Essential oils and their constituents as anticancer agents: a mechanistic view

Calculated antioxidant activity of selected phenolic compounds

Determination of the corresponding bond dissociation enthalpy, ionization potential and proton affinity, dipole moment values, highest occupied molecular orbital eigenvalues, and spin density along with the bioactivity score is central to the antioxidant activity evaluation in this paper. Molecular geometries were optimized with DFT using B3LYP and UB3LYP for parent, ionic, and radical species and 6-311+G(d,p) basis set. Bioactivity, drug likeness, and drug scores were calculated using freely available cheminformatics programs for data visualization and analysis. Overall, the values revealed two structures as promising molecules because of good reaction enthalpies (ΔHr). Lipinski rules were fully satisfied for all molecules.

Establishment of the Volatile Signature of Wine-Based Aromatic Vinegars Subjected to Maceration

The flavoring of vinegars with aromatic fruits and medicinal herbs is a practice with increasing trend mostly in countries with oenological tradition, resulting in a product of improved quality and consumer attractiveness. This study was directed towards the evaluation of the impact of the maceration process on the volatile signature of wine-based aromatic vinegars (WBAVs). The evaluation was performed using solid phase microextraction (SPME) combined with gas chromatography combined with mass spectrometry (GC-MS). Experimental parameters influencing headspace solid (HS)-SPME extraction efficiency, were optimized using an univariate experimental design. The best results were achieved using a polydimethylsiloxane (PDMS) fiber, 10 mL of vinegar sample, at 50 °C for 30 min of extraction. This way One hundred and three volatile organic compounds (VOCs), belonging to different chemical families including ethyl esters (37), higher alcohols (20), fatty acids (10), terpenoids (23), carbonyl compounds (six), lactones (five) and volatile phenols (two), were identified in wine vinegar (control) and WBAV. As far as we know, 34 of these VOCs are reported for the first time in macerated vinegars. Higher alcohols and lactones are the major chemical families in WBAV macerated with apple, whereas terpenoids are predominant in WBAV macerated with banana. The obtained data represent a suitable tool to guarantee the authenticity and genuineness of WBAV, as well as to promote the production of WBAV with improved sensorial and organoleptic properties. To the best of our knowledge, there are no reported studies dealing with the volatile signature of WBAV enriched with banana, passion fruit, apple and pennyroyal.

Involvement of Bax and Bcl-2 in Induction of Apoptosis by Essential Oils of Three Lebanese Salvia Species in Human Prostate Cancer Cells

Prostate cancer is one of the most common forms of cancer in men, and research to find more effective and less toxic drugs has become necessary. In the frame of our ongoing program on traditionally used Salvia species from the Mediterranean Area, here we report the biological activities of Salvia aurea, S. judaica and S. viscosa essential oils against human prostate cancer cells (DU-145). The cell viability was measured by 3(4,5-dimethyl-thiazol-2-yl)2,5-diphenyl-tetrazolium bromide (MTT) test and lactate dehydrogenase (LDH) release was used to quantify necrosis cell death. Genomic DNA, caspase-3 activity, expression of cleaved caspase-9, B-cell lymphoma 2 (Bcl-2) and Bcl-2 associated X (Bax) proteins were analyzed in order to study the apoptotic process. The role of reactive oxygen species in cell death was also investigated. We found that the three essential oils, containing caryophyllene oxide as a main constituent, are capable of reducing the growth of human prostate cancer cells, activating an apoptotic process and increasing reactive oxygen species generation. These results suggest it could be profitable to further investigate the effects of these essential oils for their possible use as anticancer agents in prostate cancer, alone or in combination with chemotherapy agents.

Chemical Composition and Bioactivity of Essential Oil from Blepharocalyx salicifolius

Natural products represent a source of biologically active molecules that have an important role in drug discovery. The aromatic plant Blepharocalyx salicifolius has a diverse chemical constitution but the biological activities of its essential oils have not been thoroughly investigated. The aims of this paper were to evaluate in vitro cytotoxic, antifungal and antibacterial activities of an essential oil from leaves of B. salicifolius and to identify its main chemical constituents. The essential oil was extracted by steam distillation, chemical composition was determined by gas chromatography/mass spectrometry, and biological activities were performed by a microdilution broth method. The yield of essential oil was 0.86% (w/w), and the main constituents identified were bicyclogermacrene (17.50%), globulol (14.13%), viridiflorol (8.83%), γ-eudesmol (7.89%) and α-eudesmol (6.88%). The essential oil was cytotoxic against the MDA-MB-231 (46.60 μg·mL⁻¹) breast cancer cell line, being more selective for this cell type compared to the normal breast cell line MCF-10A (314.44 μg·mL⁻¹). Flow cytometry and cytotoxicity results showed that this oil does not act by inducing cell death, but rather by impairment of cellular metabolism specifically of the cancer cells. Furthermore, it presented antifungal activity against Paracoccidioides brasiliensis (156.25 μg·mL⁻¹) but was inactive against other fungi and bacteria. Essential oil from B. salicifolius showed promising biological activities and is therefore a source of molecules to be exploited in medicine or by the pharmaceutical industry.

