A synergistic anti-bacterial and anti-adhesion activity of tea tree (Melaleuca alternifolia) and lemon eucalyptus tree (Eucalyptus citriodora Hook) essential oils on Legionella pneumophila

Legionella pneumophila is a Gram-negative bacterial pathogen that colonizes natural and artificial water systems and has the ability to form a biofilm. The biofilm protects L. pneumophila from various environmental factors and makes it more resistant to chlorine-based disinfectants. This study investigated the anti-bacterial properties of tea tree (Melaleuca alternifolia (Maiden and Betche) Cheel) oil and lemon eucalyptus tree (Eucalyptus citriodora Hook) essential oils (EOs) and their synergistic, additive inhibitory and anti-adhesive effects against L. pneumophila biofilm formation on polystyrene. The minimum effective concentration (MEC) for tea tree is 12.8 mg ml-1 and for lemon eucalyptus tree EO 6.4 mg ml-1. In the checkerboard assay, different combinations of these two EO show synergistic and additive anti-microbial activity. The minimum anti-adhesive concentration (MAC) for tea tree is 12.8 mg ml-1 and for lemon eucalyptus tree EO 6.4 mg ml-1. A combination of 3.2 mg ml-1 tea tree EO and 0.8 mg ml-1 lemon eucalyptus tree EO showed the strongest anti-adhesive effect against L. pneumophila on polystyrene. The tested oils and their combination showed intriguing potential to inhibit L. pneumophila biofilm formation.

Sage, Rosemary, and Bay Laurel Hydrodistillation By-Products as a Source of Bioactive Compounds

Essential oils from Mediterranean wild plants are widely used, but the hydrodistillation residues produced in parallel with these essential oils are significantly understudied and underexploited. Since there are only fragmentary data in the literature, we have, for the first time, systematically analyzed the chemical composition of the by-products obtained after hydrodistillation of sage, bay laurel, and rosemary leaves, i.e., hydrolates, water residues, and solid residues. The chemical composition of the hydrolates changed compared to their respective essential oils towards the dominance of more hydrophilic, oxygenated compounds, such as camphor in sage, 1,8-cineole in bay laurel, and berbenone in rosemary. However, some compounds, mostly sesquiterpenes, which were present in considerable amounts in essential oils, were absent or only present in very small amounts in the hydrolates. Furthermore, both the water and the solid residues were rich in polyphenols, such as procyanidins in bay laurel and rosmarinic acid in rosemary and sage. In conclusion, we demonstrate the valuable chemical composition of sage, rosemary, and bay laurel hydrodistillation by-products and discuss a wide range of their possible applications.

Headspace Solid-Phase Micro-Extraction Versus Hydrodistillation of Volatile Compounds from Leaves of Cultivated Mentha Taxa: Markers of Safe Chemotypes

Various mint taxa are widely cultivated and are used not only for medicinal purposes but also in cosmetic and industrial applications. The development of new varieties or cultivars of mint generates difficulties in their correct identification and safe use. Volatile organic compounds (VOCs) from the leaves of seven different taxa of the genus Mentha obtained by hydrodistillation (HD) and headspace solid-phase microextraction (HS-SPME) were analyzed using gas chromatography-mass spectrometry (GC-MS). Principal component analysis (PCA) was also performed. Comparative GC-MS analysis of the obtained extracts showed similarity in the major compounds. PCA data allowed the separation of two groups of chemotypes among the analyzed mints, characterized by the abundance of piperitenone oxide and carvone. Two out of seven analyzed taxa were not previously examined for VOC profile, one was examined only for patent application purposes, and six out of seven were investigated for the first time using the HS-SPME technique. The presented analysis provides new data on the abundance and qualitative characterization of VOCs in the studied mint plants and on the safety of their use, related to the possibility of the presence of potentially toxic components. HS-SPME is a valuable method to extend the characterization of the VOC profile obtained by hydrodistillation.

Characterization of Bee Pollen: Physico-Chemical Properties, Headspace Composition and FTIR Spectral Profiles

Chemical characterization of bee pollen is of great importance for its quality estimation. Multifloral and unifloral bee pollen samples collected from continental, mountain and Adriatic regions of Croatia were analyzed by means of physico-chemical, chromatographic (GC-MS), and spectroscopic (FTIR-ATR) analytical tools, aiming to conduct a comprehensive characterization of bee pollen. The most distinctive unifloral bee pollen with regard to nutritional value was Aesculus hippocastanum (27.26% of proteins), Quercus spp. (52.58% of total sugars), Taraxacumofficinale (19.04% of total lipids), and Prunusavium (3.81% of ash). No statistically significant differences between multifloral and unifloral bee pollen from different regions were found for most of the physico-chemical measurement data, with an exception of melezitose (p = 0.04). Remarkable differences were found among the bee pollen HS VOCs. The major ones were lower aliphatic compounds, monoterpenes (mainly linalool derivatives, especially in Prunusmahaleb and P.avium bee pollen), and benzene derivatives (mainly benzaldehyde in T.officinale and Salix spp.). Aldehydes C₉ to C₁₇ were present in almost all samples. FTIR-ATR analysis revealed unique spectral profiles of analyzed bee pollen exhibiting its overall chemical composition arising from molecular vibrations related to major macromolecules-proteins, lipids, and carbohydrates (sugars).

Essential Oils of Sage, Rosemary, and Bay Laurel Inhibit the Life Stages of Oomycete Pathogens Important in Aquaculture

Saprolegnia parasitica, the causative agent of saprolegniosis in fish, and Aphanomyces astaci, the causative agent of crayfish plague, are oomycete pathogens that cause economic losses in aquaculture. Since toxic chemicals are currently used to control them, we aimed to investigate their inhibition by essential oils of sage, rosemary, and bay laurel as environmentally acceptable alternatives. Gas Chromatography-Mass Spectrometry (GC-MS) analysis showed that the essential oils tested were rich in bioactive volatiles, mainly monoterpenes. Mycelium and zoospores of A. astaci were more sensitive compared to those of S. parasitica, where only sage essential oil completely inhibited mycelial growth. EC₅₀ values (i.e., concentrations of samples at which the growth was inhibited by 50%) for mycelial growth determined by the radial growth inhibition assay were 0.031-0.098 µL/mL for A. astaci and 0.040 µL/mL for S. parasitica. EC₅₀ values determined by the zoospore germination inhibition assay were 0.007-0.049 µL/mL for A. astaci and 0.012-0.063 µL/mL for S. parasitica. The observed inhibition, most pronounced for sage essential oil, could be partly due to dominant constituents of the essential oils, such as camphor, but more likely resulted from a synergistic effect of multiple compounds. Our results may serve as a basis for in vivo experiments and the development of environmentally friendly methods to control oomycete pathogens in aquaculture.

