Search results for "plant extracts"
showing 10 items of 510 documents
Constituents of leaves and flowers essential oils of Helichrysum pallasii (Spreng.) Ledeb. growing wild in Lebanon.
2009
The chemical compositions of the essential oils obtained from leaves and flowers of Helichrysum pallasii were analyzed by gas chromatography and gas chromatography-mass spectrometry. Among the 102 identified constituents, hexadecanoic acid (16.2%), (Z,Z)-9,12-octadecadienoic acid (6.8%), tetradecanoic acid (2.6%), and (Z)-caryophyllene (4.2%) were the main constituent of the oil from leaves, while in the oil from flowers hexadecanoic acid (14.7%), (Z,Z)-9,12-octadecadienoic acid (14.2%), (Z)-caryophyllene (3.6%), and delta-cadinene (3.1%) predominated. The oils were both characterized by sesquiterpenes (33.4% for leaves and 33.7% for flowers, respectively) and fatty acids and esters (30.3% …
Green tea extract assisted low-temperature pasteurization to inactivate enteric viruses in juices.
2020
The current popularity of minimally processed foods is an opportunity for natural antimicrobial agents to be combined with mild heat treatments to act synergistically in reducing viral foodborne pathogens. Viral inactivation by heat-treatments (at 25, 40, 50 and 63 °C for 30 min) combined with aged green tea extract (aged-GTE) was initially evaluated in phosphate buffered saline (PBS) against murine norovirus (MNV-1) and hepatitis A virus (HAV) by cell culture, and against human norovirus by in situ capture RT-qPCR. The combination of aged-GTE and heat treatment at 50 °C for 30 min exerted strong antiviral activity, reducing by more than 5 log MNV-1 infectivity in PBS. Heating at 40 °C for …
Untargeted screening of the bound / free phenolic composition in tomato cultivars for industrial transformation
2019
BACKGROUND Tomato is one of the most important agricultural crops and it is characterized by a wide bioactive compound profile. However, little information is reported on its comprehensive polyphenol profile. In this work, 13 commercial tomato cultivars for industrial transformation were screened by ultra-high-pressure liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS) for both free and bound phenolic profiles. Thereafter, the in vitro antioxidant activity of each cultivar was assessed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance activity (ORAC) assays. Multivariate statistics, i.e. orthogonal projection to latent struct…
Factors Affecting Polyphenol Biosynthesis in Wild and Field Grown St. John’s Wort (Hypericum perforatum L. Hypericaceae/Guttiferae)
2009
The increasing diffusion of herbal products is posing new questions: why are products so often different in their composition and efficacy? Which approach is more suitable to increase the biochemical productivity of medicinal plants with large-scale, low-cost solutions? Can the phytochemical profile of a medicinal plant be modulated in order to increase the accumulation of its most valuable constituents? Will polyphenol-rich medicinal crops ever be traded as commodities? Providing a proactive answer to such questions is an extremely hard task, due to the large number of variables involved: intraspecific chemodiversity, plant breeding, ontogenetic stage, post-harvest handling, biotic and abi…
Food-mediated modulation of immunity in a phytophagous insect: An effect of nutrition rather than parasitic contamination.
2015
7 pages; International audience; Inherent to the cost of immunity, the immune system itself can exhibit tradeoffs between its arms. Phytophagous insects face a wide range of microbial and eukaryotic parasites, each activating different immune pathways that could compromise the activity of the others. Feeding larvae are primarily exposed to microbes, which growth is controlled by antibiotic secondary metabolites produced by the host plant. The resulting variation in abundance of microbes on plants is expected to differentially stimulate the insect antimicrobial immune defenses. Under the above tradeoff hypothesis, stimulation of the insect antimicrobial defenses is expected to compromise imm…
Headspace Volatile Composition of the Flowers of Caralluma europaea N.E.Br. (Apocynaceae)
2009
The volatile constituents of the flowers of Caralluma (Apteranthes) europaea (Guss.) N.E. Br. (Apocynaceae - Asclepiadoideae) from Lampedusa Island were analyzed by headspace method. The analyses allowed the identification and quantification of 41 compounds. The main components were, among the monoterpenoids, terpinolene (23.3%), a-terpinene (19.1%) and linalool (18.4%), whereas, among the carbonylic compounds the major constituents were heptanal (2.0%), octanoic acid (2.4%) and hexanoic acid (1.7%). It is worth to mention the presence of a nitrogen containing compound, indole (0.8%) and of a sulphur containing compound, dimethylsulphide (t). The compounds found in the flowers of C. europea…
Control of MicroRNA Expression as a New Way for Resveratrol To Deliver Its Beneficial Effects
2012
Grapes produce large amounts of polyphenols. Many of them accumulate in the skin, pulp, and seeds and are consequently found in wine. The health benefits of a moderate consumption of wine have been attributed at least in part to grape's polyphenols. Among them, resveratrol (3,5,4'-trihydroxystilbene) is a phytoalexin that stimulates plant cell defenses against infections and also plays protective roles in humans, where it delays cardiovascular alterations and exerts anticancer and anti-inflammatory effects. Despite numerous studies, the molecular mechanisms of resveratrol action are only partially understood. Given its pleiotropic effects, it was previously suggested that resveratrol protec…
Ag Nanoparticles for Biomedical Applications—Synthesis and Characterization—A Review
2022
Silver nanoparticles have been intensively studied over a long period of time because they exhibit antibacterial properties in infection treatments, wound healing, or drug delivery systems. The advantages that silver nanoparticles offer regarding the functionalization confer prolonged stability and make them suitable for biomedical applications. Apart from functionalization, silver nanoparticles exhibit various shapes and sizes depending on the conditions used through their fabrications and depending on their final purpose. This paper presents a review of silver nanoparticles with respect to synthesis procedures, including the polluting green synthesis. Currently, the most commonly used cha…
Isomerization and increase in the antioxidant properties of lycopene from Momordica cochinchinensis (gac) by moderate heat treatment with UV-Vis spec…
2014
International audience; Momordica cochinchinensis (gac) is a plant rich in lycopene. This pigment tends to solubilize in oil and get damaged during extraction. The impact of heating on cis-isomerization of oil-free lycopene in hexane was studied at 50 and 80°C during 240min with UV-Vis spectrometry, DAD-HPLC and TEAC test. The initial all-trans-form isomerized to the 13-cis isomer more rapidly at 80°C. After this treatment, 16% of the lycopene compounds were in the 9-cis-form. This isomer triggered an increase in the antioxidant properties which was detectable from concentrations above 9% and resulted in a change from 2.4 to 3.7μmol Trolox equivalent. It is thus possible to increase the bio…
Kalanchoe pinnata inhibits mast cell activation and prevents allergic airway disease
2011
Aqueous extract of Kalanchoe pinnata (Kp) have been found effective in models to reduce acute anaphylactic reactions. In the present study, we investigate the effect of Kp and the flavonoid quercetin (QE) and quercitrin (QI) on mast cell activation in vitro and in a model of allergic airway disease in vivo. Treatment with Kp and QE in vitro inhibited degranulation and cytokine production of bone marrow-derived mast cells following IgE/FcɛRI crosslinking, whereas treatment with QI had no effect. Similarly, in vivo treatment with Kp and QE decreased development of airway hyperresponsiveness, airway inflammation, goblet cell metaplasia and production of IL-5, IL-13 and TNF. In contrast, treatm…