Treatment of Glaucoma with Natural Products and Their Mechanism of Action: An Update

Abstract

Glaucoma is one of the leading causes of irreversible blindness. It is generally caused by increased intraocular pressure, which results in damage of the optic nerve and retinal ganglion cells, ultimately leading to visual field dysfunction. However, even with the use of intraocular pressure-lowering eye drops, the disease still progresses in some patients. In addition to mechanical and vascular dysfunctions of the eye, oxidative stress, neuroinflammation and excitotoxicity have also been implicated in the pathogenesis of glaucoma. Hence, the use of natural products with antioxidant and anti-inflammatory properties may represent an alternative approach for glaucoma treatment. The present review highlights recent preclinical and clinical studies on various natural products shown to possess neuroprotective properties for retinal ganglion cells, which thereby may be effective in the treatment of glaucoma. Intraocular pressure can be reduced by baicalein, forskolin, marijuana, ginsenoside, resveratrol and hesperidin. Alternatively, Ginkgo biloba, Lycium barbarum, Diospyros kaki, Tripterygium wilfordii, saffron, curcumin, caffeine, anthocyanin, coenzyme Q10 and vitamins B3 and D have shown neuroprotective effects on retinal ganglion cells via various mechanisms, especially antioxidant, anti-inflammatory and anti-apoptosis mechanisms. Extensive studies are still required in the future to ensure natural products’ efficacy and safety to serve as an alternative therapy for glaucoma.

The Tower of Babel of Pharma-Food Study on Extra Virgin Olive Oil Polyphenols

“…For these reasons, the search for natural products with anti-inflammatory activity has been the subject of several studies. Among them, EVOO phenolic compounds have been well proven for their anti-inflammatory activity [7,[77][78][79][80][81]. In this regard, in our previous work, we extensively reported and discussed the close correlation between the chemical characterization of EVOO polyphenols, anti-inflammatory potential, and biological activities in human studies [80].…”

Diet, Oxidative Stress, and Blood Serum Nutrients in Various Types of Glaucoma: A Systematic Review

“…It is a potent antioxidant and protective agent, and its effects have been shown in neurodegenerative diseases, including Leber Hereditary Optic Atrophy, Parkinson’s disease, and Huntington’s diseases [ 25 , 26 ]; it also has an effect on retinal ganglion cells (RGCs) [ 27 ]. In preclinical trails [ 28 , 29 , 30 ], topically administrated CoQ 10 helped reduce the levels of extracellular glutamate, retinal damage, and cellular apoptosis. Treatment with the active form of CoQ 10 —ubiquinol—also enhances the survival rate of RGCs by decreasing apoptosis and increasing the expression of TFAM/oxidative phosphorylation (OXPHOS) complex 2 protein [ 25 , 28 ].…”

“…Treatment with the active form of CoQ 10 —ubiquinol—also enhances the survival rate of RGCs by decreasing apoptosis and increasing the expression of TFAM/oxidative phosphorylation (OXPHOS) complex 2 protein [ 25 , 28 ]. CoQ 10 along with α-tocopherol (vitamin E) in POAG patients improved the retinal biometric responses (pattern electroretinogram improvement) and bioelectric cortical responses (visual evoked potentials improvement) [ 28 , 30 , 31 , 32 , 33 ].…”

Current situation and progress of drugs for reducing intraocular pressure

“… 82 These glaucoma supplements are also natural products, most of which have antioxidant and anti-inflammatory properties, and they are readily available and cost-effective. 106 Although a series of experimental studies and clinical trials have shown that these drugs exhibit IOP-lowering or optic neuroprotective effects, they still cannot replace conventional glaucoma drugs for stand-alone treatment. They need to be tested repeatedly and pass approval before they can truly become part of adjuvant glaucoma treatment.…”