Is Exogenous Fatty Acid Hydroperoxide Perception as Elicitor Related to Modulation of Plant Plasma Membrane Structure ?

Oxylipins are lipid-derived molecules that are ubiquitous in eukaryotes and whose functions in plant physiology have been widely reported. They appear to play a major role in plant immunity by orchestrating reactive oxygen species (ROS) and hormone-dependent signalling pathways. The present work focuses on the specific case of fatty acid hydroperoxides (HPOs). Although some studies report their potential use as exogenous biocontrol agents for plant protection, evaluation of their efficiency in planta is lacking and no information is available about their mechanism of action. In this work, the potential of 13(S)-hydroperoxyoctadeca-(9Z,11E)-dienoic acid (13-HPOD) and 13(S)-hydroperoxy-(9Z,11E,15Z)-octadecatrienoic acid (13-HPOT), as plant defence elicitors and the underlying mechanism of action are investigated. Arabidopsis thaliana leaf resistance to Botrytis cinerea was observed after root application with HPOs. They also activate early immunity-related defence responses, like ROS. As previous studies have demonstrated their ability to interact with plant plasma membranes (PPM), we have further investigated the effects of HPOs on biomimetic PPM structure using complementary biophysics tools. Results show that HPO insertion into PPM impacts its global structure without solubilizing it. Relationship between biological assays and biophysical analysis suggests that lipid amphiphilic elicitors that directly act on membrane lipids might trigger early plant defence events

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.

GC-MS ANALYSIS OF PHYTOCHEMICALS FROM THE EXTRACT OF Hibiscus sabdariffa GROWN IN NORTHERN NIGERIA

Hibiscus sabdariffa, also known as Roselle belongs to Malvacae family. It is popularly known in Nigeria as Zobo. It has been used traditionally to cure certain ailments like cold, due to its rich pharmacological potential. Hence this study aimed at validating the pharmacological potential of Hibiscus sabdariffa by identification of the compounds present in its leaves using GC-MS technique. The extract was obtained by heating the leaves in ethanol under reflux. The ethanol extract was then subjected to GC-MS analysis. The constituents were identified by comparing their mass fragmentation (MS) pattern with those gathered in the library of NIST-MS and with those reported in literature. The graph obtained from the study revealed the presence of nine (9) organic compounds in Hibiscus sabdariffa leaf extract (HSLE) namely cyclohexane carboxylic acid ester, cyclopropane carboxylic acid methyl ester, hexanoic acid-4-octyl ester, hexadeca-2-11-dienoic acid, n-hexadecanoic acid, oleic acid, octadecanoic acid, E-13-docosenoic acid and E-11-hexadecanal. Oleic acid has the highest peak value with the retention time of 20.711 which makes it the most abundant fraction and the active ingredient in the HSLE. The presence of some of these bioactive compounds has proved the scientific evidences for the antihypertensive and anti-inflammatory properties of the plant.

20-HETE-promoted cerebral blow flow autoregulation is associated with enhanced α-smooth muscle actin positive cerebrovascular pericyte contractility

ABSTRACTWe previously reported that deficiency in 20-HETE or CYP4A impaired the myogenic response and autoregulation of cerebral blood flow (CBF) in rats. The present study demonstrated that CYP4A was coexpressed with alpha-smooth muscle actin (α-SMA) in vascular smooth muscle cells (VSMCs) and most pericytes along parenchymal arteries (PAs) isolated from SD rats. Cell contractile capabilities of cerebral VSMCs and pericytes were reduced with a 20-HETE synthesis inhibitor, N-Hydroxy-N′-(4-butyl-2-methylphenyl)-formamidine (HET0016) but restored with 20-HETE analog 20-hydroxyeicosa-5(Z),14(Z)-dienoic acid (WIT003). Similarly, intact myogenic responses of the middle cerebral artery and PA of SD rats decreased with HET0016 and rescued by WIT003. Lastly, HET0016 impaired well autoregulated CBF in the surface and deep cortex of SD rats. These results demonstrate that 20-HETE has a direct effect on cerebral mural cell contractility that may play an essential role in CBF autoregulation.

CHEMICAL CONSTITUENTS FROM POLYGONATUM KINGIANUM COLL. ET HEMSL. OF VIETNAM

Seven compounds, including two homoisoflavanones 3-(2ʹ-hydroxy-4ʹ-methoxy-benzyl)-5,7-dihydroxy-8-methyl-chroman-4-one (1), disporopsin (2) along with 2-O-methyl-α-D-fructofuranose (3), (E,E)-9-oxooctadeca-10,12-dienoic acid (4), 1-palmitoylglycerol (5), 5α,8α-ergosterol peroxide (6), daucosterol (7) were isolated from the rhizomes of Polygonatum kingianum of Vietnam. Their structures were determined by 1D and 2D NMR spectra and by comparison with the reported spectral data. Compounds 3, 4 and 6 are first reported from the genus Polygonatum. Compound 1 and 5 are reported for the first time from Polygonatum kingianum.

