Anti-staphylococcal activity of soilless cultivated cannabis across the whole vegetation cycle under various nutritional treatments in relation to cannabinoid content.

Antibiotic resistance in staphylococcal strains and its impact on public health and agriculture are global problems. The development of new anti-staphylococcal agents is an effective strategy for addressing the increasing incidence of bacterial resistance. In this study, ethanolic extracts of Cannabis sativa L. made from plant parts harvested during the whole vegetation cycle under various nutritional treatments were assessed for in vitro anti-staphylococcal effects. The results showed that all the cannabis extracts tested exhibited a certain degree of growth inhibition against bacterial strains of Staphylococcus aureus, including antibiotic-resistant and antibiotic-sensitive forms. The highest antibacterial activity of the extracts was observed from the 5th to the 13th week of plant growth across all the nutritional treatments tested, with minimum inhibitory concentrations ranging from 32 to 64 µg/mL. Using HPLC, Δ9-tetrahydrocannabinolic acid (THCA) was identified as the most abundant cannabinoid in the ethanolic extracts. A homolog of THCA, tetrahydrocannabivarinic acid (THCVA), reduced bacterial growth by 74%. These findings suggest that the cannabis extracts tested in this study can be used for the development of new anti-staphylococcal compounds with improved efficacy.

Validation of Broth Macrodilution Volatilization Method for Testing of Essential Oils in Liquid and Vapor Phase: Chemical Composition, Cytotoxicity, and Antibacterial Effect of Indian Medicinal Plants against Pneumonia-Causing Pathogens.

Essential oils (EOs) have great potential in inhalation therapy for the treatment of respiratory infections. However, innovative methods for evaluation of antimicrobial activity of their vapors are still needed. The current study reports validation of the broth macrodilution volatilization method for assessment of the antibacterial properties of EOs and shows the growth-inhibitory effect of Indian medicinal plants against pneumonia-causing bacteria in liquid and vapor phase. Among all samples tested, Trachyspermum ammi EO exhibits the strongest antibacterial effect against Haemophilus influenzae, with minimum inhibitory concentrations of 128 and 256 µg/mL in the liquid and vapor phases, respectively. Furthermore, Cyperus scariosus EO is found to be nontoxic to normal lung fibroblasts assessed by modified thiazolyl blue tetrazolium bromide assay. Chemical analysis performed using gas chromatography-mass spectrometry identified α-citral, cyperotundone, and thymol as the main constituents of Cymbopogon citratus, C. scariosus, and T. ammi EOs, respectively. In addition, ß-cymene is identified as the major compound of T. ammi EO vapors when analyzed using solid-phase microextraction and gas-tight syringe sampling techniques. This study demonstrates the validity of the broth macrodilution volatilization method for antimicrobial screening of volatile compounds in the vapor phase and suggests the therapeutic potential of Indian medicinal plants in inhalation therapy.

Ethnobotanical inventory of medicinal plants used by Cashinahua (Huni Kuin) herbalists in Purus Province, Peruvian Amazon.

This study aims to document the diversity of medicinal plants used by the Cashinahua people (also known as Huni Kuin) of the Curanja River, as well as describe and compare their uses with pharmacological and phytochemical records from previously published studies. The ethnic has been studied to a limited extent from an ethnobotanical perspective. The study area is located in the Ucayali region, eastern Central Amazon, where ancestral knowledge is preserved due to the limited accessibility of the region. Between November 2010 and June 2015, a total of 11 months were spent on the survey, which included a short-term visit to complete voucher specimen collection and taxonomic identification. We conducted semi-structured interviews with 10 Cashinahua traditional healers and 10 midwives. Vernacular names, ethnomedicinal uses, plant parts used and forms of preparation and administration were recorded. Ethnopharmacological, pharmacological and phytochemical uses were checked through survey of the previously published papers indexed on Web of Science databases between 2018 and 2022. We obtained data on 467 plant taxa, among which we highlighted 79 species unreported or rarely cited for medicinal use or phytochemical analysis. These species were spread over 60 genera and 42 botanical families, with Acanthaceae being the most represented. Leaves were used the most frequently (93.56%). Among the 79 species, the most reported therapeutic activities involved pregnancy and birth disorders (13.84%), followed by poisonings, infections and infestations. The predominant application form was external (87%). Our study indicates that there are locally valuable species that have not yet been studied for their medical potential.

