Editorial (Thematic Issue: Natural Products in Cancer Prevention and Therapy, a selection of topics presented in the 2nd Edition PSE Symposium (Naples, Italy, 25th to 28th of June 2013))

Scientists have brought an interesting trend in pharmaceutical development since the beginning of 21 century: return to nature as a source of potential drugs. However, in spite of the advances in the comprehension of benefits of natural products in medicinal applications, only little therapeutic progress was recorded for cancer disease. New strategies related to natural medicines are developing with focus on their possible role in chemoprevention and chemosensitization. This issue has been the focus of the Congress on Natural Products in Cancer Prevention and Therapy, 2 Edition. This meeting hosted by the University of Naples Federico II on behalf of the Phytochemical Society of Europe was held in Naples, Italy from 25th to 28th of June 2013. The aim of this congress was the presentation of recent results, discussion of trends, and exchange of ideas related to the medicinal chemistry aspects of natural products in cancer prevention and therapy. This special issue based on selected contributions of speakers presenting lectures at the symposium will focus on the natural compounds from plants, foods and other natural sources used in cancer therapy and chemoprevention. Colorectal cancer is a leading cause of cancer mortality in the industrialized world, second to lung cancer. Navarra and co-workers reported that the Citrus bergamia juice extract inhibited the proliferation in human colon cancer HT-29 cells. High dose of Citrus bergamia juice extract (2.5 mg/ml) enhanced ROS production, which lead to loss in mitochondrial membrane potential and oxidative DNA damage in HT-29 cells. However, low dose of Citrus bergamia juice extract (1 mg/ml) was found to inhibit ERK and p38 phosphorylation and altering apoptosis-related proteins (p21, Bax, Bcl-2 and Bcl-XL), which in turn reduced cell proliferation by inducing cell cycle arrest and apoptosis. Lorenzetti and coworkers investigated the effects of several plant bioactive polyphenols, such as apigenin, genistein, luteolin, naringenin, quercetin and resveratrol, on inhibiting DHT-induced prostate-specific antigen secretion on human metastatic prostate adenocarcinoma LNCaP cells. It was found that selected flavonoids could inhibit the secretion of prostate-specific antigen in a wide range of concentrations from 1pM to 100mM. Bour et al. investigated the anti-cancer activities of antofine N-oxide isolated from the the medicinal plant Cynanchum vincetoxicum. Antofine N-oxide showed a significant cytotoxic effect on several solid tumor cell lines (glioblastoma, breast carcinoma and lung carcinoma) and T-cell leukemia. It was interesting to find that a number of genes in TNFα signaling pathway were up-regulated in these three solid tumor cell lines. Natural polyphenols exhibit benefits in a wide variety of pathophysiological settings. Biasutto et al. summarized the development of effective prodrugs of polyphenols. Biomedical applications of polyphenols are severely hindered by their low bioavailability, rapid metabolism, and generally low water solubility. Polyphenols derivatives are under development with the aim of improving their bioavailability and/or bioefficacy. Thus, the drugs are modified by chemical reaction of the hydroxyl groups to not hinder permeation of epithelia, to prevent conjugative modifications during absorption and first-pass through the liver; and to be eliminated with opportune kinetics to regenerate the parent compound.