Antileishmanial activity of a linalool-rich essential oil from Croton cajucara

Effects of (-) mammea A/BB isolated from Calophyllum brasiliense leaves and derivatives on mitochondrial membrane of Leishmania amazonensis

We have previously demonstrated antileishmanial activity on Leishmania amazonensis of the natural (1-2), synthetic (7) and derivatives of coumarin (-) mammea A/BB (3-6) isolated from the dichloromethane extract of Calophyllum brasiliense leaves. The aim of the present study was to evaluate morphological and ultrastructural alterations in Leishmania amazonensis induced by these compounds. In promastigote forms, all seven compounds produced significant morphological and ultrastructural alterations, as revealed by scanning and transmission electron microscopy. The compound 5,7-dihydroxy-8-(2-methylbutanoyl)-6-(3-methylbutyl)-4-phenyl-chroman-2-one (3), the most active antileishmanial with LD₅₀ of 0.9 μM), induced cell shrinkage and a rounded appearance of the cells. Parasites incubated in the presence of compound (3) showed ultrastructural changes, such as the appearance of mitochondrial swelling with a reduction in the density of the mitochondrial matrix and the presence of vesicles inside the mitochondrion, indicating damage and significant change in this organelle; abnormal chromatin condensation, alterations in the nuclear envelope, intense atypical cytoplasmic vacuolization, and the appearance of autophagic vacuoles were also observed. In addition, the compound (3) may be acting to depolarize the mitochondrial membrane potential of the cells, leading to death of the parasite.

Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects

Tetrahydrocannabinol (THC) has been the primary focus of cannabis research since 1964, when Raphael Mechoulam isolated and synthesized it. More recently, the synergistic contributions of cannabidiol to cannabis pharmacology and analgesia have been scientifically demonstrated. Other phytocannabinoids, including tetrahydrocannabivarin, cannabigerol and cannabichromene, exert additional effects of therapeutic interest. Innovative conventional plant breeding has yielded cannabis chemotypes expressing high titres of each component for future study. This review will explore another echelon of phytotherapeutic agents, the cannabis terpenoids: limonene, myrcene, α-pinene, linalool, β-caryophyllene, caryophyllene oxide, nerolidol and phytol. Terpenoids share a precursor with phytocannabinoids, and are all flavour and fragrance components common to human diets that have been designated Generally Recognized as Safe by the US Food and Drug Administration and other regulatory agencies. Terpenoids are quite potent, and affect animal and even human behaviour when inhaled from ambient air at serum levels in the single digits ng·mL(-1) . They display unique therapeutic effects that may contribute meaningfully to the entourage effects of cannabis-based medicinal extracts. Particular focus will be placed on phytocannabinoid-terpenoid interactions that could produce synergy with respect to treatment of pain, inflammation, depression, anxiety, addiction, epilepsy, cancer, fungal and bacterial infections (including methicillin-resistant Staphylococcus aureus). Scientific evidence is presented for non-cannabinoid plant components as putative antidotes to intoxicating effects of THC that could increase its therapeutic index. Methods for investigating entourage effects in future experiments will be proposed. Phytocannabinoid-terpenoid synergy, if proven, increases the likelihood that an extensive pipeline of new therapeutic products is possible from this venerable plant. http://dx.doi.org/10.1111/bph.2011.163.issue-7.

Monoterpenic aldehydes as potential anti-Leishmania agents: activity of Cymbopogon citratus and citral on L. infantum, L. tropica and L. major

In order to contribute for the search of new drugs for leishmaniasis, we study the susceptibility of Leishmania infantum, Leishmania tropica and Leishmania major to Cymbopogon citratus essential oil and major compounds, mrycene and citral. C. citratus and citral were the most active inhibiting L. infantum, L. tropica and L. major growth at IC(50) concentrations ranging from 25 to 52 μg/ml and from 34 to 42 μg/ml, respectively. L. infantum promastigotes exposed to essential oil and citral underwent considerable ultrastructural alterations, namely mitochondrial and kinetoplast swelling, autophagosomal structures, disruption of nuclear membrane and nuclear chromatin condensation. C. citratus essential oil and citral promoted the leishmanicidal effect by triggering a programmed cell death. In fact, the leishmanicidal activity was mediated via apoptosis as evidenced by externalization of phosphatidylserine, loss of mitochondrial membrane potential, and cell-cycle arrest at the G(0)/G(1) phase. Taken together, ours findings lead us to propose that citral was responsible for anti-Leishmania activity of the C. citratus and both may represent a valuable source for therapeutic control of leishmaniasis.

Plant derived therapeutics for the treatment of Leishmaniasis

Diseases caused by insect borne trypanosomatid parasites are significant, yet remain a neglected public health problem. Leishmania, a unicellular protozoan parasite is the causative organism of Leishmaniasis and is transmitted by female phlebotamine sandflies affecting millions of people worldwide. In the wake of resistance to pentavalent antimonial drugs, new therapeutic alternatives are desirable. The plant kingdom has in the past provided several affordable compounds and this review aims to provide an overview of the current status of available leishmanicidal plant derived compounds that are effective singly or in combination with conventional anti-leishmanial drugs, yet are non toxic to mammalian host cells. Furthermore, delineation of the contributory biochemical mechanisms involved in mediating their effect would help develop new chemotherapeutic approaches.