Essential Oils from Neotropical Piper Species and Their Biological Activities

The Piper genus is the most representative of the Piperaceae reaching around 2000 species distributed in the pantropical region. In the Neotropics, its species are represented by herbs, shrubs, and lianas, which are used in traditional medicine to prepare teas and infusions. Its essential oils (EOs) present high yield and are chemically constituted by complex mixtures or the predominance of main volatile constituents. The chemical composition of Piper EOs displays interspecific or intraspecific variations, according to the site of collection or seasonality. The main volatile compounds identified in Piper EOs are monoterpenes hydrocarbons, oxygenated monoterpenoids, sesquiterpene hydrocarbons, oxygenated sesquiterpenoids and large amounts of phenylpropanoids. In this review, we are reporting the biological potential of Piper EOs from the Neotropical region. There are many reports of Piper EOs as antimicrobial agents (fungi and bacteria), antiprotozoal (Leishmania spp., Plasmodium spp., and Trypanosoma spp.), acetylcholinesterase inhibitor, antinociceptive, anti-inflammatory and cytotoxic activity against different tumor cells lines (breast, leukemia, melanoma, gastric, among others). These studies can contribute to the rational and economic exploration of Piper species, once they have been identified as potent natural and alternative sources to treat human diseases.

An Overview of the Biological Effects of Some Mediterranean Essential Oils on Human Health

Essential oils (EOs), extracted from aromatic plants, are interesting natural products and represent an important part of the traditional pharmacopeia. The use of some EOs as alternative antimicrobial and pharmaceutical agents has attracted considerable interest recently. Most of the EOs and their single constituents have been reported to inhibit several phytopathogens, human pathogens, and insects as well as their effective uses in food and pharmaceutical industries. The current review discussed the chemical composition and bioactivity of some important EOs extracted from some Mediterranean plants and their principal bioactive single constituents. Information has been furnished on the mechanisms, mode of actions, and factors affecting the bioactivity of some single constituents from different Mediterranean plant EOs. The current review gives an insight into some common plant EOs belonging to Lamiaceae, Apiaceae, Rutaceae, and Verbenaceae families commonly growing in Mediterranean region. Further information has been provided about the medical uses of some EOs for several human diseases covering the pharmacological effects (anti-inflammatory, antioxidant, and anticarcinogenic). The antimicrobial effects have been also considered in the current review. Although plant EOs are considered promising natural alternatives for many chemical drugs, they still need more specific research for wide application especially in food and pharmaceutical industries.

Antinflammatory and anticancer effects of terpenes from oily fractions of Teucruim alopecurus, blocker of IκBα kinase, through downregulation of NF-κB activation, potentiation of apoptosis and suppression of NF-κB-regulated gene expression

Teucrium alopecurus is an endemic plant limited to southern Tunisia. In the present study, the chemical composition, anticancer and nuclear factor-κB (NF-κB) inhibitory effects of Teucrium alopecurus leaf essential oil was investigated. The analysis of Teucrium alopecurus (TA-1) with Gas Chromatography-Mass Spectrometry (GC/MS) showed that α-Bisabolol, (+)-epi-Bicyclosesquiphellandrene and α-Cadinol, were found in relatively high amounts (16.16%, 15.40% and 8.52%, respectively). Cell viability was determined by 3-(4-5-dimethylthiazol-2-yl) 2-5-diphenyl-tetrazolium (MTT) assay. Cell cycle and apoptosis assay were determined by flow cytometry. TA-1 functions as an anticancer agent by triggering apoptosis potentiated by chemotherapeutic agents and TNF in human myeloid leukemia cells (KBM5) through a mechanism involving poly(ADP-ribose) polymerase (PARP) cleavage and initiator and effector caspases activation. Moreover, electrophoretic mobility shift assay (EMSA) revealed that TA-1 downregulated nuclear localization of NF-κB and its phosphorylation induced by TNF-α and this, allows the suppression of the degradation and phosphorylation of IκB and the inhibition of the phosphorylation of p65 phosphorylation and the p50-p65 heterodimer nuclear translocation, causing attenuation of NF-κB-regulated antiapoptotic (Survivin, Bcl-2, c-IAP1/2, Bcl-xL, Mcl-1, and cFLIP), invasion (ICAM1), metasatsis (MMP-9), and angiogenesis (VEGF) gene expression in KBM5; and finally reporter gene expression. Furthermore, treatment with essential oil and TNF-α suppressed the NF-κB DNA binding activity. Finally, the activation of nuclear factor-κB induced by different plasmids (TNFR1, TRADD, TRAF2, NIK, TAK1/TAB1, and IKKβ) was inhibited following treatment with TA-1. Overall, TA-1 inhibits NF-κB activation and further growth and proliferation of cancer cells.

