Botanical Combination Attenuates Light-Induced Retinal Damage

Written by Angeline A. De Leon, Staff Writer. Supplementation with a botanical combination of black currant, chrysanthemum, goji berry extracts, lutein ester, and zeaxanthin protected against retinal damage due to fluorescent light exposure in rats.

Given the ubiquitous presence of technology in modern life, exposure to blue light emitted from video display units (VDUs) has become more prevalent than ever, with individuals at all stages of life facing increasing rates of eye fatigue ^1,2. From a nutritional standpoint, ocular health is largely influenced by proper intake of vital nutrients ³, including xanthophyll carotenoids lutein and zeaxanthin, which are recognized for their antioxidant action ⁴. A number of studies have confirmed the association between lutein and zeaxanthin supplementation and increased macular pigment optical density ⁵. Black currant also demonstrates the ability to mitigate eye fatigue by promoting ocular blood flow ⁶, and research shows that in combination with lutein and zeaxanthin, supplementation not only significantly reduces eye fatigue, but also improves visual attention ⁷. Other botanical combinations that have proven helpful for treating ocular diseases like glaucoma include chrysanthemum and goji berry, both of which also possess potent antioxidant, anti-inflammatory properties ⁸. A recent study ⁹ in Oxidative Medicine and Cellular Longevity (2020) explored the efficacy of a novel botanical formulation containing lutein, zeaxanthin, black currant, chrysanthemum, and goji berry in protecting against light-induced retinal damage in rats.

The in vivo portion of the experiment was carried out with a litter of 32 6-8-week-old male Sprague Dawley rats which were randomly divided into four groups: a naïve control group, a light exposed group receiving a vehicle solution, a light-exposed group receiving lutein (10 mg/kg), and a light-exposed group receiving the botanical formula (100 mg of black currant extract, 75 mg of chrysanthemum extract, 75 mg of goji berry, 120 mg of lutein ester powder, 24 mg of zeaxanthin powder). During the 21 days of oral treatment, rats were also exposed to fluorescent light of 15000 lux for 2 hours daily. Rats were then kept in the dark for one week of recovery before electroretinogram recordings (ERG, measuring electrical response of retinal cells in response to a light stimulus) were taken to evaluate retinal function under low stimulus intensity and high stimulus intensity. Rats were then sacrificed, retina tissue harvested, and outer nuclear layer (ONL) thickness was measured using histological analysis. The in vitro portion of the experiment was carried out using a human retinal pigment epithelial cell line (ARPE-19) which was pre-treated with individual ingredients of the botanical formula (100 µg/mL each) for 18 hours prior to exposure to light of 2900 lux for 30 minutes. Western blot analysis was used to determine relative protein expression.

ERG analysis revealed that light exposure was associated with significantly decreased a-wave (response from outer photoreceptor layer) and b-wave (response from inner retina) amplitude (p < 0.001 for both). However, treatment with the botanical combination was able to significantly restore the decrease for b-wave under both high stimulus intensity and low stimulus intensity (p < 0.01 for both). Histological analysis showed that ONL thickness was significantly reduced following light exposure (p < 0.001), but treatment with lutein (p < 0.01) and the botanical formulation (p < 0.001) were seen to significantly improve ONL thickness. Finally, individually, chrysanthemum, black currant, lutein, and zeaxanthin significantly reduced expression of p38 and JNK (proteins involved in stress response pathways) (p < 0.01 for all). Respectively, chrysanthemum, goji berry, black currant, and lutein also significantly increased HIF expression (involved in regulation of oxygen homeostasis) (p < 0.001 for chrysanthemum, p < 0.05 for others).

Altogether, results indicate that a novel botanical combination of lutein, zeaxanthin, black currant, chrysanthemum, and goji berry may effectively protect against light-induced retinal damage. ERG data suggest that supplementation enhanced retinal function, consistent with histological analysis showing improvement in retinal structure. Individually, ingredients of the formula appeared to engage protective cellular mechanisms, suggestive of antioxidant processes. Follow-up studies are needed to verify this potential. It would also be valuable to compare the protective efficacy of a formulated supplement vs. whole food ingredients for ocular health. Overall, however, such a botanical combination appears to be therapeutically promising.

Source: Kan J, Cheng J, Guo J, et al. A novel botanical combination attenuates light-induced retinal damage through antioxidant and prosurvival mechanisms. Oxidative Medicine and Cellular Longevity. 2020; 6: 1-8. DOI: 10.1155/2020/7676818.

© 2020 Juntao Kan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Posted May 18, 2020.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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