Diurnal and seasonal variation of the essential oil labdanes and clerodanes from Cistus monspeliensis L. leaves

Chemical and transcriptomic analyses of leaf trichomes from Cistus creticus subsp. creticus reveal the biosynthetic pathways of certain labdane-type diterpenoids and their acetylated forms

Labdane-related diterpenoids (LRDs), a subgroup of terpenoids, exhibit structural diversity and significant commercial and pharmacological potential. LRDs share the characteristic decalin-labdanic core structure that derives from the cycloisomerization of geranylgeranyl diphosphate (GGPP). Labdanes derive their name from the oleoresin known as 'Labdanum', 'Ladano', or 'Aladano', used since ancient Greek times. Acetylated labdanes, rarely identified in plants, are associated with enhanced biological activities. Chemical analysis of Cistus creticus subsp. creticus revealed labda-7,13(E)-dien-15-yl acetate and labda-7,13(E)-dien-15-ol as major constituents. In addition, novel labdanes such as cis-abienol, neoabienol, ent-copalol, and one as yet unidentified labdane-type diterpenoid were detected for the first time. These compounds exhibit developmental regulation, with higher accumulation observed in young leaves. Using RNA-sequencing (RNA-seq) analysis of young leaf trichomes, it was possible to identify, clone, and eventually functionally characterize labdane-type diterpenoid synthase (diTPS) genes, encoding proteins responsible for the production of labda-7,13(E)-dien-15-yl diphosphate (endo-7,13-CPP), labda-7,13(E)-dien-15-yl acetate, and labda-13(E)-ene-8α-ol-15-yl acetate. Moreover, the reconstitution of labda-7,13(E)-dien-15-yl acetate and labda-13(E)-ene-8α-ol-15-yl acetate production in yeast is presented. Finally, the accumulation of LRDs in different plant tissues showed a correlation with the expression profiles of the corresponding genes.

Floral Aroma and Pollinator Relationships in Two Sympatric Late-Summer-Flowering Mediterranean Asparagus Species

This research delves into plant-pollinator relationships within the Mediterranean region, focusing on two synchronous and sympatric asparagus species: A. acutifolius and A. albus. For the first time, the floral scents of the genus Asparagus are reported. We investigate the volatile organic compounds (VOCs) present in their floral scents and their impact on pollinator attraction. Captured flower-emitted VOCs underwent solid-phase microextraction of headspace (SPME-HS) and gas chromatography and mass spectrometry (GC-MS) analysis. The investigation confirms distinctive aroma profiles for each species. A. albus predominantly emits benzene derivatives and sesquiterpenes, while A. acutifolius is characterized by carotenoid derivatives, monoterpenes, and sesquiterpenes. The only shared compounds between the two species are the sesquiterpenes (Z,E)-α-farnesene and (E,E)-α-farnesene. A positive correlation links peak floral aroma intensity (benzenoids in A. albus and ionones in A. acutifolius) with a higher pollinator visit frequency, emphasizing the critical role of intense floral scents in pollinator attraction. The study of reproductive aspects reveals almost complete gynodioecy in A. acutifolius, influencing unique dynamics for the two species. These adaptations hold significant importance within the Mediterranean ecosystem, particularly during the late dry summer period, when a limited number of plant species vie for a shared primary pollinator.

Molecular Characterization of Gene-Mediated Resistance and Susceptibility of ESKAPE Clinical Isolates to Cistus monspeliensis L. and Cistus salviifolius L. Extracts

Background

Multidrug resistance (MDR) and extensively drug-resistant (XDR) are now the biggest threats to human beings. Alternative antimicrobial regimens to conventional antibiotic paradigms are extensively searched. Although Cistus extracts have long been used for infections in traditional folk medicines around the world, their efficacy against resistant bacteria still needs to be elucidated. We aim to investigate the antibiotic susceptibility profiles of clinical strains Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae (acronym “ESKAPE”), and their resistance mechanisms by PCR, as well as their sensitivity to C. monspeliensis (CM) and C. salviifolius (CS) methanol extracts and their fractions.

Methods

Antibiotic susceptibility profile and resistance mechanism were done by antibiogram and PCR. Fractions of CM and CS were obtained using maceration and Soxhlet; their antibacterial activities were evaluated by determining inhibition zone diameter (IZD), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC).

