Natural resins and bioactive natural products thereof as potential anitimicrobial agents

Natural products and their derivatives have historically been invaluable as a source of therapeutic agents and have contributed to the discovery of antimicrobial agents. However, today with the development of drug-resistant strains, new scaffolds and new sources of bioactive compounds are needed. To this end, plant derived natural resins are reviewed for their potential application as antimicrobial agents. Natural gums, extracts of the whole resins, as well as specific extracts, fractions, essential oils and isolated compounds from the above resins are discussed in terms of their antifungal, antibacterial, and antiprotozoal activity. © 2011 Bentham Science Publishers Ltd

Leaf structure and histochemistry of the hardy evergreen Euphorbia characias L. (Mediterranean spurge)

The dorsiventral, hypostomatic leaf of Euphorbia characias is investigated to disclose its structural features and the chemical nature of the secondary metabolites produced. Light and scanning electron microscopy along with histochemical tests were employed to investigate the leaf of this well known perennial dwarf Mediterranean shrub. The compact leaf is characterized by numerous, rather uniform, curly, unicellular hairs on both surfaces, vaulty protrusions of the outer periclinal walls of the epidermal cells, prominent on the lower epidermis in particular, and a network of latex producing ducts (laticifers) extending in two layers within the mesophyll. Histochemical reactions proved positive only for alkaloids within the laticifers and phenolic compounds, especially for the condensed tannins accumulated within the vacuole of the epidermal cells. GC-MS and GC-FID analyses of the latex revealed the presence of several secondary metabolites, mainly belonging to the class of triterpenes. Lanosterol, butyrospermol, cycloartenol and lupeol were the major constituents in the extract examined. © 2014 Elsevier GmbH

The application of highly centrifuged honey as an improved diet for experimentally caged honey bees

Whilst sucrose syrup appears to be the most commonly used diet applied during honey bee cage experiments, dead honey bees may occur within the first week of feeding. However, sucrose syrup remains the dominant food supplement for cage experiments since past research has proved that all alternative hydrocarbon diets, including honey, decrease the lifespan of honey bees when compared to syrup. In this study we tested feeding caged honey bees with honey from which all pollen grains and possibly all pathogenic spores were removed through high speed centrifugation. This preparation significantly extended the lifespan of honey bees in cages compared with sucrose syrup and honey. The analysis of the glycoside content of centrifuged honey and of the honey from which it was produced showed that the two products were identical. The 1H NMR spectra of the two samples displayed an identical resonance pattern. This refers to the qualitative content, as well as the ratio of the constituent sugars of the two samples. This study showed that highly centrifuged honey could be applied as an improved reliable diet for experimentally caged honey bees. © IBRA 2013

Supercritical CO2 extraction of mastic gum and chemical characterization of bioactive fractions using LC-HRMS/MS and GC–MS

Chios mastic gum, the resin of Pistacia lentiscus L. var. chia, is known for its acivity against gastrointestinal disorders, mainly against damage caused by the bacterium Helicobacter pylori. Triterpenes of mastic gum are considered responsible for its anti-microbial and anti-H. Pylori properties. In the present study Supercritical Fluid Extraction parameters were fine-tuned through several trials aiming at a stepwise, efficient and environmentally friendly methodology, resulting to the extraction and enrichment of the valuable groups of constituents of mastic gum: a volatile fraction, a triterpenic fraction further separated in neutral and acidic, as well as a resinous polymer. GC–MS analysis, revealed the dominance of α-pinene and trans-verbenol in the volatile fraction and of caryophyllene oxide, mastihadienonic and oleanonic aldehyde among others in the neutral triterpenes’ fraction. HR-MS/MS analysis was implemented for the characterization of the triterpenic acid fraction, revealing the dominance of isomasticadienonic, masticadienonic, oleanonic and moronic acid. © 201

Triterpenes from Echinops spinosissimus Turra subsp. spinosissimus

The phytochemical investigation of Echinops spinosissimus aerial parts led to the isolation of nine triterpenoids, one oleanane-type (1), four taraxastane-type (2, 3, 5, 6), three lupane-type (4, 7, 9) and one phytosterol (8). Their structures were elucidated through extensive analysis of NMR and HRMS spectra data. Compound 6, 20-oxo-30-nortaraxast-21-en-3β-ol, represent a previously undescribed taraxastane-type triterpene while compound 2, 21-hydroxytaraxasterol-3β-acetate, is described herein for the first time as a natural product. Furthermore, this is the first report of isolation of compound 3-5, 8, 9 from Echinops species. Isolated compounds were tested for their inhibitory activity on acetyl cholinesterase. Only compound 4 showed a moderate activity at 25 μM (35.61 ± 1.42%). © 2019 Phytochemical Society of Europ

Phytochemical characteristics of bergamot oranges from the Ionian islands of Greece: A multi-analytical approach with emphasis in the distribution of neohesperidose flavanones

The present study describes the peculiar phytochemical characteristics of bergamots cultivated in distinct islands of the Ionian Sea. Ultrahigh-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS) supported by 1 and 2D NMR spectroscopy was used for unambiguous metabolic profiling of albedo, flavedo and juice samples. Profile differences were determined using a multi-analytical clustering approach based on high-performance thin-layer chromatography fingerprints and UHPLC-HRMS data. Finally, a validated HPLC method offering good precision (0.12–0.94%) and accuracy (95.25–103.93%) was proposed for the quantification of the major flavanones. A total of 37 secondary metabolites were characterized belonging to flavonoids, limonoids and coumarins. Their distribution was tissue-dependent and varied significantly from bergamots of other geographical locations. Surprisingly, neoeriocitrin was the major flavanone, reaching 1.69 ± 0.05 g/L in the juice and 5.24 ± 0.12 mg/g in albedo. This is the highest reported amount among Citrus species, rendering Ionian bergamots a promising candidate for novel functional products. © 2020 Elsevier Lt

Enzymatic tailoring of oleuropein from Olea europaea leaves and product identification by HRMS/MS spectrometry

Oleuropein, a bioactive compound found in all parts of olive tree, especially in leaves and branches, presents numerous health promoting properties that increase research and market interest the last few years. In addition, oleuropein degradation products, such as hydroxytyrosol, elenolic acid, and the aglycones also exhibit biological activities with different properties compared to the starting compound. Under this view, a commercial lipase preparation Lipolase 100L and a thermophilic β-glucosidase from Myceliophthora thermophila were used for the regioselective hydrolysis of oleuropein towards the production of the corresponding biologically active compounds. The enzymatic degradation products of oleuropein, such as hydroxytyrosol, elenolic acid and its glucoside, and oleuropein aglycones were identified by LC-HRMS/MS and NMR spectroscopy. The latter, was found as a mix of diastereomers of the monoaldehydic form of oleuropein aglycone, identified as (5S, 8R, 9S)-, (5S, 8S, 9S)- and (5S, 8R, 9R). The high substrate specificity exhibited by both lipase and β-glucosidase allows the successful tailoring of oleuropein towards the production of different biologically active compounds with significant potential in the cosmeceutical and food industry. © 2017 Elsevier B.V