Zerumbone, a Phytochemical of Subtropical Ginger, Protects against Hyperglycemia-Induced Retinal Damage in Experimental Diabetic Rats.

Diabetic retinopathy (DR), the most ordinary and specific microvascular complication of diabetes, is a disease of the retina. Zerumbone (ZER) is a monocyclic sesquiterpene compound, and based on reports, it is the predominant bioactive compound from the rhizomes of Zingiber zerumbet. The aim of the current study is to evaluate the protective effect of zerumbone against DR in streptozotocin (STZ)-induced diabetic rats. STZ-diabetic rats were treated with ZER (40 mg/kg) once a day orally for 8 weeks. ZER administration significantly (p < 0.05) lowered the levels of plasma glucose (32.5% ± 5.7% lower) and glycosylated hemoglobin (29.2% ± 3.4% lower) in STZ-diabetic rats. Retinal histopathological observations indicated that disarrangement and reduction in thickness of retinal layers were reversed in ZER-treated diabetic rats. ZER downregulated both the elevated levels of advanced glycosylated end products (AGEs) and the higher levels of the receptors for AGEs (RAGE) in retinas of diabetic rats. What's more, ZER significantly (p < 0.05) ameliorated diabetes-induced upregulation of tumor necrosis factor-α, interleukin (IL)-1 and IL-6. ZER also attenuated overexpression of vascular endothelial growth factor and intercellular adhesion molecule-1, and suppressed activation of nuclear factor (NF)-κB and apoptosis in the retinas of STZ-diabetic rats. Our results suggest ZER possesses retinal protective effects, which might be associated with the blockade of the AGEs/RAGE/NF-κB pathway and its anti-inflammatory activity.

The Ethanol Extract from Lonicera japonica Thunb. Regresses Nonalcoholic Steatohepatitis in a Methionine- and Choline-Deficient Diet-Fed Animal Model.

Nonalcoholic steatohepatitis (NASH) is characterized as fat accumulation in the hepatic tissue associated with various degrees of inflammation and progressive fibrosis. The potent anti-inflammatory and ethnopharmacological properties of Lonicera japonica Thunb. (Caprifoliaceae) make it an excellent source of novel medicinal targets for the treatment of NASH. The aim of the study was to investigate the effects of L. japonica ethanol extract (LJEE) on NASH in mice. C57BL/6J mice were fed with methionine-choline-deficient diet (MCDD) for eight weeks to promote the development of NASH. After development of the model, the mice were administered LJEE once daily via oral gavage at doses of 100, 200, or 300 mg/kg for another four weeks. Simultaneous treatments with LJEE (300 mg/kg/day) resulted in pronounced improvements in liver steatosis, ballooning degeneration, and inflammation. LJEE prevented MCDD-induced plasma level increases in aspartate aminotransferase and alanine aminotransferase. LJEE significantly reduced hepatic malondialdehyde level and ameliorated hepatic inflammation and fibrosis in MCDD-fed mice, which were associated with down-regulation of cytochrome P450 2E1 suppression of multiple proinflammatory and profibrotic genes. LJEE can prevent hepatic steatosis by reducing hepatic peroxisome acyl-CoA:diacylglycerol acyltransferase 2 expression, as well as by inducing proliferator-activated receptor α expression. In addition, the LJEE treatments caused significant reduction in the phosphorylated form of Jun N-terminal kinase along with an increase in the phosphorylated level of extra cellular signal-regulated kinase 1/2. Our study demonstrated the protective role of LJEE in ameliorating nutritional steatohepatitis.

Consumption of Polyphenol-Rich Zingiber Zerumbet Rhizome Extracts Protects against the Breakdown of the Blood-Retinal Barrier and Retinal Inflammation Induced by Diabetes.

The present study investigates the amelioration of diabetic retinopathy (DR) by Zingiber zerumbet rhizome ethanol extracts (ZZRext) in streptozotocin-induced diabetic rats (STZ-diabetic rats). ZZRext contains high phenolic and flavonoid contents. STZ-diabetic rats were treated orally with ZZRext (200, 300 mg/kg per day) for three months. Blood-retinal barrier (BRB) breakdown and increased vascular permeability were found in diabetic rats, with downregulation of occludin, and claudin-5. ZZRext treatment effectively preserved the expression of occludin, and claudin-5, leading to less BRB breakdown and less vascular permeability. Retinal histopathological observation showed that the disarrangement and reduction in thickness of retinal layers were reversed in ZZRext-treated diabetic rats. Retinal gene expression of tumor necrosis factor-α, interleukin (IL)-1ß, IL-6, vascular endothelial growth factor, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 were all decreased in ZZRext-treated diabetic rats. Moreover, ZZRext treatment not only inhibited the nuclear factor κB (NF-κB) activation, but also downregulated the protein expression of p38 mitogen-activated protein kinase (MAPK) in diabetic retina. In conclusion, the results suggest that the retinal protective effects of ZZRext occur through improved retinal structural change and inhibiting retinal inflammation. The antiretinopathy property of ZZRext might be related to the downregulation of p38 MAPK and NF-κB signal transduction induced by diabetes.