Anti-Obesity Effect of Bombus ignitus Queen Glycosaminoglycans in Rats on a High-Fat Diet.

The mechanism of functional insect glycosaminoglycan (GAG) on obesity caused a high fat diet has not yet been elucidated. Therefore, insect glycosaminoglycans derived from Isaria sinclairii, Bombus ignitus (a type of bumblebee) queen, and Gryllus bimaculatus were purified and investigated as a potential functional food. 14-week old male Wistar rats were fed a high-fat diet (HFD) for 6 weeks. There were five groups that received daily intraperitoneal administration of phosphate buffered saline (PBS, control), GbG (GAG from Gryllus bimaculatus) 10 mg/kg, ISG (GAG from Isaria sinclairii) 10 mg/kg, IQG (GAG from Bombus ignites) 10 mg/kg, or Pravastatin (2 mg/kg). All treatments were performed for one month. IQG produced a potential anti-inflammatory effect with the inhibition of c-reactive protein and sero-biochemical parameters of phospholipids and free fatty acids indicative of an anti-hyperlipidemic effect. Abdominal and epididymidal fat weight were reduced in conjunction with a mild increase in body weight. The level of laminin in HMVEC-C cells or fibronectin in HFD rat hepatocytes was significantly affected by these GAG treatments, which regulated adipogenesis and adipocyte function. Compared to the control rats, IQG-treated rats displayed up-regulation of 87 genes (test:control ratio >2.0) including fatty acid synthase and 3-hydroxy-3-methylglutaryl-coenzyme A reductase, with the down-regulation of 47 genes including the uridine diphosphate (UDP) glycosyltransferase 2 families, polypeptidase B, and insulin-like growth factor binding protein 1. The data suggest that IQG could potentially prevent or treat fatty liver or hyperlipidemia.

Blood-pressure-lowering effect of glycosaminoglycan derived from Isaria sinclairii in spontaneously hypertensive rats.

The antihypertensive effects of both extracts and glycosaminoglycan derived from Isaria sinclairii (IS) were investigated in a spontaneously hypertensive rat (SHR) model. Groups of rats were treated orally with 30 mg/kg each of: (1) saline control or extracts of (2) water-IS (3) methanol-IS, (4) butanol-IS, (5) ethyl acetate-IS, or (6) captopril as positive control. The 30-mg/kg dose was administered with a standard diet every day for a period of 2 wk. The antihypertensive effects of the individual extracts were in the following order: methanol > water > ethyl acetate > butanol. Glycosaminoglycan (GAG) obtained from IS as a water-soluble alcohol precipitation fraction produced an antihypertensive effect. One month following administration of GAG derived from IS to SHR animals there was a marked decrease in systolic blood pressure from 183 to 105 mm Hg and reduced diastolic blood pressure from 148 to 80 mm Hg compared to untreated control SHR rats. It was found that GAG produced an antihypertensive effect, which was more effective than the positive control captopril. In the SHR animal model a fall of 19% in body weight was observed in the group that received GAG. Data thus indicate that GAG derived from I. sinclairii may be a potent, naturally occurring antihypertensive agent.

Anti-inflammatory Effect of Isaria sinclairii Glycosaminoglycan in an Adjuvant-treated Arthritis Rat Model.

