Surface-enhanced Raman spectroscopy (SERS) is an emerging and promising technique for the chemical analysis of food. The use of metallic nanosubstrates improves the sensitivity and capacity of conventional Raman spectroscopy greatly. This paper comprehensively reviews the development and applications of SERS in the chemical analysis of food, mainly focusing on food additives and chemical contaminants. The progress of SERS development and their applications in chemical analysis of food, from detection and characterization of target analytes in simple solvents to complex food matrices, is summarized. The advantages and limitations of different SERS substrates and methodologies are discussed. As most of the current SERS research on chemical analysis of food is still in an early stage, there are still several hurdles for further advancing SERS techniques into real-world applications for complex food products. This review includes our perspectives on the future trends of the SERS technique in the field of food analysis.

Scope Nobiletin (NBT) is a major citrus flavonoid with various health benefits. Herein, we investigated the colon cancer chemopreventive effects of NBT and its colonic metabolites in a colitis-associated colon carcinogenesis mouse model as well as in human colon cancer cell models. Methods and results In azoxymethane (AOM)/dextran sulfate sodium (DSS)-treated mice, oral administration of NBT effectively decreased both incidence and multiplicity of colonic tumors. NBT showed significant anti-proliferative, pro-apoptotic and anti-inflammatory effects in the mouse colon. HPLC analysis revealed that oral administration of NBT resulted in high levels of metabolites, i.e. 3′-demethylnobiletin (M1), 4′-demethylnobiletin (M2), and 3′, 4′-didemethylnobiletin (M3) in the colonic mucosa. In contrast, the colonic level of NBT was about 20-fold lower than the total colonic level of three metabolites. Cell culture studies demonstrated that the colonic metabolites of NBT significantly inhibited the growth of human colon cancer cells, caused cell cycle arrest, induced apoptosis, and profoundly modulated signaling proteins related with cell proliferation and cell death. All of these effects were much stronger than those produced by NBT alone. Conclusions Our results demonstrated that oral administration of NBT significantly inhibited colitis-associated colon carcinogenesis in mice, and this chemopreventive effect was strongly associated with its colonic metabolites.

Two novel cyclic hexapeptides containing both anthranilic acid and dehydroamino acid units, sclerotides A (1) and B (2), were isolated from the marine-derived halotolerant Aspergillus sclerotiorum PT06-1 in a nutrient-limited hypersaline medium. Both 1 and 2 are photointerconvertible and could be interconverted via a radical reaction initiated by direct photoisomerization. Both compounds showed moderate antifungal activity. Compound 2 also showed weak cytotoxicity and antibacterial activity.