Effect of Enzymatic, Ultrasound, and Reflux Extraction Pretreatments on the Chemical Composition of Essential Oils

The effect of different hydrodistillation pretreatments, namely, reflux extraction, reflux extraction with the addition of cell wall-degrading enzymes, and ultrasound, on the yield and chemical composition of essential oils of sage, bay laurel, and rosemary was examined. All pretreatments improved essential oil yield compared to no-pretreatment control (40–64% yield increase), while the oil quality remained mostly unchanged (as shown by statistical analysis of GC-MS results). However, enzyme-assisted reflux extraction pretreatment did not significantly outperform reflux extraction (no-enzyme control), suggesting that the observed yield increase was mostly a consequence of reflux extraction and enzymatic activity had only a minute effect. Thus, we show that ultrasound and reflux extraction pretreatments are beneficial in the production of essential oils of selected Mediterranean plants, but the application of enzymes has to be carefully re-evaluated.

The Potential of High Voltage Discharges for Green Solvent Extraction of Bioactive Compounds and Aromas from Rosemary (Rosmarinus officinalis L.)-Computational Simulation and Experimental Methods

Rosemary (Rosmarinus officinalis L.) is a Mediterranean medicinal and aromatic plant widely used due to valuable bioactive compounds (BACs) and aromas. The aim of the study was to evaluate the extraction of intracellular compounds from rosemary combining experimental procedure by means of high voltage electrical discharge (HVED), with a theoretical approach using two computational simulation methods: conductor-like screening model for real solvents and Hansen solubility parameters. The optimal HVED parameters were as follows: frequency 100 Hz, pulse width 400 ns, gap between electrodes 15 mm, liquid to solid ratio 50 mL/g, voltage 15 and 20 kV for argon, and 20 and 25 kV for nitrogen gas. Green solvents were used, water and ethanol (25% and 50%). The comparison was done with modified conventional extraction (CE) extracted by magnetic stirring and physicochemical analyses of obtained extracts were done. Results showed that HVED extracts in average 2.13-times higher total phenol content compared to CE. Furthermore, nitrogen, longer treatment time and higher voltage enhanced higher yields in HVED extraction. HVED was confirmed to have a high potential for extraction of BACs from rosemary. The computational stimulation methods were confirmed by experimental study, ethanol had higher potential of solubility of BACs and aromas from rosemary compared to water.

Mediterranean Propolis from the Adriatic Sea Islands as a Source of Natural Antioxidants: Comprehensive Chemical Biodiversity Determined by GC-MS, FTIR-ATR, UHPLC-DAD-QqTOF-MS, DPPH and FRAP Assay

There is no systematic report about propolis chemical biodiversity from the Adriatic Sea islands affecting its antioxidant capacity. Therefore, the samples from the islands Krk, Rab, Pag, Biševo and Korčula were collected. Comprehensive methods were used to unlock their chemical biodiversity: headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) followed by gas chromatography and mass spectrometry (GC-MS); Fourier transform mid-infrared spectroscopy (FT-MIR); ultra high performance liquid chromatography with diode array detector and quadrupole time-of-flight mass spectrometry (UHPLC-DAD-QqTOF-MS) and DPPH and FRAP assay. The volatiles variability enabled differentiation of the samples in 2 groups of Mediterranean propolis: non-poplar type (dominated by α-pinene) and polar type (characterized by cadinane type sesquiterpenes). Spectral variations (FT-MIR) associated with phenolics and other balsam-related components were significant among the samples. The UHPLC profiles allowed to track compounds related to the different botanical sources such as poplar (pinobanksin esters, esters and glycerides of phenolic acids, including prenyl derivatives), coniferous trees (labdane, abietane diterpenes) and Cistus spp. (clerodane and labdane diterpenes, methylated myricetin derivatives). The antioxidant potential determined by DPPH ranged 2.6-81.6 mg GAE/g and in FRAP assay 0.1-0.8 mmol Fe2+/g. The highest activity was observed for the samples of Populus spp. origin. The antioxidant potential and phenolic/flavonoid content was positively, significantly correlated.

Chemical Diversity of Codium bursa (Olivi) C. Agardh Headspace Compounds, Volatiles, Fatty Acids and Insight into Its Antifungal Activity

The focus of present study is on Codium bursa collected from the Adriatic Sea. C. bursa volatiles were identified by gas chromatography and mass spectrometry (GC-FID; GC-MS) after headspace solid-phase microextraction (HS-SPME), hydrodistillation (HD), and supercritical CO₂ extraction (SC-CO₂). The headspace composition of dried (HS-D) and fresh (HS-F) C. bursa was remarkably different. Dimethyl sulfide, the major HS-F compound was present in HS-D only as a minor constituent and heptadecane percentage was raised in HS-D. The distillate of fresh C. bursa contained heptadecane and docosane among the major compounds. After air-drying, a significantly different composition of the volatile oil was obtained with (E)-phytol as the predominant compound. It was also found in SC-CO₂ extract of freeze-dried C. bursa (FD-CB) as the major constituent. Loliolide (3.51%) was only identified in SC-CO₂ extract. Fatty acids were determined from FD-CB after derivatisation as methyl esters by GC-FID. The most dominant acids were palmitic (25.4%), oleic (36.5%), linoleic (11.6%), and stearic (9.0%). FD-CB H₂O extract exhibited better antifungal effects against Fusarium spp., while dimethyl sulfoxide (DMSO) extract was better for the inhibition of Penicillium expansum, Aspergillus flavus, and Rhizophus spp. The extracts showed relatively good antifungal activity, especially against P. expansum (for DMSO extract MIC₅₀ was at 50 µg/mL).