In Vitro Selective Antibacterial and Antiproliferative Effects of Ethanolic Extracts from Cambodian and Philippine Plants Used in Folk Medicine for Diarrhea Treatment.

Bacterial diarrhea remains a global health problem, especially in developing tropical countries. Moreover, dysbiosis caused by diarrheagenic bacteria and inappropriate antimicrobial treatment has been associated with intestinal carcinogenesis. Despite the rich tradition of the use of herbs for the treatment of gastrointestinal disorders in Cambodian and Philippine folk medicine, many of them have not yet been systematically studied for their in vitro selective inhibitory effects on intestinal bacteria and cells. In the present study, in vitro inhibitory activities of 35 ethanolic extracts derived from 32 Cambodian and Philippine medicinal plants were determined by broth microdilution method against 12 pathogenic bacteria. Furthermore, cytotoxicity against intestinal cancer cells (Caco-2 and HT-29) using thiazolyl blue tetrazolium bromide cytotoxicity assay and safety to six beneficial intestinal bacteria (bifidobacteria and lactobacilli) and intestinal normal cells (FHs 74 Int) were determined for the antimicrobially active extracts. Selectivity indices (SIs) were calculated among the averages of minimum inhibitory concentrations (MICs), half-maximal inhibitory concentrations (IC50), and 80% inhibitory concentrations of proliferation (IC80) for each type of the tested agents. The extracts of Artocarpus blancoi (Elmer) Merr. (Moraceae), Ancistrocladus tectorius (Lour.) Merr. (Ancistrocladaceae), and Pentacme siamensis (Miq.) Kurz (Dipterocarpaceae) produced significant growth-inhibitory effects (MICs = 32-512 µg/ml) against intestinal pathogenic bacteria at the concentrations nontoxic to normal intestinal cells (IC80 values >512 µg/ml; SIs = 0.11-0.2). Moreover, the extract of P. siamensis (Miq.) Kurz was relatively safe to beneficial bacteria (MICs ≥512 µg/ml; SI = 0.1), and together with A. blancoi (Elmer) Merr., they selectively inhibited intestinal cancer cells (IC50 values ≥51.98 ± 19.79 µg/ml; SIs = 0.3 and 0.6). Finally, a strong selective antiproliferative effect on cancer cells (IC50 values 37.89 ± 2.68 to 130.89 ± 13.99 µg/ml; SIs = 0.5) was exerted by Ehretia microphylla Lam. (Boraginaceae), Lagerstroemia cochinchinensis Pierre ex Gagnep. (Lythraceae), and Melastoma saigonense (Kuntze) Merr. (Melastomataceae) (leaves with flower buds). The results suggest that the above-mentioned species are promising materials for the development of new selective antibacterial and antiproliferative agents for the treatment of infectious diarrhea and associated intestinal cancer diseases. However, further research is needed regarding the isolation and identification of their active constituents.

In vitro antagonistic inhibitory effects of palm seed crude oils and their main constituent, lauric acid, with oxacillin in Staphylococcus aureus.

Infections caused by Staphylococcus aureus are a serious global threat, and with the emergence of antibiotic resistance, even more difficult to treat. One of the possible complications in antistaphylococcal therapy represents negative interactions of antibiotics with food. In this study, the in vitro interaction between oxacillin and crude palm seed oil from Astrocaryum vulgare, Cocos nucifera, and Elaeis guineensis against nine strains of S. aureus was determined using the checkerboard method. Lauric acid was identified as a major constituent of all tested oils by gas chromatography. The results showed strong concentration dependent antagonistic interactions between palm oils and oxacillin with values of fractional inhibitory concentrations indices ranging from 4.02 to 8.56 at concentrations equal or higher than 1024 µg/mL of the tested oils. Similarly, lauric acid in combination with oxacillin produced antagonistic action with fractional inhibitory concentration indices ranging from 4.01 to 4.28 at 1024 µg/mL. These findings suggest that interference between oxacillin and palm oils and their constituents can negatively affect the treatment of staphylococcal infections in humans and other animals.

