibitory activity againstα-glucosidase.However,chemical components and biological activities of Noni fruit and Noni Juice have not been well studied.It is of great significance to elucidate the chemical constituents of Noni fruit and Noni Juice.The water-soluble constituents were separated by MCI chromatography,gel column chromatography and semi-preparative HPLC separation methods,respectively.89compounds（1-89）were isolated and identified from Noni and Noni juice water extract.Thirty-eight compounds were isolated from Noni fruit,including six iridoid glycosides compounds（1-6）,seven coumarin glycosides compounds（7-13）,three phenolic acid glycosides（14-20）,flavonoid glycosides（21-24）,and fourteen other compounds（25-38）.Fifty-one compounds were isolated from Noni juice,including thirty-one alkaloids compounds（39-69）and twenty other compounds（70-89）.Eight compounds（1,7,31,32,39,40,59 and 60）were new compounds.One compound（78）was new natural product.seventeen compounds（8-16,27-30 and 32-35）were isolated from the specie of Morinda for the first time.The absolute configurations of 39,40,59 and 60 were determined by electronic circular dichroism calculations or the modified Mosher’s method.All the isolated compounds were tested for glycosidase activity.Nine compounds（39,40,44,55-56,60-62 and 64）showed weak inhibitory activity againstα-glucosidase,with IC₅₀ values of 0.364-1.643 m M.Eight compounds（5,9,13,16,45-46 and 51-52）exhibited weak inhibitory activity againstβ-glucosidase with IC₅₀ values of 1.885-3.840 m M.Carboline alkaloids and carbazole compounds were modified to obtain 7 new carboline alkaloid derivatives and 5 new carbazole derivatives.All derivatives presented excellent inhibitory activity againstβ-glucosidase with IC₅₀ values rang from0.245 to 0.818 m M.