Chemical Diversity of Headspace and Volatile Oil Composition of Two Brown Algae (Taonia atomaria and Padina pavonica) from the Adriatic Sea

Two selected brown algae (Taonia atomaria and Padina pavonica from the family Dictyotaceae, order Dictyotales) growing in the same area (island Vis, central Adriatic Sea) were collected at the same time. Their phytochemical composition of the headspace volatile organic compounds (HS-VOCs; first time report) was determined by headspace solid-phase microextraction (HS-SPME). Hydrodistillation was applied for the isolation of their volatile oils (first report on T. atomaria volatile oil). The isolates were analyzed by gas chromatography (GC-FID) and mass spectrometry (GC-MS). The headspace and oil composition of T. atomaria were quite similar (containing germacrene D, epi-bicyclosesquiphellandrene, β-cubebene and gleenol as the major compounds). However, P. pavonica headspace and oil composition differed significantly (dimethyl sulfide, octan-1-ol and octanal dominated in the headspace, while the oil contained mainly higher aliphatic alcohols, trans-phytol and pachydictol A). Performed research contributes to the knowledge of the algae chemical biodiversity and reports an array of different compounds (mainly sesquiterpenes, diterpenes and aliphatic compounds); many of them were identified in both algae for the first time. Identified VOCs with distinctive chemical structures could be useful for taxonomic studies of related algae.

Insight into the Chemical Diversity of Late/Ice Harvest Gewürztraminer Wine

Late harvest (LHW) and ice harvest (IHW) Gewürztraminer wine samples from Croatia (Ilok) were investigated. Their technological parameters, chromaticity coordinates, total phenols content, and antioxidant capacity were determined. 5-(Hydroxymethyl)furfural, xanthine, and trans-caftaric acid were analyzed in the samples by high performance liquid chromatography (HPLC-DAD). Headspace solid-phase microextraction (HS-SPME) followed by gas chromatography and mass spectrometry (GC/MS) analysis revealed isoamyl alcohol as predominant compound (21.25 - 60.30%). Diethyl succinate, 2-phenylethanol, and benzaldehyde were also abundant. Ethyl octanoate (1.48 - 5.70%) and ethyl caprate (0.48 - 4.83%) decreased significantly in LHW, being the lowest in IHW. Two solvents were applied for the samples extraction (solvent A - pentane/diethyl ether 1:2 (v/v) and solvent B - dichloromethane), and the extracts were analyzed by GC/MS. Ethyl hydrogen succinate (solvent A: 27.30 - 52.04%; solvent B: 28.04 - 46.69%) and diethyl succinate (solvent A: 5.21 - 18.2%; solvent B: 2.66 - 7.72%) were predominant in IHW and LHW. Aromatic alcohols were also found: 2-phenylethanol (solvent A: 7.07 - 21.09%; solvent B: 5.50 - 11.82%), 4-hydroxybenzyl alcohol (solvent A: 1.45 - 6.68%; solvent B: 2.47 - 12.16%) and benzyl alcohol (solvent A: 0.10 - 0.77%). The obtained results complement a previous study on IHW (Gewürztraminer) from Croatia providing new features and indicating great chemical diversity among the samples.

Phytochemical study of the headspace volatile organic compounds of fresh algae and seagrass from the Adriatic Sea (single point collection)

Performed phytochemical study contributes to the knowledge of volatile organic compounds (VOCs) of Halopteris filicina (Grateloup) Kützing, Dictyota dichotoma (Hudson) J. V. Lamouroux, Posidonia oceanica (L.) Delile and Flabellia petiolata (Turra) Nizamuddin from the Adriatic Sea (single point collection). VOCs were investigated by headspace solid-phase microextraction (HS-SPME) and analysed by gas chromatography and mass spectrometry (GC-MS/FID). H. filicina headspace contained dimethyl sulfide (DMS; 12.8%), C8-compounds (e.g. fucoserratene (I; 9.5%)), benzaldehyde (II; 8.7%), alkane C17, dictyopterene D and C (III, IV), tribromomethane (V), 1-iodopentane, others. F. petiolata headspace was characterized by DMS (22.2%), 6-methylhept-5-en-2-one (9.5%), C17 (9.1%), II (6.5%), compounds I-V. DMS (59.3%), C15 (14.5%), C17 (7.2%) and C19 (6.3%) dominated in P. oceanica headspace. Sesquiterpenes were found in D. dichotoma, predominantly germacrene D (28.3%) followed by other cadinenyl (abundant), muurolenyl and amorphenyl structures. Determined VOCs may be significant for chemosystematics and chemical communications in marine ecosystem.

Unlocking Phacelia tanacetifolia Benth. honey characterization through melissopalynological analysis, color determination and volatiles chemical profiling

Phacelia tanacetifolia Benth. honey (14 samples) collected in Poland was characterized by melissopalynological analysis, color determination (CIE L*a*b*C_ab*h_ab° coordinates) and volatiles (VOCs) composition. VOCs were isolated by headspace solid-phase microextraction (HS-SPME, two fibers) and ultrasound-assisted solvent extraction (USE, two solvents) and analyzed by GC-MS. Principal component analysis (PCA) and hierarchical-tree clustering (HTC) were applied to show trends and form groups and to indicate the most representative unifloral samples. Six samples were pointed out with average pollen 74.9% and color parameters (L=85.1; a*=-0.8; b*=27.9; C_ab*=27.9; h_ab*=91.9) that were significantly correlated. High abundance of trans-linalool oxide (27.3-45.9%) that was significantly correlated with the pollen percentages, hexan-1-ol (4.4-5.7%) and lavender lactone (0.8% - 1.5%) were characteristic for their headspace. C₁₃-norisoprenoids, mainly (E)-/(Z)-3-oxo-retro-α-ionol (4.7-5.4%; 6.9-9.4%) and vomifoliol (9.0-13.0%) dominated in their USE extracts.

