The aim of this research was to investigate the effect of different extraction methods and chemical composition of the essential oil and solid-phase microextraction (SPME) from Rhododendrum caucasium Pall. The volatiles of R. caucasicum have been isolated by hydro distillation (HD) and SPME. The compositions of the volatiles were characterized by GC-FID/MS. A total of twenty-five and thirty-one compounds were identified constituting over 89.25%, and 90.33% of volatiles obtained with HD and SPME, respectively. The main volatile constituents of R. caucasicum were found to be calarene (46.13% (HD) and 54.91% (SPME)) and sandaracopimaradiene (25.93% (HD) and 8.16% (SPME)). Furthermore, the obtained essential oil (EO) and solvent extracts (n-hexane and methanol) of R. caucasicum were tested against the following nine bacteria: Escherichia coli, Yersinia pseudotuberculosis, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, Mycobacterium smegmatis, Candida albicans, and Saccharomyces cerevisiae. The EO showed moderate antimicrobial activities with the inhibition zone from 6 to18 mm against E. faecalis, S. aureus, B. cereus and M. smegmatis, respectively. Methanol extract gave better antimicrobial activity against the P. aeruginosa, E. faecalis, S. aureus, and B. cereus with the almost 15 mm inhibition zones.

In this study, novel deep eutectic solvents (DES) were synthesized and evaluated for their potential in extracting phenolic acids from Origanum micranthum and Origanum minutiflorum . The characterization of DES was carried out using FTIR and DSC techniques. Extraction parameters, including DES volume, extraction temperature, and vortex time, were optimized using the Box-Behnken design under the Response Surface Methodology (RSM) framework. The optimal conditions led to a high extraction efficiency, with a determination coefficient (R²) of 0.9727, a coefficient of variation (CV) of 5.08%, and a signal-to-noise ratio of 14.47. Seven phenolic compounds were identified, with benzoic acid being the most abundant. Antioxidant activities were assessed via CUPRAC, FRAP, and DPPH assays, revealing that 1-hexadecanol-thymol and 1-octadecanol-thymol DES mixtures provided significant activity enhancements. Antimicrobial tests demonstrated inhibitory effects against Candida albicans , Staphylococcus aureus , Bacillus cereus , and Staphylococcus epidermidis , while Escherichia coli remained unaffected. The results indicate that natural DESs are promising, sustainable solvents for phenolic extraction with notable biological activities. This study contributes to green chemistry by introducing environmentally friendly solvent systems for efficient bioactive compound recovery.

Obesity, defined as New World Syndrome, causes global health problems and big economic losses. Natural products have gained increasing importance because of their antiobesity potency. The genus Jurinea Cass. with approximately 200 described species worldwide has been traditionally used as a therapeutic agent for colic, fever, gout and rheumatism. The aim of this study was to analyze the volatile components, to determine phenolic compounds and to evaluate α-amylase, α-glucosidase, and lipase inhibitory activities of the endemic plant species Jurinea brevicaulis Boiss. The widely used solid-phase microextraction technique (SPME) was employed for Gas Chromatography-Mass Spectrometry (GC/MS) analysis of the volatile components. Quantitative analysis of phenolic compounds was performed using Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC). A total of 19 volatile components were specified and o-cymene (10.60 %), β-bisabolene (9.30 %), and sesquicineole (57.5 %) for different terpenes were described as major components. According to the RP-HPLC analysis, sinapic acid, p-coumaric acid and quercetin were determined for the species. IC50 values of the species were determined as 36.59 ± 2.37 μg/mL and 42.56 ± 2.83 μg/mL for α-amylase and α-glucosidase assays, respectively. IC50 value was found as 50.31 ± 3.75 μg/mL with the lipase inhibition analysis. In conclusion, it has been determined that J. brevicaulis included diverse volatile components, three phenolic compounds with antiobesity effect potential, which highlights J. brevicaulis as the up-and-coming candidate of natural product source to be used against obesity.

The research aimed to analyze the volatile compounds by using SPME-GC-MS and to detect anticholinesterase, antityrosinase, and antimicrobial potential of metanol extract of Alceacalvertii Boiss., an endemic species for Türkiye. The inhibitory effects of tyrosinase, acetylcholinesterase, and butyrylcholinesterase of the plant were determined by spectroscopic technique and the plant’s antimicrobial activity was assessed using the agar diffusion method. A total of 18 volatile compounds were specified belonging to terpenes classes. o-cymene (10.60%) and sesquicineole (15.55%) were detected as major volatile components of the species by the SPME-GC-MS technique. Meaningful antimicrobial activity was observed on Candida tropicalis, Enterococcus faecalis, Escherichia coli, Mycobacterium smegmatis, Staphylococcus aureus, and Pseudomonas aeruginosa. The half maximal inhibitory concentration (IC50) value of the plant was determined 60.12 ± 1.75 μg/mL as a result of tyrosinase assay. IC50 value was found 111.54 ± 1.75 μg/mL, according to butyrylcholinesterase inhibition studies. Considering all the findings, it has been determined that the plant includes diverse volatile compounds and showed promising antimicrobial, tyrosinase inhibitory, and moderate butyrylcholinesterase inhibitory effects so Alceacalvertii may be the up-and-coming source of natural medicine for microbial and dermatological diseases although limited to its effects for Alzheimer's disease.