Studies on essential oil from rose-scented geranium, Pelargonium graveolens L'Hérit. (Geraniaceae)

Phytochemical profiling of Pelargonium graveolens l'Hér and evaluation of its activity against D-galactose induced skin ageing

Pelargonium graveolens L'Hér is an evergreen small shrub with pink flowers. Metabolite profiling of its extract by UHPLC/MS analysis revealed the identification of 51 secondary metabolites. Interestingly, 29 compounds identified for the first time. The colorimetric assays revealed high content of phenolic, flavonoids and tannins (100.19 ± 3.94 µg Gallic acid Eq/mg, 47.38 ± 2.04 µg Rutin Eq/mg and 332.75 ± 8.85 µg Catechin Eq/mg of extract) respectively along with good antioxidant activity. Moreover, the in vitro analysis showed a significant anti-hyaluronidase activity (IC50 ± SD = 15.75 ± 0.8), as compared to standard luteolin. Topical application of the characterised P. graveolens hydrogel (1% and 2% w/w) was tested using the D-galactose-induced ageing model in mice. Histopathological examination demonstrated an increase in the dermal collagen expression, alleviation of ageing-related oxidative stress, and stabilisation of MMP-1/TIMP-1 balance. Ultimately, P. graveolens could be a valuable source of natural antioxidants with a promising antiaging activity.

A comparative study of the essential oil extracts of Centaurea alexanderina different parts: GC-MS analysis, antimicrobial, antioxidant, and anti-hyperglycemic activities

BACKGROUND

Natural products have been a cornerstone in the field of drug discovery for centuries, they have provided numerous therapeutic agents that have significantly impacted modern medicine. Centaurea alexanderina is a canescent herb that is native to Egypt and Libya and reported in Egyptian folk medicine as an anti-hyperglycemic, antioxidant, and antimicrobial herb. It is an understudied species, thusly, the target of this contribution was to perform a comparative study of the influence of plant part variation on its chemical and pharmacological characteristics. In this context, essential oil extracts from different parts of C. alexanderina (flowers, stems, leaves, and roots) have been analyzed chemically and tested for their antioxidant, antimicrobial, and anti-hyperglycemic activities.

METHODS

The essential oil extracts from different parts of C. alexanderina have been prepared and their chemical compositions have been analyzed using GC-MS technique. Antimicrobial activities of different essential oil extracts were evaluated via the agar cup diffusion method. DPPH radical scavenging and FRAP assays were used for determination of the antioxidant capacity. Anti-hyperglycemic activities of the four essential oil extracts under study were investigated via α-glucosidase inhibition assay. A computational study has been performed using molecular docking of the identified compounds in the most active essential oil extracts (leaves and roots) against α-glucosidase enzyme using PDB entry 5NN8.

RESULTS

A GC-MS analysis of the four essential oil extracts revealed high levels of non-terpenoid hydrocarbons in three essential oil extracts (flower, stems, and leaves) and alcohols in roots essential oil extract, followed by fatty acids in flowers, diterpenoids in stems, steroids in leaves, and fatty acid esters in roots. Roots and stems essential oil extracts exhibited selective activity against Pseudomonas aeruginosa (P. aeruginosa), whereas leaves essential oil extract showed activity against both Salmonella enterica (S. enterica) and Escherichia coli (E. coli). Essential oil extracts of different parts of the plant exhibited DPPH free radical scavenging activity with IC50 values of 128, 134, 152, and 163 μM for flowers, roots, stems, and leaves essential oil extracts; respectively, while in FRAP assay, the results showed different pattern; flowers revealed the highest activity followed by leaves, roots, and stems (107.50 ± 3.64, 125.80 ± 4.2, 139.4 ± 5.27, and 155.59 ± 5.27 ug/mL, respectively). In vitro evaluation of anti-hyperglycemic activity via inhibition of α-glucosidase enzyme assay unveiled leaves and roots essential oil extracts as the most inhibitors with IC50 values of 349 and 369 μg/mL; respectively. The molecular docking study of detected metabolites in the most active essential oil extracts against human α-glucosidase enzyme (PDB: 5NN8) revealed moderate to high binding affinities (-4.6 to -7.3 kcal/mol for leaves and -4.4 to -7.9 kcal/mol for roots essential oil metabolites).

