Lavender essential oil (LEO) is applied topically for its soothing properties, serving not only as an antiseptic in wound care but also as an insect repellent. This study investigates the impact of carrier systems on LEO encapsulation, stability, and release kinetics for potential skincare applications. The LEO carrier impact on skin hydration and barrier function was also evaluated. Conventional emulsions (CEs) and nanoemulsions (NEs) with (CELs and NELs, respectively) and without LEO incorporation were analyzed for physicochemical properties, stability, and release mechanisms. The droplet size distribution and ζ-potential remained consistent in both CE and CEL, showing the minimal influence of LEO on those parameters. NE and NEL exhibited enhanced stability and higher LEO retention compared to CE and CEL (37.38 mg/mL ± 0.48 mg/mL and 50.96 mg/mL ± 2.00 mg/mL, respectively, p < 0.05), suggesting NE as a superior carrier system for LEO delivery. NEL retained LEO over 60 days at 4 °C without a significant reduction while CEL showed a notable reduction of 94.93% ± 0.08%. Release kinetics analysis showed zero-order release kinetics of LEO from both CEL and NEL (R²: 0.973 and 0.952, respectively), revealing a diffusion-based mechanism, particularly evident in NE formulations, supporting the controlled and sustained release of LEO constituents. NEL also promoted quicker skin barrier repair and enhanced skin hydration, sustaining effects for up to 120 min post application, surpassing CEL’s performance. These findings contribute to understanding the carrier system effects on LEO delivery and underscore NE as a promising vehicle for skincare applications. Further research should explore underlying mechanisms and conduct long-term safety and efficacy studies to fully exploit the therapeutic potential of NE in dermatological applications.

Salvia fruticosa and S. pomifera subsp. calycina are native to Eastern Mediterranean and S. pomifera subsp. pomifera is endemic to Greece. The primary aim of this study was to develop an analytical methodology for metabolomic profiling and to study their efficacy in combating glycation, the major biochemical complication of diabetes. After sequential ultrasound-assisted extraction of 2 g of leaves with petroleum ether and 70% methanol, the volatile metabolites in the petroleum ether extracts were studied with GC-MS (Gas Chromatography-Mass Spectrometry), whereas the polar metabolites in the hydroalcoholic extracts were determined and quantified by UHPLC-DAD–ESI-MS (Ultra-High Performance Liquid Chromatography–Diode Array Detector–Mass Spectrometry). This methodology was applied to five populations belonging to the three native taxa. 1,8-Cineole was the predominant volatile (34.8–39.0%) in S. fruticosa, while S. pomifera had a greater content of α-thujone (19.7–41.0%) and β-thujone (6.0–39.1%). Principal Component Analysis (PCA) analysis of the volatiles could discriminate the different taxa. UHPLC-DAD-ESI-MS demonstrated the presence of 50 compounds, twenty of which were quantified. PCA revealed that not only the taxa but also the populations of S. pomifera subsp. pomifera could be differentiated. All Salvia samples inhibited advanced glycation end-product formation in a bovine serum albumin/2-deoxyribose assay; rosmarinic and carnosic acid shared this activity. This study demonstrates the antiglycation activity of S. fruticosa and S. pomifera extracts for the first time and presents a miniaturized methodology for their metabolomic profiling, which could aid chemotaxonomic studies and serve as a tool for their authentication and quality control.

Sideritis clandestina (Bory & Chaub.) Hayek subsp. peloponnesiaca (Boiss. & Heldr.) Baden (SCP) is endemic to the mountains of the Northern Peloponnese (Greece). This and other Sideritis taxa, collectively known as mountain tea, are widely ingested as beverages for refreshment or medicinal purposes. We describe a methodology for the characterization of SCP. Four iridoid glycosides (monomelittoside, melittoside, ajugoside, and 7-O-acetyl-8-epiloganic acid), two phenolic acid glycosides (vanillic and salicylic acid glycosides), and three caffeoyl ester glycosides (chlorogenic acid, verbascoside, and isoverbascoside) were isolated from SCP for the first time. We used ultrasound-assisted extraction of 3 g of plant material to produce petroleum ether and aqueous extracts, which we then analyzed using GC/MS and LC/MS. This was applied to eight samples from four different taxa. In total, 70 volatile and 27 polar metabolites were determined. The S. clandestina samples had a lower phenolic content and weaker antioxidant properties than S. raeseri and S. scardica. However, S. clandestina ssp. clandestina seemed to be the most aromatic taxon, with almost double the number of volatiles as the others. Τhis study could contribute to authentication and chemotaxonomic studies of Sideritis taxa.

