| Previous researches have proved that most sericultural material, such as leaves and cortex from mulberry trees, larvae, pupae, moths, cocoon shells and feces from silkworms, had obvious effect on reducing the blood sugar in human body. Its active components mainly include alkaloid, plant polysaccharides, flavonoids, insect hormone and degradation products of fibroin. 1-deoxynojirmycin (DNJ) in mulberry leaves and silkworm larvae has strongly inhibiting effect onα-glycosidase activity of mammalian enteron and delayed the absorption of glucose. DNJ has been a most important index to measure the effect of powder from mulberry leaves and larvae on reducing the blood sugar. To explore the most effective sericultural resources against hyperglycemia, we systematically studied the variation of DNJ contents in mulberry (Morus alba. L) and silkworm (Bombyx mori.L), then compared the effects of 6 kinds of sericultural resources on reducing the blood sugar, and proved for the first time the mulberry seed had significantly anti-hyperglycemia effect. Main results are as following:1. It was for the first time revaled that there was high DNJ contents in mulberry seed, which gradually decreased with the development process. The content of DNJ in leaves tended to a stability value after 15 days'growth of mulberry sapling.2. The DNJ accumulating rule in mulberry trees was studied using Nongsang 14 and Shansang 305 as the test materials. The results showed that the DNJ contents of mulberry leaf in winter and spring are the highest, especially in winter bud and leaf-opening stage. It approached to the lowest level in tardy growth stage, followed by an increasing trend. DNJ contents in mulberry leaf for diferrent seasons decreases from bud to young leaf, adult leaf and old leaf respectively. It showed the highest level in late autum in bud and youg leaves and especially, showed the highest in adult leaves in summer and old leaves in spring. DNJ contents in mulberry branch skin were higher in mid-autumn and late autumn, and lower in summer.3 The silkworm larvae were fed with artificial diets varying in mulberry powder contents or fresh mulberry leaf. The results showed that the DNJ contents in the silkworm depended on the DNJ contents in diet, and silkworm cound not synthesize DNJ by itself. The newly hatched silkworm contained no DNJ, and then the DNJ contents gradually increased until the middle of every instar, that is accumulation stage, then decreased (excretion stage). The DNJ contents in the molting larvae were the lowest. The contents were sharply decreased from the highest level at the 3rd or 4th day in the 5th instar, and no DNJ could be detected in the mature larvae, as well as in pupae and adult (moth). The DNJ contents in the feces reached the highest before larvae ecdysis of all instars as well as 2 days before spinning of 5th instar.4 This was first discovery that mulberry seed and prepupa had good effect against hyperglycemia, and further studies showed that mulberry seed also had significantly effect on diabetic mice, HbA1c decreased by 34.44%, superior to Acarbose. The aqueous and alcohol extracts of mulberry seed also had different effect, and the aqueous extract of mulberry seed had better effect against hyperglycemic.5 Mulberry seed could improve liver glycogen synthesis and insulin release of diabetic mice, and the extract of mulberry seed had significantly inhibition effect onα-glycosidase, and had closely positive and linear relationship. Mulberry seed could increase glucose tolerance of model mice. The area under the curve of glucose and starch decreased by 25.74% and 35.88%, respectively. at the same time the symptoms were obviously improved.6 Mulberry seed contained several active materials, in which DNJ shared 0.6015%, flavonoid shared 0.0345%, polysaccharides was rare; The DNJ contents in aqueous extract of mulberry seed was up to 2.7239%.7 The mice's appearances (body weight, behavior, visual form, intake and drinking amount, reproductive capacity, young mouse behavior) raised by mulberry seed diet had not obviously change, and the same to it's organs (liver, renal, spleen, heart, lung, gastric); further studies showed that mulberry seed could drop FBG of normal mice and had different effects on blood lipid, renal and liver index in a low level. There was no poisoning phenomenon for mice injected high dose of mulberry seed extract by gavage, and this indicated mulberry seed had no side effect. |
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