Protective Effects of Lycium barbarum Extracts on UVB‐Induced Damage in Human Retinal Pigment Epithelial Cells Accompanied by Attenuating ROS and DNA Damage

Abstract

The medicinal herb Lycium barbarum fruit has been widely used for improving and maintaining the health of the eyes in the Far East for many centuries. This study is aimed at investigating whether protective effects generated from the aqueous (LBA) and ethanol (LBE) extracts of the L. barbarum fruit existed against oxidative stress-induced apoptosis in human retinal pigment epithelial cells. L. barbarum extracts LBA and LBE exerted the activity of ROS scavenging and rescued UVB irradiation-induced growth inhibition in retinal pigment epithelial ARPE-19 cells. Compared to LBA, the ethanol extract LBE exerted a superior protective activity on UVB-induced growth arrest in ARPE-19 cells. Both L. barbarum extracts significantly reduced cell cycle G2-arrest population in ARPE-19 cells. Furthermore, the cytometer-based Annexin V/propidium iodide staining assay further showed that both L. barbarum extracts protected ARPE-19 cells from UVB-induced apoptosis. L. barbarum extracts also reduced the activation of γH2AX, a sensor of DNA damage in ARPE-19 cells in a dose-responsive manner. By using Ingenuity Pathway Analysis (IPA), the bioinformatics revealed that the protective effects of both LBA and LBE extracts might be involved in three signaling pathways, especially the Toll-like receptor (TLR) pathway associated with cellular proliferation. Our study suggests that both ethanol and aqueous extracts of L. barbarum exhibit antioxidant activity and rescue UVB-induced apoptosis of ARPE-19 cells. Collectively, the ethanol extract exerts a superior effect on rescuing UVB-induced growth arrest of ARPE-19 compared to the aqueous extract, which might be associated with the activation of TLR signaling. Our present work will benefit the preventive strategy of herbal medicine-based vision protection for treating eye diseases such as age-related macular degeneration in the future.

Detrimental Effects of UVB on Retinal Pigment Epithelial Cells and Its Role in Age-Related Macular Degeneration

“…Besides that, the upregulation of cytochrome C protein was also recorded by Balaiya et al [ 112 ], which suggests that the integrity of mitochondrial membranes was compromised. This data agrees with other studies that reported the loss of mitochondrial potential and the number of mitochondria in ARPE-19 and DrRPE cells following exposure to UVB irradiation [ 33 , 103 , 113 ]. Another interesting study displayed vast changes in the mitochondrial morphology and movement before and after UVB irradiation in ARPE-19 cells.…”

“…Many in vitro studies have shown that RPE cells which were irradiated with UVB had displayed increased cell death, DNA fragmentation, and apoptosis [ 98 , 103 , 104 ]. Microscopic images of microvillus shedding, nucleolus degeneration, the formation of vesicular structures, and mitochondrial degradation are the hallmarks of apoptosis that were seen in ARPE-19 cells after UVB irradiation [ 104 ].…”

“…While the total number of studies focusing on RPE is limited, the data available is already very promising. By decreasing the ROS levels in the cells, this reduces the oxidative stress in RPE and therefore leads to increased cell viability and decreased cell apoptosis [ 52 , 103 ]. Some of the compounds studied are also found to be actively accumulated within the macular region of the eye, for example, carotenoids like lutein and zeaxanthin which are known as macular pigment [ 152 ].…”

Advancements in therapeutic drugs targeting of senescence

“…For example, a study by Hsieh et al has shown that L. barbarum could reduce cellular oxidative stress and protect cells from apoptosis. 74 In addition, it can alleviate inflammation and improve neurotransmission in neurodegenerative diseases, 75 and reduce insulin resistance induced by a high-fat diet. 76 The antioxidative mechanism of L. barbarum may be related to AMPK and Nrf2 pathways.…”

Lycium Barbarum Exerts Protection against Glaucoma-Like Injury Via Inhibition of MMP-9 Signaling In Vitro

“…The whole plant extract has also shown protection against oxidative and apoptotic effects in cultures of human lens epithelial cells [15,16]. A recent study has shown that the ethanolic extracts of L. barbarum exhibited significant protection on UVB-induced growth arrest of in human retinal pigment epithelial cells (ARPE-19) [17].…”