Today, Alzheimer’s disease (AD)—the most common neurodegenerative disorder, which affects 50 million people—remains incurable. Several studies suggest that one of the main pathological hallmarks of AD is the accumulation of abnormal amyloid beta (Aβ) aggregates; therefore, many therapeutic approaches focus on anti-Aβ aggregation inhibitors. Taking into consideration that plant-derived secondary metabolites seem to have neuroprotective effects, we attempted to assess the effects of two flavones—eupatorin and scutellarein—on the amyloidogenesis of Aβ peptides. Biophysical experimental methods were employed to inspect the aggregation process of Aβ after its incubation with each natural product, while we monitored their interactions with the oligomerized Aβ through molecular dynamics simulations. More importantly, we validated our in vitro and in silico results in a multicellular organismal model—namely, Caenorhabditis elegans—and we concluded that eupatorin is indeed able to delay the amyloidogenesis of Aβ peptides in a concentration-dependent manner. Finally, we propose that further investigation could lead to the exploitation of eupatorin or its analogues as potential drug candidates.

Alzheimer’s disease (AD) is the most common form of dementia. Given the link between oxidative stress and AD, many studies focus on the identification of natural antioxidants against AD. Although their antioxidant capacity is important, increasing data suggest that additional activities are related to their beneficial effects, including properties against amyloid beta (Aβ) aggregation. Sideritis spp. (mountain tea) extracts possess not only antioxidant activity but also other bioactivities that confer neuroprotection. Although various Sideritis spp. extracts have been extensively studied, there are scarce data on S. clandestina subsp. peloponnesiaca (SCP) phytochemical composition and neuroprotective potential, while nothing is known of the responsible compounds. Given that SCP is a weaker antioxidant compared to other Sideritis spp., here, we investigated its potential beneficial properties against Aβ aggregation. We characterized different SCP extracts and revealed their anti-aggregation activity by taking advantage of established C. elegans AD models. Importantly, we identified two pure compounds, namely, sideridiol and verbascoside, being responsible for the beneficial effects. Furthermore, we have revealed a potential anti-Aβ aggregation mechanism for sideridiol. Our results support the use of mountain tea in the elderly against dementia and demonstrate the activity of sideridiol against Aβ aggregation that could be exploited for drug development.

This study investigated the potential of natural deep eutectic solvents (NADESs) for extracting bioactive compounds from the aerial parts of two mountain tea taxa, Sideritis clandestina ssp. peloponnesiaca (Boiss. & Heldr.) Baden and Sideritis raeseri Boiss. & Heldr. ssp. raeseri. Five NADEs, composed of betaine, glycerol, glucose, urea, citric acid, and sucrose, were evaluated for their extraction efficiency compared to conventional solvents (water and 70% ethanol). The total phenolic content (TPC) and antioxidant activity (FRAP and DPPH assays) were determined. Results showed that water was not a good extraction solvent. Despite the great solvent-dependent differences, most NADEs, particularly the betaine–glycerol–glucose mixture (BGG4), exhibited comparable or even superior extraction efficiency and antioxidant activity compared to 70% ethanol. The secondary metabolites in the BGG4 and 70% ethanol extracts were determined with HPLC-MS. The BGG4 extracts of both Sideritis taxa had a rich phenolic profile, with the major ingredients being chlorogenic acid, verbascoside, and non-, mono- and di-acetylated allosyl hypolaetin glycosides. Although distinct quantitative differences in their composition compared to the respective 70% ethanol extracts, and between them were noted, overall, the content of secondary metabolites in both S. raeseri extracts was lower than that of the S. clandestina extracts. These findings suggest that NADEs, particularly BGG4, are promising green solvents for extracting bioactive compounds from Sideritis taxa, paving the way for potential applications in the development of natural and sustainable cosmetic products.