The objective of this study was to determine the anti-diabetic effect of the water extract of Neolentinus lepideus in a diabetic mouse model. Seven-week-old C57BL/KsJ-db/db mice were fed either a control diet (CD) or diet supplemented with 1% or 5% of N. lepideus water extract (NLWE1 or NLWE5) for 10 weeks. Oral administration of NLWE significantly decreased the body weight gain compared to that of CD-fed group. Mice in the NLWE group had significantly lower levels of fasting serum glucose, fatty acids, and low-density lipoprotein cholesterol compared to those in the control group. These effects were accompanied by reduced fatty liver and improved glucose tolerance in the NLWE group. Taken together, these results suggest that N. lepideus might have potential as a dietary supplement to control diabetes.

Citrus is one of the major fruits produced in Korea. There are about 20 species mainly grown in Jeju Island, Korea. Four representative species, which are quite different in the shape of leaf and the taste of fruit, were selected and were used to profile the transcriptomes. These species are ‘Miyagawa Wase’ (C. unshiu Marcov.) satsuma mandarin, ‘Kiyomi’ (C. unshiu Marcov. × C. sinensis) mandarin hybrid, ‘Dangyuja’ (C. grandis) and ‘Natsudaidai’ (C. natsudaidai). Classification of the up-regulated and down-regulated genes using the Cluster of Orthologous Groups of proteins (COG) database reveals that the number of genes included in each group differed significantly among the four species. Several genes that showed significant differences in expression on the microarray were selected and their expression patterns were examined by reverse transcription- ploymerase chain reaction. Metabolic genes such as tyrosine decarboxylase and β-glucosidase ligase were found to be highly expressed in Miyagawa Wase, relative to other species. On the other hand, the expression level of mannose phosphate isomerase was lower in Miyagawa Wase. An efflux pump gene was found to be up-regulated in Kiyomi, whereas cinnamyl-alcohol dehydrogenase was down-regulated. β-carotene 15,15’-dioxygenase, which is involved in the vitamin metabolism, was up-regulated in Natsudaidai. Interspecific differentiations of gene expression are analyzed in terms of the metabolic pathways and their possible roles in citrus species.