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.

Acne is a highly prevalent skin condition with multifactorial pathophysiology, where Cutibacterium acnes (C. acnes) overgrowths generate inflammation. C. acnes can grow and adhere, through the formation of biofilms, to almost any surface, which enables chronic infections. Acne treatment with antibiotics can induce topical antimicrobial resistance, impair microbiome biodiversity and cause cutaneous dysbiosis. In this study, we assess the effect of a standardized propolis extract (PE) from Greece against C. acnes, whilst maintaining skin’s microbiome biodiversity, and we investigate its effect against genes related to the attachment and colonization of C. acnes, as well as against biofilm formation. The extract has been chemically characterized by GC-MS and was additionally tested for its antioxidant properties by the Folin–Ciocalteu method and the 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) assay and its regulatory activity on the expression of antimicrobial and anti-inflammatory genes in normal human epidermal keratinocytes (NHEKs). The suggested efficacy of PE in targeting pathogenic C. acnes biofilm, via downregulation of virulence genes, represents an alternative strategy to modulate the behavior of skin microbiota in acne, paving the way for next-generation acne-targeting products.

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.

Heliotropium procumbens, a Boraginaceae species native to Panama, has remained largely unexplored regarding its nitrogen-containing metabolites, including pyrrolizidine alkaloids (PAs). In the current study, a comprehensive phytochemical investigation of its aerial parts is presented using HPLC-DAD-IT-MS, UHPLC–HRMS, and GC-MS primarily to profile its PA composition. A total of twelve PAs and N-oxides (PANOs) were identified, along with two phenolamides—including N¹, N¹⁰-diferuloylspermidine, which is biosynthetically related to PAs—and the distinctive metabolite heliotropamide. The detected PAs included unsaturated necines, primarily monoesters of retronecine and heliotridine, as well as saturated PAs such as a platynecine-type PA and the less commonly encountered triol necines and their N-oxides. Among these, helifoline-N-oxide was isolated and structurally elucidated by NMR spectroscopy for the first time as a natural product. Comparison with the chemodiversity of PAs within the Heliotropium genus revealed a high degree of diversity in H. procumbens, which can be attributed both to the species’ inherent biosynthetic capacity for chemical variation and to the more comprehensive and extensive studies conducted on it, which naturally enrich the apparent diversity observed. This work expands the phytochemical knowledge of H. procumbens and contributes to a broader understanding of PA diversity in the genus, offering new insights into their potential ecological and toxicological significance.