Comparative Chemical Profiling and Citronellol Enantiomers Distribution of Industrial-Type Rose Oils Produced in China

The chemical composition and aroma profile of industrial essential oils (EOs) from species of rose grown in China, including the native Kushui rose (R. sertata × R. rugosa) and R. rugosa Thunb. cv. Plena, and the recently introduced Damask rose (R. damascena Mill.), were studied in comparison by means of GC/MS and GC-FID. More than 150 individual compounds were detected in Chinese rose samples, of which 112 were identified and their quantitative content determined, representing 88.7%, 96.7% and 97.9% of the total EO content, respectively. It was found that the main constituents of the Chinese rose EOs were representatives of terpenoid compounds (mono- and sesquiterpenoids, predominantly) and aliphatic hydrocarbons. Comparative chemical profiling revealed different chemical composition and aroma profiles: while the R. damascena oil showed a balance between the eleoptene and stearoptene fractions of the oil (the average ratio between the main terpene alcohols and paraffins was 2.65), in the Kushui and R. rugosa oils, the odorous liquid phase strongly dominated over the stearopten, with a ratio of 16.91 and 41.43, respectively. The most abundant terpene was citronellol, ranging from 36.69% in R. damascena to 48.32% in R. rugosa oil. In addition, the citronellol enantiomers distribution, which is an important marker for rose oil authenticity, was studied for the first time in R. rugosa oil.

Favipiravir-Tautomeric and Complexation Properties in Solution

The tautomeric properties of favipiravir were investigated experimentally for the first time by using molecular spectroscopy (UV-Vis absorption, fluorescence and NMR), as well as DFT quantum-chemical calculations. According to the obtained results, the enol tautomer is substantially more stable in most of the organic solvents. In the presence of water, a keto form appears to be favored due to the specific solute-solvent interactions. Upon the addition of alkaline-earth-metal ions, deprotonation and complexation occurred simultaneously, giving the formation of 2 : 1 ligand : metal complexes. According to the theoretical simulations, the metal ion is captured between the carbonyl groups as a result of the size-fit effect.

Exploring the Chemical Composition of Bulgarian Lavender Absolute (Lavandula Angustifolia Mill.) by GC/MS and GC-FID

Lavender (L. angustifolia Mill.) is an important essential oil-bearing and medicinal plant with high commercial value. Lavender scent components can be derived not only as an essential oil but also as lavender concrete or absolute. The development of reliable analytical methods for origin assessment and quality assurance is of significant fundamental importance and high practical interest. Therefore, a comprehensive chemical profiling of seven industrial samples of Bulgarian lavender absolute (L. angustifolia Mill.) was performed by means of gas chromatography-mass spectrometry (GC/MS) and gas chromatography with flame ionization detection (GC-FID). As a result, 111 individual compounds were identified by GC/MS, and their quantitative content was simultaneously determined by GC-FID, representing 94.28-97.43% of the total contents of the lavender absolute. According to our results, the main constituents of lavender absolute (LA) are representatives of the terpene compounds (with the dominating presence of oxygenated monoterpenes, 52.83-80.55%), followed by sesquiterpenes (7.80-15.21%) and triterpenoids (as minor components). Coumarins in various amounts (1.79-14.73%) and aliphatic compounds (hydrocarbons, ketones, esters, etc.) are found, as well. The acyclic monoterpene linalool is the main terpene alcohol and, together with its ester linalyl acetate, are the two main constituents in the LAs. Linalool was found in concentrations of 27.33-38.24% in the LA1-LA6 samples and 20.74% in the LA7 samples. The amount of linalyl acetate was in the range of 26.58 to 37.39% in the LA1-LA6 samples, while, surprisingly, it was not observed in LA7. This study shows that the chemical profile of the studied LAs is close to the lavender essential oil (LO), fulfilling most of the requirements of the International Standard ISO 3515:2002.

Subcritical Extracts from Major Species of Oil-Bearing Roses-A Comparative Chemical Profiling

A comprehensive chemical profiling of 1,1,1,2-tetrafluoroethane (freon R134a) subcritical extracts from the main genotypes of oil-bearing roses, was performed by gas chromatography–mass spectrometry (GC/MS) and gas chromatography with flame ionization detection (GC-FID) in order to reveal the differences in their chemical composition. One hundred and three individual compounds were identified using GC/MS and their quantitative content was determined using GC-FID, representing 89.8, 92.5, 89.7 and 93.7% of the total content of Rosa gallica L., Rosa damascena Mill., Rosa alba L. and Rosa centifolia L. extracts, respectively. The compounds found in the extracts are representatives of the following main chemical classes: mono-, sesqui- and triterpenoids, phenylethanoids and phenylpropanoids and aliphatic hydrocarbons. Fatty acids, esters and waxes were found, as well. The study revealed that 2-phenylethanol is the most abundant component, ranging 9.0–60.9% followed by nonadecane and nonadecene with 5.1–18.0% geraniol (2.9–14.4%), heneicosane (3.1–11.8%), tricosane (0.1–8.6%), nerol (1.3–6.1%) and citronellol (1.7–5.3%). The extracts demonstrate a specific chemical profile, depending on the botanical species—phenylethanoids and phenyl propanoids are the main group for R. damascena, aliphatic hydrocarbons for R. alba and R. centifolia, while both are found in almost equal amounts in R. gallica. The terpenoid compounds show relatively broad variations: monoterpenes—11.9–25.5% with maximum in R. centifolia; sesquiterpenes—0.6–7.0% with maximum in R. gallica and triterpenes—0.4–3.7% with maximum in R. gallica extract.