A 1H-NMR Based Study on Hemolymph Metabolomics in Eri Silkworm after Oral Administration of 1-Deoxynojirimycin
July
A 1H-NMR Based Study on Hemolymph Metabolomics in Eri Silkworm after Oral Administration of 1-Deoxynojirimycin
Ming-Jie Deng 0 1
Xiao-Dong Lin 0 1
Qiu-Ting Lin 0 1
De-Fu Wen 0 1
Mei-Ling Zhang 0 1
Xian- Qin Wang 0 1
Hong-Chang Gao 0 1
Jia-Ping Xu 0 1
0 1 School of Life Sciences, Anhui Agricultural University , Hefei , China , 2 Analytical and Testing Center of Wenzhou Medical University , Wenzhou , China
1 Editor: Erjun Ling, Institute of Plant Physiology and Ecology , CHINA
We aimed to investigate whether 1-deoxynojirimycin (DNJ) modulates glycometabolism and has toxicity in Eri silkworm (Samia cynthia ricini, Saturniidae). In this paper, hemolymph metabolites were used to explore metabolic changes after oral administration of DNJ or mulberry latex and to characterize the biological function of DNJ at the metabolic and systemic levels. Hemolymph samples were collected from fourth-instar larvae of Eri silkworm and exvivo high-resolution 1H nuclear magnetic resonance (NMR) spectra were acquired from the collected hemolymph samples. Then the obtained spectra were analyzed by principal component analysis (PCA) and independent-samples t-test. Metabolic pattern recognition analysis of hemolymph samples indicated that the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) were significantly different from the control group. Moreover, compared to the control group, the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) showed the decreased levels of citrate, succinate, fumarate, malate, and glutamine in hemolymph, the groups of 0.25% DNJ and the mixture of 0.5% DNJ and latex (1:1) showed the increased levels of trehalose and lactate. In addition, mulberry leaves exude latex was highly toxic to Eri silkworm because rich unidentified high-molecular-weight factor (s) acted as toxic substances. In our results, latex caused 20 deaths among 50 fourth-instar larvae of Eri silkmoth, but DNJ or the mixture did not caused death. All these results suggest that DNJ has a positive impact on the reverse glycometabolism by modulating glycometabolism and inhibiting glucogenesis and energy metabolism. DNJ is a secure substance as a single-ingredient antidiabetic medicine due to its nontoxicity and bioactivity.
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Mulberry leaves have been widely cultivated for rearing the silkworm Bombyx mori (B. mori)
in ancient times. Domesticated silkworms can grow adaptively on mulberry leaves, so the
defense response and toxic properties of the leaves to the insect are generally ignored [1,2]. In
the defense response against silkworms, mulberry leaves exude latex containing rich
1-deoxynojirimycin (DNJ), 1,4-dideoxy-1,4-imino-D-ribitol, and 1,4-dideoxy-1,4-imino-D-arabinitol
(D-AB1) (Fig 1A–1C). All the above three substances are glycosidase inhibitors. These
iminosugar inhibitors are lethal to Eri silkworms, a generalist herbivorous insect. However, they are
safe to domesticated silkworms on mulberry leaves, B. mori [3]. Mulberry leaves will lose their
toxicity to Samia cynthia ricini (S. cynthia ricini) when latex is eliminated from mulberry leaves
through cutting leaves into slim pieces and subsequent rinsing, interpreting that the defensive
ability of mulberry leaves is totally dependent upon toxic latex. In our study, after Eri
silkworms were fed with 5 μL of latex, among 50 larvae, 20 larvae died and the growth of other 30
larvae was significantly retarded with frequent vomiturition. In the meanwhile, when Eri
silkworms were fed with 5 μL of 0.25% DNJ or the mixture of latex and 0.5% DNJ, no larva died
(n = 50 in each group) and the morphology of larvae could not be distinguished from the
controls by visual examination. DNJ is a characteristic constituent of mulberry latex and DNJ
concentrations in mulberry latex are different between cultivated varieties and natural populations
[4]. Among the above three iminosugar inhibitors, only DNJ, was found in the latex from
Morus alba (M. alba, a Chinese local species) [1].
DNJ is a natural D-glucose analogue with promising physiological activity in vivo. It can
inhibit α-glucosidase in the small intestine and the liver, enhance the expression of adiponectin
mRNA in whiter adipose tissue, delay the senescence of blood vessels and affect the reverse
cholesterol metabolism [5–7]. Due to the potential medicinal value of DNJ, DNJ-enriched
products may represent a therapy or oral treatment of diabetes mellitus, and numerous DNJ
tablets have been commercially available in many countries [7]. These studies illustrate the
bioavailability of DNJ, but their DNJ content has not been specified. Previous studies focused on
the antidiabetic role of DNJ in rats or other mammals, but direct physiological evidences
clearly elaborating the detailed physiological mechanisms of glycometabolism or toxicological
effects of DNJ against insects were not reported. Glucogenesis, glycolysis, and tricarboxylic
acid (TCA) cycle related to glycometabolism exist in all aerob (...truncated)