Nature as a source of drugs for ophthalmology

Abstract

Nature has always provided an unlimited source of biologically-active compounds. Since the beginning of mankind, humans have sought resources in fauna and flora to treat eye diseases. However, it was only after the Industrial Revolution that extracts of plants and substances of animal origin could be used safely, as has been determined by controlled interventional studies. Two major challenges faced by ocular pharmacology are the following: developing drugs that are able to reduce blindness due to glaucoma; and controlling the pain associated with eye surgery. The search for a drug that effectively lowers intraocular pressure and controls the progression of glaucoma has led to the development of various ocular hypotensive agents, such as physostigmine from the Physostigma venenosum plant. The anesthetic properties of cocaine, extracted from Erythroxylon coca, finally enabled surgical procedures in the eye. Several new natural compounds have been investigated in an attempt to identify substances with the potential to provide additional benefits to eye tissue and vision. Emerging evidence of anti-inflammatory, wound-healing, antimicrobial, antioxidant, antitumor, and antiangiogenic properties attributed to plant extracts and animal tissues has encouraged more investment in research in this area. Despite technological advances in synthesizing drugs, the pharmaceutical industry still seeks new active compounds from natural sources as well as from revisiting already-established naturally derived compounds. Although a large number of naturally-occurring compounds is known, this review article focuses on the bioactive substances with scientifically-proven benefits for ocular tissues.

Flavonoids enhance rod opsin stability, folding, and self-association by directly binding to ligand-free opsin and modulating its conformation

“…The medical use of plants or plant extracts to prevent or treat various diseases has a long history and is still commonly practiced in developing countries (15)(16)(17)(18). The natural dietary polyphenol compounds, in particular flavonoids, ubiquitously present in fruits and vegetables, improve sight in several eye-related diseases, including age-related macular degeneration, glaucoma, RP, and diabetic retinopathy, most likely due to their anti-oxidant, anti-inflammatory, or anti-apoptotic properties (19 -23).…”

The Retinoid and Non-Retinoid Ligands of the Rod Visual G Protein-Coupled Receptor

“…Thus, natural products and compounds derived from natural product scaffolds could be a viable alternative to the discovery efforts for new drugs and therapies. Plants contain bioactive compounds that have been proven to have therapeutic effects for various human pathologies [52]. The utilization of plants and plant extracts for medical intervention has a long history and it is still currently practiced.…”

Leaky mutations in the zeaxanthin epoxidase in Capsicum annuum result in bright‐red fruit containing a high amount of zeaxanthin

“…Other health benefits of zeaxanthin include anti‐inflammatory effects, decreased risk of atherosclerosis, and protection against cancer (Black et al., 2020). Despite these benefits, most crops contain low zeaxanthin levels, hindering the ingestion of a sufficient amount from food (Perry et al., 2009; Pinheiro et al., 2018; Sajilata et al., 2008). The content of zeaxanthin in fruit‐bearing horticultural crops such as red peppers ( Capsicum spp.…”