Metabolites2012.2 310 Figure 4.Betulinic acid (13).Bevirimat (PA-457)(14)and Ganoderic acid B(15) HO 13 In 2002,amrubicin hydrochloride(16),related to the anthracycline,doxorubicin(17)(Adriamycin), was isolated from the fungus Streptomyces peucetius.Doxorubicin (17)is used to treat acute leukaemia,soft tissue and bone sarcomas,lung cancer,thyroid cancer and both Hodgkins and non-Hodgkins lymphomas (Figure 5)[5.26].Torrevanic acid (18)was isolated from an endophvte from the endangered tree,Torreya laxifolia [53]and was tested in several cancer cell lines and found to display 5-10 times greater potentency/cytotoxicity in cell lines that are sensitive to protein kinaseC causing cell death by apoptosis(Figure 5)[54]. Figure 5.Amrubicin hydrochloride(16),Doxorubicin(17)and Torreyanic acid(18). OH HO.C NH CH. H 00H6 H CH OH 。 17 2.2.Natural Products from Plants Plants have been well documented for their medicinal uses for thousands of years.They have evolved and adapted over millions of years to withstand bacteria,insects,fungi and weather to produce unique.structurally diverse secondary metabolites.Their ethnopharmacological properties have been used as a primary source of medicines for early drug discovery [55,56].According to the World Health Organization (WHO).80%of people still rely on plant-based traditional medicines for primary health care [57]and 80%of 122 plant derived drugs were related to their original ethnopharmacological purpose [58].The knowledge associated with traditional medicine (complementary or alternative herbal products)has promoted further investigations of medicinal plants as potential medicines and has led to the isolation of many natural products that have become well known pharmaceuticals. The most widely used breast cancer drug is paclitaxel(Taxol)(19),isolated from the bark of Taxus brevifolia (Pacific Yew).In 1962 the United States Department of Agriculture (USDA)first collected the bark as part of their exploratory plant screening program at the National Cancer InstituteMetabolites 2012, 2 310 Figure 4. Betulinic acid (13), Bevirimat (PA-457) (14) and Ganoderic acid β (15). In 2002, amrubicin hydrochloride (16), related to the anthracycline, doxorubicin (17) (Adriamycin®), was isolated from the fungus Streptomyces peucetius. Doxorubicin (17) is used to treat acute leukaemia, soft tissue and bone sarcomas, lung cancer, thyroid cancer and both Hodgkins and non-Hodgkins lymphomas (Figure 5) [5,26]. Torreyanic acid (18) was isolated from an endophyte from the endangered tree, Torreya taxifolia [53] and was tested in several cancer cell lines and found to display 5–10 times greater potentency/cytotoxicity in cell lines that are sensitive to protein kinase C causing cell death by apoptosis (Figure 5) [54]. Figure 5. Amrubicin hydrochloride (16), Doxorubicin (17) and Torreyanic acid (18). 2.2. Natural Products from Plants Plants have been well documented for their medicinal uses for thousands of years. They have evolved and adapted over millions of years to withstand bacteria, insects, fungi and weather to produce unique, structurally diverse secondary metabolites. Their ethnopharmacological properties have been used as a primary source of medicines for early drug discovery [55,56]. According to the World Health Organization (WHO), 80% of people still rely on plant-based traditional medicines for primary health care [57] and 80% of 122 plant derived drugs were related to their original ethnopharmacological purpose [58]. The knowledge associated with traditional medicine (complementary or alternative herbal products) has promoted further investigations of medicinal plants as potential medicines and has led to the isolation of many natural products that have become well known pharmaceuticals. The most widely used breast cancer drug is paclitaxel (Taxol®) (19), isolated from the bark of Taxus brevifolia (Pacific Yew). In 1962 the United States Department of Agriculture (USDA) first collected the bark as part of their exploratory plant screening program at the National Cancer Institute