The current work represents a comparative study of the phenolic profiles of three under-explored Onosma (Boraginaceae) species from Greece—Onosma leptantha (OL), Onosma erecta (OE), and Onosma graeca (OG). Although Onosma spp. have ethnopharmacological significance, previous phytochemical studies have focused primarily on roots. Methanolic extracts of the aerial parts were analyzed using qualitative LC-MS enhanced by molecular networking-based dereplication, annotating 94 phenolics categorized into hydroxybenzoic acids (7), hydroxycinnamic acids (24), lignans (14), neolignans (14), stilbenes (4), coumarins (5), and flavonoids (26). OG exhibited the broadest distribution of flavonoid glycosides. OL contained the greatest number of hydroxycinnamic and neolignan derivatives, and OE was notably abundant in lignans. Total phenolic (TPC) and total flavonoid (TFC) contents were quantified, and the antioxidant capacity and enzyme inhibition against cholinesterases, α-amylase, and α-glucosidase were assessed. OL showed a high TPC (69.03 mg GAE/g extract) and strong antioxidant activity, while OG exhibited a high TFC (45.80 mg RE/g extract). All extracts demonstrated stronger AChE inhibition than BChE, with OG showing the highest AChE inhibition (2.35 mg GALAE/g). Additionally, OL was the most active against both α-glucosidase (5.69 mmol ACAE/g) and α-amylase (0.48 mmol ACAE/g). This study improved our understanding of the chemical diversity within these species, providing a more comprehensive insight into their longstanding ethnopharmacological potential.

Helianthemum nummularium (HN) and Helianthemum oelanticum subsp. incanum (HO) are plant species, among Cistaceae, that are highly distributed in the Mediterranean region. In the current study, extracts of the aerial parts from both species have been analyzed phytochemically. The non-polar extract analysis resulted in the identification of 15 compounds in each species, mainly terpene and fatty acid derivatives, through GC–MS. The methanolic extract analysis, conducted through UHPLC–MS/MS, led to the identification of 39 metabolites in HN and 29 in HO, respectively, the majority of which were phenolics. Among the identified compounds, several have also been isolated and structurally determined (from HN: rutin, linoleic acid, gallic acid, and isoquercetin, and from HO: quercetin-3-O-(2″-O-galloyl)-galactopyranoside, methyl gallate, catechin-3-O-glucopyranoside, and astragalin, while hyperoside, and cis- and trans-tiliroside have been determined in both species). Furthermore, the methanolic extracts of HN and HO displayed a high total phenolic content (177.2 mg GA/g extract and 150.6 mg GA/g extract, respectively) and considerable free-radical scavenging activity against the DPPH radical (94.6% and 94.0% DPPH inhibition, respectively). Antimicrobial testing showed stronger inhibition of HN against Gram (+) bacterial strains (MIC values 0.07–0.15 mg/mL), while both extracts exhibited low tyrosinase-inhibitory activity. Considering the lack of studies conducted on the chemistry and biological activities of the genus Helianthemum, the chemical characterization of extracts could contribute to new sources of bioactive metabolites to be explored and exploited for further potential applications such as food and/ or the cosmetic industry.

This study aimed to characterize the chemical composition and evaluate the biological activities of the aerial parts of Alkanna corcyrensis Hayek (AC), an endemic Greek species not previously studied. Phytochemical analysis of the methanolic extract was performed using UHPLC-ESI-Q-TOF–MS/MS combined with molecular networking analysis. Additionally, the total phenolic content (TPC) and total flavonoid content (TFC) were determined. Chromatographic separations were carried out to isolate major compounds, and the antioxidant capacity, along with enzyme inhibitory activity, was assessed. The analysis led to the tentative identification of 86 compounds, including 67 phenolic compounds (mainly caffeic acid derivatives and flavonoid glycosides), 10 pyrrolizidine alkaloids of trachelanthamidine, platynecine, and retronecine types, and nine organic and fatty acid derivatives. Among these, one flavonol glycoside (kaempferol-O-malonyl methyl ester hexoside) and three pyrrolizidine alkaloids (9-sarracinoyl-trachelanthamidine/isoretronecanol, retronecine-pentoside, and trachelanthamidine/isoretronecanol-hexoside) were reported for the first time. The extract exhibited high TPC (74.45 mg GAE/g extract) and TFC (46.66 mg GAE/g extract). Chromatographic separations resulted in the isolation of five major metabolites, namely rosmarinic acid, danshensu, kaempferol-3-O-glucoside, kaempferol-3-O-galactoside, and quercetin-3-O-glycoside. Biological evaluation revealed considerable antioxidant activity and inhibitory effects against α-glucosidase (6.65 mmol ACAE/g extract). Overall, this study highlights the remarkable phytochemical diversity and richness of AC among alkanet species and demonstrates its promising antioxidant potential, laying the foundation for further investigations towards its future exploitation.

