Sea fennel (Crithmum maritimum L.) is a wild-growing halophyte used in cuisine, traditional medicine or cosmetic products for its beneficial nutritive value and pleasant sensory characteristics. This study aimed to investigate sea fennel essential oils (EOs) from different parts of the plant (flowers, leaves and stems) and the corresponding hydrodistillation by-products (residual water) to validate their potential use and application in different industries. EOs were analyzed by gas chromatography coupled with mass spectrometry (GC-MS), while the phenolic profile of the residual water was analyzed by high-performance liquid chromatography (HPLC) and spectrophotometric methods. The EO analysis confirmed the presence of 14 compounds, dominated by sabinene (from 42.55 to 51.47%) and limonene (from 36.28 to 43.58%), while among the 12 detected phenolics, chlorogenic acid and its isomers (cryptochlorogenic and neochlorogenic acid) were found in the highest concentrations. Total phenolic, flavonoid and tannin contents were concentrated in the order flowers > leaves > stems. Although the sea fennel samples showed differences in chemical profiles, overall they were rich in bioactive compounds with relatively high amounts of key compounds with already proved good biological properties, especially in waste-water, indicating great potential for re-use in accordance with green processing technology trends.

In this study, different extraction methods were compared for the isolation of bioactive phenolic compounds from sea fennel: microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and conventional solvent extraction (CSE). Total phenolics, flavonoids, and tannins were determined spectrophotometrically. In contrast, the determination of individual phenolics was performed by high-performance liquid chromatography coupled with an ultraviolet/visible detector (HPLC-UV/VIS). Two in vitro assays (ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picryl-hydrazyl (DPPH)) were performed to determine antioxidant activity. The maximum extraction of phenolic compounds was achieved with 50% ethanol, while the MAE method showed the highest extraction efficiency, with a total phenolic content of more than 25 mg of gallic acid equivalents (GAE)/mg and a chlorogenic acid content of more than 10 mg/g, respectively. The highest antioxidant potential was also observed in the samples from MAE (the FRAP value ranged from 173 to 185 µmol Fe²⁺/g, and the DPPH inhibition ranged from 55 to 59%), which was consistent with the extraction results. Although the phenolic antioxidants of sea fennel have been extensively studied recently, to the authors’ knowledge, this study was the first to evaluate the application of the new techniques for their isolation and to show the advantages of MAE compared to the other techniques used.

The main objectives of this study were to investigate the effects of the applied essential oil (EO) isolation method, conventional hydro-distillation (HD), and microwave-assisted hydro-distillation (MHD) on the chemical profile of sea fennel (Crithmum maritimum L.) essential oil and to investigate the main constituents present in the liquid by-products of EOs isolation (hydrolate and residual wastewater). Headspace-solid phase microextraction (HS-SPME) was used to isolate hydrolate components, while gas chromatography coupled with mass spectrometry (GC-MS) was used to detect and analyse the chemical constituents of the essential oils and hydrolates. The phenolic composition of the wastewater extracts was analysed by high performance liquid chromatography (HPLC). The EO obtained by MHD had a higher yield of limonene and sabinene. The chemical composition of the hydrolates differed from the EO compositions. The content of terpinen-4-ol in the MHD hydrolate was higher, while several compounds were detected in relatively high proportions only in the HD hydrolate. MHD also resulted in a higher phenolic content of the wastewater, where an increase in the concentration of chlorogenic acid was also observed. It can be concluded that the isolation method had a great influence on the profile of sea fennel EOs, especially on their corresponding hydrolates and residual wastewater extracts. Due to their valuable chemical composition, these by-products can be a cost-effective source of bioactive compounds that have great potential for use in various industries.

Extreme environmental conditions affect the synthesis and accumulation of bioactive metabolites in halophytic plants. The aim of this study was to investigate the presence and quantity of key health-promoting phytochemicals in Croatian sea fennel, one of the most popular Mediterranean halophytes with a wide range of uses. The EOs were characterised by a high content of limonene (up to 93%), while the fatty acid profile shows a low content of oleic acid and the presence of valuable linoleic acid (ω-6) and linolenic acid (ω-3) in high percentages. The dominances of lutein and α-tocopherol were also confirmed in all samples. The results confirm the great variability in the chemistry of sea fennel populations in the Mediterranean region, with significant differences in the composition of the Croatian samples compared to the others, as well as the presence and high concentrations of the analysed bioactive compounds that contribute to the plant's health-promoting attributes.

Olive leaves are a highly available by-product from table olive and olive oil production. They are nowadays strongly valuable for their major bioactive compounds and their beneficial effects. To determine the differences between two Croatian domestic (Lastovka, Oblica) and two introduced (Leccino, Frantoio) cultivars, physical and chemical analysis of olive leaves were performed: surface area, color variability, total phenolic amounts, and essential oil volatile profiles were analyzed at three harvest periods. All cultivars greatly differed in surface area, with cv. Lastovka being the smallest. Color variability resulted in an overall decrease in darkness and amounts of green and yellow that could be attributed to a decrease in photosynthetic demand and chlorophyll content. The highest amount of total phenolic content occurred in the summer months, followed by a reduction until October. Essential oils volatiles were determined by GC-MS and showed great diversity not only amongst cultivars but also between harvest periods, with overall 45 compounds identified. Principal component analysis distinguished domestic cultivar Oblica from the other observed cultivars, mainly due to its essential oil volatile fingerprint. Compounds that differentiated cv. Oblica were aldehydes ((E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal, decanal), ketones ((E)-β-damascone, dihydrodehydro-β-ionone), sesquiterpenes (cyclosativene, α-copaene, α-muurolene) and saturated hydrocarbons (tetradecane, hexadecane). Essential oil volatile fingerprint attributed the highest to the biodiversity of domestic cv. Oblica through all three harvest periods.

Cantharellus cibarius, the golden chanterelle, is the second most-collected wild edible mushroom in Europe and very frequently harvested in Croatia. Wild mushrooms have been considered a healthy food since ancient times and are today highly valued for their beneficial nutritional as well as medicinal properties. Since golden chanterelle is added to different food products to improve their nutritive value, we studied the chemical profile of aqueous extracts of golden chanterelle (at 25 °C and 70 °C) and their antioxidant and cytotoxic activities. Malic acid, pyrogallol and oleic acid were some of the main compounds identified by GC-MS from derivatized extract. p-Hydroxybenzoic acid, protocatechuic acid and gallic acid were the most abundant phenolics quantitatively determined by HPLC, with somewhat higher amounts for samples extracted at 70 °C. Antioxidant activity was determined by ferric reducing antioxidant power assay and oxygen radical absorption method, and the highest results were recorded for golden chanterelle extracted at 70 °C, being 41.54 ± 1.54 and 38.72 ± 2.47 µM TE/L, respectively. Aqueous extract at 25 °C showed the better response against human breast adenocarcinoma MDA-MB-231 (IC₅₀ = 375µg/mL). Our results confirm the beneficial effect of golden chanterelle even under aqueous extraction conditions and highlight its significance as a dietary supplement and in the development of new beverage products.