Results

Results revealed that all strains were XDR except S. aureus, which was MDR. The PCR indicates the presence of gene-mediated resistance (bla_CTX-M, bla_SHV, bla_OXA-48, bla_NDM, bla_OXA-51, bla_OXA-58, bla_IMP, bla_VIM, and bla_mecA). Also, maceration was slightly better for bioactivity preservation. Overall, the extracts of CM (IZD = 20 mm, MIC = 0.01 mg/mL) were more active than those of CS. All extracts inhibited MRSA (methicillin-resistant Staphylococcus aureus) and ERV (Enterococcus faecium Vancomycin-Resistant) with interesting MICs. The ethyl acetate fraction manifested great efficacy against all strains. Monoterpene hydrocarbons and sesquiterpenes oxygenated were the chemical classes of compounds dominating the analyzed fractions. Viridiflorol was the major compound in ethyl acetate fractions of 59.84% and 70.77% for CM and CS, respectively.

Conclusions

The superior activity of extracts to conventional antibiotics was seen for the first time in the pathogens group, and their bactericidal effect could be a promising alternative for developing clinical antibacterial agents against MDR and XDR ESKAPE bacteria.

A Review on Cistus sp.: Phytochemical and Antimicrobial Activities

Resistance to drugs is reaching alarming levels and is placing human health at risk. With the lack of new antimicrobials drugs, infectious diseases are becoming harder to treat. Hence, there is an increasing awareness of active phytochemicals with therapeutic functions. The tremendous research interest on the Cistus L. genus includes numerous plants used in traditional medicine by people living around the Mediterranean Sea, also resulted in some interesting discoveries and written literature. This review aimed at gathering scientific literature about Cistus species, describing phytochemical profiles and the various pharmacological activities. We also extensively reviewed the antimicrobial activities, including antiviral, antiparasitic, antifungal, and antibacterial potentials of Essential Oils (EO), raw extracts as well as isolated compounds. Mechanisms of action along with methods used are also investigated in this review. Considering the findings of the Cistus species extracts, this genus offers an adequate reserve of active phytochemicals since many have been used to create drugs. Therefore, this review work can serve society by providing a global view on Cistus L. sp. regarding pharmacological potentials and their chemical profiles.

Antiparasitic activity of synthetic curcumin monocarbonyl analogues against Trichomonas vaginalis

Trichomoniasis is a parasitic infection caused by Trichomonas vaginalis and it is considered to be the most common non-viral sexually transmitted infection in the world. Since the 1960s, nitroimidazoles such as metronidazole are the drugs of choice for the treatment of trichomoniasis, but many adverse effects and allergic reactions may result from their use. Reports of metronidazole-resistant infections also highlight the importance for the search of new anti-T. vaginalis agents. Considering this, herein we report the anti-T. vaginalis evaluation of 21 synthetic monocarbonyl analogues of curcumin, which itself has been reported to possess antiparasitic potential. From the in vitro analysis of the synthetic molecules, untreated trophozoites, and metronidazole at 100 μM, it was observed that three curcumin analogues (3a, 3e, and 5e) exhibited anti-T. vaginalis activity comparable to metronidazole (no significant statistical difference). Optimal antiparasitic concentrations were determined to be 80 μM and 90 μM for propanone derivatives 3a and 3e, respectively, and 200 μM for cyclohexanone derivative 5e. Kinetic growth curves showed that, after 24 h, the trophozoites were completely inhibited. At the tested concentrations, natural curcumin did not significantly inhibit the growth of trophozoites, therefore demonstrating that the designed synthetic molecules not only have better chemical stability, but also higher anti-T. vaginalis potential. Cytotoxicity analysis, performed on VERO cells, demonstrated low, moderate and high cytotoxic effects for analogues 3e, 5e and 3a, respectively. This study suggests that these analogues possess chemical features of interest to be further explored as alternatives for the treatment of trichomoniasis.