CONCLUSION

Current research demonstrated the variations in chemical composition and biological activities of essential oil extracts from different parts of Centaurea alexanderina and reported anti-hyperglycemic, antioxidant, and antimicrobial potentials of the different essential oil extracts.

Antioxidant activity analysis of new interspecific hybrid germplasm thyme and oregano essential oils with different chemotypes

Thyme and oregano essential oils (EOs) and their components have numerous applications in the pharmaceutical, food, and cosmetic industries owing to their antioxidant, antibacterial, antifungal, anti-inflammatory, antiviral, and immunological properties. We attempted to create new chemotypes through the hybridization of thyme and oregano for functional EO research and product development. Here, we used interspecific hybridization to create new thyme and oregano germplasms with new EO chemotypes. The antioxidant activities of these new chemotype EOs were verified by DPPH, ABTS, and FRAP analyses. We determined that there are five types of thyme hybrid EOs: geraniol-type, carvacrol-type, thymol-type, parent polymerization-type, and α-terpineol/α-terpinyl acetate-type. Moreover, there are five types of oregano hybrid EOs: carvacrol-type, thymol-type, sabinene hydrate-type, parent polymerization-type, and carvacrol/sabinene hydrate-type. The geraniol, thymol, and carvacrol contents ranged from 30.45%, 1.21% and 0.00%, respectively, in the parents to 81.66%, 52.65%, and 46.16%, respectively, in the thyme hybrids. The carvacrol and thymol contents ranged from 2.33% to 24.18%, respectively, in the parents to 94.16% and 76.77%, respectively, in the oregano hybrids, indicating obvious heterosis. We further used three antioxidant assays, DPPH, ABTS, and FRAP, to analyse the antioxidant activity of thyme and oregano hybrid EO samples. The antioxidant capacities of carvacrol- and thymol-type EOs were significantly superior to those of other chemotypes. Our data suggest that carvacrol- and thymol-type EOs with greater antioxidant potential can be applied in many industries. In addition, the function of high geraniol-type thyme EO should be further researched. The results will also be very useful for the selection of new varieties, functional research on carvacrol-, thymol-, and geraniol-type essential oils, and product development of feed additives, cosmetics, etc.

Recent progress in the extraction of terpenoids from essential oils and separation of the enantiomers by GC-MS

Terpenoids possess significant physiological activities and are rich in essential oils. Some terpenoids have chiral centers and could form enantiomers with distinct physiological activities. Therefore, the extraction and separation of terpenoids enantiomers are very important and have attracted extensive attention in recent years. Meanwhile, the specific distribution and enantiomer excess results (the excess of one enantiomer over the other in a mixture of enantiomers) could be used as quality markers for illegitimate adulteration, origin identification, and exploring component variations and functional interrelations across different plant tissues. In this study, an overview of the progress in the extraction of terpenoids from essential oils and the separation of their enantiomers over the past two decades has been made. Extraction methods were retrieved by the resultant network visualization findings. The results showed that the predominant methods are hydrodistillation, solvent-free microwave extraction, headspace solid-phase microextraction and supercritical fluid extraction methods. GC-MS combined with chiral chromatography columns is commonly used for the separation of enantiomers, while 2D GC is found to have stronger resolution ability. Finally, some prospects for future research directions in the extraction and separation identification of essential oils are proposed.

