Characterization and Antioxidant Activity of Essential Oil of Four Sympatric Orchid Species

Surviving adversity: Exploring the presence of Lunularia cruciata (L.) Dum. on metal-polluted mining waste

The tailings dump of Barraxiutta (Sardinia, Italy) contains considerable concentrations of heavy metals and, consequently, is scarcely colonized by plants. However, wild populations of the liverwort Lunularia cruciata (L.) Dum. form dense and healthy-looking carpets on this tailing dump. L. cruciata colonizing the tailing dump was compared with a control population growing in a pristine environment in terms of: (i) pollutant content, (ii) photochemical efficiency, and (iii) volatile secondary metabolites in thalli extracts. L. cruciata maintained optimal photosynthesis despite containing considerable amounts of soil pollutants in its thalli and had higher sesquiterpene content compared to control plants. Sesquiterpenes have a role in plant stress resistance and adaptation to adverse environments. In the present study, we propose enhanced sesquiterpenes featuring Contaminated L. cruciata as a defence strategy implemented in the post-mining environment.

Phytochemical Analysis of Anacamptis coriophora Plant Cultivated Using Ex Vitro Symbiotic Propagation

This study aims to investigate the functional groups and phytochemical profile of Anacamptis coriophora seeds, tubers, and flowers. Symbiotic seedlings produced using the ex vitro method were transferred to their natural habitat and grown to analyze the functional groups and phytochemical profiles of tubers and flowers. The life cycles of the transferred seedlings were monitored, and tubers and flowers were harvested for analysis. ATR-FTIR spectroscopy revealed the presence of functional groups such as polysaccharides, lignin, and proteins in both tubers and flowers. Differences in spectral frequencies between first-year and second-year tubers were observed. Fatty acid analysis identified 30 different compounds in seeds, flowers, and tubers, with linoleic acid being the most abundant (27 % in seeds, 33 % in tubers), and palmitic acid present in flowers (24 %). GC-MS analysis of ethanol extracts from these components highlighted the presence of 32 compounds, including hydroxyacetic acid, hydrazide, cytidine (Z)-7-hexadecenal, 2,2-dimethoxyethane, 2,5,6-trimethyldecane, and butanamide, 4-amino-N-hydroxy. A. coriophora's tubers, flowers, and seeds may contain active metabolites with therapeutic potential. These results are valuable for the commercial cultivation of the plant.

Chemical Composition, In Vitro Antioxidant Activities, and Inhibitory Effects of the Acetylcholinesterase of Liparis nervosa (Thunb.) Lindl. Essential Oil

The present study aimed to investigate the essential oil composition of Liparis nervosa (Thunb.) Lindl., grown in China, and to determine its antioxidant and inhibitory effects on acetylcholinesterase. The essential oil was obtained by hydrodistillation, and the chemical compounds were analyzed by GC-MS and GC-FID. We used 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing assay power (FRAP) to evaluate the antioxidant activity. The anti-acetylcholinesterase activity of the essential oil was also examined. Sixty-seven compounds were identified, representing 98.50 % of the total essential oil, which was shown to be rich in methyl (9E,11E)-octadeca-9,11-dienoate (31.69%), n-hexadecanoic acid (15.08%), isopropyl palmitate (12.44%), propyl tetradecanoate (7.20%), tetradecanoic acid (4.01%), 17-octadecynoic acid (3.71%), and pentacosane (2.24%). Its antioxidant ability was analyzed via ABTS (IC₅₀ = 721.95 ± 9.93 μg/mL), DPPH scavenging capacity (IC₅₀ > 10,000 μg/mL), and the FRAP method (Trolox equivalent antioxidant concentration 39.64 ± 3.38 μM/g). Acetylcholinesterase inhibition effects were evaluated and had an IC₅₀ value of 51.96 ± 14.26 μg/mL. The results show that this essential oil has interesting biological potential, encouraging further investigations, especially regarding the mechanisms of action of its antioxidant and anti-acetylcholinesterase activity. This is the first time that the chemical composition, antioxidant activity, and acetylcholinesterase inhibition effects of essential oil from L. nervosa have been studied.

Traditional, Therapeutic Uses and Phytochemistry of Terrestrial European Orchids and Implications for Conservation

The Orchidaceae family accounts for about 28,000 species, and most of them are mentioned in the folk medicine of nations around the world. The use of terrestrial orchids in European and Mediterranean regions has been reported since ancient times, but little information is available on their medicinal properties, as well as on their phytochemicals and biological activities. However, plant collection for human use is still listed as one of the main threats for terrestrial orchids, alongside other menacing factors such as wrong habitat management and disturbance to symbionts, such as pollinators and mycorrhizal fungi. Therefore, the primary aim of this review was to resume and discuss available information regarding the past and current popular uses of European orchids. We then grouped phytochemical data to evaluate the presence of bioactive compounds of pharmacological relevance, and we discussed whether these could support the therapeutic employment of the different organs. Finally, we briefly debated the sustainability of orchid utilizations, considering the different threatening factors and conservation actions including plant propagation methods.