Terpenoid Emissions of Two Mediterranean Woody Species in Response to Drought Stress

Drought is a major environmental constrain affecting plant performance and survival, particularly in Mediterranean ecosystems. Terpenoids may play a protective role under these conditions, however, observations of drought effects on plant terpenoid emissions are controversial ranging from decreased emissions to unaffected or increased release of terpenoids. In the present study we investigated terpenoid emissions of cork oak (Quercus suber) and gum rockrose (Cistus ladanifer) in response to summer drought stress in 2017. Pre-dawn leaf water potential (ΨPD) decreased from -0.64 to -1.72 MPa in Q. suber and from -1.69 to -4.05 MPa in C. ladanifer, indicating a transition from mild to severe drought along summer. Total terpenoid emissions decreased with drought, but differed significantly between species (p < 0.001) and in response to ΨPD, air temperature and assimilation rates. C. ladanifer emitted a large variety of >75 compounds comprising monoterpenes, sesquiterpenes and even diterpenes, which strongly decreased from 1.37 ± 0.23 μg g-1h-1 to 0.40 ± 0.08 μg g-1h-1 (p < 0.001) in response to drought. Total emission rates were positively correlated to air temperature (p < 0.001). C. ladanifer behavior points toward terpenoid leaf storage depletion and reduced substrate availability for terpenoid synthesis with increasing drought, most likely accelerated by high air temperatures. Q. suber emitted mainly monoterpenes and emissions declined significantly from June (0.50 ± 0.08 μg g-1h-1) to August (0.29 ± 0.02 μg g-1h-1) (p < 0.01). Emission rates were weakly correlated with net assimilation rates (R2 = 0.19, p < 0.001), but did not respond strongly to ΨPD and air temperature. Early onset of drought in 2017 most likely reduced plant metabolism in Q. suber, resulting in diminished, but stable terpenoid fluxes. Calculation of standard emission factors (at 30°C) revealed contrasting emission patterns of decreasing, unaffected, or increasing fluxes of single terpenoid compounds. Unaffected or drought-enhanced emissions of compounds such as α-pinene, camphene or manoyl oxide may point toward a specific role of these terpenoids in abiotic stress adaptation. In conclusion, these results suggest a strong negative, but species- and compound-specific effect of severe drought on terpenoid fluxes in Mediterranean ecosystems.

Comparison of essential oils from Cistus species growing in Sardinia

Cistus genus is present in Sardinia with large populations of C. monspeliensis, C. salvifolius, C. creticus subsp. eriocephalus and few stations of C. albidus, C. creticus subsp. creticus and C. creticus subsp. corsicus. No chemical studies are currently being carried on Cistus species of Sardinia. The essential oils have shown six different profiles. C. creticus subsp. eriocephalus showed a high amount of manoyl oxide and its isomer (70%). C. salvifolius has pointed out the group of labdans, (20%); another consistent percentage is made of perfumed molecules as ionone and its derivate. Several linear hydrocarbons were produced by C. monspeliensis, and the heneicosane was the most represented element. In C. albidus no labdane-type diterpenes were identified. Analysis of C. creticus subsp creticus revealed several oxygenated sesquiterpenes and labdane-type diterpenes, especially manoyl oxide. C. creticus subsp. corsicus was qualitatively very similar to C. creticus subsp. creticus, notably concerning the labdane-type compounds.

Non-Oxygenated Sesquiterpenes in the Essential Oil of Copaifera langsdorffii Desf. Increase during the Day in the Dry Season

The present study aimed to evaluate the effect of seasonal and diurnal events on the chemical profile of the essential oil obtained from the leaves of Copaifera langsdorffii Desf. This study was performed in a Brazilian savanna named Cerrado. We identified the best harvesting period for obtaining the highest amount of compounds used for commercial and industrial purposes. The chemical profile of the essential oils was evaluated by GC-FID and GC-MS, and the results were assessed through multivariate analyses. The data showed that the time of day and seasonal variations affect the quality of the essential oil obtained. Leaves harvested at the end of the day (5:00 pm) in the dry season resulted in richer essential oils with higher amounts of non-oxygenated sesquiterpenes. To the best of our knowledge, environmental conditions induce metabolic responses in the leaves of C. langsdorffii, which changes the patterns of sesquiterpene production. Therefore, these factors need to be considered to obtain better concentrations of bioactive compounds for pharmacological studies.