Mechanisms of cancer cell killing by sea cucumber-derived compounds

The aim of cancer therapy is to specifically eradicate tumor cells while causing minimal damage to normal tissues and minimal side-effects. Because of this, the use of natural substances with low toxicity is a good option. Sea cucumbers are one of many potential marine animals that contain valuable nutrients and medicinal properties. The medicinal value of sea cucumbers is attributed to the presence of bioactive agents with promising biological and pharmacological properties that include cytotoxic activity, induction of apoptosis, cell cycle arrest, inhibition of tumor growth, anti-metastatic and anti-angiogenic properties, and inhibition of drug resistance. This review discusses the mechanisms of cancer cell death induced by sea cucumber-derived compounds with regard to exploring the potential use of these marine natural products for cancer therapy.

Composition, Antioxidant, and Cytotoxic Activities of the Essential Oils from Fresh and Air-Dried Aerial Parts of Pallenis spinosa

This study was performed to determine the chemical composition, antioxidant and cytotoxic effects of essential oils extracted from the aerial parts of fresh (F-PSEO) and air-dried (D-PSEO) Pallenis spinosa. The composition of the oils was analyzed by gas chromatography (GC) and GC/mass spectrometry, the antioxidant activity by free radical scavenging and metal chelating assays, and their cytotoxicity by a flow cytometry analysis. The primary components in both oils were sesquiterpene hydrocarbons and oxygentated sesquiterpenes. F-PSEO contained 36 different compounds; α-cadinol (16.48%), germacra-1(10),5-diene-3,4-diol (14.45%), γ-cadinene (12.03%), and α-muurolol (9.89%) were the principal components. D-PSEO contained 53 molecules; α-cadinol (19.26%), δ-cadinene (13.93%), α-muurolol (12.88%), and germacra-1(10),5-diene-3,4-diol (8.41%) constituted the highest percentages. Although both oils exhibited a weak radical scavenging and chelating activity, compared to α-tocopherol and ascorbic acid, D-PSEO showed a 2-fold greater antioxidant activity than F-PSEO. Furthermore, low doses of F-PSEO were able to inhibit the growth of leukemic (HL-60, K562, and Jurkat) and solid tumor cells (MCF-7, HepG2, HT-1080, and Caco-2) with an IC₅₀ range of 0.25 - 0.66 μg/ml and 0.50 - 2.35 μg/ml, respectively. F-PSEO showed a ca. 2 - 3-fold stronger cytotoxicity against the tested cells than D-PSEO. The potent growth inhibitory effect of the plant essential oil encourages further studies to characterize the molecular mechanisms of its cytotoxicity.

Chemical Composition of Four Essential Oils of Eugenia from the Brazilian Amazon and Their Cytotoxic and Antioxidant Activity

Background:Eugenia species are appreciated for their edible fruits and are known as having anticonvulsant, antimicrobial and insecticidal actions. Methods: The plant material was collected in the southeastern Pará state of Brazil and submitted to hydrodistillation. GC-MS analyzed the oils, and their antioxidant and cytotoxic activities were evaluated by the DPPH and MTT assays. Results: The main components identified in the Eugenia oils were 5-hydroxy-cis-calemene, (2E,6E)-farnesol, (2E,6Z)-farnesol, caryophylla-4(12),8(13)-dien-5α-ol-5β-ol, E-γ-bisabolene, β-bisabolene, germacrene D, and ishwarane. The oil of E. egensis showed the most significant antioxidant activity (216.5 ± 11.6 mg TE/mL), followed by the oils of E. flavescens (122.6 ± 6.8 mg TE/mL) and E. patrisii (111.2 ± 12.4 mg TE/mL). Eugenia oils were cytotoxic to HCT-116 (colon cancer) cells by the MTT assay, where the most active was the oil of E. polystachya (10.3 µg/mL), followed by the oils of E. flavescens (13.9 µg/mL) and E. patrisii (16.4 µg/mL). The oils of E. flavescens and E. patrisii showed the highest toxicity for MRC5 (human fibroblast) cells, with values of 14.0 µg/mL and 18.1 µg/mL, respectively. Conclusions: These results suggest that Eugenia oils could be tested in future studies for the treatment of colon cancer and oxidative stress management.