Screening of Polish Fir Honeydew Honey Using GC/MS, HPLC-DAD, and Physical-Chemical Parameters: Benzene Derivatives and Terpenes as Chemical Markers

GC/MS of headspace solid phase micro extraction (HS-SPME) and solvent extractives along with targeted HPLC-DAD of Polish fir (Abies alba Mill.) honeydew honey (FHH), were used to determine the chemical profiles and potential markers of botanical origin. Additionally, typical physical-chemical parameters were also assigned. The values determined for FHH were: conductivity (1.2 mS/cm), water content (16.7 g/100 g), pH (4.5), and CIE chromaticity coordinates (L* = 48.4, a* = 20.6, b* = 69.7, C* = 72.9, and h° = 73.5). FHH contained moderate-high total phenolic content (533.2 mg GAE/kg) and antioxidant activity (1.1 mmol TEAC/kg) and (3.2 mmol Fe²⁺ /kg) in DPPH and FRAP assays. The chemical profiles were dominated by source plant-originated benzene derivatives: 3,4-dihydroxybenzoic acid (up to 8.7 mg/kg, HPLC/honey solution), methyl syringate (up to 14.5%, GC/solvent extracts) or benzaldehyde (up to 43.7%, GC/headspace). Other markers were terpenes including norisoprenoid (4-hydroxy-3,5,6-trimethyl-4-(3-oxobut-1-enyl)cyclohex-2-en-1-one, up to 20.3%, GC/solvent extracts) and monoterpenes, mainly linalool derivatives (up to 49%, GC/headspace) as well as borneol (up to 5.9%, GC/headspace). The application of various techniques allowed comprehensive characterisation of FHH. 4-Hydroxy-3,5,6-trimethyl-4-(3-oxobut-1-enyl)cyclohex-2-en-1-one, coniferyl alcohol, borneol, and benzaldehyde were first time proposed for FHH screening. Protocatechuic acid may be a potential marker of FFH regardless of the geographical origin.

Evaluation of natural occurring bioactive compounds and antioxidant activity in Nuragus white wines

The aim of the present study is to highlight volatile and targeted non-volatile bioactive compounds in Nuragus wines, as a part of Italian DOC (Controlled Origin Designation) white wines. So far there has not been any systematic study of the chemical compositions and antioxidant activity of this monovarietal wine. Phenolic compounds, volatiles and organic acids were analysed and antioxidant capacity was assessed by spectrophotometric assays. Chromaticity coordinates and technological parameters (alcohol, reducing sugars, pH, total and volatile acidity) were also evaluated. Gallic acid (128±87mg/L), trans-caftaric acid (81±27mg/L) and tyrosol (25±8mg/L) were the most abundant phenolic compounds. The major headspace volatiles were isoamyl alcohol (35.8-76.6%) and 2-phenylethanol (5.9-24.9%). In the wine extracts, the most abundant were 2-phenylethanol (12.3-40.0%), 4-hydroxy-2-phenylethanol (12.5-33.3%), diethyl succinate (5.8-30.3%), (Z)-octadec-9-en-1-ol (5.9-18.3%) and tryptophol (2.8-15.6%). Nuragus wines exhibited an excellent antioxidant capacity. The data obtained may help Nuragus wine producers to promote this monovarietal wine as a valid complement associated with the Mediterranean diet.

Phenolic Compounds, Volatiles and Antioxidant Capacity of White Myrtle Berry Liqueurs

The aim of this research was to evaluate the antioxidant capacity and physical-chemical characteristics of commercial white myrtle berry (Myrtus communis L. var. leucocarpa DC) liqueur (WMBL). The total phenolic (TP) content was measured spectrophotometrically, applying a modified Folin-Ciocalteu's method, and phenolic compounds were identified by high-performance liquid chromatography (HPLC) coupled with electrospray mass spectrometry, and quantified by HPLC coupled with ultraviolet/visible detection. The antioxidant capacities were evaluated by FRAP, CUPRAC, DPPH^•, and ABTS^•+ assays. The volatiles were assessed by gas chromatography and mass spectrometry (GC-MS/FID) after headspace solid-phase microextraction (HS-SPME) and liquid-liquid extraction (LLE). WMBL showed lower TP levels (636.3 ± 39.2 mg GAE/L) than in purple myrtle berry liqueur (PMBL). Nevertheless, WMBL exhibited better antioxidant capacities, potentially due to high concentrations of gallic acid (294.2 ± 14.2 mg/L) and its derivatives (58.3 ± 2.1 mg/L). Other phenolic compounds detected by HPLC-DAD and LC-MS/MS were flavonols like myricetin and its derivatives (myricetin-3-O-galactoside and myricetin-3-O-rhamnoside) with concentrations similar to those found in PMBL. GC-MS/FID analysis revealed 44 compounds (terpenes, higher aliphatic compounds and shikimic acid pathway derivatives). 1,8-Cineole was the most abundant terpene in the liqueur (26.5% (HS-SPME) and 9.6% (LLE)).

First Report on Rare Unifloral Honey of Endemic Moltkia petraea (Tratt.) Griseb. from Croatia: Detailed Chemical Screening and Antioxidant Capacity

Rare Moltkia petraea (Tratt.) Griseb. honey from Croatia was first time characterised. The spectrophotometric assays on CIE L*a*b*C_ab *h_ab ° colour coordinates, total phenol content and antioxidant capacity (FRAP, CUPRAC, DPPH^• and ABTS^•+ assays) determined higher honey values generally close to dark honeys ranges. Headspace solid-phase microextraction (HS-SPME) on two fibres after GC-FID and GC/MS revealed the major compounds 2-phenylacetaldehyde (12.8%; 15.6%), benzaldehyde (11.1%; 10.0%), octane (9.3%; 7.6%), nonane, propan-2-one, pentan-2-one, pentanal and nonanal (4.9%; 14.5%). Ultrasonic solvent extraction (USE) mainly isolated non-specific higher molecular compounds characteristic of the comb environment. Targeted HLPC-DAD analysis of the honey determined higher concentration of phenylalanine (212.08 mg/kg) and lumichrome (16.25 mg/kg) along with tyrosine and kojic acid. The headspace composition (chemical fingerprint) and high concentration of lumichrome can be considered particular for M. petraea honey.

Essential Oil Composition of Three Globularia Species

The chemical composition of the essential oils obtained by hydrodistillation from the aerial parts of Globularia cordifolia L., G. meridionalis (Podp.) O.Schwarz, and G. punctata Lapeyr. was characterized by GC-FID and GC/MS analyses. Among the 33 identified compounds, the most abundant present in all investigated samples were oct-1-en-3-ol (2.9-47.0%), 6-(1,5-dimethylhex-4-enyl)-3-methylcyclohex-2-enone (8.2-40.9%), and fukinanolid (7.4-31.6%). Multivariate statistical analyses (PCA and HCA) of the hitherto studied Globularia volatile compounds confirmed to some extent the assumed phylogenetic relationships of the Globularia species studied, including the close relationship between the morphologically similar species G. cordifolia and G. meridionalis, but also evidenced several discrepancies in the current classification of Globularia species.