A chemical analysis of the Pelargonium species: P. odoratissimum, P. graveolens, and P. zonale identifies secondary metabolites with activity against gram-positive bacteria with multidrug-resistance

The Pelargonium genus encompasses around 280 species, most of which are used for medicinal purposes. While P. graveolens, P. odoratissimum, and P. zonale are known to exhibit antimicrobial activity, there is an evident absence of studies evaluating all three species to understand their chemical differences and biological effects. Through the analysis of the hydroalcoholic extracts of P. graveolens, P. odoratissimum, and P. zonale, using HPLC-DAD-MS/MS, quercetin and kaempferol derivatives were identified in these three species. Conversely, gallotannins and anthocyanins were uniquely detected in P. zonale. P. graveolens stood out due to the various types of myricetin derivatives that were not detected in P. odoratissimum and P. zonale extracts. Evaluation of their biological activities revealed that P. zonale displayed superior antibacterial and antibiofilm activities in comparison to the other two species. The antibacterial efficacy of P. zonale was observed towards the clinically relevant strains of Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus (MRSA) 333, Enterococcus faecalis ATCC 29212, and the Vancomycin-resistant E. faecalis INSPI 032. Fractionation analysis of P. zonale suggested that the antibacterial activity attributed to this plant is due to the presence of quercetin derivatives and kaempferol and its derivatives, alongside their synergistic interaction with gallotannins and anthocyanins. Lastly, the three Pelargonium species exhibited notable antioxidant activity, which may be attributed to their high content of total phenolic compounds.

Inhalation of Pelargonium graveolens Essential Oil Alleviates Pain and Related Anxiety and Stress in Patients with Lumbar Spinal Stenosis and Moderate to Severe Pain

Pain in lumbar spinal stenosis (LSS) patients is closely associated with psychological factors, including anxiety, stress, and depression, and is a critical determinant of patient daily functionality and overall quality of life. The present study evaluated the effects of inhalation of Pelargonium graveolens (geranium) essential oil (GEO) on pain and related psychological factors in LSS patients. Fifty-nine patients, categorized as having mild or moderate to severe pain based on pain visual analog scale (VAS) scores, were randomly assigned to inhalation of 1% GEO or placebo control (PC). No significant differences between GEO and PC were observed in patients with mild pain, whereas differences in anxiety-VAS and stress-VAS scores were observed in patients with moderate to severe pain. Anxiety-VAS and stress-VAS scores decreased significantly after GEO but not after PC inhalation. Regardless of the severity of pain, post-intervention pain-VAS scores were significantly lower in the GEO group than in the PC group. In summary, GEO reduced pain and improved anxiety and stress, particularly among patients with moderate to severe pain. These findings suggest that GEO inhalation may have potential as an adjunct therapy for improving pain management and alleviating anxiety and stress in LSS patients with insufficient responses to pharmacological pain control.

Therapeutic Effects of Geranium Oil in MPTP-Induced Parkinsonian Mouse Model

Parkinson's disease (PD) is an incurable neurodegenerative disease characterized by motor and non-motor disabilities resulting from neuronal cell death in the substantia nigra and striatum. Microglial activation and oxidative stress are two of the primary mechanisms driving that neuronal death. Here, we evaluated the effects of geranium oil on 1-methyl-4-phenyl-1,2,3,6-tetra-hydropyridine (MPTP) mouse model for PD, on microglial activation, and oxidative stress. We demonstrate that oral treatment with geranium oil improved motor performance in this model. The therapeutic effects of geranium oil were observed as a significant increase in rotarod latency and distance among the mice treated with geranium oil, as compared to vehicle-treated MPTP mice. Geranium oil also prevented dopaminergic neuron death in the substantia nigra of the treated mice. These therapeutic effects can be partially attributed to the antioxidant and anti-inflammatory properties of geranium oil, which were observed as attenuated accumulation of reactive oxygen species and inhibition of the secretion of proinflammatory cytokines from geranium oil-treated activated microglial cells. A repeated-dose oral toxicity study showed that geranium oil is not toxic to mice. In light of that finding and since geranium oil is defined by the FDA as generally recognized as safe (GRAS), we do not foresee any toxicity problems in the future and suggest that geranium oil may be a safe and effective oral treatment for PD. Since the MPTP model is only one of the preclinical models for PD, further studies are needed to confirm that geranium oil can be used to prevent or treat PD.

