Influence of olive leaf processing on the bioaccessibility of bioactive polyphenols.

Olive leaves are rich in bioactive compounds, which are beneficial for humans. The objective of this work was to assess the influence of processing conditions (drying and extraction) of olive leaves on the extract's bioaccessibility. Thus, extracts obtained from dried olive leaves (hot air drying at 70 and 120 °C or freeze-drying) by means of conventional or ultrasound-assisted extraction were subjected to in vitro digestion. Antioxidant capacity, total phenolic content, and HPLC-DAD/MS/MS analysis were carried out during digestion. The dehydration treatment used for the olive leaves did not have a meaningful influence on bioaccessibility. The digestion process significantly (p<0.05) affected the composition of the extracts. Oleuropein and verbascoside were quite resistant to gastric digestion but were largely degraded in the intestinal phase. Nevertheless, luteolin-7-O-glucoside was the most stable polyphenol during the in vitro simulation (43% bioaccessibility). Therefore, this compound may be taken into consideration in further studies that focus on the bioactivity of olive leaf extracts.

The human bitter taste receptor hTAS2R50 is activated by the two natural bitter terpenoids andrographolide and amarogentin.

Bitterness perception in mammals is mediated through activation of dedicated bitter taste receptors located in the oral cavity. Genomic analyses revealed the existence of orthologous mammalian bitter taste receptor genes, which presumably recognize the same compounds in different species, as well as species-specific receptor gene expansions believed to fulfill a critical role during evolution. In man, 8 of the 25 bitter taste receptors (hTAS2Rs) are closely related members of such an expanded subfamily of receptor genes. This study identified two natural bitter terpenoids, andrographolide and amarogentin, that are agonists for the orphan receptor hTAS2R50, the most distant member of the subfamily. This paper presents the pharmacological characterization of this receptor and analyzes its functional relationship with the previously deorphaned hTAS2R43, hTAS2R44, hTAS2R46, and hTAS2R47. Insights into the general breadth of tuning, functional redundancies, and relationships between pharmacological activation patterns and amino acid homologies for this receptor subfamily are presented.

Immunological cost of chemical defence and the evolution of herbivore diet breadth.

Selective pressures from host plant chemistry and natural enemies may contribute independently to driving insect herbivores towards narrow diet breadths. We used the specialist caterpillar, Junonia coenia (Nymphalidae), which sequesters defensive compounds, iridoid glycosides, from its host plants to assess the effects of plant chemistry and sequestration on the larval immune response. A series of experiments using implanted glass beads to challenge immune function showed that larvae feeding on diets with high concentrations of iridoid glycosides are more likely to have their immune response compromised than those feeding on diets low in these compounds. These results indicate that larvae feeding on plants with high concentrations of toxins might be more poorly defended against parasitoids, while at the same time being better defended against predators, suggesting that predators and parasitoids can exert different selective pressures on the evolution of herbivore diet breadth.

Nuclear factor-kappaB bioluminescence imaging-guided transcriptomic analysis for the assessment of host-biomaterial interaction in vivo.

Establishment of a comprehensive platform for the assessment of host-biomaterial interaction in vivo is an important issue. Nuclear factor-kappaB (NF-kappaB) is an inducible transcription factor that is activated by numerous stimuli. Therefore, NF-kappaB-dependent luminescent signal in transgenic mice carrying the luciferase genes was used as the guide to monitor the biomaterials-affected organs, and transcriptomic analysis was further applied to evaluate the complex host responses in affected organs in this study. In vivo imaging showed that genipin-cross-linked gelatin conduit (GGC) implantation evoked the strong NF-kappaB activity at 6h in the implanted region, and transcriptomic analysis showed that the expressions of interleukin-6 (IL-6), IL-24, and IL-1 family were up-regulated. A strong luminescent signal was observed in spleen on 14 d, suggesting that GGC implantation might elicit the biological events in spleen. Transcriptomic analysis of spleen showed that 13 Kyoto Encyclopedia of Genes and Genomes pathways belonging to cell cycles, immune responses, and metabolism were significantly altered by GGC implants. Connectivity Map analysis suggested that the gene signatures of GGC were similar to those of compounds that affect lipid or glucose metabolism. GeneSetTest analysis further showed that host responses to GGC implants might be related to diseases states, especially the metabolic and cardiovascular diseases. In conclusion, our data provided a concept of molecular imaging-guided transcriptomic platform for the evaluation and the prediction of host-biomaterial interaction in vivo.

Noninvasive nuclear factor-kappaB bioluminescence imaging for the assessment of host-biomaterial interaction in transgenic mice.

The inflammatory response is a key component in the biocompatibility of biomaterials. Among the factors that control the development of inflammation is a critical molecule nuclear factor-kappaB (NF-kappaB). Therefore, the aim of this study was to assess the feasibility of noninvasive whole-body real-time imaging for the evaluation of host-biomaterial interaction in the NF-kappaB transgenic mice. Transgenic mice, carrying the luciferase gene under the control of NF-kappaB, were constructed. In vivo bioluminescence imaging showed that the constitutive and induced NF-kappaB activities of transgenic mice were detected in most of the lymphoid tissues, demonstrating that NF-kappaB-driven luminescence reflected the inflammatory response in vivo. By the implantation of genipin-cross-linked gelatin conduit (GGC) and bacterial endotoxin-immersed GGC in the dorsal region, we detected a strong and specific luminescent signal from the tissue around the bacterial endotoxin-immersed GGC implant. Histological and immunohistochemical analysis also demonstrated that inflammation, characterized by the infiltration of immune cells, the accumulation of fluid, and the activation of NF-kappaB, was evoked around the same region. The correlation between the bioluminescence imaging and histological changes indicated that noninvasive imaging technique could be used to monitor the real-time inflammation in the implanted mice.