Anti-plasmodial and insecticidal activities of the essential oils of aromatic plants growing in the Mediterranean area

A Nano-Based Approach to Deliver Satureja thymbra Essential Oil to the Skin: Formulation and Characterization

Essential oils are well known for their biological properties, making them useful for the treatment of various diseases. However, because of their poor stability and high volatility, their potential cannot be fully exploited. The use of nanoformulations to deliver essential oils can solve these critical issues and amplify their biological activities. We characterized an essential oil from Satureja thymbra via GC-MS and HPLC-DAD to provide qualitative and quantitative data. The essential oil was formulated in phospholipid vesicles which were characterized for size, surface charge, and storage stability. The entrapment efficiency was evaluated as the quantification of the major monoterpenoid phenols via HPLC-DAD. The morphological characterization of the vesicles was carried out via cryo-TEM and SAXS analyses. The essential oil's antioxidant potential was assayed via two colorimetric tests (DPPH• and FRAP) and its cytocompatibility was evaluated in HaCaT skin cell cultures. The results showed that the nanoformulations developed for the loading of S. thymbra essential oil were below 100 nm in size, predominantly unilamellar, stable in storage, and had high entrapment efficiencies. The vesicles also displayed antioxidant properties and high cytocompatibility. These promising findings pave the way for further investigation of the therapeutic potential of S. thymbra nanoformulations upon skin application.

Screening of the activity of sixty essential oils against plasmodium early mosquito stages in vitro and machine learning analysis reveals new putative inhibitors of malaria parasites

Malaria, an infectious disease with a tremendous impact on human health is caused by Plasmodium parasites, and transmitted by Anopheles mosquitoes. New approaches to control the disease involve transmission blocking strategies aiming to target the parasite in the mosquito. Here, we investigated the putative inhibitory activity of essential oils and their components on the early mosquito stages of the parasite. We employed an in vitro assay of gametocyte-to-ookinete development of the rodent model parasite Plasmodium berghei combined with high content screening. 60 essential oils with known composition were tested. The results revealed that fifteen EOs had inhibitory activity. Furthermore, a machine learning approach was used to identify the putative inhibitory components. Five of the most important chemical components indicated by the machine learning-based models were actually confirmed by the experimental approach. This combined approach was used for the first time to identify the potential transmission blocking activity of essential oils and single components at the zygote and ookinete stages.

Acaricidal, Insecticidal, and Nematicidal Efficiency of Essential Oils Isolated from the Satureja Genus

The overuse of synthetic pesticides in plant protection strategies has resulted in numerous side effects, including environmental contamination, food staff residues, and a threat to non-target organisms. Several studies have been performed to assess the pesticidal effects of plant-derived essential oils and their components, as partially safe and effective agents, on economically important pests. The essential oils isolated from Satureja species are being used in medicinal, cosmetic, and food industries. Their great potential in pest management is promising, which is related to high amounts of terpenes presented in this genus. This review is focused on the acute and chronic acaricidal, insecticidal, and nematicidal effects of Satureja essential oil and their main components. The effects of eighteen Satureja species are documented, considering lethality, repellency, developmental inhibitory, and adverse effects on the feeding, life cycle, oviposition, and egg hatching. Further, the biochemical impairment, including impairments in esterases, acetylcholinesterase, and cytochrome P450 monooxygenases functions, are also considered. Finally, encapsulation and emulsification methods, based on controlled-release techniques, are suggested to overcome the low persistence and water solubility restrictions of these biopesticides. The present review offers Satureja essential oils and their major components as valuable alternatives to synthetic pesticides in the future of pest management.

