Roasting Enhances the Anti-Cataract Effect of Coffee Beans: Ameliorating Selenite-Induced Cataracts in Rats

ABSTRACT

Purpose: Coffee is a widely consumed beverage. While recent studies have linked its intake to a reduced risk of cataracts, caffeine is believed to be the key factor for its effect. To know how roasting beans affects the effect of coffee on cataract formation, we investigated the impact roasting using a selenite-induced cataract rat model.

Materials and Methods: Sprague Dawley rats were given a single injection of sodium selenite, which induced formation of nuclear cataracts by day 6, with or without coffee intake (100% coffee, 0.2 mL/day) for following 3 days.

Results: The concentrations of glutathione (GSH) and ascorbic acid (AsA) in selenite-induced cataract lenses declined to half that of controls. However, 3 days of coffee intake ameliorated the reduction of GSH and AsA so that concentrations remained at 70–80% that of controls. Roasting enhanced the preventive effect of coffee by further reducing cataract formation and ameliorating selenite-induced reduction of antioxidants. High-performance liquid chromatography analysis revealed degradation of chlorogenic acid and generation of pyrocatechol during the coffee roasting process. We discovered that pyrocatechol, at doses equivalent to that found in dark-roasted coffee, was equally effective as caffeine at reducing cataract formation and ameliorating the reduction of antioxidants.

Conclusion: Our results indicate that pyrocatechol, generated during the roasting process, acts as an antioxidant together with caffeine to prevent cataract formation.

KEYWORDS:

• Caffeine
• cataract
• coffee
• pyrocatechol
• selenite

ABBREVIATIONS:

• ANOVA
• one-way analysis of variance
• AsA
• l-ascorbic acid
• DCPIP
• 2
• 6-dichlorophenol-indophenol
• DTNB
• dithionitrobenzene
• GSH
• glutathione
• HO-1
• heme oxygenase 1
• HPLC
• high-performance liquid chromatography
• NQO-1
• NAD(P)H:quinone oxyreductase 1
• PBS
• phosphate-buffered saline
• ROS
• reactive oxygen species
• SD
• Sprague Dawley

Funding

This work was supported by JSPS KAKENHI Grant Number 15K00883 and by a grant from the MEXT-Supported Program for the Strategic Research Foundation at Private Universities.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was supported by JSPS KAKENHI Grant Number 15K00883 and by a grant from the MEXT-Supported Program for the Strategic Research Foundation at Private Universities.