.ALPHA.-Glucosidase Inhibitory Activity in Leaves of Some Mulberry Varieties

Abstract

The seasonal and polyploidal changes of ␣-glucosidase (rat-intestinal) inhibitory activity in mulberry leaves were compared in 12 mulberry varieties. Enashi, Fusoumaru, No. 325 and Kenmochi which are classified as 3 major varieties in Japan were harvested in May or August as the field samples. Shimaguwa and the 3 different wild types such as Kuromiguwa, Nagamiguwa, Midoriguwa were harvested in May as the greenhouse samples. Some varieties harvested in the field or greenhouse indicated a difference in ␣-glucosidase. In the field Enashi was strong, while Kenmochi was rather weak. The seasonal changes of inhibition between May and August were differed among the varieties. The 3x variety in the field or greenhouse showed the strong inhibition within the same variety. Keywords: ␣-glucosidase, inhibitor, mulberry, Morus, polyploidy, variety Mulberry leaves (Morus alba L.) have been used as a traditional medicine with anti-inflammatory and anti-hyperglycemic action . The mulberry leaf component such as 1-deoxynojirimycin (DNJ;Yoshikuni, 1988;Asano et al., 1994), 2-arylbenzofuran derivatives (Basnet et al., 1993) and polyhydroxylated alkaloids (Asano et al., 2001) inhibit the activity of ␣-glucosidase of the small intestine, and also prevent sudden hydrolysis of disaccharides, absorption of glucose into the blood vessel, and resultant increase of blood glucose level. DNJ showed stronger inhibitory activity towards rat intestinal maltase and yeast ␣-glucosidase compared with DNJ-trehalamine-fused and -linked compounds (Shiozaki et al., 1998). The extract derived from mulberry leaves potentiated the pilocarpine-induced salivary flow which was correlated with antihyperglycemic effects . Fagomine from mulberry leaves increased the plasma insulin level in STZ-diabetic mice, and this insulin release by fagomine might partly contribute to the antihyperglycemic action (Nojima et al., 1998;Taniguchi et al., 1998). The maximum reduction in blood glucose of leaf extract was ob-served among fruit, trunk bark and root bark (Hosseinzadeh & Sadeghi, 1999).On the other hand, there are many reports concerning artificially polyploidy from the point of view of cytology (Seki & Oshigane, 1953, 1957, 1959Tojyo, 1954Tojyo, , 1963Tojyo, , 1966Das & Krishnaswami, 1964;Das et al., 1970) as mulberry breeding is extremely valuable for the sericulture. It is well accepted that major characteristics of 3, 4x polyploidy are indicated a large leaf, high saccharide content, high yield and high feed efficiency on silkworm among the different polyploidy. We observed that the changes of ␣-glucosidase inhibitory activity in leaves were occurred among mulberry polyploidy. Activity for lowering blood-glucose levels of autumn-rearing silkworm was higher than that of spring-rearing silkworm (Ryu et al., 1997). The changes in ␣-glucosidase inhibitory activity in leaves can be observed in some mulberry varieties, there is no reports concerning of seasonal or varietal changes on the ␣-glucosidase inhibition in leaves of any mulberry variety.In this study the ...

Effect of Environmental Conditions on the α-Glucosidase Inhibitory Activity of Mulberry Leaves

“…[8][9][10][11] Yatsunami et al have reported the relationship between the -glucosidase inhibitory activity and 1-DNJ concentration from a group of species, 10) but not enough is known about -glucosidase inhibitors other than 1-DNJ from each cultivar. Since the -glucosidase inhibitory activity was not consistent with the 1-DNJ concentration in several cultivars, it is thought that -glucosidase inhibitors besides 1-DNJ were involved in the effective defense by mulberry plants against insect herbivores.…”

“…The typical cultivars of mulberry plants are maintained and administered in Japan at the National Institute of Agrobiological Sciences (Tsukuba, Ibaraki, Japan) and the Experimental Farm of Textile Science and Technology of Shinshu University (Ueda, Nagano, Japan). It has been reported that the -glucosidase inhibitory activity and 1-DNJ concentration of mulberry leaves differ among various cultivars and seasons, [8][9][10][11] but it is unknown which environmental conditions influence the -glucosidase inhibitory activity. We therefore investigated in this study the relationship between the environmental conditions and -glucosidase inhibitory activity.…”

The relationship between 1-deoxynojirimycin content and α-glucosidase inhibitory activity in leaves of 276 mulberry cultivars (Morus spp.) in Kyoto, Japan

“…Variations in a-glucosidase inhibitory activity in Morus leaves were previously observed in association with polyploidy of the same variety [1]. An active component of Morus leaves, 1-deoxynojirimycin (DNJ), is known to be a strong intestinal a-glucosidase inhibitor [2,3].…”

Investigation of the Safety and Antihyperglycemic Effect of <i>Apios americana</i> Flower Intake as a Food Material in Normal and Diabetic Mice

“…This test was designed to investigate the maltase inhibitory There are a number of reports about the antihyperglycemic effects of natural resources such as Morus alba, Rosa damascena, Lonicera japonica, and Ganoderma lucidum (Yatsunami et al, 2003;Naowaboot et al, 2009;Gholamhoseinian et al, 2009;Zhang et al, 2013;Usui et al, 2007). AFS60 showed 15%…”