Applying a bioactivity-guided isolation strategy for the ethanolic extract of crown gall tumours induced on an Eucalyptus tereticornis tree, two new compounds in addition to a known one were isolated. The new compounds were identified as an amino acid derivative named 1-ethyl-6-(1´-methyl-1´-phenylethyl) piperidin-2-one (1) and a lanostane tetracyclic triterpene named 3β-hydroxy-24-methyllanosta-8,17(20),24(28)-trien-22-oic acid (2), together with stigmasterol-3-O-glucoside (3). The three compounds exhibited significant cytotoxic activity against two human cell lines, breast (MCF7) and colon (HCT116), with IC50 values of 1.01, 1.54, and 2.15 μg/ml, respectively, against MCF7 and 3.49, 3.83, and 3.39 μg/ ml, respectively, against HCT116. Furthermore, in rats elevated levels of blood cholesterol, triglycerides, and low-density lipoprotein (LDLc) were significantly reduced, while the level of high-density lipoprotein (HDLc) was significantly increased by administration of the ethanolic extract as well as of 3. These results support a correlation between the reduction of blood cholesterol levels and improvement of colorectal cancer.
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