Vapors of Volatile Plant-Derived Products Significantly Affect the Results of Antimicrobial, Antioxidative and Cytotoxicity Microplate-Based Assays.

Volatile plant-derived products were observed to exhibit broad spectrum of biological effects. However, due to their volatility, results of conventional microplate-based bioassays can be significantly affected by the vapors. With aim to demonstrate this phenomenon, antimicrobial, antioxidant, and cytotoxic activities of three essential oils (Alpinia elegans, Cinnamomum iners, and Xanthostemon verdugonianus), one supercritical CO2 extract (Nigella sativa), and four plant-derived compounds (capsaicin, caryophyllene oxide, 8-hydroxyquinoline, and thymoquinone) were evaluated in series of experiments including both ethylene vinyl acetate (EVA) Capmat sealed and nonsealed microplates. The results clearly illustrate that vapor transition to adjoining wells causes false-positive results of bioassays performed in nonsealed microtiter plates. The microplate layout and a duration of the assay were demonstrated as the key aspects defining level of the results affection by the vapors of volatile agents. Additionally, we reported biological activities and chemical composition of essential oils from A. elegans seeds and X. verdugonianus leaves, which were, according to our best knowledge, analyzed for the first time. Considering our findings, certain modifications of conventional microplate-based assays are necessary (e.g., using EVA Capmat as vapor barrier) to obtain reliable results when biological properties of volatile agents are evaluated.

Volatile Antimicrobial Agents and In Vitro Methods for Evaluating Their Activity in the Vapour Phase: A Review.

This review summarizes data on the in vitro antimicrobial effectiveness of volatile agents of plant origin and in vitro methods for evaluating their activity in the vapour phase. As a result of literature analysis, the antimicrobial efficacy of vapours from 122 different plant species and 19 pure compounds examined in 61 studies using different in vitro tests against a broad spectrum of microorganisms was identified and summarized. In addition, 11 different techniques found in the literature are described in detail. An original classification of methods based on the solid and liquid matrix volatilization principle is proposed because carrier medium/matrix selection is crucial for the volatilization of any agents tested. This review should be useful for medicinal, pharmaceutical, food, and agricultural experts working in areas related to the management of infectious diseases (especially respiratory and skin infections), food preservation (active packaging), and protection of agriculture products (controlled atmosphere). It may also stimulate the interest of pharmaceutical, cosmetic, food, and agriculture industries in the research and development of new antimicrobial agents of natural origin. Since several original apparatuses previously developed for antimicrobial susceptibility testing in the vapour phase are described in this review, labware manufacturers may also be interested in this topic. The review also provides specific guidelines and recommendations for researchers studying the antimicrobial activity of volatile agents. The article will therefore appeal to communities of industrial stakeholders, pharmacists, physicians, food experts, agriculturists, and researchers in related areas such as pharmacology, medicinal chemistry, microbiology, natural product chemistry, food preservation and plant protection.

Maytenus macrocarpa (Ruiz & Pav.) Briq.: Phytochemistry and Pharmacological Activity.

Maytenus macrocarpa (Celastraceae) is a tree native to Amazonia. Its roots, leaves, bark, and combinations of these are used in traditional medicine mainly to treat rheumatism and, to a lesser extent, to heal wounds and to combat bronchitis and diarrhea. To date, mainly triterpenes and dihydro-ß-agarofuran sesquiterpenes were isolated from M. macrocarpa. Extracts and selected pure compounds isolated from the leaves, roots, and stem bark showed antibacterial, antiviral, antiparasitic, anti-inflammatory, and cytotoxic activities in vitro. The aim of this review is to summarize the available ethnobotanical, phytochemical, and pharmacological information about this traditional Amazonian medicinal tree, as well as to attract the attention of phytochemists and pharmacognosists to this potentially interesting source of ethnopharmaceuticals.

