The effect of Ginkgo biloba and Nifedipine on DNA breaks in circulating leukocytes of glaucoma patients

Abstract

Purpose: Oxidative stress plays an important role in the pathogenesis of glaucomatous optic neuropathy. One indirect measure of oxidative stress is the quantification of DNA breaks by comet assay. This study aims to quantify single-stranded DNA (ss-DNA) breaks in circulating leukocytes of glaucoma patients treated with Ginkgo biloba and Nifedipine and compare results with an untreated group. Design: Retrospective clinical study. Participants: Sixty patients with bilateral open-angle glaucoma. Methods: The following groups (n = 20) were retrospectively compared: Primary open-angle glaucoma (POAG) patients without any systemic treatment; POAG patients treated with 5 mg of Nifedipine daily; POAG patients treated with 120 mg of Ginkgo biloba daily. The damage to ss-DNA was quantified as tail-moment by comet assay. Main outcome measures: Damage to single-stranded DNA (ss-DNA) quantified as tail moment in three groups of patients. Results: Patients treated with Ginkgo biloba and Nifedipine exerted a significant lower amount of comet tails indicative of DNA damage, in comparison with control leukocytes of untreated patients (p < 0.001). There was a trend in the difference of tail-moment with the group being treated with Ginkgo biloba having a stronger effect in lowering DNA breaks compared with the group treated with Nifedipine (p = 0.052). Conclusions: POAG patients treated with either Ginkgo biloba or Nifedipine have a lower rate of DNA breaks than POAG patients who are not on these systemic treatments.

Keywords:

• Ginkgo biloba
• Nifedipine
• POAG
• ss-DNA breaks

Financial & competing interests disclosure

The study was supported by the Velux Stiftung, Zürich, Switzerland. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Besides increased intraocular pressure factors, such as disturbed ocular blood flow and oxidative stress play a role in the pathogenesis of glaucomatous optic neuropathy.

• Oxidative stress plays an important role in the pathogenesis of glaucomatous optic neuropathy.

• There are many different ways of measuring oxidative stress.

• One method is the comet assay analysis, also known as single-cell gel electrophoresis.

• Comet assay quantifies single-stranded DNA breaks.

• DNA breaks lead to smaller pieces of DNA that migrate away from the intact DNA when put in an electric field.

• The amount of migrated DNA is a measure of the extent of DNA damage and damaged cells have the appearance of a ‘comet’.

• Treatment with Ginkgo Biloba and Nifedipine appears to lower the extent of DNA damage in cells.