Genus Cistus: a model for exploring labdane-type diterpenes' biosynthesis and a natural source of high value products with biological, aromatic, and pharmacological properties

The family Cistaceae (Angiosperm, Malvales) consists of 8 genera and 180 species, with 5 genera native to the Mediterranean area (Cistus, Fumara, Halimium, Helianthemum, and Tuberaria). Traditionally, a number of Cistus species have been used in Mediterranean folk medicine as herbal tea infusions for healing digestive problems and colds, as extracts for the treatment of diseases, and as fragrances. The resin, ladano, secreted by the glandular trichomes of certain Cistus species contains a number of phytochemicals with antioxidant, antibacterial, antifungal, and anticancer properties. Furthermore, total leaf aqueous extracts possess anti-influenza virus activity. All these properties have been attributed to phytochemicals such as terpenoids, including diterpenes, labdane-type diterpenes and clerodanes, phenylpropanoids, including flavonoids and ellagitannins, several groups of alkaloids and other types of secondary metabolites. In the past 20 years, research on Cistus involved chemical, biological and phylogenetic analyses but recent investigations have involved genomic and molecular approaches. Our lab is exploring the biosynthetic machinery that generates terpenoids and phenylpropanoids, with a goal to harness their numerous properties that have applications in the pharmaceutical, chemical and aromatic industries. This review focuses on the systematics, botanical characteristics, geographic distribution, chemical analyses, biological function and biosynthesis of major compounds, as well as genomic analyses and biotechnological approaches of the main Cistus species found in the Mediterranean basin, namely C. albidus, C. creticus, C. crispus, C. parviflorus, C. monspeliensis, C. populifolius, C. salviifolius, C. ladanifer, C. laurifolius, and C. clusii.

Diurnal Variation of Essential of the Oil Components of Pycnocycla spinosa Decne. ex Boiss

Background:

Pycnocycla spinosa Decne. ex Boiss is an aromatic plant which showed relaxant effects on isolated ileum contractions and antidiarrheal activity. Thirty four components have been extracted from P. spinosa essential oil, of which several major constituents were found to show seasonal variation.

Objectives:

The aim of this work is to evaluate the diurnal variation of its oil constituents during specific hours of the day.

Materials and Methods:

The Pycnocycla spinosa samples were collected at different times of the day. The hydro-distilled aerial parts oils of collected P. spinosa were analyzed by GC and GC/MS.

Results:

Fourteen monoterpenoid and nine sesquiterpenoid components were identified, of which the fluctuating constituents were p-cymene, trans-β-ocimene, β-citronellol, citronellyl pentanoate, geranyl isovalerate, α-humulene, caryophyllen oxide, α-cadinol, and α-eudesmol. The content of p-cymene in the essential oil in different daily times varied from 0.16 to 4.19%, and the geranyl isovalerate 7.75 -23.99%.

Conclusions:

Essential oils with different qualities can be obtained according to the harvest time of the plant in a day.

Environmental control of terpene emissions from Cistus monspeliensis L. in natural Mediterranean shrublands

The large amount of volatile organic compound (VOC) emitted by vegetation modifies air quality contributing to both tropospheric ozone and secondary organic aerosol production. A better understanding of the factors controlling VOC emissions by vegetation is mandatory in order to improve emission estimates derived from tropospheric chemistry models. Although the Mediterranean shrublands are particularly abundant and rich in emitting species, their emission potential is poorly known. Focusing on a VOC-emitting shrub species widespread in the Mediterranean area (Cistus monspeliensis L.), we measured and analysed its emissions of terpenes taking into account the age of individuals, the season of sampling and the soil type. Sampling was done under natural environmental conditions. Species of the genus Cistus are frequently reported to be storing species, although we found only one stored monoterpene and three sesquiterpenes in very low amount. Major emitted compounds were alpha-pinene and beta-myrcene. Total terpene emissions were not influenced by plant age but emission of some individual terpenes was positively correlated with age. A strong seasonal effect was evidenced. A larger amount of terpenes was emitted during spring and summer than during fall and winter. Summer emission rates were nearly 70 times higher than winter emission rates. Total and individual terpene emissions were influenced by soil type; emissions on siliceous substrate were ca. seven times higher than those on calcareous substrate. In conclusion, it appears clearly that environmental factors such as soil nature and season should be taken into account in order to achieve improved modelling of terpene emissions by shrub species.