Black locust (Robinia pseudoacacia L.), an invasive tree in Europe, commonly known for its negative impact on biodiversity, is a rich source of phenolic compounds recognized in traditional medicine. Since the metabolite profile depends on the environment and climate, this study aimed to provide the first LC-MS phytochemical screening of the black locust from the Istria region (Croatia). The compounds were extracted from leaves and flowers with 70% ethanol and 80% methanol. Total phenolics (TP) and flavonoids (TF), as well as antioxidant capacity (AC) measured by ABTS (17.49–146.41 mg TE/g DW), DPPH (24.67–118.49 mg TE/g DW), and FRAP (7.38–77.53 mg TE/g DW) assays, were higher in leaf than in flower extracts. Higher TP and total non-flavonoid (TNF) values were displayed in ethanolic than in methanolic extracts. In total, 64 compounds were identified, of which flavonols (20) and hydroxycinnamic acid derivatives (15) were the most represented. Flavanols such as catechin dominated in leaf extracts, followed by flavonols, with kaempferol glucuronyl rhamnosyl hexosides as the main compound, respectively. Flower extracts had the highest share of flavones, followed by ellagitannins, with luteolin dirhamnosyl hexosides and vescalagin, respectively, being predominant. The extracts had good quorum sensing, biofilm formation prevention, and eradicating capacity. The results provided new insights into the phytochemical properties of R. pseudoacacia as the first step toward its potential pharmaceutical use.

Canadian goldenrod (Solidago canadensis L.), an invasive plant in Europe, is known for its allelopathic activity and is rich in bioactive compounds like flavonoids and phenolic acids, with significant pharmacological potential. This study presents the LC-MS phenolic profiles of leaf and flower extracts from S. canadensis, an invasive alien plant in the Istria region (Croatia). Total phenolics (TP) (45.78–110.68 mg GAE/g DW) and non-flavonoids (TNF) (28.38–72.20 mg GAE/g DW) were found to be more abundant in ethanolic than in methanolic extracts. The antioxidant capacity (AC), as measured by ABTS, DPPH, and FRAP assays, was higher in flower extracts compared to leaf extracts. A non-targeted metabolomics approach was used, and 41 phenolic compounds in leaves and 36 in flowers were identified, with hydroxycinnamic acids and flavonols being the most abundant. 5-caffeoylquinic acid was quantitatively predominant in the leaf extracts, while quercetin-3-rutinoside dominated the flower extracts. Five leaf-specific compounds were identified (dicaffeoylquinic acid 2, 4-p-coumaroylquinic acid 1, p-hydroxybenzoic acid, quercetin-3-rhamnoside, and quercetin acetylhexoside 1), suggesting targeted extraction for different pharmacological applications. This study highlights the therapeutic potential of S. canadensis and underscores the need for further research on the bioavailability, efficacy, and safety of its compounds, potentially transforming this ecological threat into a valuable resource for drug development.

Invasive alien plant species, while ecologically and economically problematic, represent an underutilized source of bioactive phytochemicals with promising phytopharmaceutical applications. This study investigates the LC-DAD-MS phenolic profiles of 70% ethanol and 80% methanol leaf and flower extracts of Ailanthus altissima (Mill.) Swingle and Helianthus tuberosus L., collected in the Istria region of Croatia, alongside their antioxidant capacities using ABTS, DPPH, and FRAP assays. Both species exhibited high levels of flavonoids and phenolic acids, with consistently higher concentrations in leaf versus flower tissues and in ethanolic versus methanolic extracts. Strong correlations (r > 0.9) between total phenolics and antioxidant activity confirmed the functional significance of these compounds. With a targeted metabolomics approach, in A. altissima, 51 phenolics were identified in leaves and 47 in flowers, with ellagitannins predominating; vescalagin isomers reached 94 mg/g DW in leaves and 82 mg/g DW in flowers. H. tuberosus extracts contained 34 phenolics in leaves and 33 in flowers, with hydroxycinnamic acids and flavonols dominating; 5-caffeoylquinic acid was the principal compound (25 mg/g DW in leaves, 2 mg/g DW in flowers). The identified phytochemicals are known for their potent antioxidant, anti-inflammatory, anticancer, antimicrobial, and metabolic-regulating properties. Additionally, four leaf-specific compounds were identified in each species, indicating potential for targeted extraction. These findings advance the phytochemical characterization of invasive taxa and highlight their potential as sources of natural antioxidants for functional food and pharmaceutical development.

Immortelle (Helichrysum italicum) is a xerophytic plant species naturally present in the wild population of Mediterranean on karst and dry terrains. Since ancient times, the immortelle has been known as a “non-vein plant” and is highly valued due to its wide application in folk medicine. Antimicrobial, antiviral, anti-inflammatory, antioxidative, regenerative, insecticidal and repellent properties of essential oil and hydrolates are a frequent subject of recent research. The chemical composition of the essential oil and characteristics of plant material have a direct effect on market price. This research was conducted by a survey of producers and buyers of immortelle plant material and essential oil with the aim to gather information on the quality criteria of plant material and essential oil. The collected data showed that the basic criteria for quality determination of plant material are controlled growing conditions and the main parameters affecting the price of the essential oil are chemical composition, i.e. the content and ratio of α-pinene and neryl acetate.

Helichrysum italicum (Roth.) G. Don is an aromatic perennial shrub widespread across the Mediterranean Basin. Plants from this species show a high degree of morphological variability. This research examines morphological variation inside the H. italicum population growing in natural conditions and the correlation between observed morphological traits. Morphometric characteristics of shrub and synflorescence were measured on H. italicum plants from the wild population on the northwestern coast of Istria, at eight locations a short distance apart. Results showed significant variation in the plants’ height and diameter. Pearson’s correlation analysis showed a strong positive correlation between the diameter and height of the shrubs. Hierarchical cluster analysis (HCA) indicates that the observed plants are divided into two clades, based on characteristics measured. Principal component analysis (PCA) showed clear separation of the plants into two groups. Observed characteristics accounted for nearly 76% of the total variance.

The genus Helichrysum Mill., specifically Helichrysum italicum (Roth.) G. Don, commonly known as immortelle, is renowned for its aromatic and ornamental qualities. The plant, which thrives in the dry, sandy and stony areas of the Mediterranean, holds significant economic value, primarily for the extraction of essential oil and its by-product hydrosol. This study explored the phenolic content variations in dried immortelle flowers from eleven wild populations along the Adriatic coast of Croatia in order to evaluate the potential for obtaining the highest concentration of phenolic compounds in hydrosol by examining the total phenolic content of dried inflorescence before distillation. The results revealed substantial differences in phenolic content among researched locations. Immortelle from wild populations on the Pelješac peninsula and the island of Brač exhibited the highest levels of total phenolic compounds in dried flowers. The sample from the island of Hvar had the lowest content of phenolic compounds, making it the least suitable for obtaining highly concentrated hydrosol. Further investigation is needed to identify the impact of location, genotype and orthogenesis on the phenolic content of immortelle from wild populations.