Leishmanicidal effect of Spiranthera odoratíssima (Rutaceae) and its isolated alkaloid skimmianine occurs by a nitric oxide dependent mechanism

Leishmaniasis is one of the neglected diseases. High cost, systemic toxicity, and diminished efficacy due to development of resistance by the parasites has a negative impact on the current treatment options. Thus, the search for a new, effective and safer anti-leishmanial drug becomes of paramount importance. Compounds derived from natural products may be a better and cheaper source in this regard. This study evaluated the in vitro anti-leishmanial activity of Spiranthera odoratíssima (Rutaceae) fractions and isolated compounds, using promastigote and amastigote forms of different Leishmania species. J774 A.1 macrophage was used as the parasite host cell for the in vitro assays. Evaluations of cytoxicity, nitric oxide (NO), interleukin-10 and in silico analysis were carried out. In vitro experiments showed that the fruit hexanic fraction (Fhf) and its alkaloid skimmianine (Skm) have a significant (P<0·001) effect against L. braziliensis. This anti-L. braziliensis activity of Fhf and Skm was due to increased production of NO and attenuation of IL-10 production in the macrophages at concentrations ranging from 1·6 to 40·0 μg/ml. The in silico assay demonstrated significant interaction between Skm and amino acid residues of NOS2. Skm is thus a promising drug candidate for L. braziliensis due to its potent immunomodulatory activity.

Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects

Tetrahydrocannabinol (THC) has been the primary focus of cannabis research since 1964, when Raphael Mechoulam isolated and synthesized it. More recently, the synergistic contributions of cannabidiol to cannabis pharmacology and analgesia have been scientifically demonstrated. Other phytocannabinoids, including tetrahydrocannabivarin, cannabigerol and cannabichromene, exert additional effects of therapeutic interest. Innovative conventional plant breeding has yielded cannabis chemotypes expressing high titres of each component for future study. This review will explore another echelon of phytotherapeutic agents, the cannabis terpenoids: limonene, myrcene, α-pinene, linalool, β-caryophyllene, caryophyllene oxide, nerolidol and phytol. Terpenoids share a precursor with phytocannabinoids, and are all flavour and fragrance components common to human diets that have been designated Generally Recognized as Safe by the US Food and Drug Administration and other regulatory agencies. Terpenoids are quite potent, and affect animal and even human behaviour when inhaled from ambient air at serum levels in the single digits ng·mL(-1) . They display unique therapeutic effects that may contribute meaningfully to the entourage effects of cannabis-based medicinal extracts. Particular focus will be placed on phytocannabinoid-terpenoid interactions that could produce synergy with respect to treatment of pain, inflammation, depression, anxiety, addiction, epilepsy, cancer, fungal and bacterial infections (including methicillin-resistant Staphylococcus aureus). Scientific evidence is presented for non-cannabinoid plant components as putative antidotes to intoxicating effects of THC that could increase its therapeutic index. Methods for investigating entourage effects in future experiments will be proposed. Phytocannabinoid-terpenoid synergy, if proven, increases the likelihood that an extensive pipeline of new therapeutic products is possible from this venerable plant. http://dx.doi.org/10.1111/bph.2011.163.issue-7.

Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects

Tetrahydrocannabinol (THC) has been the primary focus of cannabis research since 1964, when Raphael Mechoulam isolated and synthesized it. More recently, the synergistic contributions of cannabidiol to cannabis pharmacology and analgesia have been scientifically demonstrated. Other phytocannabinoids, including tetrahydrocannabivarin, cannabigerol and cannabichromene, exert additional effects of therapeutic interest. Innovative conventional plant breeding has yielded cannabis chemotypes expressing high titres of each component for future study. This review will explore another echelon of phytotherapeutic agents, the cannabis terpenoids: limonene, myrcene, α-pinene, linalool, β-caryophyllene, caryophyllene oxide, nerolidol and phytol. Terpenoids share a precursor with phytocannabinoids, and are all flavour and fragrance components common to human diets that have been designated Generally Recognized as Safe by the US Food and Drug Administration and other regulatory agencies. Terpenoids are quite potent, and affect animal and even human behaviour when inhaled from ambient air at serum levels in the single digits ng·mL(-1) . They display unique therapeutic effects that may contribute meaningfully to the entourage effects of cannabis-based medicinal extracts. Particular focus will be placed on phytocannabinoid-terpenoid interactions that could produce synergy with respect to treatment of pain, inflammation, depression, anxiety, addiction, epilepsy, cancer, fungal and bacterial infections (including methicillin-resistant Staphylococcus aureus). Scientific evidence is presented for non-cannabinoid plant components as putative antidotes to intoxicating effects of THC that could increase its therapeutic index. Methods for investigating entourage effects in future experiments will be proposed. Phytocannabinoid-terpenoid synergy, if proven, increases the likelihood that an extensive pipeline of new therapeutic products is possible from this venerable plant. http://dx.doi.org/10.1111/bph.2011.163.issue-7.

Evaluation of antimicrobial effectiveness of C-8 xylitol monoester as an alternative preservative for cosmetic products

Xylitol is a natural sugar derived from plants, fruits and vegetables, whose antimicrobial properties are described in the literature. This study aimed to evaluate the antimicrobial effectiveness of C-8 xylitol monoester, for its use as a preservative in cosmetic formulations. The minimum inhibitory concentration (MIC) was determined by the broth macrodilution method, and the antimicrobial effectiveness of C-8 xylitol monoester was determined by using challenge test method. The results obtained in the determination of minimum inhibitory concentration are between 1.0% and 1.25% for Staphylococcus aureus, Escherichia coli and Candida albicans and between 1.0% and 1.5% for Pseudomonas aeruginosa and Aspergillus niger. The amount of 1% of C-8 xylitol monoester was added to the lotion used in the challenge test, observing a rapid decline in the number of CFU g(-1) in stages of evaluation after contamination of the product by all bacteria. The same occurs in relation to C. albicans, which shows a 90% reduction in the number of CFU g(-1). Regarding A. niger, similar reduction is observed when pH value of the lotion is adjusted from 5.5 to 7.0. The results indicate that under the tests conditions, C-8 xylitol monoester has antimicrobial activity and could be considered as an alternative preservative for cosmetic formulations.