Active Compounds with Medicinal Potential Found in Maxillariinae Benth. (Orchidaceae Juss.) Representatives-A Review

Orchids are widely used in traditional medicine for the treatment of a whole range of different health conditions, and representatives of the Neotropical subtribe Maxillariinae are not an exception. They are utilized, for instance, for their spasmolytic and anti-inflammatory activities. In this work, we analyze the literature concerning the chemical composition of the plant extracts and secretions of this subtribe's representatives published between 1991 and 2022. Maxillariinae is one of the biggest taxa within the orchid family; however, to date, only 19 species have been investigated in this regard and, as we report, they produce 62 semiochemicals of medical potential. The presented review is the first summary of biologically active compounds found in Maxillariinae.

Chemical profiling, cytotoxic activities through apoptosis induction in MCF-7 cells and molecular docking of Phyllostachys heterocycla bark nonpolar extract

The chemical constituents of the nonpolar fractions of the bamboo shoot skin Phyllostachys heterocycla were extensively studied. The phytochemical study was divided into two parts: the first deals with isolation of the chemical constituents using different chromatographic techniques that resulted in isolation of four compounds. The chemical structures of the pure isolated compounds were elucidated using different spectroscopic data. The second part deals with identification of the rest of the constituents using the GC technique. Additionally, both crude extract and the pure isolated compounds were investigated for cytotoxic activity. One of the isolated compounds; namely glyceryl 1-monopalmitate showed highly promising effect against the MCF-7 cells with (IC₅₀ = 19.78 µM) compared to 5-FU (26.98 µM), and it remarkably stimulated apoptotic breast cancer cell death with 31.6-fold (16.13% compared to 0.51 for the control) at pre-G1 and G2/M-phase cell cycle arrest and blocked the progression of MCF-7 cells. Moreover, the identified compounds especially 1 were found to have high binding affinity towards both TPK and VEGFR-2 through the molecular docking studies which highlight its mode of action. HighlightsChemical profiling of Phyllostachys heterocycla bark nonpolar extract was fully identified.Glyceryl 1-monopalmitate showed highly promising effect against the MCF-7 cells with (IC₅₀ = 19.78 µM) compared to 5-FU (26.98 µM).Glyceryl 1-monopalmitate significantly stimulated apoptotic breast cancer cell death with 31.6-fold by arresting cell cycle at G2/M and preG1 phases.Molecular docking simulation showed good binding affinities towards TPK and VEGFR-2 proteins.Communicated by Ramaswamy H. Sarma.

Volatile Organic Compounds (VOCs) Diversity in the Orchid Himantoglossum robertianum (Loisel.) P. Delforge from Sardinia (Italy)

Volatile Organic Compounds (VOCs) are produced by plants to address a variety of physiological and ecological tasks (among others, stress resistance, and pollinator attraction). Genetics is a key factor in determining plants’ VOCs content and emission, nevertheless, environment strongly influences VOCs profiles in plants. Orchids are a widespread group of plants that colonize diverse environments and rely on complex and refined pollination mechanisms to reproduce. Orchids VOCs are rarely studied and discussed in relation to growing conditions. In the present study, we compare the volatile profiles of inflorescences of Himantoglossum robertianum (Loisel.) P. Delforge sampled in six ecologically diverse populations on Sardinia Island (Italy). The essential oils obtained by steam distillation were characterized by GC-FID and GC-MS analysis. A total of 79 compounds were detected, belonging to the chemical classes of saturated hydrocarbons, esters, alcohols, ketones, unsaturated hydrocarbons, sesquiterpenes, oxygenated terpenes, terpenes, acids, and aldehydes. Multivariate statistics separated H. robertianum populations based on their chemical profiles. Differences were positively linked to the distance separating populations and reflected climatological features of the sampling sites. Interestingly, our results differed from those available in the literature, pointing out the high variability of VOCs profiles in this food-deceptive orchid.

