Supercritical CO2 Extraction of Narcissus poeticus L. Flowers for the Isolation of Volatile Fragrance Compounds

The flowers of Narcissus poeticus are used for the isolation of valuable fragrance substances. So far, as the majority of these substances consist of volatile and sensitive to heat compounds, there is a need of developing effective methods for their recovery. In this study, freeze-dried N. poeticus inflorescences were extracted with pure supercritical CO2 (SFE-CO2) and its mixture with 5% co-solvent ethanol (EtOH) at 40 °C. Extract yields varied from 1.63% (12 MPa) to 3.12% (48 MPa, 5% EtOH). In total, 116 volatile compounds were identified by GC-TOF/MS in the extracts, which were divided into 20 different groups. Benzyl benzoate (9.44–10.22%), benzyl linoleate (1.72–2.17%) and benzyl alcohol (0.18–1.00%) were the major volatiles among aromatic compounds. The amount of the recovered benzyl benzoate in N. poeticus SFE-CO2 extracts varied from 58.98 ± 2.61 (24 MPa) to 91.52 ± 1.36 (48 MPa) mg/kg plant dry weight (pdw). α-Terpineol dominated among oxygenated monoterpenes (1.08–3.42%); its yield was from 9.25 ± 0.63 (12 MPa) to 29.88 ± 1.25 (48 MPa/EtOH) mg/kg pdw. Limonene was the major monoterpene hydrocarbon; (3E)-hexenol and heneicosanol dominated among alcohols and phenols; dihydroactinidiolide and 4,8,12,16-tetramethyl heptadecan-4-olide were the most abundant lactones; heptanal, nonanal, (2E,4E)-decadienal and octadecanal were the most abundant aldehydes. The most important prenol lipids were triterpenoid squalene, from 0.86 ± 0.10 (24 MPa) to 7.73 ± 0.18 (48 MPa/EtOH) mg/kg pdw and D-α-tocopherol, from 1.20 ± 0.04 (12 MPa) to 15.39 ± 0.31 (48 MPa/EtOH) mg/kg pdw. Aliphatic hydrocarbons (waxes) constituted the main part (41.47 to 54.93%) in the extracts; while in case of a 5% EtOH the percentage of alkanes was the lowest. The fraction of waxes may be removed for the separation of higher value fragrance materials. In general, the results obtained are promising for a wider application of SFE-CO2 for the recovery of fragrance substances from N. poeticus flowers.

Hexosomal Dispersion: A Nano-Based Approach to Boost the Antifungal Potential of Citrus Essential Oils against Plant Fungal Pathogens

The demand for natural fungicides to replace synthetic ones has surged since toxic residues persist in soils, causing environmental contamination and posing a serious threat to worldwide public health. In the context of crop protection and enhancing the efficiency and safety of fungicides, nanotechnology is an eco-friendly strategy in managing fungal pathogens. In the present study, essential oils were isolated from the peels of four citrus fruits (Citrus lemon, Citrus aurantifolia, Citrus maxima, and Citrus sinensis) and were investigated using gas chromatography-mass spectrometric analysis. Monoterpene hydrocarbon was the most predominant group and limonene was the most abundant in the four oils. The antifungal potential of the oils was investigated, and the most active oil (Citrus lemon) was loaded into hexosomal dispersion, and its antifungal potential was retested against the same fungi. The structurally unique nano-based formulation showed great potency for fungal control. To the best of our knowledge, it is the first time the oil of Citrus lemon in nano-hexosomes has been formulated and its fungicidal activity examined. The data collected suggest that citrus essential oils (CEOs), especially when nano-formulated, could be successfully used in integrated fungus management programs.

