This review focuses on the synthesis and biological activity of flavones and their related flavonoidic compounds: flavonols and aurones. Among the biological activities of flavones and aurones, the anticancer, antioxidant and antimicrobial properties are highlighted and detailed in this review. The most applied method for the synthesis of flavones and aurones is based on the oxidative cyclisation of o-hydroxychalcones. Depending on the reaction conditions and the structure of the precursor, in some cases several cyclization products result simultaneously: flavones, flavanones, flavonols and aurones. Based on the literature data and the results obtained in our research group, our aim is to highlight the most promising methods for the synthesis of flavones, as well as the synthetic routes for the other structurally related cyclization products, hydroxyflavones and aurones, considering that in practice it is difficult to predict which is the main or exclusive cyclisation product of o-hydroxychalcones under certain reaction conditions.

Flavonoids are a biochemically diverse group of specialized metabolites in plants that are derived from phenylalanine. While the biosynthesis of the flavonoid aglycone is highly conserved across species and well characterized, numerous species-specific decoration steps and their relevance remained largely unexplored. The flavonoid biosynthesis takes place at the cytosolic site of the endoplasmatic reticulum (ER), but accumulation of various flavonoids was observed in the central vacuole. A universal explanation for the subcellular transport of flavonoids has eluded researchers for decades. Current knowledge suggests that a glutathione S-transferase-like protein (ligandin) protects anthocyanins and potentially proanthocyanidin precursors during the transport to the central vacuole. ABCC transporters and to a lower extend MATE transporters sequester anthocyanins into the vacuole. Glycosides of specific proanthocyanidin precursors are sequestered through MATE transporters. A P-ATPase in the tonoplast and potentially other proteins generate the proton gradient that is required for the MATE-mediated antiport. Vesicle-mediated transport of flavonoids from the ER to the vacuole is considered as an alternative or additional route.

Cestrum parqui L'Herit. (Solanaceae family) is a species of forest shrub, self-incompatible and specialized in pollination, widespread in the subtropical area of the planet and now widely dis-tributed also in the Mediterranean area. The constituents of its leaves have antimicrobial, anti-cancer, insecticidal, antifeedant, and herbicidal properties. The spread of this species represents a valuable source of compounds with high biological value. Research on potential uses, under-standing of the nutritional and functional composition, and applications of C. parqui extracts is important and very promising for its commercial use. To date, there are some reports on the potential applications of C. parqui extracts as selective natural pesticides and for their potential phytotoxic role. Scientific knowledge and the use of extraction techniques for these components are essential for commercial applications. This article summarizes the research and recent studies available on the botany, phytochemistry, functional properties, and commercial applications of C. parqui as a biopesticide.

The purpose of this investigation was to prepare a water-soluble complex by encapsulation of propolis extract with the carrier 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and to examine the influence of in vitro simulated gastrointestinal digestion (GID) on the content of the main polyphenolic groups when administered as aqueous suspension. The research was conducted on two continental samples of propolis from Croatia and a mixture of selected polyphenol standards. By applying UAE followed by a lyophilization procedure, it was possible to obtain a powder with a high content of polyphenols. The content of total phenols (TPs), total flavonols/flavones (TFFs) and total flavanones/dihydroflavonols (TFDs) in the fractions of oral and gastric phase and small intestinal phase performed with two models: centrifugation and dialysis through a semi-permeable membrane, was determined by three UV/Vis spectrophotometric methods: Folin-Ciocalteu, aluminium complexation and 2,4-dinitrophenylhydrazine method. The obtained results for both propolis complexes showed stability in the polyphenol content and high bioaccessibility during all three phases of digestion. The bioaccessibility of TPs, TFFs and TFDs under in vitro conditions after dialysis through a semipermeable membrane was lower compared to the intestinal phase model with centrifugation.