Comprehensive Study of Mediterranean (Croatian) Propolis Peculiarity: Headspace, Volatiles, Anti-Varroa-Treatment Residue, Phenolics, and Antioxidant Properties

Eight propolis samples from Croatia were analyzed in detail, to study the headspace, volatiles, anti-Varroa-treatment residue, phenolics, and antioxidant properties. The samples exhibited high qualitative/quantitative variability of the chemical profiles, total phenolic content (1,589.3-14,398.3 mg GAE (gallic acid equivalent)/l EtOH extract), and antioxidant activity (11.1-133.5 mmol Fe(2+) /l extract and 6.2-65.3 mmol TEAC (Trolox® equivalent antioxidant capacity)/l extract). The main phenolics quantified by HPLC-DAD at 280 and 360 nm were vanillin, p-coumaric acid, ferulic acid, chrysin, galangin, and caffeic acid phenethyl ester. The major compounds identified by headspace solid-phase microextraction (HS-SPME), simultaneous distillation extraction (SDE), and subsequent GC-FID and GC/MS analyses were α-eudesmol (up to 19.9%), β-eudesmol (up to 12.6%), γ-eudesmol (up to 10.5%), benzyl benzoate (up to 28.5%), and 4-vinyl-2-methoxyphenol (up to 18.1%). Vanillin was determined as minor constituent by SDE/GC-FID/MS and HPLC-DAD. The identified acaricide residue thymol was ca. three times more abundant by HS-SPME/GC-FID/MS than by SDE/GC-FID/MS and was not detected by HPLC-DAD.

Chemical Profiles and Anti-inflammatory Activity of the Essential Oils from Seseli gummiferum and Seseli corymbosum subsp. corymbosum

The anti-inflammatory activity of the essential oils from Seseli corymbosum subsp. corymbosum Pall. ex Sm. (SC) and Seseli gummiferum Boiss. & Heldr. subsp. corymbosum (SG) was investigated for the first time on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The main constituents (determined by GC-FID and GC-MS analyses) were germacrene D (54.1%) and sabinene (22.4%) in SG oil and β-phellandrene (29.2%), α-phellandrene (8.2%) and germacrene D (2.5%) in SC oil. SC and SG oils inhibited nitric oxide (NO) production with IC50 values of 56.1 and 108.2 μg/mL, respectively. The oils also inhibited prostaglandin E2 (PGE2) with IC50 values of 49.4 μg/mL (SC oil) and 95.5 μg/mL (SG oil). The inhibitory effect of SC and SG oils was accompanied by dose-dependent decreases of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expressions in LPS-induced RAW 264.7 cells. The research of the reporter gene assay on nuclear factor κB (NF-κB) showed that SC and SG oils inhibited NF-κB transcriptional activity. The obtained results suggest that SC and SG oils exert the anti-inflammatory effects in LPS-stimulated RAW 264.7 cells by suppressing NF-κB activation.

Chemical Profiles and Anti-inflammatory Activity of the Essential Oils from Seseli gummiferum and Seseli corymbosum subsp. corymbosum

The anti-inflammatory activity of the essential oils from Seseli corymbosum subsp. coiymbosum Pall. ex Sm. (SC) and Seseli gummiferum Boiss. & Heldr. subsp. corymbosum (SG) was investigated for the first time on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The main constituents (determined by GC-FID and GC-MS analyses) were germacrene D (54.1%) and sabinene (22.4%) in SG oil and β-phellandrene (29.2%), α-phellandrene (8.2%) and germacrene D (2.5%) in SC oil. SC and SG oils inhibited nitric oxide (NO) production with IC50 values of 56.1 and 108.2 μg/mL, respectively. The oils also inhibited prostaglandin E2 (PGE2) with IC50 values of 49.4 μg/mL (SC oil) and 95.5 μg/mL (SG oil). The inhibitory effect of SC and SG oils was accompanied by dose-dependent decreases of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expressions in LPS-induced RAW 264.7 cells. The research of the reporter gene assay on nuclear factor KB (NF-KB) showed that SC and SG oils inhibited NF-KB transcriptional activity. The obtained results suggest that SC and SG oils exert the anti-inflammatory effects in LPS-stimulated RAW 264.7 cells by suppressing NF-KB activation.

Traceability of Satsuma Mandarin (Citrus unshiu Marc.) Honey through Nectar/Honey-Sac/Honey Pathways of the Headspace, Volatiles, and Semi-Volatiles: Chemical Markers

Headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE), followed by GC-MS/FID, were applied for monitoring the nectar (NE)/honey-sac (HoS)/honey (HO) pathways of the headspace, volatiles, and semi-volatiles. The major NE (4 varieties of Citrus unshiu) headspace compounds were linalool, α-terpineol, 1H-indole, methyl anthranilate, and phenylacetonitrile. Corresponding extracts contained, among others, 1H-indole, methyl anthranilate, 1,3-dihydro-2H-indol-2-one and caffeine. The major HoS headspace compounds were linalool, α-terpineol, 1,8-cineole, 1H-indole, methyl anthranilate, and cis-jasmone. Characteristic compounds from HoS extract were caffeine, 1H-indole, 1,3-dihydro-2H-indol-2-one, methyl anthranilate, and phenylacetonitrile. However, HO headspace composition was significantly different in comparison to NE and HoS with respect to phenylacetaldehyde and linalool derivatives abundance that appeared as the consequence of the hive conditions and the bee enzyme activity. C. unshiu honey traceability is determined by chemical markers: phenylacetaldehyde, phenylacetonitrile, linalool and its derivatives, as well as 1H-indole, 1,3-dihydro-2H-indol-2-one, and caffeine.

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

The present study is focused on the antioxidant capacity and chemical profiling of eight Croatian Satureja montana L. honey samples. Among the 20 compounds obtained by headspace solid-phase microextraction (HS-SPME) and identified by GC-FID and GC/MS analyses, hotrienol was predominant (75.9-81.7%). The honey matrix volatile/semivolatile profile was investigated by ultrasonic solvent extraction (USE) followed by GC-FID and GC/MS analyses. The major compounds identified by this latter method were the sinapic-acid derivatives methyl syringate (36.2-72.8%) and syringaldehyde (2.2-43.1%). Direct, targeted HPLC-DAD analyses of the native honey samples revealed the presence of methyl syringate (7.10-39.60 mg/kg) and syringic acid (0.10-1.70 mg/kg). In addition, the total phenolic content of the samples was determined by the FolinCiocalteu assay (311.0-465.9 mg GAE/kg), and the antioxidant capacity was evaluated by the DPPH radical-scavenging activity (0.5-1.0 mmol TEAC/kg) and the ferric reducing antioxidant power (2.5-5.1 mmol Fe(2+) /kg).