Immunomodulatory properties of borage (Echium amoenum) on BALB/c mice infected with Leishmania major

Leishmaniasis is caused by parasitic protozoa transmitted by the bite of a female sand fly and is currently endemic in 88 countries. BALB/c mice are highly susceptible to the infection with the parasite Leishmania major, and this susceptibility has been attributed, in part, to the expansion of Th2 cells, production of their cytokines, and downregulation of Th1 cytokine, interferon gamma (IFN-γ). In this report, we used both aqueous and alcoholic extracts of Iranian borage (Echium amoenum Fisch & C.A. Mey) for treatment of L. major infection in BALB/c mice. We found that both extracts had immunomodulatory properties and increased the level of IFN-γ and lowered the parasite burden in the proximal lymph nodes and prevented the necrosis of the footpad as compared with the untreated infected mice. These results may provide a basis for further studies directed toward the use of the Iranian borage against L. major infection.

Chemistry and Biological Activity of Essential Oils from Piper Claussenianum (Piperaceae)

Analyses of essential oils obtained from fresh and dried leaves and inflorescences of Piper clausenianum were performed using GC-FID, GC-MS and NMR techniques. Forty compounds were detected for these four oils with the total of identified constituents ranging from 88.7% for the dried inflorescences to 97.7% for the dried leaves. Sesquiterpenes were the main constituents in the volatile fraction from leaves with a high percentage of ( E)-nerolidol (up to 83%). However, monoterpenes were identified in greater amount in the inflorescences, with linalool percentages from 50% up. The essential oils from fresh leaves and inflorescences were submitted to anti-parasitic activity against a strain of Leishmania amazonensis. Both samples showed biological activity, but the essential oil from P. claussenianum fresh leaves, which was rich in ( E)-nerolidol, showed effective growth inhibition of L. amazonensis due to the high percentage of this metabolite in the mixture.

Morphological and physiological changes in Leishmania promastigotes induced by yangambin, a lignan obtained from Ocotea duckei

We have previously demonstrated that yangambin, a lignan obtained from Ocotea duckei Vattimo (Lauraceae), shows antileishmanial activity against promastigote forms of Leishmania chagasi and Leishmania amazonensis. The aim of this study was to determine the in vitro effects of yangambin against these parasites using electron and confocal microscopy. L. chagasi and L. amazonensis promastigotes were incubated respectively with 50 μg/mL and 65 μg/mL of pure yangambin and stained with acridine orange. Treated-parasites showed significant alterations in fluorescence emission pattern and cell morphology when compared with control cells, including the appearance of abnormal round-shaped cells, loss of cell motility, nuclear pyknosis, cytoplasm acidification and increased number of acidic vesicular organelles (AVOs), suggesting important physiological changes. Ultrastructural analysis of treated-promatigotes showed characteristics of cell death by apoptosis as well as by autophagy. The presence of parasites exhibiting multiples nuclei suggests that yangambin may also affect the microtubule dynamic in both Leishmania species. Taken together our results show that yangambin is a promising agent against Leishmania.

Chemistry, cytotoxicity and antileishmanial activity of the essential oil from Piper auritum

Leishmaniasis is one of the most important parasitic infections, but current treatments are unsatisfactory due to their toxicity, cost and resistance. Therefore, the development of new antileishmanial compounds is imperative. Many people who live in endemic areas use plants as an alternative to treat the disease. In this paper, we characterised the essential oil from Piper auritum, evaluated its cytotoxicity and determined its antileishmanial activity. The chromatogram obtained by gas chromatography revealed 60 peaks and we found that safrole was the most abundant compound, composing 87% of the oil. The oil was active against the promastigotes of Leishmania major, Leishmania mexicana, Leishmania braziliensis and Leishmania donovani with a favourable selectivity index against peritoneal macrophages from BALB/c mice. The Piper-oil inhibited the growing of intracellular amastigotes of L. donovani with an IC50 value of 22.3 +/- 1.8 microg/mL. This study demonstrates the usefulness of the essential oils as a promising alternative to treat leishmaniasis.

Chemical composition and antiprotozoal activities of Colombian Lippia spp essential oils and their major components

The chemical composition and biological activities of 19 essential oils and seven of their major components were tested against free and intracellular forms of Leishmania chagasi and Trypanosoma cruzi parasites as well as Vero and THP-1 mammalian cell lines. The essential oils were obtained from different species of Lippia, a widely distributed genus of Colombian plants. They were extracted by microwave radiation-assisted hydro-distillation and characterised by GC-FID and GC-MS. The major components were geranial, neral, limonene, nerol, carvacrol, p-cymene, gamma-terpinene, carvone and thymol. The essential oil of Lippia alba exhibited the highest activity against T. cruzi epimastigotes and intracellular amastigotes with an IC50 of 5.5 microg/mL and 12.2 microg/mL, respectively. The essential oil of Lippia origanoides had an IC50 of 4.4 microg/mL in L. chagasi promastigotes and exhibited no toxicity in mammalian cells. Thymol (IC50 3.2 +/- 0.4 microg/mL) and S-carvone (IC50 6.1 +/- 2.2 microg/mL), two of the major components of the active essential oils, were active on intracellular amastigotes of T. cruziinfected Vero cells, with a selective index greater than 10. None of the essential oils or major components tested in this study was active on amastigotes of L. chagasi infected THP-1 cells.

Activity of the julocrotine, a glutarimide alkaloid from Croton pullei var. glabrior, on Leishmania (L.) amazonensis

The antiproliferative effect of julocrotine, an alkaloid isolated from Croton pullei var. glabrior (Euphorbiaceae), was studied in the macrophage amastigote and promastigote stages of the protozoan Leishmania (L.) amazonensis, which causes cutaneous leishmaniasis in the New World. Julocrotine showed a dose-dependent effect against the amastigote and promastigote forms, where 79 μM julocrotine inhibited promastigote growth by 54%, with an IC50 of 67 μM. To analyze the antiamastigote activity of the drug, murine peritoneal macrophages infected with L. amazonensis promastigotes were treated with different concentrations of julocrotine. An 80% inhibition of amastigote development was observed using 79 μM julocrotine for 72 h, with an IC50 of 19.8 μM. In addition, ultrastructural observation of the parasites showed a significant reduction in the number of amastigotes in the parasitophorous vacuoles and morphological changes in promastigotes, such as swelling of the mitochondrion, chromatin condensation, presence of membranous structures near the Golgi complex, and some vesicle bodies in the flagellar pocket. A colorimetric assay (MTT), which measures cytotoxic metabolic activity, showed that macrophages maintain their viability after treatment with the drug. These results suggest that julocrotine effectively inhibits the growth of parasites and does not have any cytototoxic effects on the host cell.