So Uncommon and so Singular, but Underexplored: An Updated Overview on Ethnobotanical Uses, Biological Properties and Phytoconstituents of Sardinian Endemic Plants

The last decades have recorded an increase of plant-based drug discovery processes. Indeed, natural products possess a superior chemical diversity as compared to synthetic ones, leading to a renewal in searching for new therapeutic agents from the plant kingdom. In particular, since the structural variety of natural compounds reflects the biodiversity of their source organisms, regions of the world with high biodiversity and endemism deserve particular interest. In this context, Sardinia Island (Italy), with 290 endemic taxa (12% of the total flora), is expected to provide unique and structurally diverse phytochemicals for drug development. Several research groups built up a large program dedicated to the analysis of Sardinian endemic species, highlighting their peculiar features, both in respect of phytochemical and biological profiles. On this basis, the aim of this review is to provide an up-to-date and comprehensive overview on ethnobotanical uses, biological properties and phytoconstituents of Sardinian endemic plants in order to support their beneficial potential and to provide input for future investigations. We documented 152 articles published from 1965 to June 2020 in which a broad range of biological activities and the identification of previously undescribed compounds have been reported, supporting their great value as sources of therapeutic agents.

Antimalarial Activity of Meriandra dianthera Leaf Extracts in Plasmodium berghei-Infected Mice

Objective

To evaluate the antimalarial effect of aqueous methanolic extract and solvent fractions of Meriandra dianthera leaves against Plasmodium berghei in mice model.

Method

M. dianthera leaves were extracted with 80% methanol and dried. The dried crude extract was then defatted and further fractionated with chloroform, ethyl acetate, and butanol. Acute oral toxicity test was performed as per the Organization for Economic Cooperation and Development guideline 425. Peter's 4-day suppressive test was used to determine the in vivo antimalarial activity of the extract and fractions.

Result

The crude leaf extract of Meriandra dianthera leaves against P < 0.001) chemosuppression compared to the negative control. Both the extract and fractions were able to prevent P. berghei induced body weight loss and body temperature reduction and also increased the survival time of the mice as compared to the negative control. The aqueous methanolic leaf extract of M. dianthera leaves were extracted with 80% methanol and dried. The dried crude extract was then defatted and further fractionated with chloroform, ethyl acetate, and butanol. Acute oral toxicity test was performed as per the Organization for Economic Cooperation and Development guideline 425. Peter's 4-day suppressive test was used to determine the

Conclusion

The extracts of M. dianthera leaves showed promising antimalarial activity, with no sign of toxicity and therefore may support its traditional use for the treatment of malaria.M. dianthera leaves were extracted with 80% methanol and dried. The dried crude extract was then defatted and further fractionated with chloroform, ethyl acetate, and butanol. Acute oral toxicity test was performed as per the Organization for Economic Cooperation and Development guideline 425. Peter's 4-day suppressive test was used to determine the

Synergistic terpene combinations as larvicides against the dengue vector Aedes aegypti Linn

Most of the essential oils (EO) known for mosquitocidal activity contain terpenes as part of their chemical constituents. In this study, four monoterpenes namely γ-terpinene (T), R-(+)-limonene (L), carvacrol (C), and trans-anethole (A) were screened against late third instar Aedes aegypti Linn. larvae singly and in combination to find out the synergistic interaction. The monoterpenes γ-terpinene, R-(+)-limonene, trans-anethole, and carvacrol showed larvicidal activity with LC₅₀ values of 9.76, 11.88, 50.19, 48.57 ppm and LC₉₀ values of 16.99, 17.78, 65.21, 75.02 ppm, respectively for Ae. aegypti when tested individually. Prepared binary combinations at LC₂₀ values and studied the synergistic interactions based on cotoxicity factor (CTF) and found that all the binary combinations showed synergistic interactions (CTF > 20). Further, the binary (1:1), ternary (1:1:1), and quaternary (1:1:1:1) terpene combinations on equal weight basis were prepared, evaluated against Ae. aegypti larvae and synergistic interactions were studied by Wadley's method. Among the eight combinations two combinations viz. LC (LC₅₀ 10.42 ppm) and LA (LC₅₀ 11.86 ppm) were showing synergistic interactions (R > 1.5) and others were exhibiting additive effect (1.5 ≥ R > 0.5) and none of the combinations showed antagonism (R < 0.5). Among the two methods used the Wadley's method found suitable when combinations were made on an equal weight basis. The two binary combinations found in this study are promising synergistic mixtures which has scope in designing mosquito larvicidal EOs by enriching the EOs with terpenes or by producing EO combinations with these terpenes as chemical constituents in the correct proportions.

