Study On The Alkaloids Of Faeces Bombycis

Faeces bombycis(Cansha in Chinese), the larvae of silkworm’s dried dejecta, is a traditional Chinese medicine, which is recorded in ComPendium of Materia Medica. Faeces bombycis is regarded as slightly bitter in taste, mild in nature, and attributive to the liver meridian. Its pharmacological effects are to expel wind, dredge the meridians, and ease joint pains. Additionally, Faeces bombycis have been shown to lower blood pressure and cholesterol levels, as well as anti-cancer effects. Owing to monophagous characteristic and simple digestive system of silkworm, Faeces bombycis mainly compose of crude protESIns and carbohydrates. Moreover, sugar-mimic alkaloids (also called polyhydroxylated alkaloids) are its main secondary metabolites. In this study, the chemical compositions of Faeces bombycis have been further studied on the basis of former researchers.In some case, sugar-mimic alkaloids almost could competitively inhibit a-glucosidase because of a structural resemblance to the sugar moiety of the natural substrate. Therefore the peak blood sugar content after meal could significantly decrease by using the α-glucosidase inhibitor before meal. This effect is therapeutic benefit to diabetes. Morus L. is the main source of sugar-mimic alkaloids, and 1-deoxynojirimycin (DNJ, a sugar-mimic alkaloid) is the highest content compound in it, which has been used for the treatment of diabetes in clinic.Thirteen compounds were isolated from Faeces bombycis by kinds of chromamatographic techniques, such as Sephadex LH-20, ion-exchange resins and so on. According to physical constants and spectroscopic analysis,13 compounds were identified, in which they were:(2R,3R,4R)-2-hydroxymethyl-3,4-dihydroxypyrrolidine-N-glyoxylamide (1), (2R,3R,4R)-[(S)-1,2-Dihydroxyethyl] piperidine-3,4-diol (2),1-DNJ (3),1,5-Dideoxy-1,5-imino-D-glucitolhydro chloride (4),2-O-α-D-Galactopyranosyl-l-deoxynojirimycin (5),Fagomine (6),Trigonelline (7),4-carboxy-N,N, N-trimethyl-Benzenemethanaminium chloride (8), Betaine (9), N-dimethyl-N,ethanaminium chloride (10), N,N-B-Bis (2-chloroethyl)ethylenedia (11), meso-Erythritol (12), Urea (13). Among them, Compounds 1-6 are polyhydroxylated alkaloids, compound 1 was new compounds, compound 2 is the first report of its natural occurrence, Compounds 9-13 were first isolated from Faeces bombycis.The inhibition against a-glucosidase was performed for 13 compounds isolated from Faeces bombycis. The resulst showed that all of the 13 isolated compounds exhibited potent a-glucosidase inhibition activity. Especially, Compounds 1 and 2 exhibited remarkable inhibitory activity against a-glucosidase with the IC50 values of 1.9±0.1 and 6.2±0.1μM respectively which were 93.4 and 28.6 potent folds than that of acarbose. Other four sugar-mimic alkaloids also exhibited obvious inhibitory activity. The results showed that the sugar-mimic alkaloids from Faeces bombycis exhibit significant a-glucosidase inhibitory activity, which may be useful in the prevention of the postprandial hyperglycemia and provide new candidates for the treatment of diabetes mellitus.