Anthocyanidin pigments in clinical ophthalmology. Analysis of their profile in eye supplements and food additives containing bilberry extract

Currently, several eye nutritional supplements and food additives with bilberry extract are approved in Russia. Bilberry effects directly depend on anthocyanidin content. Hence, the expertise of nutritional supplements and food additives with bilberry extract is required to determine their qualitative and quantitative composition. Aim. To determine qualitative and quantitative content of bilberry anthocyanidin pigments in food additives. Materials and methods. Anthocyanidins from five samples were extracted with distilled water per anthocyanidin content. The samples were obtained by the dilution of a pill or capsule in 50 mL of water. Extraction was performed under continuous mixing on hot shaker. 1 mL aliquots were taken from the solutions, centrifuged for 10 min at 14,000 rpm, and filtered through syringe filters. Total level (i.e., quantitative and qualitative content) of bilberry anthocyanidin pigments in five samples was evaluated using UV spectroscopy. Experiment was performed twice for each sample. Qualitative content of anthocyanidin pigments was evaluated using reversed-phase HPLC. Results. All examined samples contain anthocyanidin pigments from bilberry extracts but no other natural sources. Their quantity which was measured by pH differential spectrophotometry varies greatly (from 0.168% to 8.30%) and may significantly differ from that of declared by manufacturer. This is due to phytogenic raw material and difficulties in standardization of active component content. Conclusions. The data obtained optimize dosing of food additives with bilberry extract by clinicians and patients considering individual tolerance, needs, and disease severity.