Volatile Constituents of Two Rare Subspecies of Thymus praecox

Hydrodistilled essential oil and the corresponding headspace volatiles of Bosnian wild growing Thymus praecox ssp. polytrichus (A. Kern. Ex Borbàs) Jalas and Thymus praecox ssp. skorpilii (Velen.) Jalas were subjected to capillary GC-MS analysis. This work presents a detailed essential oil analysis of these two rare Thymus subspecies from Bosnia, as well as the very first report on their headspace composition. Eighty-seven volatile constituents were identified in four samples. Two alcohols were the major constituents in the essential oil of T. praecox ssp. polytrichus, a monoterpene, linalool (13.9%), and a sesquiterpene, ( E)-nerolidol (10.4%), while linalyl acetate (36.7%) and linalool (22.7%) were the most abundant volatiles in the corresponding headspace sample. Oxygenated monoterpenes (57.5%) predominate in the essential oil of T. praecox ssp. skorpilii with linalyl acetate (28.7%) and linalool (14.4%) as the main representatives. Headspace sample of this subspecies also showed richness in linalyl acetate (52.4%), while the second most abundant compound was α-pinene (14.5%), a monoterpene hydrocarbon.

Compositional Variability in Essential Oil from Different Parts of Alpinia speciosa from India

The essential oils from the leaves, flowers and roots of cultivated Alpinia speciosa K. Schum. were examined by capillary GC and GC-MS. Monoterpenoids composed 89.6% of the total identified constituents of the leaf oil, out of which 59.3% were oxygenated, represented mainly by terpinen-4-ol (28.4%) and 1,8-cineole (19.2%). The flower and leaf oils had a uniform qualitative, but different quantitative composition. However, the flowers oil was also dominated by oxygenated monoterpenoids (68.9%) viz., terpinen-4-ol (26.0%), 1,8-cineole (24.4%) and linalool (6.1%), along with the monoterpene hydrocarbon, sabinene (11.3%). On the contrary, the root oil had an entirely different composition and was characterized by endo-fenchyl acetate (40.1%), 1,8-cineole (11.8%), camphene (7.8%), bornyl acetate (6.9%) and borneol (5.8%). Moreover, endo-fenchyl acetate, exo-fenchyl acetate and endo-fenchol were characteristic of only the A. speciosa root oil.

Chemical Composition and Antimicrobial Activity of Essential Oil of Bupleurum montanum and B. plantagineum

The hydrodistilled oils from the aerial parts of Bupleurum montanum and B. plantagineum, which are endemic to North Africa, including Algeria, were analyzed by gas chromatography-mass spectrometry (GC-MS). Ninety-eight compounds were detected in the oil of B. montanum, representing 98.6% of the total oil, and 68 in the oil of B. plantagineum, representing 99.8% of the total. Megastigma-4,6-(E),8(2)-triene was the major constituent of B. montana oil (25.3%). Other important compounds were myrcene, α-pinene and benzyl tiglate. Conversely, the major constituents of the oil of B. plantagineum were α-pinene (31.9%), cis-chrysanthenyl acetate (28.2%), and myrcene (24.8%), followed by the monoterpene hydrocarbon limonene (5.1%). The mutagenic, antiplasmodial and antimicrobial activities of the essential oils were individually evaluated against eleven microorganisms, using the agar diffusion method, by determination of MIC values. The investigated oils exhibited moderate antimicrobial activity. Maximum activity of the oils was observed against Nocardia asteroides, Staphylococcus aureus and Enterococcus faecalis. Fungicidal activity against Candida albicans was also found for both oils.

Limonene - a Review: Biosynthetic, Ecological and Pharmacological Relevance

Limonene is one of the most common compounds found in the essential oils of aromatic plants. The occurrence of this monoterpene hydrocarbon in various plant genera could be attributed to its precursory role in the biosynthesis of other monoterpenes and its defensive role against herbivores. Due to the medicinal potential and application in the flavor and fragrance industries, limonene has been extensively investigated. In this paper the biosynthetic, ecological and pharmacological importance of limonene is presented in an attempt to coherently summarize some of the most salient aspects from various studies in a form of a concise review.