Bee Bread: Physicochemical Characterization and Phenolic Content Extraction Optimization

Beebread or ambrosia is a unique product for humans and bees, which is the result of lactic fermentation on pollen in honeycombs. Bee bread is a rich source of nutrients (proteins, vitamins) and polyphenols (such as flavonoids, flavonols, phenolic acids). This study aimed to characterize bee bread in terms of physicochemical properties: pH, free acidity, glucose, fructose, sucrose, raffinose and melesitose content, total phenolic content (TPC), total flavones content (TFC), fatty acids and individual phenolics (gallic acid, protocatechiuc acid, p-hydroxybenzoic acid, caffeic acid, vanillic acid, chlorogenic acid, p-coumaric acid, rosmarinic acid, myricetin, luteolin, quercetin and kaempferol). The main phenolic compound identified in the bee bread was kaempferol, followed by myricetin and luteolin. The TPC, TFC and extraction yield were optimized in function of ultrasonic amplitude, temperature and time and the suitable conditions for achieving the maximum level were 87.20% amplitude of ultrasonic treatment, 64.70 °C and 23.10 min, respectively for reaching 146.2 mg GAE/L of TPC, 1231.5 mg QE/g of TFC and a 5.72% extraction yield. The most abundant fatty acids were C18:3 (all-cis-9,12,15) octadeca-6,9,15-trienoic acid, followed by C16:1 (9Z)-hexadec-9-enoic acid, C21:0 heneicosanoic acid and C18:2 (all-cis-9,12) (9Z,12Z)-octadeca-9,12-dienoic acid, respectively.

Monitoring of the oxidation of the oil from sacha inchi (Plukenetia volubilis) seeds supplemented with extracts from tara (Caesalpinia spinosa) pods using conventional and MIR techniques

This work focuses on the characterization of the oxidation of the oil from sacha inchi seeds (Plukenetia volubilis) under accelerated conditions at 60 ºC for 15 days. Five samples were monitored: three supplemented with 200 ppm of non-hydrolyzed or partially hydrolyzed (for 4 and 9 hours) extracts from tara (Caesalpinia spinosa) pods, one without antioxidant and one with 200 ppm of BHT. Several conventional tech­niques (induction time, peroxide value, conjugated dienoic acid, p-anisidine value, total unsaturated fatty acids and α-linolenic acid contents) and the MIR spectroscopy coupled with chemometric tools were used and com­pared. The results revealed that whatever the antioxidant added, the oil from sacha inchi is fairly stable over time. The results also pointed out that extracts from tara pods, mainly those partially hydrolyzed, were more efficient than BHT against oil oxidation for up to 7 days. Finally, this paper shows that MIR spectroscopy pres­ents an interesting alternative technique for the monitoring of the oxidation of the oil from sacha inchi.

A bacterial biosynthetic pathway for methylated furan fatty acids

Fatty acids play many important roles in cells and also in industrial processes. Furan fatty acids (FuFAs) are present in the lipids of some plant, fish, and microbial species and appear to function as second messengers in pathways that protect cells from membrane-damaging agents. We report here the results of chemical, genetic, and synthetic biology experiments to decipher the biosynthesis of the monomethylated FuFA, methyl 9-(3-methyl-5-pentylfuran-2-yl) nonanoate (9M5-FuFA), and its dimethyl counterpart, methyl 9-(3,4-dimethyl-5-pentylfuran-2-yl) nonanoate (9D5-FuFA), in two α-proteobacteria. Each of the steps in FuFA biosynthesis occurs on pre-existing phospholipid fatty acid chains, and we identified pathway intermediates and the gene products that catalyze 9M5-FuFA and 9D5-FuFA synthesis in Rhodobacter sphaeroides 2.4.1 and Rhodopseudomonas palustris CGA009. One previously unknown pathway intermediate was a methylated diunsaturated fatty acid, (10E,12E)-11-methyloctadeca-10,12-dienoic acid (11Me-10t,12t-18:2), produced from (11E)-methyloctadeca-11-enoic acid (11Me-12t-18:1) by a newly identified fatty acid desaturase, UfaD. We also show that molecular oxygen (O2) is the source of the oxygen atom in the furan ring of 9M5-FuFA, and our findings predict that an O2-derived oxygen atom is incorporated into 9M5-FuFA via a protein, UfaO, that uses the 11Me-10t,12t-18:2 fatty acid phospholipid chain as a substrate. We discovered that R. palustris also contains a SAM-dependent methylase, FufM, that produces 9D5-FuFA from 9M5-FuFA. These results uncover the biochemical sequence of intermediates in a bacterial pathway for 9M5-FuFA and 9D5-FuFA biosynthesis and suggest the existence of homologs of the enzymes identified here that could function in FuFA biosynthesis in other organisms.