The invention relates to nitric oxide (NO) stimulating extracts from various plants. Such extracts contain compounds known as healthin I and healthin II. Specifically, the invention provides partially purified plant extracts that have NO stimulating activity, methods of isolating and partially purifying such extracts from plant materials. In addition, the invention provides methods and materials for treating diseases and conditions that require modification of cellular levels of NO, for example, diseases and conditions involving inflammation.