Recently, substances possessing antioxidant can prevent cataractogenesis of diabetic cataract. Therefore, this study was carried out to determine the anticataract effect of Zea mays L. (purple waxy corn), a flavonoids rich plant, in experimental diabetic cataract. Enucleated rat lenses were incubated in artificial aqueous humor containing 55 mM glucose with various concentrations of Zea mays L. (purple waxy corn) ranging between 2, 10, and 50 mg/mL at room temperature for 72 h. At the end of the incubation period, the evaluation of lens opacification, MDA level, and the activities of SOD, CAT, GPx, and AR in lens were performed. The results showed that both medium and high doses of extract decreased lens opacity together with the decreased MDA level. In addition, medium dose of extract increased GPx activity while the high dose decreased AR activity. No other significant changes were observed. The purple waxy corn seeds extract is the potential candidate to protect against diabetic cataract. The mechanism of action may occur via the decreased oxidative stress and the suppression of AR. However, further research in vivo is still essential.

Based on the crucial roles of oxidative stress and aldose reductase on diabetic complications and the protective effect against diabetic eye complication of purple waxy corn and ginger (PWCG) together with the synergistic effect concept, we aimed to determine anticataract and antiretinopathy effects of the combined extract of purple waxy corn and ginger (PWCG). The streptozotocin diabetics with the blood glucose levels >250 mg·dL−1 were orally given the extract at doses of 50, 100, and 200 mg/kg·BW−1 for 10 weeks. Then, lens opacity and histopathology of retina were determined. The changes of MDA together with the activities of SOD, CAT, GPx, and AR in lens were also determined using biochemical assays. All doses of PWCG decreased lens opacity, MDA, and AR in the lens of diabetic rats. The elevation of CAT and GPx activities was also observed. The antiretinopathy property of the combined extract was also confirmed by the increased number of neurons in ganglion cell layer and thickness of total retina and retinal nuclear layer in diabetic rats. PWCG is the potential functional food to protect against diabetic cataract and retinopathy. However, further studies concerning toxicity and clinical trial are still essential.

The novel protectant against diabetic cataract and diabetic retinopathy is currently required due to the increased prevalence and therapeutic limitation. Based on the advantage of polyphenol on diabetic eye complications, we hypothesized that the combined extract of mango seed Vietnamese coriander (MPO), a polyphenol-rich substance, should possess anticataractogenesis and antiretinopathy in streptozotocin- (STZ-) diabetic rats. MPO at doses of 2, 10, and 50 mg/kg·BW were orally given to STZ-diabetic rats for 10 weeks. Lens opacity was evaluated every week throughout a study period whereas the evaluation of cataract severity and histological changes of both rat lens epithelium and retina together with the biochemical assays of oxidative stress status, aldose reductase, p38MAPK, ERK1/2, and VEGF were performed at the end of experiment. Our data showed that MPO improved cataract and retinopathy in STZ-diabetic rats. The improved oxidative stress status and the decreased p38MAPK, ERK1/2, and VEGF were also observed. Therefore, anticataractogenesis and antiretinopathy of MPO might occur partly via the decreased oxidative stress status and the suppression of aldose reductase, p38MAPK, ERK1/2, and VEGF. This study points out that MPO is the potential candidate protectant against diabetic cataract and diabetic retinopathy. However, the exploration for possible active ingredient (S) still requires further researches.

Based on the protective effect of the combined extract of purple waxy corn and ginger (PWCG) on oxidative stress related disorders in diabetic condition, we aimed to determine the effect of PWCG on the functional, biochemical, and structural change of the lesion nerve in streptozotocin- (STZ-) diabetic rats. PWCG at doses of 100, 200, and 300 mg·kg−1 BW were orally given to STZ-diabetic rats which were subjected to chronic constriction (CCI) at right sciatic nerve for 21 days. The blood sugar was assessed before and at the end of study whereas the sciatic function index (SFI), paw withdrawal threshold intensity (PWTI), and paw withdrawal latency (PWL) were assessed every 3 days until the end of study. At the end of study, the determination of nerve conduction velocity (NCV), axon density, oxidative stress status, and aldose reductase (AR) activity of the lesion nerve were performed. It was found that PWCG improved SFI, PWTI, PWL, and NCV together with the improved oxidative stress status and the axon density in the lesion nerve. No changes of AR activity or blood sugar level were observed. Therefore, PWCG might improve the functional and structural changes in STZ-diabetic rats plus CCI via the improved oxidative stress status.