Chemical Composition of Essential Oil from Four Sympatric Orchids in NW-Italy

Orchidaceae is a flowering plant family worldwide distributed known for producing volatile organic compounds (VOCs) which can act as olfactory signals for pollinators. Despite the importance of VOCs in the different reproductive strategies, in the literature there are only a few publications on the characterization of orchids' volatile profiles. In this study, the essential oils from fresh inflorescences of sympatric orchids Anacamptis morio, Himantoglossum robertianum, Ophrys sphegodes and Orchis purpurea, naturally growing in Piedmont (Italy) were isolated by steam distillation and characterized by GC/FID and GC/MS. A number of compounds were identified, with a peculiar distribution in the species: alcohols (range 16.93-50.60%), from which p-cresol (range 12.75-38.10%) was the most representative compound; saturated hydrocarbons (range 5.81-59.29%), represented by pentacosane (range 2.22-40.17%) and tricosane (range 0.78-27.48%); long-chain monounsaturated hydrocarbons (range 0.29-5.20%) represented by 9-pentacosene, 11-tricosene, and 1-heneicosene. The structure of positional isomers in linear alkenes was elucidated by derivatization with dimethyl disulfide and MS fragmentation patterns. Coumarin (68.84%) was the dominant compound in O. purpurea and was detected in lower concentrations (range 0.21-0.26%) in the other taxa. These volatile compounds may represent a particular feature of these plant species and play an essential role in pollinator interaction.

An Integrated Analysis of Metabolomics and Transcriptomics Reveals Significant Differences in Floral Scents and Related Gene Expression between Two Varieties of Dendrobium loddigesii

Flower fragrance is one of the traits that holds important economical values in flowering plants. Extensive attention has converged on fragrance preservation in flower cultivation and breeding. Dendrobium loddigesii is an important species for cultivating aromatic Dendrobium orchid varieties for the long term due to its fragrance. Few studies focus on exploring related genes responsible for the aroma components in D. loddigesii. We analyzed flowers from two aromatic D. loddigesii varieties using high-throughput RNA sequencing and gas chromatography-mass spectrometry (GC-MS). The metabolomics results showed that the main volatile compounds responsible for the aroma formation of D. loddigesii were terpenes, especially monoterpenes. The de novo transcriptome assembly comprised 175,089 unigenes, and 24,570 unigenes of the genes were identified as differential expressed genes (DEGs) between the two varieties. Among these DEGs, 525 genes were mapped into seven pathways that related to the floral scent synthesis. Seventeen key genes were significantly correlated with volatile aroma metabolites, including geraniol, α-pinene, eugenol, and (Z)-3-hexenal. These results provide references for understanding the aroma biosynthesis and perfume formulations of D. loddigesii.

Comparative Study of the Petal Structure and Fragrance Components of the Nymphaea hybrid, a Precious Water Lily

Nymphaea hybrid, a precious water lily, is a widely-cultivated aquatic flower with high ornamental, economic, medicinal, and ecological value; it blooms recurrently and emits a strong fragrance. In the present study, in order to understand the volatile components of N. hybrid and its relationship with petals structure characteristics, the morphologies and anatomical structures of the flower petals of N. hybrid were investigated, and volatile compounds emitted from the petals were identified. Scanning and transmission electron microscopy were used to describe petal structures, and the volatile constituents were collected using headspace solid-phase microextraction (HS-SPME) fibers and analyzed using gas chromatography coupled with mass spectrometry (GC-MS). The results indicated that the density and degree of protrusion and the number of plastids and osmiophilic matrix granules in the petals play key roles in emitting the fragrance. There were distinct differences in the components and relative contents of volatile compounds among the different strains of N. hybrid. In total, 29, 34, 39, and 43 volatile compounds were detected in the cut flower petals of the blue-purple type (Nh-1), pink type (Nh-2), yellow type (Nh-3) and white type (Nh-4) of N. hybrid at the flowering stage, with total relative contents of 96.78%, 97.64%, 98.56%, and 96.15%, respectively. Analyses of these volatile components indicated that alkenes, alcohols, and alkanes were the three major types of volatile components in the flower petals of N. hybrid. The predominant volatile compounds were benzyl alcohol, pentadecane, trans-α-bergamotene, (E)-β-farnesene, and (6E,9E)-6,9-heptadecadiene, and some of these volatile compounds were terpenes, which varied among the different strains. Moreover, on the basis of hierarchical cluster analysis (HCA) and principal component analysis (PCA), the N. hybrid samples were divided into four groups: alcohols were the most important volatile compounds for Nh-4 samples; esters and aldehydes were the predominant volatiles in Nh-3 samples; and ketones and alkenes were important for Nh-2 samples. These compounds contribute to the unique flavors and aromas of the four strains of N. hybrid.

