Is Pycnogenol a Double-edged Sword? Cataractogenic In Vitro, but Reduces Cataract Risk in Diabetic Rats

AbstractPurpose: Pycnogenol was used (a) to study its antioxidant activity, (b) to study its effects on lens integrity in organ culture and (c) in vivo to determine whether it could reduce the damage in model diabetic cataract.Methods: For (a) our luminescent antioxidant assay was used, (b) lenses were incubated in medium 199, with 55.6 mM glucose. Lenses were stained with 0.014 mM rhodamine 123 for 15 min to stain mitochondria, immobilized in 1% agarose in M199, and the equatorial region examined by a Zeiss confocal microscope. For (c) cataract grades of streptozotocin diabetic rats fed 1% pycnogenol were followed for 12 weeks.Results: (a) Pycnogenol in vitro was an antioxidant when challenged with peroxide. (b) In vitro, when [570 mg/L] pycnogenol in dimethyl sulfoxide (DMSO) was used, lenses turned opaque after 3 d of incubation, in both pycnogenol controls and glucose + pycnogenol. Normal controls (DMSO, n = 4) and controls (n = 4) remained clear after 8 d of incubation. After 3 d of incubation with p...