Ingestion of Proanthocyanidins Derived from Cacao Inhibits Diabetes-Induced Cataract Formation in Rats

Abstract

Proanthocyanidins derived from cacao (CLP) have various antipathophysiological functions. We have tested whether dietary supplementation with CLP prevents cataract formation in rats with diabetes induced by streptozotocin (STZ), using histological, histochemical, and biochemical analyses. Starting at 7 days after the streptozotocin challenge, the animals were fed either a normal diet or a diet containing 0.5% w/w CLP over 10 weeks. There were no significant differences in plasma and urine glucose concentrations, plasma fructose amines, and plasma thiobarbituric reactive substances (TBARS) between the two dietary groups. Antioxidant status as assessed by measuring lipid peroxide production in plasma in response to azocompounds was lower in the STZ-rats fed control diet than in animals fed CLP. Opacity was first detected in the lenses of the control dietary group 5 weeks after STZ injection and cataracts had developed in the majority of these animals by 10 weeks. These changes were rarely seen in the STZ/CLP diet group. Histological examinations of the eyes of the STZ-treated normal diet group revealed focal hyperplasia of the lens epithelium and liquefaction of cortical fibers. There were similar but considerably less severe changes in the animals fed CLP. Hydroxynonenal (HNE), a marker of oxidative stress, was detected immunohistochemically in the lenses of the STZ-treated normal diet group, but not of those receiving CLP. Our findings suggest that CLP inhibits diabetes-induced cataract formation possibly by virtue of its antioxidative activity.

Ingestion of IH636 grape seed proanthocyanidin extract to prevent selenite-induced oxidative stress in experimental cataract

“…26,27 In a recent study, proanthocyanidins derived from cacao (CLP) were tested for their preventive effect on cataract development in rats with diabetes induced by streptozotocin. 28 The authors found that dietary supplementation with CLP did not affect hyperglycemia but made a significant change in production of hydroxynonenal, a marker of oxidative stress. Hydroxynonenal was only detected when rats were fed a normal diet without CLP.…”

“…These observations suggested that the CLP may prevent cataract formation by decreasing oxidative stress induced by hyperglycemia. 28 An IH636 grape seed proanthocyanidin extract effectively suppressed cataract formation in rats. The protective effect was supported by lower GSH and higher MDA levels.…”

Bioavailability issues in studying the health effects of plant polyphenolic compounds

“…The effects of these PC oligomers on diabetic cataracts, blood sugar, and blood lipid peroxides have been demonstrated in mice [129,130]. PCs derived from cocoa have also been shown to inhibit diabetes-induced eye lens cataract formation possibly via antioxidant effects [130]. A recent study has shown that type-A PC trimers isolated from the aqueous extract of cinnamon have insulin-enhancing activity in in vitro assays measuring insulin-dependent glucose metabolism [131].…”

“…The effects of these PC oligomers on diabetic cataracts, blood sugar, and blood lipid peroxides have been demonstrated in mice [129,130]. PCs derived from cocoa have also been shown to inhibit diabetes-induced eye lens cataract formation possibly via antioxidant effects [130].…”

Tannins: Current knowledge of food sources, intake, bioavailability and biological effects

“…Procyanidins derived from cacao have been found to inhibit diabetes-induced cataract formation in rats [214]. These inhibitory effects are probably due to the antioxidant capacity of proanthocyanidins…”