This study investigates the impact of rootstock selection on the essential oil (EO) composition of clementine mandarin (Citrus clementina Hort. ex Tan.) var. SRA 63 cultivated in southern Greece. EOs were extracted from the peel and leaves of trees grafted on four commonly used rootstocks: Cleopatra mandarin, sour orange, Troyer citrange, and Swingle citrumelo. The GC-MS analysis revealed significant qualitative and quantitative differences in EO profiles across the different rootstock combinations. In peel EOs, limonene was the dominant compound, particularly in trees grafted onto Cleopatra mandarin and Swingle citrumelo, while Troyer citrange favored a more diverse chemical profile rich in oxygenated monoterpenes, sesquiterpenes, and aldehydes. Leaf EOs were characterized by high levels of sabinene, linalool, and limonene, with Swingle citrumelo promoting sabinene production and Troyer citrange enhancing limonene content and sesquiterpene diversity. Sour orange showed an intermediate effect, increasing both compound diversity and abundance. These results underscore the critical role played by rootstock in modulating the biosynthesis of volatile compounds, likely through physiological and molecular interactions with the scion. These findings offer valuable insights into optimizing EO yield and quality in citriculture and support the broader goal of valorizing Citrus by-products through targeted agricultural practices. This research contributes to the implementation of targeted agricultural practices (rootstock choice) for the development of high-value Citrus-based products with specific quality traits.

In the present study, the essential oils (EOs) of peels and leaves from the new limonime lime, ‘Eugene’ hybrid, were analyzed for the first time and compared with those of its parental plants, Citrus latifolia var. latifolia (Persian lime) and Citrus × limon cv. Zambetakis (lemon). This hybrid represents the first successful cross between these two species, exhibiting distinctive features such as aroma and shape. GC-MS analysis identified a total of 30 and 44 metabolites in the hybrid’s peel and leaf EOs, respectively. Limonene was the predominant volatile in both peels and leaves across all genotypes. In the peel EOs, the monoterpenes γ-terpinene, β-pinene, and geranial were among the most abundant compounds. In contrast, the leaf EOs showed differences between genotypes: the hybrid and Persian lime had similar volatile profiles dominated by geranial, neral, and neryl acetate, while β-pinene was only detected in lemon. Additionally, the total phenolic content and DPPH radical scavenging activity of the methanolic extracts of peels and leaves were evaluated, and revealed that lemon extracts were richer in phenolic compounds and with higher antioxidant activity compared to those of hybrid and Persian lime. Overall, the development of improved Greek varieties like the ‘Eugene’ hybrid holds significant potential to enrich the genetic diversity of Greek Citrus germplasm and broaden the commercial portfolio of citrus fruits with unique and desirable traits.

Propolis is a resinous natural product produced by honeybees from plant exudates and beeswax. Its complex chemical composition varies significantly with geographical origin and seasonal factors. This study aimed to characterize the chemical composition of propolis samples collected from different regions of Latvia using gas chromatography–mass spectrometry (GC-MS). In total, 47 metabolites were identified, with chemical profiles dominated by phenolic acids and their esters—compounds typical of European propolis. Regional variations reflected differences in local vegetation, and two samples exhibited flavonoid constituents indicative of poplar-type botanical sources. The Daugavpils sample, which showed a particularly rich chemical profile, was further fractionated chromatographically, leading to the isolation of twelve metabolites: 2’,4’,6’-trihydroxy-4-methoxy dihydrochalcone, 2’,6’,4-trihydroxy-4’-methoxy dihydrochalcone, 2’,6’-dihydroxy-4,4’-dimethoxy dihydrochalcone, 2’,6’-dihydroxy-4’-methoxy dihydrochalcone, 2’,4’,6’-trihydroxy dihydrochalcone, palmitic acid, benzyl benzoate, cinnamyl cinnamate, pinostrobin, pinostrobin chalcone, pinocembrin, and pinobanksin. Given the limited prior research on Latvian propolis, this study provides valuable insights into its chemical diversity and the influence of regional flora on its composition.