Antioxidant capacity and chemical profiles of Satureja montana L. Honey: hotrienol and syringyl derivatives as biomarkers

Variation in Phenolic Content, Antioxidant Activity and Alpha-amylase and Acetylcholinesterase Inhibitory Capacities of Different Extracts from Tunisian Satureja barceloi (Willk) L

The antioxidant activity and the anti-α-amylase and anti-acetylcholinesterase capacities of secondary metabolites from different organs (roots, stems, leaves and flowers) of Tunisian Satureja barceloi were determined. The variation in the distribution of phenolic metabolites among roots, stems, leaves and flowers extracts of S. barceloi with various solvent systems (methanol, ethyl acetate, hexane and distilled water) has not been characterized before. Significant variation of phenolic compounds was observed according to organs rather than to extracting solvents. The analyzed organs show a high level of phenolic compounds although the stems contains the highest total polyphenols (132.53±0.48 mg AGE/g Ex), flavonoids (48.99±0.65 mg RE/g Ex) and flavonols (34.93±0.29 mg QE/g Ex) contents. The phenolic fraction was dominated by sagerinic acid, caffeic acid glucoside and epigallocatechin, detected using HPLC-PDA/ESI-MS. The antioxidant activity of all extracts, evaluated by four in vitro tests, was high and varied significantly according to the type of solvent used and the plant organ. The aqueous extracts of leaves exhibited the greatest inhibitory effect on alpha-amylase while the methanolic extract of leaves and stems revealed the most important acetylcholinesterase inhibitory effect. Hence, S. barceloi extracts could be used as a source of various bioactive molecules in pharmaceutical industry.

French Guiana honeys from the Amazon biome: First description of volatile fraction and antioxidant capacity

Various honeys from French Guiana were collected and analyzed to investigate their volatile fraction composition and antioxidant activity. Volatile composition was assessed using HS-SPME/GC, GC-MS technique. Oxygenated monoterpenes like hotrienol (0.5-45.3%) were found as major molecules, followed by non terpenic compounds like phenylacetaldehyde (0.8-18.2%) or 3-hydroxy-4-phenyl-2-butanone (0.1-29.3%). Three chemical groups using statistical analysis were classified within investigated honey samples: norisoprenoids/shikimates, mevalonate and their combination. Total phenolics content (TPC) was determined by Folin-Ciocalteu method. Antioxidant activity was assessed by oxygen radical absorbance capacity (ORAC) and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. TPC and anti-radical activity were compared with multifloral honeys from neighboring regions, indicating the possible presence of compounds from the polyphenol family. These results are promising for further biological studies involving honeys from French Guiana.

Characterization of Rare Himalayan Balsam (Impatiens glandulifera Royle) Honey from Croatia

Himalayan balsam (Impatiens glandulifera Royle) is an invasive garden ornamental plant species originating from Asia, which produces significant amounts of nectar. In Croatia, it is widely distributed along the banks of the Mura River. Although this plant species is widespread in Europe, there are still no available scientific data about this unifloral honey type. The results showed that Himalayan balsam honey is characterized by the high presence of pollen grains in the pollen spectrum (59−85%), natural higher diastase activity (39.1 ± 7.98 DN), negative specific rotation (−21.2° ± 6.89) and an extra light amber color (48.5 ± 12.69 mm Pfund). The carbohydrate profile is characterized by monosaccharides fructose (39.34 ± 0.65 g/100 g) and glucose (31.91 ± 1.42 g/100 g) with a ratio >1.23, while the most commonly represented disaccharide was maltose (3.04 ± 0.79 g/100 g). The average total phenolic content was 130.97 ± 11.17 mg gallic acid/kg honey, and the average antioxidant capacity value was 225.38 ± 29.58 µM Fe(II). The major mineral element was K, with an average of 533.92 ± 139.70 mg/kg. The sensory profile was characteristic with a light orange color and medium-intensity odor and aroma. The crystallization rate was moderate and characterized by the appearance of opalescence and gelatinous forms of crystals. The results of this study provide the first insight into the melissopalynological, physico-chemical and sensory profile of Himalayan balsam honey.

A narrative review: The pharmaceutical evolution of phenolic syringaldehyde

To better understand the pharmacological characters of syringaldehyde (SA), which is a key-odorant compound of whisky and brandy, this review article is the first to compile the published literature for molecular docking that were subsequently validated by in vitro and in vivo assays to predict and develop insights into the medicinal properties of SA in terms of anti-oxidation, anti-inflammation, and anti-diabetes. The molecular docking displayed significantly binding affinity for SA towards tumor necrosis factor-α, interleukin-6, and antioxidant enzymes when inflammation from myocardial infarction and spinal cord ischemia. Moreover, SA nicely docked with dipeptidyl peptidase-IV, glucagon-like peptide 1 receptor, peroxisome proliferator-activated receptor, acetylcholine M2 receptor, and acetylcholinesterase in anti-diabetes investigations. These are associated with (1) an increase glucose utilization and insulin sensitivity to an anti-hyperglycemic effect; and (2) to potentiate intestinal contractility to abolish the α-amylase reaction when concurrently reducing retention time and glucose absorption of the intestinal tract to achieve a glucose-lowering effect. In silico screening of multi-targets concomitantly with preclinical tests could provide a potential exploration for new indications for drug discovery and development.

