Three new [n-pentyl beta-carboline-1-propionate (1), 5-hydroxymethyl-9-methoxycanthin-6-one (2), and 1-hydroxy-9-methoxycanthin-6-one (3)] and 19 known beta-carboline alkaloids were isolated from the roots of Eurycoma longifolia. The new structures were determined by comprehensive analyses of their 1D and 2D NMR and mass spectral data and by chemical transformation. These compounds were screened for in vitro cytotoxic and antimalarial activities, and 9-methoxycanthin-6-one (4) and canthin-6-one (5) demonstrated significant cytotoxicity against human lung cancer (A-549) and human breast cancer (MCF-7) cell lines.

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Prostate cancer is the most prevalent type of cancer in the United States. The most common site of prostate cancer metastasis is bone. CXCL12 is preferentially expressed in bone and is targeted by prostate cancer cells, which over-express the receptor for CXCL12, CXCR4. In response to CXCL12 stimulation, Rac1, a GTPase, along with its effectors, regulates actin polymerization to form lamellipodia, which is a critical event for cell migration. Cortactin, an actin-binding protein, is recruited to the lamellipodia and is phosphorylated at tyrosine residues. The phosphorylated cortactin is also involved in cell migration. The inhibition of Rac1 activity using a dominant negative Rac1 impairs lamellipodial protrusion as well as cortactin translocation and cortactin phosphorylation. Denbinobin, a substance extracted from Dendrobium nobile, has anticancer effects in many cancer cell lines. Whether denbinobin can inhibit prostate cancer cell migration is not clear. Here, we report that denbinobin inhibited Rac1 activity. The inhibition of Rac1 activity prevented lamellipodial formation. Cortactin phosphorylation and translocation to the lamellipodia were also impaired, and PC3 cells were unable to migrate. These results indicate that denbinobin prevents CXCL12-induced PC3 cell migration by inhibiting Rac1 activity.

UV-guided isolation of polyacetylenes from Codonopsis pilosula has successfully led to the characterization of new polyynes and polyenes. The HCVcc infection assay was used to evaluate the anti-HCV activity of compounds 1–12.