Chemical composition, acute toxicity, antioxidant and anti-inflammatory activities of Moroccan Tetraclinis articulata L

Hydro-distilled essential oil (EO) from the leaves of the western Mediterranean and Moroccan endemic plant Tetraclinis articulata was analyzed by GC/MS and examined for its acute toxicity on mice, in order to establish the safe doses. Furthermore, the anti-Inflammatory activity was evaluated based on carrageenan and trauma induced rats paw edema and the antioxidant potential has been investigated using different methods including DPPH radical-scavenging assay, Trolox equivalent antioxidant capacity (TEAC) and Ferric-reducing antioxidant power assay (FRAP). The major identified compounds in GC/MS analysis were bornyl acetate (26.81%), camphor (22.40%) and α-pinene (7.16%), with 25 other minor constituents. No mortalities in acute toxicity were observed, indicating that the LD50 of T. articulata essential oil is highest than 5 g/kg. In the anti-inflammatory test based on chemical and mechanical induced trauma, the EO demonstrated an effective reduce swelling by 64.71 ± 9.38% and 69.09 ± 6.02% respectively obtained 6 h after administration at the dose of 200 mg/kg when compared to the control groups. Moreover in the antioxidant testing battery, T. articulata essential oil showed a promising scavenging effect measured by DPPH, TEAC and ferric-reducing power assays with IC50 values of 12.05 ± 0.24 mg/mL, 8.90 ± 0.17 mg/mL and 0.15 ± 0.01 mg/mL respectively. These results suggest that, the EO from the leaves of T. articulata constitutes a valuable source of anti-inflammatory and antioxidant metabolites. These findings argue for the possible integration of this oil in pharmaceutical, cosmetic and food industries.

Dietary mastic oil extracted from Pistacia lentiscus var. chia suppresses tumor growth in experimental colon cancer models

Plant-derived bioactive compounds attract considerable interest as potential chemopreventive anticancer agents. We analyzed the volatile dietary phytochemicals (terpenes) present in mastic oil extracted from the resin of Pistacia lentiscus var. chia and comparatively investigated their effects on colon carcinoma proliferation, a) in vitro against colon cancer cell lines and b) in vivo on tumor growth in mice following oral administration. Mastic oil inhibited - more effectively than its major constituents- proliferation of colon cancer cells in vitro, attenuated migration and downregulated transcriptional expression of survivin (BIRC5a). When administered orally, mastic oil inhibited the growth of colon carcinoma tumors in mice. A reduced expression of Ki-67 and survivin in tumor tissues accompanied the observed effects. Notably, only mastic oil -which is comprised of 67.7% α-pinene and 18.8% myrcene- induced a statistically significant anti-tumor effect in mice but not α-pinene, myrcene or a combination thereof. Thus, mastic oil, as a combination of terpenes, exerts growth inhibitory effects against colon carcinoma, suggesting a nutraceutical potential in the fight against colon cancer. To our knowledge, this is the first report showing that orally administered mastic oil induces tumor-suppressing effects against experimental colon cancer.

Terpinen-4-ol inhibits colorectal cancer growth via reactive oxygen species

Terpinen-4-ol (TP4O) is the main component of the essential oil extracted from Melaleuca alternifolia, known as the tea tree, of the botanical family Myrtaceae. The anticancer effects of TP4O have been reported in several cancer cell lines. Previous reports have demonstrated that TP4O exerts anticancer effects by inducing apoptotic cell death in several cell lines; however, the underlying molecular mechanisms of these effects remain unclear. In the present study, the anticancer effects of TP4O against the colorectal cancer (CRC) cell lines HCT116 and RKO were evaluated using WST-8 and bromodeoxyuridine assays. The mechanism of cell death was investigated by the measurement of caspase-3/7, Annexin V and lactate dehydrogenase release. Reactive oxygen species (ROS) levels induced by TP4O were evaluated by electron spin resonance and quantitative measurement of dihydroethidium. Localization of the ROS derived from mitochondria was observed by confocal inverted microscopy. Protein levels of ROS scavengers were assessed by western blotting analysis. To confirm the role of ROS, cell viability was measured in the presence of antioxidant reagents. In an in vivo xenograft model of ICR-SCID mice implanted with HCT116 cells, 200 mg/kg TP4O was injected locally, and tumor growth was compared with that of the control. TP4O induced apoptotic cell death in HCT116 and RKO cells in a dose-dependent manner, and TP4O also increased the levels of ROS generated by mitochondria. TP4O-induced cell death was rescued by administration of antioxidant regents. In vivo, TP4O inhibited the proliferation of HCT116 xenografts compared with that of the control group. The results of the present study suggest that TP4O induces apoptosis in CRC cells through ROS generation. Furthermore, TP4O is potentially useful for the development of novel therapies against CRC.