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.

Evaluation of HS-SPME and ultrasonic solvent extraction for monitoring of plant flavours added by the bees to herbhoneys: traceability biomarkers

The volatile composition of 21 herbhoneys (HHs) of 7 different botanical origins was characterised for the first time. Ultrasound solvent extraction (USE) and headspace solid-phase microextraction (HS-SPME) followed by GC-FID/MS were successfully applied as complementary methods for monitoring the volatile plant flavours added by the bees. HHs showed significant compositional variability related to the botanical origin and compounds that could serve as traceability biomarkers were identified. The most important compounds with high abundance were (E,extract; H, headspace): caffeine (up to 68.7%, E) and trans-linalool oxide (up to 26.0%, H) in coffee HH, α-terpineol (up to 8.2%, E; 27.1%, H) and bornyl acetate (up to 3.1, E; 11.9%, H) in pine HH, thymol (up to 3.1%, E; 55.4%, H) in thyme HH. Hawthorn HH was characterised by the presence of herniarin (up to 13.4%, E) and lemon HH contained limonene (up to 1.6%, E; 33.2%, H). Other HHs (nettle and aloe) contained lower amounts of volatiles and their profiles were not specific. In all the HHs, methyl syringate was found and it was most abundant in thyme HH (up to 17.4%, E). The volatile fraction of HHs showed some substantial similarities and differences with the composition of herbs from which they derive. It confirms the selective bee-mediated transfer of phytochemicals, including known flavour-active volatiles into the final product, but also biotransformation of several compounds. Additionally, several similarities to the corresponding natural honeys were observed, but in general HHs exhibited less rich volatile profiles.

GC-FID/MS Profiling of Supercritical CO2 Extracts of Peels from Citrus aurantium, C. sinensis cv. Washington navel, C. sinensis cv. Tarocco and C. sinensis cv. Doppio Sanguigno from Dubrovnik Area (Croatia)

The peels of Citrus aurantium L. and Citrus sinensis Osbeck cultivars from the Dubrovnik region (south Croatia) were extracted by supercritical CO2 at 40°C and 10 MPa at 1.76 kg/h to obtain enriched extracts in comparison with simple pressing of the peels. The extracts were analyzed in detail by gas chromatography and mass spectrometry (GC-FID/MS). Relevant similarities among the peel oil compositions of C. aurantium and C. sinensis cultivars were found with limonene predominance (up to 54.3%). The principal oxygenated monoterpenes were linalool (3.0%–5.9%), α-terpineol (0.7%–2.4%), linalyl acetate (0.0%–5.0%), geranyl acetate (0.0%-0.4%), ( Z)-citral (0.0%–1.8%) and ( E)-citral (0.0%–1.9%). Several sesquiterpenes were found with minor percentages. Coumarin derivatives were identified in all the samples among the relevant compounds. Isogeijerin dominated in the peels of C. sinensis cv. Tarocco (15.3%) and C. aurantium (11.2%). Scoparone ranged from 0.1% to 0.5% in all the samples. Bergapten (up to 1.4%), osthole (up to 1.1%) and 7-methoxy-8-(2-formylpropyl)coumarin (up to 1.1%) were found mostly in C. sinensis cv. Doppio Sanguigno. It was possible to indicate a few other differences among the extracts such as higher percentage of linalool, linalyl and geranyl acetates, as well as the abundance of sabinene and isogeijerin in C. aurantium or the occurrence of β-sinensal in C. sinensis cultivars.

GC-FID/MS Profiling of Supercritical CO2 Extracts of Peels from Citrus aurantium, C. sinensis cv. Washington navel, C. sinensis cv. Tarocco and C. sinensis cv. Doppio Sanguigno from Dubrovnik Area (Croatia)

The peels of Citrus aurantium L. and Citrus sinensis Osbeck cultivars from the Dubrovnik region (south Croatia) were extracted by supercritical CO2 at 40 degrees C and 10 MPa at 1.76 kg/h to obtain enriched extracts in comparison with simple pressing of the peels. The extracts were analyzed in detail by gas chromatography and mass spectrometry (GC-FID/MS). Relevant similarities among the peel oil compositions of C. aurantium and C. sinensis cultivars were found with limonene predominance (up to 54.3%). The principal oxygenated monoterpenes were linalool (3.0%-5.9%), α-terpineol (0.7%-2.4%), linalyl acetate (0.0%-5.0%), geranyl acetate (0.0%-0.4%), (Z)-citral (0.0%-1.8%) and (E)-citral (0.0%-1.9%). Several sesquiterpenes were found with minor percentages. Coumarin derivatives were identified in all the samples among the relevant compounds. Isogeijerin dominated in the peels of C. sinensis cv. Tarocco (15.3%) and C. aurantium (11.2%). Scoparone ranged from 0.1% to 0.5% in all the samples. Bergapten (up to 1.4%), osthole (up to 1.1%) and 7-methoxy-8-(2-formylpropyl)coumarin (up to 1.1%) were found mostly in C. sinensis cv. Doppio Sanguigno. It was possible to indicate a few other differences among the extracts such as higher percentage of linalool, linalyl and geranyl acetates, as well as the abundance of sabinene and isogeijerin in C. aurantium or the occurrence of β-sinensal in C. sinensis cultivars.