Insecticidal Activity of Local Plants Essential Oils Against Laboratory and Field Strains of Anopheles gambiae s. l. (Diptera: Culicidae) From Burkina Faso

The emergence and intensification of resistance to insecticides in malaria vector populations is the main obstacle to insecticide-based control efforts. The main objective of this study was to evaluate the larvicidal and adulticidal properties of the essential oils (EOs) of Ocimum canum, Hyptis suaveolens, Hyptis spicigera, and Lantana camara on field-collected, pyrethroids-resistant mosquitoes, local laboratory strains, and susceptible 'Kisumu' strain of Anopheles gambiae (Meigen) (Diptera: Culicidae) populations. Larvae and adults of these mosquitoes were challenged against four EOs. The mortality rates of larvae and adults were assessed 24 h after exposure to the EOs. Species identifications and detection of the L1014F and L1014S kdr mutations and the 1575Y super-kdr mutation were carried out using polymerase chain reaction on the pyrethroid-resistant mosquitoes from the field. EO compositions were analyzed by gas chromatography and mass spectrometry. Monoterpene hydrocarbons were the major components of H. suaveolens and H. spicigera EOs (49.8%) and (69.6%), respectively, whereas oxygenated monoterpenes (68.7%) were predominant in the O. canum EO. For L. camara, the component yields were variable, but it was the most effective EO against all strains. The LC50 values for the larvae were 7.73 and 25.63 ppm for the susceptible 'Kisumu' and resistant field strains, respectively. The LC50 for adults was 0.24% for the susceptible strain and 1.98% for the resistant strain. Molecular analysis confirmed the presence of L1014F and N1575Y mutations in resistant Anopheles arabiensis and Anopheles coluzzii mosquitoes from the field. Our results highlighted the potential of the EOs of local plants as insecticides against resistant and susceptible strains of An. gambiae populations.

Antifungal and Herbicidal Effects of Fruit Essential Oils of Four Myrtus communis Genotypes

The chemical composition of the essential oils isolated by hydrodistillation from the fruits of four selected Myrtus communis L. genotypes from Turkey was characterized by GC-FID and GC/MS analyses. 1,8-Cineole (29.20-31.40%), linalool (15.67-19.13%), α-terpineol (8.40-18.43%), α-pinene (6.04-20.71%), and geranyl acetate (3.98-7.54%) were found to be the major constituents of the fruit essential oils of all M. communis genotypes investigated. The oils were characterized by high amounts of oxygenated monoterpenes, representing 73.02-83.83% of the total oil compositions. The results of the fungal growth inhibition assays showed that the oils inhibited the growth of 19 phytopathogenic fungi. However, their antifungal activity was generally lower than that of the commercial pesticide benomyl. The herbicidal effects of the oils on the seed germination and seedling growth of Amaranthus retroflexus L., Chenopodium album L., Cirsium arvense (L.) Scop., Lactuca serriola L., and Rumex crispus L. were also determined. The oils completely or partly inhibited the seed germinations and seedling growths of the plants. The findings of the present study suggest that the M. communis essential oils might have potential to be used as natural herbicides as well as fungicides.

A pharmacological and phytochemical overview on Satureja

CONTEXT

Satureja (Lamiaceae) species are used as flavoring compounds in food, pharmaceutical, and cosmetic industries because of its sweetness and simple cultivation characteristics. They have traditionally been used as muscle pain relievers, tonic, and carminative agents to treat stomach and intestinal disorders such as cramps, nausea, indigestion, and diarrhea, due to their considerable phytochemical characteristics.

OBJECTIVE

This review evaluates some information published since 1989 on Satureja genus from a systematic perspective in terms of its pharmacological and phytochemical characteristics.

