A review of medicinal plants that modulate nitric oxide activity

Modulation of nitric oxide (NO) may offer novel approaches in the treatment of a variety of diseases, such as Alzheimer’s, cardiovascular disease, and diabetes. A strategy in the modulation of NO expression may be through the use of herbal medicines. We surveyed medicinal plant research that utilized multicomponent extracts similar to what is used in clinical phytotherapy or in commerce, for demonstrated effects on NO activity. SciFinder Scholar, Pubmed, Web of Science, and BIOSIS were searched to identify human, animal, in vivo, ex vivo or in vitro research on botanical medicines, in whole or standardized form, that act on nitric oxide activity. iNOS was the most frequently investigated enzyme system and this system was up-regulated by many plant extracts, including, Chicorium intybus, Cocos nucifera, Echinacea purpurea, Euonymus alatus, Ixeris dentate, Oldenlandia diffusa, Rhinacanthus nasutus, and Sida cordifolia. Many plant extracts down-regulated iNOS, including Centella asiatica, Dichroa Febrifuga, Echinacea purpurea, Evolvulus alsinoides, Fagonia cretica, Ginkgo biloba, Mollugo verticillata, Lactuca indica, Lithospermum erythrorhizon, Pueraria thunbergiana, and Taraxacum officinale. The eNOS system was stimulated by Eucommia ulmoides, Sida cordifolia, and Thymus pulegioides while Fagonia cretica, Rubia cordifolia and Tinospora cordifolia down-regulated nNOS. Given the activity demonstrated by many of these herbal medicines, the increasing awareness of the effects of nitric oxide on a wide variety of disease processes and the growing incidence of these conditions in the population, further study of medicinal plants on nitric oxide signaling may lead to novel therapies and further insight into human physiology.