Comparison of different methodologies for detailed screening of Taraxacum officinale honey volatiles

Headspace solid-phase microextraction (HS-SPME), ultrasonic solvent extraction (USE) and solid phase extraction (SPE), followed by GC-FID/MS were used for screening of dandelion (Taraxacum officinale Weber) honey headspace, volatiles and semi-volatiles. The obtained results constitute a breakthrough towards screening of dandelion honey since dominant compounds identified in the extracts were not previously reported for this honey type. Nitriles dominated in the headspace, particularly 3-methylpentanenitrile (up to 29.9%) and phenylacetonitrile (up to 20.9%). Lower methyl branched aliphatic acids and norisoprenoids were relevant minor constituents of the headspace. The extracts contained phenylacetic acid (up to 24.0%) and dehydrovomifoliol (up to 19.3%) as predominant compounds, while 3-methylpentanenitrile and phenylacetonitrile were detected in the extracts in minor abundance. Dehydrovomifoliol can be considered more characteristic for dandelion honey in distinction from phenylacetic acid. Low molecular aliphatic acids, benzene derivatives and an array of higher aliphatic compounds were also found in the extracts. The results of SPE/GC-FID/MS were very similar to USE/GC-FID/MS with the solvent dichloromethane. The use of all applied methodologies was relevant for the comprehensive chemical fingerprinting of dandelion honey volatiles.

Bioorganic research of Galactites tomentosa Moench. Honey extracts: enantiomeric purity of chiral marker 3-phenyllactic acid

Thistle (Galactites tomentosa Moench.) honey organic extracts were obtained by headspace solid-phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE) and analyzed by gas chromatography (GC-FID and GC-MS) for the first time. Most abundant headspace compounds were terpenes, particularly linalool derivatives (hotrienol was predominant with a range of 38.6-57.5%). 3-Phenyllactic acid dominated in the solvent extracts (77.4-86.4%) followed by minor percentages of other shikimate pathway derivatives. After determination of an adequate enantioseparation protocol on Chirallica PST-4 column, the honey solvent extracts were analyzed by high-performance liquid chromatography (HPLC). The chiral analysis revealed high enantiomeric excess (>95%) of (-)-3-phenyllactic acid in all samples. Therefore, previous findings of chemical markers of thistle honey were extended, providing new potential for advanced chemical fingerprinting (optical pure chemical marker).

Color evaluation of seventeen European unifloral honey types by means of spectrophotometrically determined CIE L*Cab*h(ab)° chromaticity coordinates

CIE (Commission Internationale de l'Eclairage) L(*)Cab(*)h(ab)° color coordinates for 305 samples of 17 unifloral honeys types (asphodel, buckwheat, black locust, sweet chestnut, citrus, eucalyptus, Garland thorn, honeydew, heather, lime, mint, rapeseed, sage, strawberry tree, sulla flower, savory and thistle) from different geographic locations in Europe were spectrophotometrically assessed and statistically evaluated. Preliminary separation of unifloral honeys was obtained by means of L(*)-C(ab)(*) color coordination correlation. Hierarchical Cluster Analysis (HCA) revealed an expected segregation of the honeys types according to their chromatic characteristics. Principal Component Analysis (PCA) allowed to obtain a more defined distinction of the 17 unifloral honey types, particularly when using 3D graphics. CIE L(*)C(ab)(*)hab(*) color coordinates were useful for the identification of several honey types. The proposed method represents a simple and efficient procedure that can be used as a basis for the authentication of unifloral honeys worldwide.

Cornflower (Centaurea cyanus L.) honey quality parameters: chromatographic fingerprints, chemical biomarkers, antioxidant capacity and others

The samples of cornflower (Centaurea cyanus L.) honey from Poland were subjected to ultrasonic solvent extraction applying the mixture of pentane and diethyl ether 1:2v/v (solvent A) as well as dichloromethane (solvent B). The major compounds of the extracts (analysed by GC-MS/GC-FID) were C13 and C9 norisoprenoids. Among them, (E)-3-oxo-retro-α-ionol (2.4-23.9% (solvent A); 3.9-14.4% (solvent B)) and (Z)-3-oxo-retro-α-ionol (3.7-29.9% (solvent A); 8.4-20.4% (solvent B)) were found to be useful as chemical biomarkers of this honey. Other abundant compounds were: methyl syringate (0.0-31.4% (solvent A); 0.0-25.4% (solvent B)) and 3-hydroxy-4-phenylbutan-2-one (1.6-15.8% (solvent A); 5.1-15.1% (solvent B)). HPLC-DAD analysis of the samples revealed lumichrome (4.7-10.0mg/kg), riboflavin (1.9-2.7mg/kg) and phenyllactic acid (112.1-250.5mg/kg) as typical compounds for this honey type. Antioxidant and antiradical properties as well as total phenolic content of the samples were found to be rather moderate by FRAP (ferric reducing antioxidant power), DPPH (1,1-diphenyl-2-picrylhydrazyl radical) and Folin-Ciocalteu assays, respectively. Additionally, CIE L(∗)a(∗)b(∗)C(∗)h chromatic coordinates were evaluated. Colour attributes of cornflower honey were characterised by elevated values of L(∗) and particularly high values of b(∗) and h coordinates, which correspond to medium bright honey with intense yellow colour.

GC-MS Fingerprints and Other Physico-chemical Characteristics of Rare Unifloral Prunus cerasus L. Honey

GC-MS fingerprints of unifloral sour cherry ( Prunus cerasus L.) honey were investigated for the first time by GC-FID and GC-MS {after headspace solid phase microextraction (HS-SPME) and ultrasonic solvent extraction (USE)}. Additionally, other physico-chemical characteristics of the samples were determined (total phenolic content, antioxidant activity and CIE L*a*b*C*h chromatic coordinates). The principal volatile components of the honey headspace were lilac aldehydes (46.0; 50.6%) along with benzaldehyde (18.0; 19.4%). The dominant component of the dichloromethane USE extract was vomifoliol (39.6; 44.9%). The abundant identified compounds may only serve as non-specific markers of the honey's botanical origin since they also occur in other honey types. The honey contained low-moderate amount of polyphenols (209.0 - 309.5 mg GAE/kg) and exhibited moderate antioxidant activity (0.4 - 0.6 mmol TEAC/kg; 1.6 - 1.9 mmol Fe2+/kg).