Bioactive compounds in Apis mellifera monofloral honeys

Honey is a natural product with a sweet flavor. Honey is made by the honeybee (Apis mellifera L.) from the nectar of flowers or other plant secretions that are collected near the hive. These products are mixed with bee saliva and stored. Several studies have demonstrated that honey exhibits antioxidant, antimicrobial, nematicidal, antifungal, anticancer, and anti-inflammatory activities. These properties are influenced by the plants from which the secretions are harvested, from the naturally occurring compounds present in the nectar. Studies of the properties and applications of honey have distinguished honey from other natural products due to the presence of certain compounds and due its bioactive properties. The focus of this review is to discuss the identified and isolated compounds from monofloral honey produced by A. mellifera, with specific emphasis on antioxidant and antimicrobial properties of honey and its therapeutic health benefits.

Potent antioxidant peptides derived from honey major protein enhance tolerance of eukaryotic cells toward oxidative stress

Honey is known for its medicinal benefits and receiving renewed attention as natural medicine. Studies on health benefits of honey attributed its antioxidant activity to phenolic compounds, but the contribution of proteins and peptides to the antioxidant activity of honey is lacking. The aim of this study was to explore the contribution of proteins and peptides to the antioxidant activity of honey, which remained obscure for decades.

Total honey proteins (THP) were isolated by dialysis method and hydrolyzed through simulated gastrointestinal digestion. The hydrolysates were fractionated using size-exclusion chromatography. The antioxidant activity was determined by using superoxide radical-scavenging, DPPH reduction and intracellular ROS assays.

THP was shown to exhibit superoxide-scavenging activity but its pepsin-hydrolysate (HP-p) showed superior scavenging activity. The HP-p produced five peptide fractions (P1~P5) when fractionated on Sephacryl S-100 size-exclusion column. The five fractions showed superoxide-scavenging activities and DPPH reducing activities, whereas the slow-eluting peptide fractions (P3 and P4) were the most potent. MALDI-TOF/MS analysis identified a pentapeptide (TSNTF) as the dominant peptide in the active fractions P3 and P4. Human colonic epithelial cells treated with P3 and P4 peptides exhibited lower intracellular ROS, when oxidative stress was induced by H2O2 or diethyl maleate (DEM), indicating strong tolerance to oxidative stress. The viabilities of human cells or yeast cells were largely decreases under oxidative stress, but treated cells with P3 and P4 showed higher viability compared with the untreated cells. The results are the first to describe a novel antioxidant peptide from honey that confer ex vivo anti-oxidative function within a complicated milieu of eukaryotic cells and pave the way for its potential as nutraceutical or therapeutic peptide for risk-reduction of oxidative-stress and related diseases.

Graphical abstract

Blood pressure-reducing activity of Gongronema latifolium Benth. (Apocynaeceae) and the identification of its main phytochemicals by UHPLC Q-Orbitrap mass spectrometry

Background Gongronema latifolium Benth. (family Apocynaceae) leaves (GL) has interesting medicinal properties. The effects of extracts from G. latifolium on blood pressure (BP) and the possible mechanisms of action were also investigated. Methods The ultrahigh resolution liquid chromatography orbitrap MS analysis was used to identify the phytochemicals present. Normotensive Wistar rats were anesthetized with sodium pentobarbitone (40 mg/kg) intraperitoneally, and the jugular vein was cannulated for infusion of drugs while the carotid artery was cannulated for direct BP measurement. GL extract (5-20 mg) alone or with nifedipine (10 mg/kg), atropine (2 mg/kg), L-NAME (5 mg/kg), methyl blue (3 mg/kg) and propranolol (1 mg/kg) were administered intravenously to Wistar rats and direct BP measurements were carried out. Results Systolic and diastolic BP levels (128/90 mm Hg; MAP 103 ± 3 mm Hg) and heart rates were all significantly (p < 0.01) decreased after GL administration. Raised mean arterial pressure (MAP) and heart rate by atropine, L-NAME and methyl blue were significantly (p < 0.01) reduced after GL administration, while propranolol significantly (p < 0.01) inhibited hypotension caused by GL. Infusion of GL reduced MAP (95 ± 3 mm Hg) comparable with nifedipine (93 ± 2 mm Hg), a calcium channel blocker. The phytochemicals identified were 34 compounds, including oleanolic acid derivatives, flavonoids, antioxidant fatty acids, 2 coumarins and 2 iridoids. Conclusions These results suggest that G. latifolium has hypotensive properties mediated by the synergistic activity of the compounds, probably via the β-adrenergic blockade mechanism.

