COVID-19 and retinal degenerative diseases: Promising link "Kaempferol"

Abstract

Coronavirus disease (COVID-19) outbreak has caused unprecedented global disruption since 2020. Approximately 238 million people are affected worldwide where the elderly succumb to mortality. Post-COVID syndrome and its side effects have popped up with several health hazards, such as macular degeneration and vision loss. It thus necessitates better medical care and management of our dietary practices. Natural flavonoids have been included in traditional medicine and have also been used safely against COVID-19 and several other diseases. Kaempferol is an essential flavonoid that has been demonstrated to influence several vital cellular signaling pathways involved in apoptosis, angiogenesis, inflammation, and autophagy. In this review, we emphasize the plausible regulatory effects of Kaempferol on hallmarks of COVID-19 and macular degeneration.

Figure 1

Ultimate inflammasome activation and multiorgan damage under SARS-CoV-2 infection. SAR-CoV-2 downregulates ACE2 expression which leads to the accumulation of angiotensin II and upregulation of proinflammatory mediators; green circle entitled with P represents phosphorylation; arrow represents the induction.

Figure 2

Diagrammatic abstract of kaempferol against molecular web of pathogenesis. Kaempferol – (PubChem CID5280863); ER, Endoplasmic reticulum.

Figure 3

NLRP3 signalling and inflammasome formation. Kaempferol mitigates the cytokine storm by inhibiting caspase activation; Dotted arrow (Translocation into nucleus); Red represents the inhibition); Kaempferol- (PubChem CID5280863).

Figure 4

Potential benefits of kaempferol against oxidative stress in COVID-19 and retinal degeneration. Yellow spots represent the lipofuscin accumulation inside the retinal pigment epithelial cells (RPE); PR, Photoreceptors; BM, Bruch's membrane; CC, Choriocapillaris.

Figure 5

Modulation of autophagy by SARS-CoV-2. Kaempferol enhances the maturation of autophagosome to autolysosome in autophagy; DMV, Double-membrane vesicle; ER, Endoplasmic Reticulum; LC3, Microtubule-associated protein 1A/1B-light chain 3; PLpro-TM, membrane-anchored papain-like protease; NSP6, Non-structural Protein 6; Arrow shows the induction; Red represents the inhibition.

Figure 6

SARS-CoV-2 infection and UPR; S, SARS-CoV spike protein; E, SARS-CoV-2 envelope protein; 3a/ORF3a, SARS-CoV-2 Open Reading Frame 3a; Arrow shows the activation; Red represents the inhibition.