COMPOUNDS FROM PEPPER FLOWERS AND FRUITS AS POTENTIAL ATTRACTANTS FOR THE CAPTURE OF PEPPER WEEVIL

Two field experiments were conducted to evaluate synthetic attractants derived from pepper flowers, flower buds and fruits, alone or in combination with the aggregation pheromone. The evaluation was carried out with the release and recapture of Anthonomus eugenii adults at different distances from the four cardinal points in separate trials. The volatility of the synthetic mixture and aggregation pheromone was determined by gas chromatographic analysis of the volatiles captured by dynamic headspace. The traps with synthetic mixture and essential oil captured insects at 10 m, while the aggregation pheromone trapped up to 60 m. The combination of synthetic mixture or essential oil with the aggregation pheromone did not increase the number of recaptures compared to the single pheromone. The synthetic mixture together with geranic acid recaptured adults up to 15 m, although they were not significantly different from the control. The exclusion of geranic acid from the aggregation pheromone significantly reduced the number of recaptured insects (P<0.05), while geranic acid alone failed to capture weevils. The results could be improved by increasing the concentrations of the compounds or by adding other compounds released during the reproductive stages of pepper. These results could guide future efforts for the development of tools based on synthetic plant volatiles for the monitoring of this pest.

Isoprenoid Derivatives of Lysophosphatidylcholines Enhance Insulin and GLP-1 Secretion through Lipid-Binding GPCRs

Insulin plays a significant role in carbohydrate homeostasis as the blood glucose lowering hormone. Glucose-induced insulin secretion (GSIS) is augmented by glucagon-like peptide (GLP-1), a gastrointestinal peptide released in response to ingesting nutriments. The secretion of insulin and GLP-1 is mediated by the binding of nutrients to G protein-coupled receptors (GPCRs) expressed by pancreatic β-cells and enteroendocrine cells, respectively. Therefore, insulin secretagogues and incretin mimetics currently serve as antidiabetic treatments. This study demonstrates the potency of synthetic isoprenoid derivatives of lysophosphatidylcholines (LPCs) to stimulate GSIS and GLP-1 release. Murine insulinoma cell line (MIN6) and enteroendocrinal L cells (GLUTag) were incubated with LPCs bearing geranic acid (1-GA-LPC), citronellic acid (1-CA-LPC), 3,7-dimethyl-3-vinyloct-6-enoic acid (GERA-LPC), and (E)-3,7,11-trimethyl- 3-vinyldodeca-6,10-dienoic acid (1-FARA-LPC). Respective free terpene acids were also tested for comparison. Besides their insulin- and GLP-1-secreting capabilities, we also investigated the cytotoxicity of tested compounds, the ability to intracellular calcium ion mobilization, and targeted GPCRs involved in maintaining lipid and carbohydrate homeostasis. We observed the high cytotoxicity of 1-GERA-LPC and 1-FARA-LPC in contrast 1-CA-LPC and 1-GA-LPC. Moreover, 1-CA-LPC and 1-GA-LPC demonstrated the stimulatory effect on GSIS and 1-CA-LPC augmented GLP-1 secretion. Insulin and GLP-1 release appeared to be GPR40-, GPR55-, GPR119- and GPR120-dependent.

Biosyntheses of geranic acid and citronellic acid from monoterpene alcohols by Saccharomyces cerevisiae

ABSTRACT Geraniol is one of the important aromatic ingredients in alcoholic beverages. Bioconversions of geraniol to other terpenoids and genes involved in the oxidation of geraniol were investigated. Geranic acid and citronellic acid were detected in yeast culture, where geraniol or nerol was added. Addition of citral, a mixture of geranial and neral, resulted in the production of geranic acid and citronellic acid, whereas the addition of citral or citronellal resulted in the production of citronellic acid, suggesting that citronellic acid might be produced through the conversion of citral to citronellal followed by the oxidation of citronellal. Consumption of geraniol and production of geranic acid, citronellic acid, and citronellol were affected in adh1Δ, adh3Δ, adh4Δ, and sfa1Δ yeast strains, which possess single deletion of a gene encoding alcohol dehydrogenase. This is the first report of the bioconversion of monoterpene alcohols, geraniol and nerol, to geranic acid and citronellic acid in yeast culture.

CHEMICAL COMPOSITION AND BIOLOGICAL ACTIVITIES ASSESS-MENT OF OLIVE FRUIT VOLATILES FROM DIFFERENT VARIETIES GROWN IN TUNISIA

Volatile compounds, present in olives, are responsible for the olive fruit flavor and oil aroma, influencing the consumer’s preference. These compounds have a biological activity to fight off pathogens. The aim of this work is to characterize volatiles in pulps and cores of Chemlali, Arbequina and Koroneiki olives, collected from Menzel Mhiri-Kairouan, and to test both the efficiency of these compounds against two bacteria and six phytopathogenic fungal species, by diffusion and dilution methods, and their antioxidants activities. The analyzis of volatiles were determined by GC-FID and GC-MS in three cultivars at the full ripening stage. Thirty five compounds were identified, such us an assortment of phenol, alcohol, hydrocarbon, aldehyde and terpenes derivatives. A high changes in volatiles was noted between cultivars and fruit organs. In fact, the major compounds in the pulps and the cores, of different cultivars, are (E)-2-decenal (46.9%), nonanal (19.6%), 1-hexadecene (16.3%), 7-Methyl-1,3,5-cycloheptatriene 7-Methyl-1,3,5-Cycloheptatriene (15.47%), (E,E)-2,4-decadienal (14.5%) and 1-tetradecene (14.6%). Also, the cores volatiles illustrated more richness in aldehydes than the pulps for all cultivars. Volatile fractions exhibited a moderate to important antibacterial activities against bacteria. However, Arbequina cores volatiles and both Chemlali and Koroneiki pulps volatiles established a moderate to higher activities against tested fungi. The DPPH and ABTS•+ tests demonstrated that the highest antioxidant capacity of volatiles were assigned to Arbequina cores and Koroneiki pulps. The Principal Components Analysis showed a significant relationship between antioxidants and/or antimicrobial properties and the levels of the main volatile compounds (limonene, methyldecane, nonanal, E-2-decenal, camphor, geranic acid, tetradecene, hexadecane, tetradecane) in different fruit organs.