Isophorone derivatives as a new structural motif of aggregation pheromones in Curculionidae

The beetle Homalinotus depressus (Coleoptera: Curculionidae) is a major pest of coconuts in the Northern region of Brazil, for which environmentally friendly methods of control are desired. Behavioral responses of H. depressus to airborne volatile extracts from conspecifics suggested the presence of a male-produced aggregation pheromone. GC analyses of these extracts showed the presence of four male-specific compounds. Analytical data in combination with the synthesis of standards led to the identification of the male-released semiochemicals as epoxyisophorone (1), isophorone (2), homalinol (3), and 2-hydroxyisophorone (4), of which (3) was the major constituent. The configuration of homalinol was determined to be cis on the basis of retention times of synthetic cis and trans synthetic standards. Enantiomers of cis-homalinol were obtained in high enantiomeric excess by using biocatalysis. Their separation on a GC enantioselective column (β-Dex325®), allowed us to unambiguously determine that the absolute configuration of natural homalinol was (1R,2R,6S). Field bioassays demonstrated that both the synthetic major compound per se and mixtures of all four male-specific compounds were attractive to H. depressus.

Quercus ilex L.: How season, Plant Organ and Extraction Procedure Can Influence Chemistry and Bioactivities

Quercus species have a plethora of applications, either in wine and wood industries, in human and animal nutrition or in human health. In order to improve the knowledge on this genus, the aim of the present study was to correlate, for the first time, the phenolic composition of different Quercus ilex L. plant tissues (leaves in two maturation stages, acorns, teguments and cotyledons) and different extraction procedures with scavenging and anticholinesterase activities. The hydromethanolic and aqueous extracts obtained showed strong radical scavenging activity against DPPH, superoxide anion radical and nitric oxide radical, leaves exhibiting higher total phenolic content and revealing the best antioxidant properties, followed by tegument and acorns. Concerning the phenolic profile, fifteen compounds were identified and quantified by HPLC-DAD, ranging from 1568.43 to 45,803.16 mg/kg dried extract. The results indicate that Q. ilex can be a source of strong antioxidant phenolic compounds with possible interest for food and pharmaceutical industries.

Screening of Satureja subspicata Vis. Honey by HPLC-DAD, GC-FID/MS and UV/VIS: Prephenate Derivatives as Biomarkers

The samples of Satureja subspicata Vis. honey were confirmed to be unifloral by melissopalynological analysis with the characteristic pollen share from 36% to 71%. Bioprospecting of the samples was performed by HPLC-DAD, GC-FID/MS, and UV/VIS. Prephenate derivatives were shown to be dominant by the HPLC-DAD analysis, particularly phenylalanine (167.8 mg/kg) and methyl syringate (MSYR, 114.1 mg/kg), followed by tyrosine and benzoic acid. Higher amounts of MSYR (3-4 times) can be pointed out for distinguishing S. subspicata Vis. honey from other Satureja spp. honey types. GC-FID/MS analysis of ultrasonic solvent extracts of the samples revealed MSYR (46.68%, solvent pentane/Et2O 1:2 (v/v); 52.98%, solvent CH2Cl2) and minor abundance of other volatile prephenate derivatives, as well as higher aliphatic compounds characteristic of the comb environment. Two combined extracts (according to the solvents) of all samples were evaluated for their antioxidant properties by FRAP and DPPH assay; the combined extracts demonstrated higher activity (at lower concentrations) in comparison with the average honey sample. UV/VIS analysis of the samples was applied for determination of CIE Lab colour coordinates, total phenolics (425.38 mg GAE/kg), and antioxidant properties (4.26 mmol Fe(2+)/kg (FRAP assay) and 0.8 mmol TEAC/kg (DDPH assay)).

Red clover (Trifolium pratense L.) honey: volatiles chemical-profiling and unlocking antioxidant and anticorrosion capacity

Headspace solid-phase micro-extraction (HS-SPME) and ultrasonic solvent extraction (USE) were used for red clover honey volatiles extraction. The extracts were analysed using gas chromatography and mass spectrometry (GC-MS). Lilac aldehyde isomers dominated in the headspace (individual range from 7.6 % to 21.4 %) followed by phenylacetaldehyde (10.1-31.2 %) and benzaldehyde (7.0-15.7 %). Higher aliphatic alcohols and hydrocarbons were the predominant constituents of the honey extracts. The honey and its extracts exhibited rather weak anti-radical activity (DPPH assay) and total antioxidant activity (FRAP assay). On the other hand, the honey’s inhibitive properties towards the corrosion of AA 2017A alloy in NaCl solution (potentiodynamic polarisation and potentiostatic pulse measurements) revealed the honey to be a very good anodic inhibitor (efficiency up to 76 %) while the honey extracts (USE) showed better inhibition efficacy.