Cytokine-mimetic properties of some Philippine food and medicinal plants.

This study evaluated Philippine indigenous plants for cytokine-mimetic properties and partially characterized candidate mimetics for their stability as well as their sensitivity to variations in temperature and pH. Forty-five plant extract preparations were tested for their ability to stimulate proliferation of mouse spleen cells and bone marrow cells. Temperature and pH effects were determined by subjecting the extracts to different temperature and pH levels and measuring their residual proliferative activities. Results revealed that 24 and 14 extracts were able to stimulate proliferation of bone marrow cells and spleen cells, respectively. Extracts from yam (Dioscorea alata L.) (Dioscoreaceae) roots and leaves, taro (Colocasia esculenta L.) (Araceae) roots, and buyo (Piper betle L.) (Piperaceae) leaf were among the extracts that strongly stimulated proliferation of both bone marrow cells and splenocytes, significantly increasing cell concentrations. Heating the extracts beyond 40 degrees C markedly reduced their proliferative ability, while a pH level below 4.0 and above 8.0 also significantly decreased the extracts' activity. Three protein-mimetics with sizes of 26 kDa, 35 kDa, and 50 kDa were isolated from buyo leaf, yam root, and taro root extracts, respectively. All three molecules are biologically active and stimulate a dose-dependent proliferative response.