Chemical Composition of Hypericum richeri subsp. grisebachii Essential Oil from Croatia

The aerial parts of Hypericum richeri Vill. subsp. grisebachii (Boiss.) Nyman were collected from two different locations in Croatia and subjected to hydrodistillation. GC/FID and GC/MS analysis of the isolated essential oils revealed 64 compounds representing 94.7% and 98.2% of the total oils. Predominant constituents in both samples were: germacrene D (10.9%; 6.0%), bicyclogermacrene (4.7%; 3.5%), α-pinene (6.8%; 6.9%), β-pinene (8.1%; 5.1%), decanoic acid (4.5%; 6.8%), β-caryophyllene (3.3%; 7.5%), δ-cadinene (7.0%; 4.4%), spathulenol (6.0%; 9.5%) and tetracosane (3.1%; 5.8%). Comparison of both samples revealed similarity in the chemical composition with minor fluctuations of constituent percentages. The chemical profile of Croatian oils was in general similar to those reported for other geographic areas regarding major mono- and sesquiterpene constituents. However, spathulenol, 5-cadinene and bicyclogermacrene were more abundant in Croatian oils. The presence of decanoic acid (4.5%; 6.8%) in Croatian oils was the major difference between acids and fatty acids derivatives. Higher abundance of alkanes (particularly tetracosane and docosane) was also noticed.

Chemical composition of Hypericum richeri subsp. grisebachii essential oil from Croatia

The aerial parts of Hypericum richeri Vill. subsp. grisebachii (Boiss.) Nyman were collected from two different locations in Croatia and subjected to hydrodistillation. GC/FID and GC/MS analysis of the isolated essential oils revealed 64 compounds representing 94.7% and 98.2% of the total oils. Predominant constituents in both samples were: germacrene D (10.90%; 6.0%), bicyclogermacrene (4.7%; 3.5%), alpha-pinene (6.8%; 6.9%), beta-pinene (8.1%; 5.1%), decanoic acid (4.5%; 6.8%), beta-caryophyllene (3.3%; 7.5%), delta-cadinene (7.0%; 4.4%), spathulenol (6.0%; 9.5%) and tetracosane (3.1%; 5.8%). Comparison of both samples revealed similarity in the chemical composition with minor fluctuations of constituent percentages. The chemical profile of Croatian oils was in general similar to those reported for other geographic areas regarding major mono- and sesquiterpene constituents. However, spathulenol, delta-cadinene and bicyclogermacrene were more abundant in Croatian oils. The presence of decanoic acid (4.5%; 6.8%) in Croatian oils was the major difference between acids and fatty acids derivatives. Higher abundance of alkanes (particularly tetracosane and docosane) was also noticed.

Volatile organic compounds from Centaurium erythraea Rafn (Croatia) and the antimicrobial potential of its essential oil

GC and MS were used for the analysis of Croatian Centaurium erythraea Rafn essential oil (obtained by hydrodistillation) and headspace (applying headspace solid-phase microextraction). The headspace contained numerous monoterpene hydrocarbons (the major ones were terpinene-4-ol, methone, p-cymene, γ-terpinene and limonene). Oxygenated monoterpenes were present in the headspace and oil, while 1,8-cineole, bornyl acetate and verbenone were present only in the headspace. High headspace percentages of toluene and naphthalene were found, followed by hemimellitene. Lot of similarities were observed with Serbian C.erythraea oil [neophytadiene (1.4%), thymol (2.6%), carvacrol (6.1%) and hexadecanoic acid (5.7%)], but different features were also noted such as the presence of menthol, menthone and phytone. The oil fractionation enabled identification of other minor compounds not found in total oil such as norisoprenoides, alk-1-enes or chromolaenin. The essential oil showed antimicrobial potential on Escherichia coli, Salmonella enteritidis, Staphylococcus aureus and Bacillus cereus. On the other hand, no antibacterial activity of the oil was observed on Pseudomonas fluorescens and Lysteria monocytogenes.

Biodiversity of Salix spp. honeydew and nectar honeys determined by RP-HPLC and evaluation of their antioxidant capacity

Rare unifloral willow (Salix spp.) honeys obtained from nectar or honeydew were investigated by direct RP-HPLC-DAD method in order to identify and quantify compounds that can be used as possible markers of their origin. Antioxidant and antiradical activities of willow honeys were evaluated using FRAP (=ferric reducing antioxidant assay) and DPPH (=1,1-diphenyl-2-picrylhydrazyl radical) tests, respectively. Also HMF (=5-(hydroxymethyl)furfural), diastase activity, and CIE L*a*b*C*h* chromatic coordinates were evaluated. Abscisic acids (ABA) are typical of willow nectar honey, with a predominance of (Z,E)-ABA on (E,E)-ABA (98.2 and 31.7 mg/kg, resp.). Kinurenic acid and salicylic acid are useful to mark willow honeydew honey. The proposed HPLC-DAD method proved to be easy and reliable to identify the two different Salix spp. honeys, being not affected from any sample preparation artifact. Total antioxidant activity measured with the FRAP assay ranged from 3.2 to 12.6 mmol Fe(2+) /kg, and the antiradical activity measured with the DPPH assay ranged from 0.6 to 3.0 mmol TEAC (=Trolox equivalent antioxidant capacity)/kg in nectar and honeydew honeys, respectively. Salix spp. nectar and honeydew honeys proved to be two completely different honeys, because, besides color attributes, they show different antioxidant properties and specific compounds.

Volatile compounds of Asphodelus microcarpus Salzm. et Viv. Honey obtained by HS-SPME and USE analyzed by GC/MS

Chemical analysis of Asphodelus microcarpus Salzm. et Viv. honey is of great importance, since melissopalynology does not allow the unambiguous determination of its botanical origin. Therefore, the volatile compounds of eight unifloral asphodel honeys have been investigated for the first time. The honey extracts were obtained by headspace solid-phase microextraction (HS-SPME) and ultrasonicsolvent extraction (USE) and analyzed by GC and GC/MS. In the honey headspace, 31 volatile compounds were identified with high percentages of 2-phenylacetaldehyde (2; 14.8–34.7%), followed by somewhat lower percentages of methyl syringate (1; 10.5–11.5%). Compound 2 is not a specific marker of the botanical origin of the honey, but its high percentage can be emphasized as headspace characteristic of asphodel honey. The extraction solvent for all the samples was selected after extracting a representative sample with pentane, Et(2)O, pentane/Et(2)O 1:2 (v/v), and CH(2)Cl(2) . Compound 1 was the major constituent of all the USE extracts (46.8–87.0%). According to these preliminary results, all the honey samples were extracted by USE with the solvent pentane/Et(2)O 1:2. A total of 60 volatile compounds were identified with 1 as predominant compound (69.4–87.0%), pointing out 1 as Asphodelus honey volatile marker.