Monitoring ZEO apoptotic potential in 2D and 3D cell cultures and associated spectroscopic evidence on mode of interaction with DNA

Recognizing new anticancer compounds to improve Breast cancer treatment seems crucial. Essential oil of Zataria Multiflora (ZEO) is a secondary metabolite with some biological properties, yet underlying cellular and molecular anticancer properties of ZEO is unclear. GC/MS analysis revealed that carvacrol is the major ingredient of the essential oil. ZEO increasingly suppressed viability in MDA-MB-231, MCF-7 and T47D Breast cancer cells while nontoxic to L929 normal cells in monolayer cell cultures (2D), whereas MDA-MB-231 multicellular spheroids (3D) were more resistant to inhibition. ZEO significantly induced cell apoptosis confirmed by fluorescent staining, flow cytometry analysis and DNA fragmentation in MDA-MB-231 2D and 3D cell cultures. ZEO increased ROS generation and subsequent loss of ΔΨm, caspase 3 activation and DNA damage which consequently caused G1 and G2/M cell cycle arrest in a dose- and time-dependent manner in 2D. S phase arrest occurred in cell spheroids therefore ZEO possible DNA interaction with gDNA was investigated and revealed ZEO binds DNA via intercalation. Altogether, these data corroborate anticancer properties of ZEO and suggest that cell culture format (2D monolayer vs. 3D spheroid) plays a critical role in drug response and provides new insights into the mechanisms underlying ZEO cytotoxicity effect on Breast cancer cells.

Chemical Diversity, Biological Activity, and Genetic Aspects of Three Ocotea Species from the Amazon

Ocotea species present economic importance and biological activities attributed to their essential oils (EOs) and extracts. For this reason, various strategies have been developed for their conservation. The chemical compositions of the essential oils and matK DNA sequences of O. caudata, O. cujumary, and O. caniculata were subjected to comparison with data from O. floribunda, O. veraguensis, and O. whitei, previously reported. The multivariate analysis of chemical composition classified the EOs into two main clusters. Group I was characterized by the presence of α-pinene (9.8-22.5%) and β-pinene (9.7-21.3%) and it includes O. caudata, O. whitei, and O. floribunda. In group II, the oils of O. cujumary and O. caniculata showed high similarity due amounts of β-caryophyllene (22.2% and 18.9%, respectively). The EO of O. veraguensis, rich in p-cymene (19.8%), showed minor similarity among all samples. The oils displayed promising antimicrobial and cytotoxic activities against Escherichia coli (minimum inhibitory concentration (MIC) < 19.5 µg·mL^-1) and MCF-7 cells (median inhibitory concentration (IC₅₀) ≅ 65.0 µg·mL^-1), respectively. The analysis of matK gene displayed a good correlation with the main class of chemical compounds present in the EOs. However, the matK gene data did not show correlation with specific compounds.

Real-Time Cell Analysis of the Cytotoxicity of Origanum acutidens Essential Oil on HT-29 and HeLa Cell Lines

Objectives

The aim of this study was to investigate the cytotoxic and radical scavenging effects of the essential oil from Origanum acutidens (Hand-Mazz.) Ietswaart and to determine its chemical composition.

Materials and Methods

The essential oil was obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC-MS). The cytotoxic effect of the essential oil on the growth of human colorectal adenocarcinoma (HT-29) and human cervical adenocarcinoma (HeLa) cell lines was investigated by xCELLigence Real Time Cell Analyzer instrument. Moreover, radical scavenging effect of the oil was determined by using DPPH method.

Results

The main constituents of the oil were found to be carvacrol (61.69%), p-cymene (17.32%), γ-terpinene (4.05%), and borneol (3.96%). The essential oil of O. acutidens exhibited significant cytotoxic effect against HeLa and HT-29 cell lines at the tested concentrations. The essential oil had moderate DPPH radical scavenging activity compared to butylated hydroxytoluene (BHT).

Conclusion

The data in the present study clearly demonstrated inhibitory effect of the oil on two human cancer cell lines. According to these results and other reported studies, this observed high effect may be attributed to the presence of the carvacrol component in the oil.

Change in Caco-2 cells following treatment with various lavender essential oils

Lavender is an aromatic evergreen shrub diffused in the Mediterranean basin appreciated since antiquity. The genus Lavandula is part of Lamiaceae family and includes more than 20 species, among which true lavender (L. vera D.C. or L. angustifolia Miller.) and spike lavender (L. latifolia Medikus); there are also numerous hybrids known as lavandins (L. hybrida Rev.). L. vera, spike lavender and several hybrids are the most intensely used breeding species for the production of essential oils. Lavender and lavandin essential oils have been applied in food, pharmaceutical and other agro industries as biological products. In their chemical composition, terpenes linalool and linalyl acetate along with terpenoids such as 1,8-cineole are mostly responsible for biological and therapeutic activities. This study evaluates cytotoxic activity of essential oils derived from four lavender species on human epithelial colorectal adenocarcinoma cells. Analysis of pre- and post-treatment cell morphology has been performed using scanning electron microscope.