Chemical Composition of Essential Oil from Flowers of Five Fragrant Dendrobium (Orchidaceae)

A detailed chemical composition of Dendrobium essential oil has been only reported for a few main species. This article is the first to evaluate the essential oil composition, obtained by steam distillation, of five Indian Dendrobium species: Dendrobium chrysotoxum Lindl., Dendrobium harveyanum Rchb.f., and Dendrobium wardianum R.Warner (section Dendrobium), Dendrobium amabile (Lour.) O'Brien, and Dendrobium chrysanthum Wall. ex Lindl. (section Densiflora). We investigate fresh flower essential oil obtained by steam distillation, by GC/FID and GC/MS. Several compounds are identified, with a peculiar distribution in the species: Saturated hydrocarbons (range 2.19-80.20%), organic acids (range 0.45-46.80%), esters (range 1.03-49.33%), and alcohols (range 0.12-22.81%). Organic acids are detected in higher concentrations in D. chrysantum, D. wardianum, and D. harveyanum (46.80%, 26.89%, and 7.84%, respectively). This class is represented by palmitic acid (13.52%, 5.76, and 7.52%) linoleic acid (D. wardianum 17.54%), and (Z)-11-hexadecenoic acid (D. chrysantum 29.22%). Esters are detected especially in species from section Dendrobium, with ethyl linolenate, methyl linoleate, ethyl oleate, and ethyl palmitate as the most abundant compounds. Alcohols are present in higher concentrations in D. chrysantum (2.4-di-tert-butylphenol, 22.81%), D. chrysotoxum (1-octanol, and 2-phenylethanol, 2.80% and 2.36%), and D. wardianum (2-phenylethanol, 4.65%). Coumarin (95.59%) is the dominant compound in D. amabile (section Densiflora) and detected in lower concentrations (range 0.19-0.54%) in other samples. These volatile compounds may represent a particular feature of these plant species, playing a critical role in interacting with pollinators.

Crocetin as New Cross-Linker for Bioactive Sericin Nanoparticles

The nose-to-brain delivery route is used to bypass the blood–brain barrier and deliver drugs directly into the brain. Over the years, significant signs of progress have been made in developing nano-drug delivery systems to address the very low drug transfer levels seen with conventional formulations (e.g., nasal solutions). In this paper, sericin nanoparticles were prepared using crocetin as a new bioactive natural cross-linker (NPc) and compared to sericin nanoparticles prepared with glutaraldehyde (NPg). The mean diameter of NPc and NPg was about 248 and 225 nm, respectively, and suitable for nose-to-brain delivery. The morphological investigation revealed that NPc are spherical-like particles with a smooth surface, whereas NPg seem small and rough. NPc remained stable at 4 °C for 28 days, and when freeze-dried with 0.1% w/v of trehalose, the aggregation was prevented. The use of crocetin as a natural cross-linker significantly improved the in vitro ROS-scavenging ability of NPc with respect to NPg. Both formulations were cytocompatible at all the concentrations tested on human fibroblasts and Caco-2 cells and protected them against oxidative stress damage. In detail, for NPc, the concentration of 400 µg/mL resulted in the most promising to maintain the cell metabolic activity of fibroblasts higher than 90%. Overall, the results reported in this paper support the employment of NPc as a nose-to-brain drug delivery system, as the brain targeting of antioxidants is a potential tool for the therapy of neurological diseases.

Combined Analysis of Volatile Terpenoid Metabolism and Transcriptome Reveals Transcription Factors Related to Terpene Synthase in Two Cultivars of Dendrobium officinale Flowers

Dendrobium officinale is a kind of traditional Chinese herbal medicine. Its flowers could be used as health care tea for its aroma flavor and medicinal value. Most recent studies demonstrated that terpenoids are the main components of the aromatic compounds in the flowers, but the biosynthesis of terpenoids is poorly understood in D. officinale. In the experiment, the flowers from two cultivars of D. officinale with different smells were collected. The transcriptome analysis and combined volatile terpenoids determination were performed to identify the genes related to the biosynthesis of the terpenoids. The results showed that the different products of volatile terpenoids are α-thujene, linalool, α-terpineol, α-phellandrene, γ-muurolene, α-patchoulene, and δ-elemene in two cultivar flowers. The transcriptome analysis detected 25,484 genes in the flowers. And 18,650 differentially expressed genes were identified between the two cultivars. Of these genes, 253 genes were mapped to the terpenoid metabolism pathway. Among these genes, 13 terpene synthase (TPS) genes may have correlations with AP2/ERF, WRKY, MYB, bHLH, and bZIP transcription factors by weighted gene co-expression network analysis (WGCNA). The transcription factors have regulatory effects on TPS genes. These results may provide ideas for the terpenoid biosynthesis and regulatory network of D. officinale flowers.

