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Targeted therapies, such as agents that inhibit angiogenesis, offer hope as complementary agents in cancer therapy. Angiogenesis-inhibiting agents have the potential for inhibiting tumor growth and limiting the dissemination of metastasis, thus keeping cancers in a static growth state for prolonged periods. Black raspberry (Rubus occidentalis) extract was discovered to be antiangiogenic (0.1% w/v) in a novel human tissue-based in vitro fibrin clot angiogenesis assay. Assay-guided fractionation of a crude black raspberry extract resulted in a highly potent antiangiogenic fraction that accounted for only 1% of the fresh weight of whole black raspberries. At 0.075% (w/v), the active fraction completely inhibited angiogenic initiation and angiogenic vessel growth. Further subfractionation of this active fraction revealed the coexistence of multiple antiangiogenic compounds, one of which has been identified as gallic acid. However, the individual subfractions did not outperform the active whole fraction. These findings suggest that an active black raspberry fraction may be a promising complementary cancer therapy. It is natural and potent enough for manageable dosing regimens. These extracts contain multiple active ingredients that may be additive or synergistic in their antiangiogenic effects. These observations warrant further investigations in animals and human trials.

The in vivo test on the chorioallantoic membrane of the fertilized hen's egg (CAM assay) is a current method to determine antiangiogenic, antiinflammatory activity and toxic effects of individual compounds or complex plant extracts. The method is used for testing natural compounds in small amounts for revealing various modes of action and the complex mechanisms related to angiogenesis and inflammation. Furthermore, possible side effects such as membrane irritation, toxic, and anticoagulant properties of the investigated material in question can be detected. For the evaluation, the essential oil obtained by hydrodistillation of the aerial parts of Origanum onites L., a common spice and medicinal plant, was tested for its effect in the chorioallantoic membrane (CAM) assay. The essential oil composition was revealed by means of gas chromatography-mass spectrometry (GC-MS). Eighty three components were identified, representing 99.1% of the total oil. Carvacrol, thymol, p-cymene, and gamma-terpinene were found as major components and were also individually tested in the CAM assay. Along with the monoterpenes carvacrol and thymol, their methyl ether derivatives were also examined for comparison of their physiological action. Neither the essential oil nor its components showed any pronounced antiinflammatory or antiangiogenic property in the CAM assay, at 10-250 microg/pellet. However, the irritant effect of the essential oil was linked to thymol in a dose-response fashion, up to 10 microg/pellet, where it was still showing irritation.