Screening of medicinal plants traditionally used in Peruvian Amazon for in vitro antioxidant and anticancer potential.

Plants mentioned in this study have numerous records in traditional Peruvian medicine being used in treatment of cancer and other diseases likely to be associated with oxidative stress. Amongst the eight plant species tested, only Dysphania ambrosioides exhibited combinatory antioxidant and anti-proliferative effect on a broad spectrum of cancer cells (DPPH and ORAC values = 80.6 and 687.3 µg TE/mg extract, respectively; IC50 against Caco-2, HT-29 and Hep-G2 = 129.2, 69.9 and 130.6, respectively). Alkaloids and phenolic compounds might significantly contribute to anticancer/antioxidant activity of this plant. The results justify the traditional medicinal use of this plant. Our findings further suggest that D. ambrosioides might serve as a prospective material for further development of novel plant-based antioxidant and/or anti-proliferative agents. Detailed analysis of chemical composition together with toxicology assessments and in vivo antioxidant/anti-proliferative activity of this plant should be carried out in order to verify its potential practical use.

Plant-Derived Products as Antibacterial and Antifungal Agents in Human Health Care.

A number of papers reporting antimicrobial properties of extracts, essential oils, resins and various classes of compounds isolated from higher plants have been published in recent years; however, a comprehensive analysis of plant-derived antimicrobial agents currently applied in practice for the improvement of human health is still lacking. This review summarizes data on clinical efficacy, antimicrobial effects and the chemistry of commercially available antibacterial and antifungal agents of plant origin currently used in the prevention and treatment of gastrointestinal, oral, respiratory, skin, and urinary infections. As a result of an analysis of the literature, more than 40 plant-derived over-the-counter pharmaceuticals, dietary supplements, cosmetics, herbal medicines, and functional foods containing complex mixtures (e.g. Glycyrrhiza glabra extract, Melaleuca alternifolia essential oil, and Pistacia lentiscus resin), pure compounds (e.g. benzoic acid, berberine, eucalyptol, salicylic acid and thymol) as well as their derivatives and complexes (e.g. bismuth subsalicylate and zinc pyrithione) have been identified. The effectiveness of many of these products is illustrated by results of clinical trials and supported by data on there in vitro antimicrobial activity. A broad spectrum of various commercial products currently available on the market and their welldocumented clinical efficacy suggests that plants are prospective sources for the identification of new types of antimicrobial agents in future. Innovative approaches and methodologies for effective proof-of-concept research and the development of new types of plant-derived products effective against recently emerging problems related to human microbial diseases (e.g. antimicrobial resistance) are also proposed in this review.

Evaluation of in vitro growth-inhibitory effect of carvacrol and thymol combination against Staphylococcus aureus in liquid and vapour phase using new broth volatilization chequerboard method.

Carvacrol and thymol, both plant-derived volatile compounds, have extensively been studied individually as well as in combination with other agents for their antimicrobial activity in liquid phase. However, in contrast to well-established assays for testing of antimicrobial combinatory effects in liquid media, there are no standardized methods for evaluation of interactions between volatile compounds in vapour phase. The objective of this study was to verify new broth volatilization chequerboard method by testing the combination of carvacrol and thymol and to determine in vitro inhibitory effect of these compounds in liquid and vapour phase against twelve Staphylococcus aureus strains. The new method, based on combination of standard microdilution chequerboard and new broth volatilization tests allowing calculation of fractional inhibitory concentrations (FICs), was used. Combination of carvacrol and thymol produced the additive antimicrobial effect against all strains tested. In several cases, they reached ΣFIC values lower than 0.6, which can be considered as a strong additive interaction. The best result was found in vapour phase against one standard strain at combination of 128 µg/mL of carvacrol and 16-256 µg/mL of thymol (ΣFIC = 0.51) and in liquid phase against one clinical isolate at combination of 256 µg/mL of carvacrol and 256 µg/mL of thymol (ΣFIC = 0.53). The study verified that the new technique is suitable for simple and rapid high-throughput combinatory antimicrobial screening of volatile compounds simultaneously in vapour and liquid phase and that it allows determination and comparison of MIC and FIC values in both, liquid and solid media.