Biological Activities of Essential Oils: From Plant Chemoecology to Traditional Healing Systems

Essential oils are complex mixtures of hydrocarbons and their oxygenated derivatives arising from two different isoprenoid pathways. Essential oils are produced by glandular trichomes and other secretory structures, specialized secretory tissues mainly diffused onto the surface of plant organs, particularly flowers and leaves, thus exerting a pivotal ecological role in plant. In addition, essential oils have been used, since ancient times, in many different traditional healing systems all over the world, because of their biological activities. Many preclinical studies have documented antimicrobial, antioxidant, anti-inflammatory and anticancer activities of essential oils in a number of cell and animal models, also elucidating their mechanism of action and pharmacological targets, though the paucity of in human studies limits the potential of essential oils as effective and safe phytotherapeutic agents. More well-designed clinical trials are needed in order to ascertain the real efficacy and safety of these plant products.

Phytochemical Profile and Evaluation of the Biological Activities of Essential Oils Derived from the Greek Aromatic Plant Species Ocimum basilicum, Mentha spicata, Pimpinella anisum and Fortunella margarita

Natural products, known for their medicinal properties since antiquity, are continuously being studied for their biological properties. In the present study, we analyzed the composition of the volatile preparations of essential oils of the Greek plants Ocimum basilicum (sweet basil), Mentha spicata (spearmint), Pimpinella anisum (anise) and Fortunella margarita (kumquat). GC/MS analyses revealed that the major components in the essential oil fractions, were carvone (85.4%) in spearmint, methyl chavicol (74.9%) in sweet basil, trans-anethole (88.1%) in anise, and limonene (93.8%) in kumquat. We further explored their biological potential by studying their antimicrobial, antioxidant and antiproliferative activities. Only the essential oils from spearmint and sweet basil demonstrated cytotoxicity against common foodborne bacteria, while all preparations were active against the fungi Saccharomyces cerevisiae and Aspergillus niger. Antioxidant evaluation by DPPH and ABTS radical scavenging activity assays revealed a variable degree of antioxidant potency. Finally, their antiproliferative potential was tested against a panel of human cancer cell lines and evaluated by using the sulforhodamine B (SRB) assay. All essential oil preparations exhibited a variable degree of antiproliferative activity, depending on the cancer model used, with the most potent one being sweet basil against an in vitro model of human colon carcinoma.

Decatropis bicolor (Zucc.) Radlk essential oil induces apoptosis of the MDA-MB-231 breast cancer cell line

Background

Decatropis bicolor (Zucc.)Radlk is a plant that has been traditionally used for the treatment of breast cancer in some communities of Mexico. So, the aim of this study was to determine the cytotoxic and apoptotic effect of the essential oil of Decatropis bicolor against breast cancer cell line, MDA-MB-231.

Methods

The essential oil obtained from hydrodestillation of leaves of Decatropis bicolor was studied for its biological activity against breast cancer cells MDA-MB-231 by MTT assay, Hematoxylin-eosin stain, Annexin V-FITC, TUNEL and western blot assays and for its chemical composition by GC-MS.

Results

The results showed a relevant cytotoxic effect of the essential oil towards MDA-MB-231 cells in a dose- and time- dependent manner, with an IC₅₀ of 53.81 ± 1.691 μg/ml but not in the epithelial mammary cell line MCF10A (207.51 ± 3.26 μg/ml). Morphological examination displayed apoptotic characteristics in the treated cells like cell size reduction, membrane blebbing and apoptotic bodies. In addition, the apoptotic rate significantly increased as well as DNA fragmentation and western blot analysis revealed that the essential oil induced apoptosis in the MDA-MB-231 cells via intrinsic pathways due to the activation of Bax, caspases 9 and 3. Phytochemical analysis of the Decatropis bicolor essential oil showed the presence of twenty-three compounds. Major components of the oil were 1,5-cyclooctadiene,3-(methyl-2)propenyl (18.38 %), β-terpineol (8.16 %) and 1-(3-methyl-cyclopent-2-enyl)-cyclohexene (6.12 %).

Conclusions

This study suggests that essential oil of Decatropis bicolor has a potential cytotoxic and antitumoral effect against breast cancer cells, with the presence of potential bioactive compounds. Our results contribute to the validation of the anticancer activity of the plant in Mexican traditional medicine.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1136-7) contains supplementary material, which is available to authorized users.