Constituents, Antileishmanial Activity and Toxicity Profile of Volatile Oil from Berries of Croton macrostachyus

The chemical composition of the volatile oil from berries of Croton macrostachyus Hochst. ex Del. was determined by GC and GC/MS. The oil was tested for its in vitro antileishmanial activity on two Leishmania strains, and its toxicity on the human monocytic leukemia (THP-1) cell line and erythrocytes from sheep blood. The main constituents of the oil were benzyl benzoate (51.8%), linalool (10.1%), γ-muurolene (9.3%), ( E,E)-α-farnesene (3.2%), δ-cadinene (2.8%) and α-curcumene (2.7%). The oil was effective against L. donovani and L. aethiopica promastigotes (MIC = 0.08 μL/mL and 0.16 μL/mL, respectively) and axenic amastigote stages (EC50 = 20.00 nL/mL and 6.66 nL/mL, respectively). The CC50 value for the oil was 10.00 nL/mL on THP-1 cells with selectivity index values of 0.5 for L. donovani and 1.5 for L. aethiopica. The median lethal concentration (LC50) of the oil was 2.45 μL/mL. Thus the observed high efficacy and moderate toxicity of the volatile oil from C. macrostachyus, makes the plant a promising source of new lead compounds in the search for safe and effective antileishmanial drugs.

In vitro effects of Warburgia ugandensis, Psiadia punctulata and Chasmanthera dependens on Leishmania major promastigotes

Plant extracts from Warburgia ugandensis Sprague (Family: Canellaceae), Psiadia punctulata Vatke (Family: Compositae) and Chasmanthera dependens Hoschst (Family: Menispermaceae) were tested for activity on Leishmania major promastigotes (Strain IDU/KE/83 = NLB-144) and infected macrophages in vitro. Plants were collected from Baringo district, dried, extracted, weighed and tested for antileishmanial activity. Serial dilutions of the crude extracts were assayed for their activity against Leishmania major in cell free cultures and in infected macrophages in vitro. Inhibitory concentrations and levels of cytotoxicity were determined. Warburgia ugandensis, Psiadia punctulata and Chasmanthera dependens had an IC(50) of 1.114 mg/ml, 2.216 mg/ml and 4.648 mg/ml, respectively. The cytotoxicity of the drugs on BALB/c peritoneal macrophage cells was insignificant as compared to the highly toxic drug of choice Pentostam(®). The supernatants from control and Leishmania infected macrophages were analyzed for their nitrite contents by Griess reaction and nitrite absorbance measured at 540 nm. Warburgia ugandensis (stem bark water extract), Chasmanthera dependens (stem bark water extract) and Psiadia punctulata (stem bark methanol extract) produced 112.3%, 94% and 88.5% more nitric oxide than the untreated infected macrophages respectively. Plant crude extracts had significant (p<0.05) anti-leishmanial and immunomodulative effects but insignificant cytotoxic effects at 1mg/ml concentration. All experiments were performed in triplicate. Statistical analysis of the differences between mean values obtained from the experimental group compared to the controls was done by students't test. ANOVA was used to determine the differences between the various treatment groups. The analysis program Probit was used to determine IC(50)s.

Activity of (-)alpha-bisabolol against Leishmania infantum promastigotes

Many of the drugs used to treat leishmaniasis are associated with numerous adverse effects. Agents of natural origin have shown activity against different parasites. With this background, an in vitro study was conducted on the activity of (-)alpha-bisabolol, the principal component of Chamomilla recutita essential oil, against Leishmania infantum promastigotes, the main species responsible for human leishmaniasis in Spain. At the two highest concentrations tested (1000 and 500mug/ml), (-)alpha-bisabolol and pentamidine (control agent) achieved 100% inhibition of L. infantum promastigote. These in vitro data can be considered promising in support of the therapeutic use of (-)alpha-bisabolol preparations to treat leishmaniasis caused by L. infantum species.

Mitracarpus frigidus aerial parts exhibited potent antimicrobial, antileishmanial, and antioxidant effects

The crude extract and the hexane, CH(2)Cl(2), EtOAc, n-BuOH, and hydromethanolic fractions of the aerial parts of Mitracarpus frigidus were evaluated against promastigote forms of two species of Leishmania (L. chagasi and L. amazonensis), 11 strains of bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella enterica sorovar Tythimurium, Shigella sonnei, Klebsiella pneumoniae, Escherichia coli, Micrococcus luteus, Enterococcus faecalis, Enterobacter cloacae, Streptococcus pyogenes and Bacillus cereus) and two yeasts (Candida albicans and Cryptococcus neoformans). The antioxidant activity (DPPH radical scavenging activity and reducing power), cytotoxicity against mammalian cells, and the contents of phenolics and flavonoids were determined. Phytochemical analysis of the major groups of phytoconstituents is also reported. All samples showed antioxidant activity which was positively correlated to the content of phenolic compounds. S. sonnei, B. cereus and C. neoformans were susceptible to all extracts tested, except for the n-BuOH and hydromethanolic fractions, which demonstrated no antimicrobial activity. The lowest MIC was recorded for the CH(2)Cl(2) fraction against C. neoformans (MIC of 10 microg/ml), followed by B. cereus, S. sonnei, and E. cloacae (MIC of 20, 39 and 39 microg/ml, respectively). The CH(2)Cl(2) fraction was the most effective against L. chagasi (IC(50) of 6.7 microg/ml), and the hydromethanolic fraction exhibited the best activity against L. amazonensis (IC(50) of 9 microg/ml). A cytotoxic effect on mammalian cells was observed only for the crude extract and CH(2)Cl(2) fraction at the concentrations of 130 and 31 microg/ml, respectively. These results suggest that M. frigidus has interesting antimicrobial, antileishmanial and antioxidant activities.