Chemical composition, antimicrobial, and lipase enzyme activity of essential oil and solvent extracts from Serapias orientalis subsp. orientalis

The volatile components of essential oil (EO), SPME, and SPME of solvent extracts ( n -hexane, methanol, and water) obtained from fresh Serapias orientalis subsp. orientalis ( Soo ) were analyzed by GC-FID/MS. EO of Soo gave 11 compounds in the percentage of 99.97%; capronaldehyde (37.01%), 2-( E )-hexenal (23.19%), and n -nonanal (19.05%) were found to be major constituents. SPME GC-FID/MS analyses of fresh plant and solvent extracts of Soo revealed 7, 12, 7, and 4 compounds within the range of 99.7% to 99.9%. Limonene (76.5%, 41.7%, and 61.3%) was the major compound in SPMEs of the n -hexane and methanol extracts. α -Methoxy- p -cresol (52.9%) was the main component in its water extract. The antimicrobial activity of EO and the solvent extracts of Soo were screened against 9microorganisms. EO showed the best activity against Mycobacterium smegmatis , with 79.5 µg/mL MIC value. The n -hexane, methanol, and water extracts were the most active against the Staphylococcus aureus within the range of 81.25-125.0 µg/mL (MIC). IC 50 values for the lipase enzyme inhibitory activity of EO and solvent extracts ( n -hexane, methanol, and water) were determined to be 59.87 µg/mL, 64.03 µg/mL, 101.91 µg/mL, and 121.24 µg/mL, respectively.

Chemical Composition and Bioactivity of Essential Oil of Ten Labiatae Species

Using antibiotics as feed additives have been successively banned worldwide from 1986; therefore, it is an urgent task to finding safe and effective alternatives. As natural products of plant origin, essential oils (EOs) are an outstanding option due to their reported bioactivity. In this research, ten EOs of Labiatae species were extracted by steam distillation and its chemical constituents were identified by gas chromatography-mass spectrometry (GC-MS). A total of 123 chemical compounds, including alkenes, phenols, aldehydes and ketones, were identified. The results of antioxidant activity carried out through DPPH free radical scavenging (DPPH) and ferric reducing antioxidant power (FRAP), showing that EOs of Ocimum basilicum Linn. (ObEO), Thymus mongolicus Ronn. (TmEO), Origanum vulgare Linn. (OvEO) and Mosla chinensis Maxim. (McEO) have strong antioxidant activities. Their 50%-inhibitory concentration (IC₅₀) value was <1.00, 1.42, 1.47 and 1.92 μg/mL, respectively; and their FRAP value was 1536.67 ± 24.22, 271.84 ± 4.93, 633.71 ± 13.14 and 480.66 ± 29.90, respectively. The results of filter paper diffusion showing that McEO, OvEO and TmEO inhibition zone diameter (IZD) are all over 30 mm. The results of two-fold dilution method showed that McEO, OvEO and TmEO have strong antibacterial activities against Staphylococcus aureus (S. aureus) and their minimal inhibitory concentrations (MIC) value was 1 μL/mL, 2 μL/mL, and 2 μL/mL, respectively. In conclusion, the results in this work demonstrate the possibility for development and application of EOs as potential feed additives.

Polyphenols-Loaded Sericin Self-Assembling Nanoparticles: A Slow-Release for Regeneration by Tissue-Resident Mesenchymal Stem/Stromal Cells

Mesenchymal stem/stromal cells (MSCs) are a therapeutic target to promote tissue regeneration, mainly when oxidative stress-mediated damage is involved in disease pathogenesis. Here, slow-release silk sericin nanoparticles (SNPs) loaded with natural antioxidant polyphenols were developed to sustain regeneration by tissue-resident MSCs. SNPs were prepared by exploiting a self-assembly method with poloxamer and were loaded with proanthocyanidins (P), quercetin (Q) or epigallocatechin gallate (E). SNPs, with a diameter less than 150 nm, were able to encapsulate both hydrophilic (P and E) and hydrophobic (Q) drugs. A slow and controlled release was obtained from SNPs for all the actives in PBS, while in EtOH, Q and E showed a burst release but P did not. Kinetic models revealed lower diffusion of P than other biomolecules, probably due to the higher steric hindrance of P. The in vitro anti-oxidant, anti-elastase and anti-tyrosinase properties of SNPs were assessed: loading the P and E into SNPs preserved the in vitro biological activities whereas for Q, the anti-elastase activity was strongly improved. Moreover, all formulations promoted MSC metabolic activity over 72 h. Finally, SNPs exhibited a strong ability to protect MSCs from oxidative stress, which supports their potential use for regenerative purposes mediated by tissue-resident MSCs.