Synergistic and Additive Effect of Oregano Essential Oil and Biological Silver Nanoparticles against Multidrug-Resistant Bacterial Strains

Bacterial resistance to conventional antibiotics has become a clinical and public health problem, making therapeutic decisions more challenging. Plant compounds and nanodrugs have been proposed as potential antimicrobial alternatives. Studies have shown that oregano (Origanum vulgare) essential oil (OEO) and silver nanoparticles have potent antibacterial activity, also against multidrug-resistant strains; however, the strong organoleptic characteristics of OEO and the development of resistance to these metal nanoparticles can limit their use. This study evaluated the antibacterial effect of a two-drug combination of biologically synthesized silver nanoparticles (bio-AgNP), produced by Fusarium oxysporum, and OEO against Gram-positive and Gram-negative bacteria, including multidrug-resistant strains. OEO and bio-AgNP showed bactericidal effects against all 17 strains tested, with minimal inhibitory concentrations (MIC) ranging from 0.298 to 1.193 mg/mL and 62.5 to 250 μM, respectively. Time-kill curves indicated that OEO acted rapidly (within 10 min), while the metallic nanoparticles took 4 h to kill Gram-negative bacteria and 24 h to kill Gram-positive bacteria. The combination of the two compounds resulted in a synergistic or additive effect, reducing their MIC values and reducing the time of action compared to bio-AgNP used alone, i.e., 20 min for Gram-negative bacteria and 7 h for Gram-positive bacteria. Scanning electron microscopy (SEM) revealed similar morphological alterations in Staphylococcus aureus (non-methicillin-resistant S. aureus, non-MRSA) cells exposed to three different treatments (OEO, bio-AgNP and combination of the two), which appeared cell surface blebbing. Individual and combined treatments showed reduction in cell density and decrease in exopolysaccharide matrix compared to untreated bacterial cells. It indicated that this composition have an antimicrobial activity against S. aureus by disrupting cells. Both compounds showed very low hemolytic activity, especially at MIC levels. This study describes for the first time the synergistic and additive interaction between OEO and bio-AgNP produced by F. oxysporum against multidrug-resistant bacteria, such as MRSA, and β-lactamase- and carbapenemase-producing Escherichia coli and Acinetobacter baumannii strains. These results indicated that this combination can be an alternative in the control of infections with few or no treatment options.

Verbesina encelioides: cytotoxicity, cell cycle arrest, and oxidative DNA damage in human liver cancer (HepG2) cell line

BACKGROUND

Cancer is a major health problem and exploiting natural products have been one of the most successful methods to combat this disease. Verbesina encelioides is a notorious weed with various pharmacological properties. The aim of the present investigation was to screen the anticancer potential of V. encelioides extract against human lung cancer (A-549), breast cancer (MCF-7), and liver cancer (HepG2) cell lines.

METHODS

A-549, MCF-7, and HepG2 cells were exposed to various concentrations of (10-1000 μg/ml) of V. encelioides for 24 h. Further, cytotoxic concentrations (250, 500, and 1000 μg/ml) of V. encelioides induced oxidative stress (GSH and LPO), reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP), cell cycle arrest, and DNA damage in HepG2 cells were studied.

RESULTS

The exposure of cells to 10-1000 μg/ml of extract for 24 h, revealed the concentrations 250-1000 μg/ml was cytotoxic against MCF-7 and HepG2 cells, but not against A-549 cells. Moreover, the extract showed higher decrease in the cell viability against HepG2 cells than MCF-7 cells. Therefore, HepG2 cells were selected for further studies viz. oxidative stress (GSH and LPO), reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP), cell cycle arrest, and DNA damage. The results revealed differential anticancer activity of V. encelioides against A-549, MCF-7 and HepG2 cells. A significant induction of oxidative stress, ROS generation, and MMP levels was observed in HepG2 cells. The cell cycle analysis and comet assay showed that V. encelioides significantly induced G2/M arrests and DNA damage.

CONCLUSION

These results indicate that V. encelioides possess substantial cytotoxic potential and may warrant further investigation to develop potential anticancer agent.

Nerolidol: A Sesquiterpene Alcohol with Multi-Faceted Pharmacological and Biological Activities

Nerolidol (3,7,11-trimethyl-1,6,10-dodecatrien-3-ol) is a naturally occurring sesquiterpene alcohol that is present in various plants with a floral odor. It is synthesized as an intermediate in the production of (3E)-4,8-dimethy-1,3,7-nonatriene (DMNT), a herbivore-induced volatile that protects plants from herbivore damage. Chemically, nerolidol exists in two geometric isomers, a trans and a cis form. The usage of nerolidol is widespread across different industries. It has been widely used in cosmetics (e.g., shampoos and perfumes) and in non-cosmetic products (e.g., detergents and cleansers). In fact, U.S. Food and Drug Administration (FDA) has also permitted the use of nerolidol as a food flavoring agent. The fact that nerolidol is a common ingredient in many products has attracted researchers to explore more medicinal properties of nerolidol that may exert beneficial effect on human health. Therefore, the aim of this review is to compile and consolidate the data on the various pharmacological and biological activities displayed by nerolidol. Furthermore, this review also includes pharmacokinetic and toxicological studies of nerolidol. In summary, the various pharmacological and biological activities demonstrated in this review highlight the prospects of nerolidol as a promising chemical or drug candidate in the field of agriculture and medicine.