Efficacy of the tubercidin antileishmania action associated with an inhibitor of the nucleoside transport

Tubercidin (TUB) is an adenosine analog with potent antiparasite action, unfortunately associated with severe host toxicity. Prevention of TUB toxicity can be reached associating nitrobenzylthioinosine (NBMPR), an inhibitor of the purine nucleoside transport, specifically target to the mammal cells. It was demonstrated that this nucleoside transport inhibitor has no significant effect in the in vitro uptake of TUB by Schistosoma mansoni and Trypanosoma gambiense. Seeking to evaluate if the association of these compounds is also effective against leishmania, we analyzed the TUB-NBMPR combined treatment in in vitro cultures of promastigote forms of Leishmania (L.) amazonensis, Leishmania (L.) chagasi, Leishmania (L.) major, and Leishmania (V.) braziliensis as well as in cultures of amastigote forms of L. (L.) amazonensis, mice macrophages infected with L. (L.) amazonensis, and in vivo tests in BALB/c mice infected with L. (L.) amazonensis. We demonstrated that TUB-NBMPR combined treatment can be effective against leishmania cells protecting mammalian cells from TUB toxicity.

Linalool – a Review of a Biologically Active Compound of Commercial Importance

Since the earliest times fragrant materials have been used in rituals. Today, a lucrative industry has developed to produce and deliver fragrances and aromatic chemicals with various applications in modern society. Linalool, a much sought after compound in the flavor and fragrance industry is a monoterpene alcohol which occurs naturally in many aromatic plants. Linalool and linalool-rich essential oils are known to exhibit various biological activities such as antimicrobial, anti-inflammatory, anticancer, anti-oxidant properties and several in vivo studies have confirmed various effects of linalool on the central nervous system. The applications of linalool are not confined to simply adding or enhancing a specific scent to domestic products such as soaps, detergents and shampoos. Linalool also plays an import role in nature as a key compound in the complex pollination biology of various plant species to ensure reproduction and survival. Linalool is also a key compound for the industrial production of a variety of fragrance chemicals such as geraniol, nerol, citral and its derivatives, as well as a lead compound in the synthesis of vitamins A and E. The repellent properties of linalool on various crop-destroying insects has been well documented accentuating the application of this molecule in eco-friendly pest management. This review aims to highlight the various biological properties of linalool and to emphasize the value of linalool and linalool-rich essential oils in phytotherapy.

In vitro Antiprotozoal Activity and Chemical Composition of Ambrosia tenuifolia and A. scabra Essential Oils

The in vitro antimalarial, trypanocidal and leishmanicidal activities and the chemical composition of Ambrosia tenuifolia and A. scabra essential oils were investigated. The oils, obtained by hydrodistillation of the aerial parts, showed significant antimalarial activity against the chloroquine sensitive (F32) and the chloroquine resistant (W2) strains of Plasmodium falciparum with 50% inhibitory concentration (IC50) values ranged from 2.8 to 7 μg/mL. Against Trypanosoma cruzi epimastigotes, only A. tenuifolia exerted slight activity (IC50 = 59.7 μg/mL). None of the essential oils showed toxicity towards Leishmania mexicana. Cytotoxicity for murine T-lymphocytes was compared with the parasiticidal activity by using the selectivity index (SI) ratio. The chemical composition of A. tenuifolia and A. scabra essential oils was analyzed by GC-FID-MS. Thirty-eight and twenty-four compounds were identified in A. tenuifolia and A. scabra, respectively. The major constituents of A. tenuifolia oil were germacrene D (22.9%) and bicyclogermacrene (14.2%), while the oil of A. scabra contained limonene (22.0%), caryophyllene oxide (13.8%) and ( E)-caryophyllene (13.5%). This is the first time that the antiprotozoal activity of both oils and the chemical composition of A. scabra essential oil have been reported.

Content, composition, and bioactivity of the essential oils of three basil genotypes as a function of harvesting

A study was conducted to evaluate the effect of cut on biomass productivity, oil content, composition, and bioactivity of Ocimum basilicum L. (cvs. German and Mesten) and Ocimum sanctum L. (syn. O. tenuiflorum L.) (cv. Local) in Mississippi. Yields of basil herbage and essential oil were high and comparable to those reported in the literature. Essential oil content of O. basilicum cv. German varied from 0.40 to 0.75%, the oil content of cv. Mesten varied from 0.50 to 0.72%, and the oil content of cv. Local (of O. sanctum) ranged from 0.17 to 0.50% in air-dried basil. Herbage and essential oil yields of cvs. German and Mesten of O. basilicum increased with the second and then again with the third cut, whereas herbage and oil yields of cv. Local of O. sanctum increased with the third cut relative to the previous cuts. Overall, essential oil yields were 115, 123, and 51 kg/ha for the cvs. German, Mesten, and Local, respectively. The major oil constituents of cvs. German and Mesten (of O. basilicum) were (-)-linalool (30-40%) and eugenol (8-30%), whereas the major oil constituents of cv. Local (of O. sanctum) were eugenol (8-43%) and methylchavicol (15-27%). Essential oils from both species grown in Mississippi showed in vitro activity against Leishmania donovani (IC50 = 37.3-49.6 microg/mL), which was comparable to the activity of commercial oil (IC50 = 40-50 microg/mL). Minor basil oil constituents (+)-delta-cadinene, 3-carene, alpha-humulene, citral, and (-)- trans-caryophyllene had antileishmanial activity, whereas other constituents were ineffective. None of the oil was cytotoxic to mammalian cells.