The anti-inflammatory effects of glycosaminoglycan (GAG) derived from Isaria sinclairii (IS) and of IS extracts were investigated in a complete Freund's adjuvant (CFA)-treated chronic arthritis rat model. Groups of rats were treated orally with 30 mg/kg one of the following: [1] saline control, extracts of [2] water-IS, [3] methanol-IS, [4] butanol-IS, [5] ethyl acetate-IS, or [6] Indomethacin® as the positive control for a period of two weeks. The anti-paw edema effects of the individual extracts were in the following order: water-IS ex. > methanol ex. > butanol ex. > ethyl acetate ex. The water/methanol extract from I. sinclairii remarkably inhibited UV-mediated upregulation of NF-κB activity in transfected HaCaT cells. GAG as a water-soluble alcohol precipitated fraction also produced a noticeable anti-edema effect. This GAG also inhibited the pro-inflammatory cytokine levels of prostaglandin E2-stimulated lipopolysaccharide in LAW 264.7 cells, cytokine TNF-α production in splenocytes, and atherogenesis cytokine levels of vascular endothelial growth factor (VEGF) production in HUVEC cells in a dose-dependent manner. In the histological analysis, the LV dorsal root ganglion, including the articular cartilage, and linked to the paw-treated IS GAG, was repaired against CFA-induced cartilage destruction. Combined treatment with Indomethacin® (5 mg/kg) and IS GAG (10 mg/kg) also more effectively inhibited CFA-induced paw edema at 3 hr, 24 hr, and 48 hr to levels comparable to the anti-inflammatory drug, indomethacin. Thus, the IS GAG described here holds great promise as an anti-inflammatory drug in the future.

Antidiabetic effects and gene expression profiling in obese mice treated with Isaria sinclairii over a 6-month period.

The molecular mechanisms underlying the glucose-lowering effects of Isaria sinclairii (Cicada Dongchunghacho), a fungus cultured on silkworm, are not fully elucidated. Thus the glucose-lowering effects of I. sinclairii as potential an antidiabetic agent were investigated in C57BL/6 obese (ob/ob) mice over a 6-mo period. For a period of 26 wk, ob mice were administered either 5 or 10% (w/w) I. sinclairii powder (IS), 10% dry mulberry leaf powder (ML), or 10% silkworm (SW) powder in the standard diet while a control group received only standard diet. The ML and SW preparations served as positive controls. Isaria sinclairii at 10% in the diet was more effective in reducing body weight compared to 10% ML, 10% SW, or 5% I. sinclairii. The fall in blood glucose levels in the groups treated for 26 wk was greater in both IS groups at 1 mo compared to ML or SW but equal in all groups at 6 mo. Microarray analyses were performed with a mouse 7.4K cDNA clone set array to identify the gene-expression profiles for the IS-, ML-, and SW-exposed ob mouse liver. The 10% IS group, compared to control, showed that 15 genes including glucokinase (Gk-rs1) and LDL receptor relating protein 1 were upregulated and 12 genes including cell translocation gene2 (antiproliferative) and hydroxyprostaglandin dehydrogenase (Hpgd 15) were downregulated. Upregulation of Gk-rs 1 and downregulation of Hpgd 15 were previously shown to occur in drug-induced suppression of diabetes. With ML, Lepr (leptin receptor), Pik3cb (phosphatidylinositol 3-kinase), and Prodh (proline dehydrogenase), related to suppression of diabetes, were upregulated. In the case of SW, the enzymes (G2an, alpha glucosidase 2) and Mmp9 (matrix metalloproteinase 9) involved in elevation of blood glucose levels were both downregulated. Data suggest that I. sinclarii is effective in lowering blood glucose due to the upregulation of glucokinase (Gk-rs1) and downregulation of hydroxyprostaglandin dehydrogenase (Hpgd 15), both associated with suppression of diabetes, indicating that microarray analysis is a useful tool to assess pharmacological potency of therapeutic compounds.

Genotoxicity evaluation of Isaria sinclairii (ISE) extract.

The mutagenic potential Isaria sinclairii, a traditional Chinese medicine composed of the fruiting bodies of I. sinclairii and its parasitic host larva, was evaluated using short-term genotoxicity tests, namely, the Ames test, chromosome aberration (CA), and micronuclei (MN) tests. In a Salmonella typhimurium assay, I. sinclairii extract (ISE) did not produce any mutagenic response in the absence or presence of 59 mix with TA98, TA100, TA1535, and TA1537. In the chromosome aberration (CA) test, ISE induced no significant effect on Chinese hamster ovary (CHO) cells compared with control. In the MN test, no significant change in the occurrence of micronucleated polychromatic erythrocytes was observed in male ICR mice intraperitoneally administered ISE at doses of 15, 150, or 1500 mg/kg. These results indicate that ISE has no mutagenic potential in these in vitro and in vivo systems.