Effects of Chinese herbal products on mammalian retinal functions

Ocular ischemia and inflammation are two major factors which induce retinal degeneration. Treatment of these diseases has been difficult, though numerous agents have been tried. Natural products could be a good field to venture into because various medicinal plants have been used for centuries to treat circulation stasis, inflammation, visual disturbances, and eyesight failure. Tetramethylpyrazine, coumarin, methyl tyramine, rescinnamine, apocynin, and hesperetin are some natural products isolated from Chinese herbs for improving ocular blood flow, particularly in the choroid and retina. For ocular inflammation, at least a dozen natural products are reviewed in this article. Among those, matrine, tetrandrine and osthole draw particular attention, because they are effective mainly as interleukin-l blockers, but not as arachidonate blockers. As a result, these agents are potent anti-inflammatory agents and are even more potent than the prototype corticosteroid, prednisolone. It is hoped that all aforementioned agents can be used to treat retinopathies resulting from ocular ischemia and/or ocular inflammation. Scoparone, corylifolinin, epigallocatechin-3-0-gallate, esculetin, and lespedezaflavanone A are some natural products which can improve retinal functions measured with electroretinogram's b-wave recovery. Further research should be carried out to relate natural products which can improve ocular blood flow and inflammation to retinal function and vice versa.