Prevention of Candida albicans biofilm by plant oils

The inhibitory effect of 30 plant oils was evaluated against biofilm forming Candida albicans strain (CA I) isolated from clinical samples, which was sensitive to 4 microg/ml of fluconazole, used as a positive control. The standard strain (MTCC 227, CA II) used in this study was found to be highly resistant to fluconazole, 3,000 microg/ml of which was required to inhibit the growth of this strain partially, and complete inhibition could not be achieved. Eighteen among the 30 plant oils tested were found to show anti-Candida activity by disc diffusion assay. Effective plant oils were assessed using XTT (2, 3-bis [2-Methoxy-4-nitro-5-sulphophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay for biofilm quantification. Four oils eucalyptus, peppermint, ginger grass and clove showed 80.87%, 74.16%, 40.46% and 28.57% biofilm reduction respectively. Minimum inhibitory concentration (MIC) values were calculated using agar dilution assay. Scanning electron microscopic (SEM) analysis further revealed reduction in C. albicans biofilm in response to effective oils. The substantial antifungal activity shown by these plant oils suggests their potential against infections caused by C. albicans.

Modifications of the chemical structure of terpenes in antiplasmodial and antifungal drug research

Pure natural monoterpenes were evaluated in vitro for their antiplasmodial activities against Plasmodium falciparum. Chemically modified terpenes were also tested to see whether the introduction of an alkyne, a cyclopropane, a diene, or a cyclopentenone moiety had an influence on the biological activity. The IC(50) obtained on a chloroquine-resistant strain of Plasmodium (FcM29-Cameroon) showed moderate activity, but with the alkyne and the cyclopentenone derivatives showing a promising enhancement of activity compared with the parent molecules. On the contrary, no antifungal activity was found in vitro using Candida albicans. Given the observed antiplasmodial activity of some of these modified monoterpenes, new monoterpene derivatives could be the basis for new antimalarial drugs to be researched.

Anti-proliferative effect of the essential oil ofCymbopogon citratus(DC) Stapf (lemongrass) on intracellular amastigotes, bloodstream trypomastigotes and culture epimastigotes ofTrypanosoma cruzi(Protozoa: Kinetoplastida)

This study analyses the anti-proliferative effect of lemongrass essential oil and its main constituent (citral) on all 3 evolutive forms ofTrypanosoma cruzi. Steam distillation was used to obtain lemongrass essential oil, with chemical composition determined by gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS). The IC50/24 h (concentration that reduced the parasite population by 50%) of the oil and of citral uponT. cruziwas determined by cell counting in a Neubauer chamber, while morphological alterations were visualized by scanning and transmission electron microscopy. Treatment with the essential oil resulted in epimastigote growth inhibition with IC50=126·5 μg/ml, while the IC50for trypomastigote lysis was 15·5 μg/ml. The IC50/48 h for the Association Index (% macrophage infection×number of amastigotes per cell) was 5·1 μg/ml, with a strong inhibition of intracellular amastigote proliferation. Ultrastructural analysis demonstrated cytoplasmic and nuclear extraction, while the plasma membrane remained morphologically preserved. Our data show that lemongrass essential oil is effective againstT. cruzitrypomastigotes and amastigotes, and that its main component, citral, is responsible for the trypanocidal activity. These results indicate that essential oils can be promising anti-parasitic agents, opening perspectives to the discovery of more effective drugs of vegetal origin for treatment of parasitic diseases. However, additional cytotoxicity experiments on different cell lines and tests in aT. cruzi-mouse model are needed to support these data.

Trypanosoma cruzi: Activity of essential oils from Achillea millefolium L., Syzygium aromaticum L. and Ocimum basilicum L. on epimastigotes and trypomastigotes

Trypanocidal activity of clove (Syzygium aromaticum L.), basil (Ocimum basilicum L.) and yarrow (Achillea millefolium L.) essential oils and some of their constituents (eugenol and linalool) was investigated on Trypanosoma cruzi epimastigote and bloodstream trypomastigote forms. Steam distillation was used to isolate the essential oils, with chemical analyses performed by gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS). The IC(50) (concentration that inhibits 50% parasite growth) of the oils and constituents upon T. cruzi was determined by cell counting in a Neubauer chamber. Cell morphology alterations were observed by scanning and transmission electron microscopy. Treatment with oils and constituents demonstrated that they inhibit parasite growth, with clove essential being the most effective one (IC(50)=99.5 microg/ml for epimastigotes and 57.5 microg/ml for trypomastigotes). Ultrastructural alterations were observed mainly in the nucleus.

Antileishmanial activity of crude extract and coumarin from Calophyllum brasiliense leaves against Leishmania amazonensis

Infections by protozoans of the genus Leishmania are a major worldwide health problem, with high endemicity in developing countries. The drugs of choice for the treatment of leishmaniasis are the pentavalent antimonials, which show renal and cardiac toxicity. As part of a search for new drugs against leishmaniasis, we evaluated the in vitro leishmanicidal activity of the (-) mammea A/BB. The compound (-) mammea A/BB is a coumarin-type mammea purified from a dichloromethane crude extract of leaves of Calophyllum brasiliense Cambess (Clusiaceae). The isolated compound was characterized using spectral analyses by UV, infrared, nuclear magnetic resonance of (1)H, (13)C, distortionless enhancement by polarization transfer, correlation spectroscopy, heteronuclear multiple bond correlation, and heteronuclear multiple quantum coherence. The compound (-) mammea A/BB showed significant activity against promastigote and amastigote forms of L. amazonensis, with IC(50) (50% inhibition concentration of cell growth) at a concentration of 3.0 and 0.88 mug/ml and IC(90) (90% inhibition concentration of cell growth) of 5.0 and 2.3 microg/ml, respectively. The coumarin (-) mammea A/BB showed no cytotoxicity against J774G8 macrophages in culture, when it was tested at high concentrations that inhibited promastigote forms. Electron microscopy studies revealed considerable ultrastructural changes when promastigote forms of L. amazonensis were treated with 3.0 microg/ml of the coumarin (-) mammea A/BB for 72 h. We observed significant changes such as mitochondrial swelling with concentric membranes in the mitochondrial matrix and intense exocytic activity in the region of the flagellar pocket. Other alterations included the appearance of binucleate cells and multiple cytoplasmic vacuolization. These results showed that (-) mammea A/BB is a potent growth inhibitor of L. amazonensis and caused important changes in the parasite's ultrastructure. This study provided new perspectives on the development of novel drugs with leishmanicidal activity obtained from natural products.