Current and Potential Applications of Monoterpenes and Their Derivatives in Oral Health Care

Plant products have been employed in medicine for centuries. As the world becomes more health-conscious, there is a growing interest in natural and minimally processed products for oral health care. This has led to an increase in research into the bioactive compounds found in plant products, particularly monoterpenes. Monoterpenes are known to have beneficial biological properties, but the specific mechanisms by which they exert their effects are not yet fully understood. Despite this, some monoterpenes are already being used in oral health care. For example, thymol, which has antibacterial properties, is an ingredient in varnish used for caries prevention. In addition to this, monoterpenes have also demonstrated antifungal, antiviral, and anti-inflammatory properties, making them versatile for various applications. As research continues, there is potential for even more discoveries regarding the benefits of monoterpenes in oral health care. This narrative literature review gives an overview of the biological properties and current and potential applications of selected monoterpenes and their derivatives in oral health care. These compounds demonstrate promising potential for future medical development, and their applications in future research are expected to expand.

Odor Perception and Descriptions of Rose-Scented Geranium Pelargonium graveolens 'Dr. Westerlund'-Sensory and Chemical Analyses

A recent study found that the natural scent from the rose-scented geranium Pelargonium graveolens 'Dr. Westerlund' had positive effects on stress reduction. Essential oils from many pelargonium species are known to have phytochemical properties and pharmacological activities. No study has, so far, explored and identified the chemical compounds and the sensory perception of these compounds in 'Dr. Westerlund' plants. Such knowledge would be an important contribution to an increased understanding of the effects of plants' chemical odor properties on human well-being, and link this to the expressed perceived scents. This study aimed to identify the sensory profile and suggest responsible chemical compounds of Pelargonium graveolens 'Dr. Westerlund'. The sensory and chemical analysis results revealed sensory profiles of Pelargonium graveolens 'Dr. Westerlund's and provided suggestions for the chemical compounds attributed to the sensory profiles. Further studies are recommended to investigate the correlation between volatile compounds and possible stress reduction in humans.

Essential oil composition and antimicrobial potential of aromatic plants grown in the mid-hill conditions of the Western Himalayas

Essential oils are highly concentrated natural extracts obtained from plants, rich in bioactive constituents with antimicrobial properties, but the distinctive climate of the Western Himalayan region influences the same. Aromatic and medicinal plants, viz., Origanum majorana, Origanum vulgare, Cymbopogon winterianus, Pelargonium graveolens, and Nepeta cataria were grown in the foothills of the Western Himalayan condition and evaluated for essential oil content, composition, and their effect on some of the most common pathogenic microorganisms. The essential oil content (%) was 0.77, 0.45, 1.37, 0.15 and 0.17% in O. majorana, O. vulgare, C. winterianus, P. graveolens, and N. cataria, respectively. The major essential oil constituents of the isolated oils were terpinen-4-ol, thymol, citronellal, citronellol, and nepetalactone, contributing 41.24%, 31.81%, 43.13%, 43.35% and 91.43% in O. majorana, O. vulgare, C. winterianus, P. graveolens, and N. cataria, respectively. Well-diffusion assay revealed that the essential oil of O. majorana and O. vulgare was active against both the tested Gram-positive, viz., Bacillus subtilis MTCC 121, Micrococcus luteus MTCC 2470, and Staphylococcus aureus MTCC 96; and Gram-negative, viz., Escherichia coli MTCC 43, Klebsiella pneumoniae MTCC 109, and Pseudomonas aeruginosa MTCC 2453 bacteria, while the essential oil of C. winterianus, P. graveolens, and N. cataria showed activity against only some Gram-positive bacteria. Minimum inhibitory concentration (v/v) values indicated the highest efficacy of O. majorana essential oil against B. subtilis (0.5%), M. luteus (1%), and S. aureus (1%), while O. vulgare was most efficient to E. coli (2%) and K. pneumoniae (2%). C. winterianus essential oil did not inhibit any bacterial strains. M. luteus was susceptible to the essential oil of P. graveolens (1%) and N. cataria (0.5%) at low concentrations. Present findings showed the association between the chemical constituents' profile of isolated essential oils from the Himalayan region and their antimicrobial activity, indicating their perspective to be utilized as antibacterial means.