Oxidation Study of Oleocanthal and Oleacein Induced by Oxone.

A selective Oxone-induced oxidation of oleocanthal and oleacein, the two main secoiridoids of olive oil, to their bis-oxidized products is described. This protocol is based on a Baeyer-Villiger mechanism and the concentration of Oxone in the final solution. The bis-oxidation of the aldehydic compounds could be extended for the synthesis of various semisynthetic analogs. The obtained acids exhibit strong antioxidant activity, being efficient free radical scavengers.

Gentiopicroside-An Insight into Its Pharmacological Significance and Future Perspectives.

Gentiopicroside (GPS) is a leading component of several plant species from the Gentianaceae botanical family. As a compound with plenty of biological activities and a component of herbal drugs, GPS has an important role in the regulation of physiological processes in humans. The results of recently published scientific studies underline a meaningful role of this molecule as an active factor in metabolic pathways and mechanisms, which may have an influence in the treatment of different diseases, including digestive tract disorders, malignant changes, neurological disorders, microbial infections, bone formation disorders, inflammatory conditions, and others. This review aims to collect previously published reports on the biological properties of GPS as a single compound that were confirmed by in vitro and in vivo studies, and to draw attention to the newly discovered role of this bitter-tasting secoiridoid. Thanks to these properties, the research on this substance could be revisited.

Oxidized Forms of Olive Oil Secoiridoids: Semisynthesis, Identification and Correlation with Quality Parameters.

Secoiridoids is the prominent chemical class of olive oil polar constituents and are characterized by significant biological properties. They are abundant in different chemical forms and relatively high concentrations compared to other components, while prone to oxidation due to their chemical motif. In recent years, oxidized derivatives of secoiridoids have been reported, either as natural constituents of olive oil or as components which are gradually formed in all stages of its production and storage. The mono-oxidized forms of oleocanthal and oleacein named as the respective acids have been recently isolated from olive oil and unambiguously structurally characterized. Other oxidized forms of elenolic acid or more complex secoiridoids, such as those of oleuropein and ligstroside aglycones are also sporadically mentioned in the literature. No further information is provided since they have not been isolated in pure form in order to be accurately identified. Most of the time, they are generally referred as oxidized forms of the parent compounds and commonly identified based on mass spectrometric data. In the current study, the semi-synthesis of the main oxidized olive oil secoiridoids, i.e., oleocanthalic acid, oleaceinic acid, EDA acid, carboxylic form of elenolic acid, carboxylic form of ligstroside aglycon, and carboxylic form of oleuropein aglycon is described starting from the corresponding aldehydic derivatives, using SeO2/H2O2 as oxidative agents. Furthermore, their presence in a number of Greek olive oils was investigated as well, as possible correlation thereof with quality parameters.

Development and physicochemical characterization of nanoliposomes with incorporated oleocanthal, oleacein, oleuropein and hydroxytyrosol.

Oleocanthal, oleacein, oleuropein and hydroxytyrosol comprise characteristic polyphenols of olive with high biological value. However, stability problems hinder their further investigation. Thus, in the present study they were incorporated in nanoliposomes by thin film hydration method. The particles sizes, PDI, zeta-potential and physicochemical stabilities of nanoliposomes were evaluated by light scattering methods while FTIR, XRD, TGA and DSC methods were carried out for further physicochemical characterization. Their micromorphology was illustrated by negative-staining TEM and Cryo-TEM, revealing well-dispersed round-shaped vesicles. According to in vitro release studies, oleocanthal and oleacein were rapidly released in a higher percentage than oleuropein and hydroxytyrosol and compatible with the Ritger-Peppas model release mechanism while only oleuropein liposomes were governed by anomalous diffusion of non-Fickian diffusion. Antioxidant assays showed that nanoliposomes presented comparable activity with pure compounds enabling them as suitable carriers for the delivery of olive active biophenols in the human organism.

Discovering the Next-Generation Plant Protection Products: A Proof-of-Concept via the Isolation and Bioactivity Assessment of the Olive Tree Endophyte Bacillus sp. PTA13 Lipopeptides.

Endophytic microorganisms (EMs) have recently attracted interest for applications in plant protection, mainly due to their bioactive compound-producing capacity. Therefore, we underwent the task of isolating olive tree EMs and investigating their bioactivity against the devastating pathogen Colletotrichum acutatum. Several EMs were isolated; however, the Bacillus sp. PTA13 isolate exhibited the highest toxicity to the phytopathogen. Bacteria of the genus Bacillus exhibit superior bioactive metabolite-producing capacity, with the lipopeptides (LPs) of surfactin, iturin, and fengycin groups being the most studied. A total LP extract and several fractions were obtained, and their bioactivity was assessed against C. acutatum strains. LPs of the major surfactin, iturin, and fengycin groups and the minor gageotetrin and bacilotetrin groups were annotated. The results confirmed the bioactivity of the major LPs, with fengycins being the most fungitoxic. Interestingly, the minor LP fraction exhibited selective toxicity to the fungicide-resistant C. acutatum isolate, an observation that highlights the significance of our approach to comprehensively mine the total LP extract. This work represents a proof of concept of the exploitation of EMs in customized olive tree plant protection and aligns well with strategies that focus on the sustainability and safety of food production via the development of next-generation plant protection products.

Phytochemical Analysis and Dermo-Cosmetic Evaluation of Cymbidium sp. (Orchidaceae) Cultivation By-Products.

Cymbidium is one of the most popular genera in Orchidaceae family, commercialized either as loose flowers or as potted plants in floriculture worldwide. The non-marketable parts are typically discarded (e.g., unsuitable flowers, leaves, pseudobulbs, roots), generating an enormous quantity of unutilized biomass. The above by-products were studied through phytochemical analysis and investigated for their dermo-cosmetic potential. The initial antioxidant, anti-tyrosinase, anti-elastase, and anti-collagenase assays of the total extracts indicated that the pseudobulb and root ethyl acetate extracts were the most potent. Those extracts were then submitted to chromatographic separation leading to the isolation of 16 secondary metabolites (four phenanthrenes, three 1,4-phenanthrenquinones, three dibenzyls, two phenolic acid derivatives, two sterols, one dehydrodiconiferyl alcohol derivative, and one simple phenolic compound), including 6-hydroxy-5,7-dimethoxy-1,4-phenanthrenequinone (cymbisamoquinone), which was identified as a new natural product. In parallel, 48 metabolites were identified by UPLC-HRMS analysis of the extracts. The biological evaluation of the isolated compounds revealed that gigantol and tristin present important anti-tyrosinase activity, while bulbophyllanthrin, 3-hydroxy-2,4,7-trimethoxy-phenanthrene, marylaurencinol A, 5-hydroxy-2-methoxy-1,4-phenanthrenequinone, and ephemeranthroquinone B show dose-dependent anti-collagenase activity. In contrast to isolated metabolites, which may act selectively on specific enzymes, the initial total extracts exhibited inhibitory activity against tyrosinase, elastase, and collagenase enzymes, thus showing better prospects for use in dermo-cosmetic formulations.