Effect of oregano (Origanum vulgare L.) and thyme (Thymus vulgaris L.) essential oils on Trypanosoma cruzi (Protozoa: Kinetoplastida) growth and ultrastructure

In the present work, we have investigated the effect of essential oils obtained from Origanum vulgare L. (oregano) and Thymus vulgaris L. (thyme) on growth and ultrastructure of diverse evolutive forms of Trypanosoma cruzi. Culture epimastigotes and bloodstream trypomastigotes were incubated for 24 h with different concentrations of oregano or thyme essential oils and with thymol (the main constituent of thyme), and the inhibitory concentration (IC)(50) was determined by cell counting. Crude extract of oregano essential oil inhibited epimastigote growth (IC(50)/24 h = 175 microg/ml) and also induced trypomastigote lysis (IC(50)/24 h = 115 microg/ml). Thyme essential oil presented IC(50)/24 h values of 77 microg/ml for epimastigotes and 38 mug/ml for trypomastigotes, while treatment with thymol resulted in an IC(50)/24 h of 62 microg/ml for epimastigotes and 53 microg/ml for trypomastigotes. Scanning electron microscopy of treated cells showed few morphological alterations at the plasma membrane. Observation by transmission electron microscopy showed cytoplasmic swelling with occasional morphological alterations in plasma and flagellar membrane. Our data indicate that oregano and thyme essential oils are effective against T. cruzi, with higher activity of thyme, and that thymol may be the main component responsible for the trypanocidal activity.

Antileishmanial activity of Eugenol-rich essential oil from Ocimum gratissimum

Leishmaniasis is a group of diseases with a large spectrum of clinical manifestations caused by protozoans of the genus Leishmania. Here we demonstrate the leishmanicidal activity of the essential oil of Ocimum gratissimum as well as its main constituent, eugenol. The eugenol-rich essential oil of O. gratissimum progressively inhibited Leishmania amazonensis growth at concentrations ranging from 100 to 1000 microg/ml. The IC50 (sub-inhibitory concentration) of the essential oil for promastigotes and amastigotes were respectively 135 and 100 microg/ml and the IC50 of eugenol was 80 microg/ml for promastigote forms. L. amazonensis exposed to essential oil at concentrations corresponding to IC50 for promastigotes and for amastigotes underwent considerable ultrastructural alterations, as shown by transmission electron microscopy. Two or more nuclei or flagella were observed in 31% and 23.3% of treated amastigote and promastigote forms, respectively, suggesting interference in cell division. Considerable mitochondrial swelling was observed in essential oil-treated promastigotes and amastigotes, which had the inner mitochondrial membrane altered, with a significant increase in the number of cristae; in some amastigotes the mitochondrial matrix became less electron-dense. The minimum inhibitory concentration for both promastigotes and amastigotes was 150 microg/ml. Pretreatment of mouse peritoneal macrophages with 100 and 150 microg/ml essential oil reduced the indices of association between promastigotes and the macrophages, followed by increased in nitric oxide production by the infected macrophages. The essential oil showed no cytototoxic effects against mammalian cells. This set of results suggests that O. gratissimum essential oil and its compounds could be used as sources for new antileishmanial drugs.

Plant active components - a resource for antiparasitic agents?

Plant essential oils (and/or active components) can be used as alternatives or adjuncts to current antiparasitic therapies. Garlic oil has broad-spectrum activity against Trypanosoma, Plasmodium, Giardia and Leishmania, and Cochlospermum planchonii and Croton cajucara oils specifically inhibit Plasmodium falciparum and Leishmania amazonensis, respectively. Some plant oils have immunomodulatory effects that could modify host-parasite immunobiology, and the lipid solubility of plant oils might offer alternative, transcutaneous delivery routes. The emergence of parasites resistant to current chemotherapies highlights the importance of plant essential oils as novel antiparasitic agents.

Antileishmanial activity of the terpene nerolidol

The activity of nerolidol, a sesquiterpene used as a food-flavoring agent and currently under testing as a skin penetration enhancer for the transdermal delivery of therapeutic drugs, was evaluated against Leishmania species. Nerolidol inhibited the growth of Leishmania amazonensis, L. braziliensis, and L. chagasi promastigotes and L. amazonensis amastigotes with in vitro 50% inhibitory concentrations of 85, 74, 75, and 67 microM, respectively. The treatment of L. amazonensis-infected macrophages with 100 microM nerolidol resulted in 95% reduction in infection rates. Inhibition of isoprenoid biosynthesis, as shown by reduced incorporation of [2-(14)C]mevalonic acid (MVA) or [1-(14)C]acetic acid precursors into dolichol, ergosterol, and ubiquinone, was observed in nerolidol-treated promastigotes. This drug effect can be attributed to the blockage of an early step in the mevalonate pathway, since incorporation of the precursor [1(n)-(3)H]farnesyl pyrophosphate in polyisoprenoids is not inhibited by nerolidol. L. amazonensis-infected BALB/c mice were treated with intraperitoneal doses of 100 mg/kg/day for 12 days or topically with 5 or 10% ointments for 4 weeks. Significant reduction of lesion sizes in nerolidol treated mice was observed for both treatment routes. However, long-term follow up indicated that the disease was not cured in this highly susceptible animal model. Nonetheless, the in vitro activity of nerolidol against these parasites may prove a useful tool for the development of new drugs for the treatment of leishmaniasis. In addition, biosynthesis of dolichols with 11 and 12 isoprene units was identified in Leishmania, as described for other trypanosomatids and Apicomplexa.