Biological effects of various chemically characterized essential oils: investigation of the mode of action against Candida albicans and HeLa cells

Essential oils of different chemical compositions show a specificity in amplitude but not in the mode of biological action againstCandida albicansand HeLa cells.

Properties and limits of some essential oils: chemical characterisation, antimicrobial activity, interaction with antibiotics and cytotoxicity

Because of the emergence of multi-drug resistance bacteria and fungi, alternatives to conventional antimicrobial therapy are needed. This study aims to evaluate in vitro the antimicrobial activity of: Mirtus communis, Coriandrum sativum, Pelargonium capitatum, Cuminum cyminum, Ocimum basilicum, Citrus aurantium amara, Cymbopogon. winterianus, Cymbopogon martini, Salvia sclarea, Melaleuca alternifolia and Mentha suaveolens essential oils on bacteria and fungi, in relation to their chemical composition. The potential interaction of M. alternifolia (TTO), C. sativum (CDO) and M. suaveolens (EOMS) essential oils when used in combination with gentamicin and fluconazole has been evaluated. The results obtained showed a synergic effect on some bacteria and fungi, with FICI values ≤5. The cytotoxicity of TTO, CDO and EOMS was investigated towards HeLa cells. Only EOMS did not result cytotoxic at the active concentrations on micro-organisms. Further studies are necessary to obtain optimal ratios and dosing regimens for higher therapeutic efficacy and to decrease toxicological profiles.

Recent Developments and Biological Activities of N-Substituted Carbazole Derivatives: A Review

Carbazoles represent an important class of heterocycles. These have been reported to exhibit diverse biological activities such as antimicrobial, antitumor, antiepileptic, antihistaminic, antioxidative, anti-inflammatory, antidiarrhoeal, analgesic, neuroprotective and pancreatic lipase inhibition properties. A series of carbazole derivatives such as N-substituted carbazoles, benzocarbazoles, furocarbazoles, pyrrolocarbazoles, indolocarbazoles, imidazocarbazoles, etc. have been synthesized. The N-substituted derivatives have gained the attention of researchers due to their therapeutic potential against neurological disorders and cell proliferation. Herein an attempt is made to review the medicinal importance of recently synthesized N-substituted carbazoles.

Composition, antimicrobial, antioxidant, and antiproliferative activity of Origanum dictamnus (dittany) essential oil

Background

Nowadays, there has been an increased interest in essential oils from various plant origins as potential antimicrobial, antioxidant, and antiproliferative agents. This trend can be mainly attributed to the rising number and severity of food poisoning outbreaks worldwide along with the recent negative consumer perception against artificial food additives and the demand for novel functional foods with possible health benefits. Origanum dictamnus (dittany) is an aromatic, tender perennial plant that only grows wild on the mountainsides and gorges of the island of Crete in Greece.

Objective

The aim of the present study was to investigate the antimicrobial, antioxidant, and antiproliferative properties of O. dictamnus essential oil and its main components and assess its commercial potential in the food industry.

Design

O. dictamnus essential oil was initially analyzed by gas chromatography–mass spectrometry (GC–MS) to determine semi-quantitative chemical composition of the essential oils. Subsequently, the antimicrobial properties were assayed and the minimum inhibitory and non-inhibitory concentration values were determined. The antioxidant activity and cytotoxic action against the hepatoma adenocarcinoma cell line HepG2 of the essential oil and its main components were further evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and by the sulforhodamine B (SRB) assay, respectively.

Results

The main constituents of O. dictamnus essential oil identified by GC–MS analysis were carvacrol (52.2%), γ-terpinene (8.4%), p-cymene (6.1%), linalool (1.4%), and caryophyllene (1.3%). O. dictamnus essential oil and its main components were effective against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Listeria monocytogenes, Salmonella Enteritidis, Salmonella typhimurium, Saccharomyces cerevisiae, and Aspergillus niger. In addition, the estimated IC₅₀ value for the DPPH radical scavenging activity for O. dictamnus essential oil was 0.045±0.0042% (v/v) and was mainly attributed to carvacrol. The EC₅₀ value for the essential oil in the 72h SRB assay in HepG2 cells was estimated to be 0.0069±0.00014% (v/v). Among the individual constituents tested, carvacrol was the most bioactive compound and accounted for the observed antiproliferative activity of the essential oil.

Conclusions

The results revealed that O. dictamnus essential oil is a noteworthy growth inhibitor against the microbes studied. It also possesses significant antioxidant activity and demonstrated excellent cytotoxicity against HepG2 cells. Taken together, O. dictamnus essential oil may represent an effective and inexpensive source of potent natural antimicrobial agents with health-promoting properties, which may be incorporated in food systems.