Screening of in vitro antimicrobial activity of plants used in traditional Indonesian medicine.

CONTEXT: In many regions of Indonesia, there are numerous traditional herbal preparations for treatment of infectious diseases. However, their antimicrobial potential has been poorly studied by modern laboratory methods. OBJECTIVE: This study investigates in vitro antimicrobial activity of 49 ethanol extracts from 37 plant species used in Indonesian traditional medicine for treatment against Candida albicans, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. MATERIALS AND METHODS: The plants were collected from the Biopharmaca collection garden, Bogor, Indonesia. The plant material was dried, finely grounded, extracted using ethanol, concentrated, and the dried residue was dissolved in 100% DMSO. Antimicrobial activity was determined in terms of a minimum inhibitory concentration (MIC) using a broth microdilution method in 96-well microplates. RESULTS: The extract of Orthosiphon aristatus (Blume) Miq. (Lamiaceae) leaf produced the strongest antimicrobial effect, inhibiting the growth of C. albicans (MIC 128 µg/mL), S. aureus (MIC 256 µg/mL), E. faecalis (MIC 256 µg/mL) and P. aeruginosa (MIC 256 µg/mL). The leaf extract of Woodfordia floribunda Salisb. (Lythraceae) also exhibited significant effect against C. albicans (MIC 128 µg/mL), S. aureus (MIC 256 µg/mL) and E. faecalis (MIC 256 µg/mL). Rotheca serrata (L.) Steane & Mabb. (Lamiaceae) leaf extract inhibited the growth of S. aureus (MIC 256 µg/mL) and C. albicans (MIC 256 µg/mL). DISCUSSION AND CONCLUSIONS: The leaf extract of O. aristatus and W. floribunda exhibited a significant anti-candidal effect. Therefore, both of these plants can serve as prospective source materials for the development of new anti-candidal agents.

Evaluation of antibacterial potential and toxicity of plant volatile compounds using new broth microdilution volatilization method and modified MTT assay.

With aim to develop effective proof-of-concept approach which can be used in a development of new preparations for the inhalation therapy, we designed a new screening method for simple and rapid simultaneous determination of antibacterial potential of plant volatiles in the liquid and the vapour phase at different concentrations. In addition, EVA (ethylene vinyl acetate) capmat™ as vapour barrier cover was used as reliable modification of thiazolyl blue tetrazolium bromide (MTT) assay for cytotoxicity testing of volatiles on microtiter plates. Antibacterial activity of carvacrol, cinnamaldehyde, eugenol, 8-hydroxyquinoline, thymol and thymoquinone was determined against Haemophilus influenzae, Staphylococcus aureus, and Streptococcus pneumoniae using new broth microdilution volatilization method. The cytotoxicity of these compounds was evaluated using MTT test in lung fibroblast cells MRC-5. The most effective antibacterial agents were 8-hydroxyquinoline and thymoquinone with the lowest minimum inhibitory concentrations (MICs) ranging from 2 to 128µg/mL, but they also possessed the highest toxicity in lung cell lines with half maximal inhibitory concentration (IC50) values 0.86-2.95µg/mL. The lowest cytotoxicity effect was identified for eugenol with IC50 295.71µg/mL, however this compound produced only weak antibacterial potency with MICs 512-1024µg/mL. The results demonstrate validity of our novel broth microdilution volatilization method, which allows cost and labour effective high-throughput antimicrobial screening of volatile agents without need of special apparatus. In our opinion, this assay can also potentially be used for development of various medicinal, agricultural, and food applications that are based on volatile antimicrobials.