MATERIALS AND METHODS

Web of Science, PubMed, Scopus, and Google Scholar databases were searched up to March 2014. "Satureja" was used as a research term without narrowing or limiting research elements. After obtaining all reports from database (a total number is about 637), the papers were carefully analyzed in order to find data related to the topic of this review.

RESULTS

In this review, 453 reports were used which were published between 1989 and 2014. The study was compiled into two sections (Pharmacology and Phytochemistry). In the pharmacology section, more than 50 different activities were studied. In the second section, in addition to other compounds and inorganic substances, volatiles, phenolic acids, and flavonoids were discussed.

DISCUSSION AND CONCLUSION

According to our contemporary information, Satureja species have been evaluated for their wide range of biological activities. However, a small part of these studies have been carried out on the active principles. Therefore, in the future, more studies should be carried out to identify responsible phytochemicals for the various activities.

Insecticidal and repellent effects of tea tree and andiroba oils on flies associated with livestock

This study aimed to evaluate the insecticidal and repellent effects of tea tree, Melaleuca alternifolia (Myrtales: Myrtaceae), and andiroba, Carapa guianensis (Sapindales: Meliaceae), essential oils on two species of fly. For in vitro studies, free-living adult flies were captured and reared in the laboratory. To evaluate the insecticidal effects of the oils, adult flies of Haematobia irritans (L.) and Musca domestica L. (both: Diptera: Muscidae) were separated by species in test cages (n = 10 per group), and subsequently tested with oils at concentrations of 1.0% and 5.0% using a negative control to validate the test. Both oils showed insecticidal activity. Tea tree oil at a concentration of 5.0% was able to kill M. domestica with 100.0% efficacy after 12 h of exposure. However, the effectiveness of andiroba oil at a concentration of 5.0% was only 67.0%. The insecticidal efficacy (100.0%) of both oils against H. irritans was observed at both concentrations for up to 4 h. The repellency effects of the oils at concentrations of 5.0% were tested in vivo on Holstein cows naturally infested by H. irritans. Both oils demonstrated repellency at 24 h, when the numbers of flies on cows treated with tea tree and andiroba oil were 61.6% and 57.7%, respectively, lower than the number of flies on control animals. It is possible to conclude that these essential oils have insecticidal and repellent effects against the species of fly used in this study.

Anti-malarial activity and HS-SPME-GC-MS chemical profiling of Plinia cerrocampanensis leaf essential oil

Background

Plinia cerrocampanensis is an endemic plant of Panama. The leaf essential oil of this plant has shown antibacterial activity. However, anti-malarial activity and chemical profiling by HS-SPME-GC-MS of this essential oil have not been reported before.

Methods

Anti-malarial activity of the essential oil (EO) was evaluated in vitro against chloroquine-sensitive HB3 and chloroquine-resistant W2 strains of Plasmodium falciparum. Synergistic effect of chloroquine and the EO on parasite growth was evaluated by calculating the combination index. A methodology involving headspace solid phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) was developed to investigate the composition of Plinia cerrocampanensis EO.

Results

Plinia cerrocampanensis EO showed a high anti-malarial activity and a synergistic interaction with chloroquine. The Plinia cerrocampanensis EO inhibited P. falciparum growth in vitro at an IC₅₀ of 7.3 μg/mL. Chloroquine together with the EO decreased the IC₅₀ of chloroquine from 0.1 μg/mL to 0.05 μg/mL, and of the EO from 7.3 μg/mL to 1.1 μg/mL. The measured combination index was 0.58, which clearly indicates that the EO acts synergistically with chloroquine. Since the EO maintained its inhibitory activity on the chloroquine-sensitive strain of the parasite, it could be acting by a different mechanism of action than chloroquine. The best HS-SPME-GC-MS analytical conditions were obtained when the temperature of extraction was 49°C, incubation time 14 min, and the time of extraction 10 min. This method allowed for the identification of 53 volatile constituents in the EO, including new compounds not reported earlier.

Conclusions

The anti-malarial activity exhibited by the Plinia cerrocampanensis EO may lend support for its possible use as an alternative for anti-malarial therapy.