Antimicrobial activity of Croton cajucara Benth linalool-rich essential oil on artificial biofilms and planktonic microorganisms

We have previously demonstrated that a linalool-rich essential oil from Croton cajucara Benth presents leishmanicidal activity. In the present study, we demonstrate that this essential oil inhibits the growth of reference samples of Candida albicans, Lactobacillus casei, Staphylococcus aureus, Streptococcus sobrinus, Porphyromonas gingivalis and Streptococcus mutans cell suspensions, all of them associated with oral cavity disease. The purified linalool fraction was only inhibitory for C. albicans. Microbes of saliva specimens from human individuals with fixed orthodontic appliances, as well as the reference strains, were used to construct an artificial biofilm which was exposed to linalool or to the essential oil. As in microbial suspensions, the essential oil was toxic for all the microorganisms, while the purified linalool fraction mainly inhibited the growth of C. albicans. The compounds of the essential oil were separated by thin layer chromatography and exposed to the above-cited microorganisms. In this analysis, the proliferation of the bacterial cells was inhibited by still uncharacterized molecules, and linalool was confirmed as the antifungal component of the essential oil. The effects of linalool on the cell biology of C. albicans were evaluated by electron microscopy, which showed that linalool induced a reduction in cell size and abnormal germination. Neither the crude essential oil nor the purified linalool fraction is toxic to mammalian cells, which suggests that the essential oil or its purified components may be useful to control the microbial population in patients with fixed orthodontic appliances.

Antimicrobial activity of euplotin C, the sesquiterpene taxonomic marker from the marine ciliate Euplotes crassus

Strains of the marine ciliate protist Euplotes crassus produce exclusive terpenoids called euplotins that play an ecological role. Among these derivatives, euplotin C is the main of four secondary metabolites isolated from cultures of this protozoon and represents the sesquiterpene taxonomic marker from E. crassus. Because different terpenoid metabolites of plant origin showed a certain antimicrobial activity, we assessed the compound euplotin C, purified by high-pressure liquid chromatography and solubilized in two solubility enhancers, against the protozoa Leishmania major and Leishmani infantum, the fungus Candida albicans, and nine strains of gram-positive and gram-negative microorganisms. An activity of euplotin C against Leishmania promastigotes was demonstrated (50% lethal doses were 4.6 or 8.1 microg/ml depending on the agent used to solubilize the compound), while the effect was less evident on Candida and nearly absent on bacteria. A nonsignificant cytotoxicity (50% lethal dose, >200 microg/ml) against the J774 cell line was observed. A leishmanicidal activity was also shown by the living, euplotin-producing cells of E. crassus cultured together with promastigotes; this activity increased with time from 10 min to 6 h of incubation. This study provides an initial rationale for the evaluation of euplotin C and other similar natural products as alternative or possibly synergistic compounds for current antiprotozoon chemotherapeutics.

Terpenes arrest parasite development and inhibit biosynthesis of isoprenoids in Plasmodium falciparum

Development of new drugs is one of the strategies for malaria control. The biosynthesis of several isoprenoids in Plasmodium falciparum was recently described. Interestingly, some intermediates and final products biosynthesized by this pathway in mammals differ from those biosynthesized in P. falciparum. These facts prompted us to evaluate various terpenes, molecules with a similar chemical structure to the intermediates of the isoprenoids pathway, as potential antimalarial drugs. Different terpenes and S-farnesylthiosalicylic acid were tested on cultures of the intraerythrocytic stages of P. falciparum, and the 50% inhibitory concentrations for each one were found: farnesol, 64 microM; nerolidol, 760 nM; limonene, 1.22 mM; linalool, 0.28 mM; and S-farnesylthiosalicylic acid, 14 microM. All the terpenes tested inhibited dolichol biosynthesis in the trophozoite and schizont stages when [1-(n)-(3)H]farnesyl pyrophosphate triammonium salt ([(3)H]FPP) was used as precursor. Farnesol, nerolidol, and linalool showed stronger inhibitory activity on the biosynthesis of the isoprenic side chain of the benzoquinone ring of ubiquinones in the schizont stage. Treatment of schizont stages with S-farnesylthiosalicylic acid led to a decrease in intensity of the band corresponding a p21(ras) protein. The inhibitory effect of terpenes and S-farnesylthiosalicylic acid on the biosynthesis of both dolichol and the isoprenic side chain of ubiquinones and the isoprenylation of proteins in the intraerythrocytic stages of P. falciparum appears to be specific, because overall protein biosynthesis was not affected. Combinations of some terpenes or S-farnesylthiosalicylic acid tested in this work with other antimalarial drugs, like fosmidomycin, could be a new strategy for the treatment of malaria.

Leishmanicidal activity of polyphenolic-rich extract from husk fiber of Cocos nucifera Linn. (Palmae)

The available therapy for leishmaniasis, which affects 2 million people per annum, still causes serious side effects. The polyphenolic-rich extract from the husk fiber of Cocos nucifera Linn. (Palmae) presents antibacterial and antiviral activities, also inhibiting lymphocyte proliferation, as shown by our group in previous works. In the present study, the in vitro leishmanicidal effects of C. nucifera on Leishmania amazonensis were evaluated. The minimal inhibitory concentration of the polyphenolic-rich extract from C. nucifera to completely abrogate parasite growth was 10 microg/ml. Pretreatment of peritoneal mouse macrophages with 10 microg/ml of C. nucifera polyphenolic-rich extract reduced approximately 44% the association index between these macrophages and L. amazonensis promastigotes, with a concomitant increase of 182% in nitric oxide production by the infected macrophage in comparison to nontreated macrophages. These results provide new perspectives on drug development against leishmaniasis, since the extract of C. nucifera at 10 microg/ml is a strikingly potent leishmanicidal substance which inhibited the growth of both promastigote and amastigote developmental stages of L. amazonensis after 60 min, presenting no in vivo allergenic reactions or in vitro cytotoxic effects in mammalian systems.