Phenolic composition, antioxidant and anti-proliferative activities of edible and medicinal plants from the Peruvian Amazon

ABSTRACT Among 23 extracts of medicinal and edible plants tested, Mauritia flexuosa L.f., Arecaceae, showed significant antioxidant ability (DPPH and ORAC = 1062.9 and 645.9 ± 51.4 µg TE/mg extract, respectively), while Annona montana Macfad., Annonaceae, demonstrated the most promising anti-proliferative effect (IC50 for Hep-G2 and HT-29 = 2.7 and 9.0 µg/ml, respectively). However, combinatory antioxidant/anti-proliferative effect was only detected in Oenocarpus bataua Mart., Arecaceae (DPPH = 903.8 and ORAC = 1024 µg TE/mg extract; IC50 for Hep-G2 and HT-29 at 102.6 and 38.8 µg/ml, respectively) and Inga edulis Mart., Fabaceae (DPPH = 337.0 and ORAC = 795.7 µg TE/mg extract; IC50 for Hep-G2 and HT-29 at 36.3 and 57.9 µg/ml, respectively). Phenolic content was positively correlated with antioxidant potential, however not with anti-proliferative effect. None of these extracts possessed toxicity towards normal foetal lung cells, suggesting their possible use in development of novel plant-based agents with preventive and/or therapeutic action against oxidative stress-related diseases.

In Vitro Digestibility of Aluminum from Hibiscus sabdariffa Hot Watery Infusion and Its Concentration in Urine of Healthy Individuals.

Increased ingestion of aluminum (Al) can lead to its accumulation in the human body, especially in people with kidney problems. Al is also associated with several nervous diseases and its negative influence on embryo development during pregnancy has been proven in animal models. Hibiscus sabdariffa L. petals are widely used alone or in fruit tea formulas, which are recommended for drinking during pregnancy instead of tea. Its petals can contain similar and even higher amounts of Al as tea, which is a known Al accumulator. Our research investigated whether the regular intake of H. sabdariffa infusion leads to increased burden of Al. Sixteen days of ingestion of H. sabdariffa infusion (c Al = 0.5 mg.L-1) led to increased but unbalanced levels (15-86 µg L-1) of Al in urine compared to a period when the infusion was not ingested. The highest amounts of Al excreted were observed every third day during the ingestion. Mild health problems, such as nausea and dizziness (which could be related to plant properties) were reported by more sensitive volunteers.Our results suggest that the tea infusion from H. sabdariffa petals increases body burden of Al and, therefore, sensitive individuals as pregnant women and people with kidney problems should be cautious with excessive consumption of hibiscus infusion or fruit teas containing this plant. However, further study including more individuals is needed to fully confirm our preliminary results.

Antifungal and Antibacterial Activity of Extracts and Alkaloids of Selected Amaryllidaceae Species.

Alkaloidal extracts of six selected species of Amaryllidaceae were studied with respect to their antibacterial and anti-yeast activity and their alkaloidal fingerprint. Twenty-five alkaloids were determined by GC/MS, and sixteen of them identified from their mass spectra, retention times and retention indexes. In the antimicrobial assay, Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were used, along with isolates of the human pathogenic yeasts Candida albicans, C. glabrata, C. dubliniensis and Lodderomyces elongiosporus. The six extracts, together with 19 Amaryllidaceae alkaloids isolated in our laboratory, showed almost no inhibitory activity against the bacteria tested. However, promising anti-yeast properties were detected; the most potent activity was shown by lycorine, which inhibited C. dubliniensis with a MIC of 32 µg/mL, C. albicans and L. elongiosporus, both with MICs of 64 µg/mL, followed by caranine inhibiting C. dubliniensis with a MIC of 128 µg/mL. Among the alkaloidal extracts, Narcissus jonquilla cv. Baby Moon showed the most potent anti-yeast activity, with minimal and average MIC values of 128 and 192 µg/mL, respectively, followed by Leucojum aestivum, Narcissus poeticus var. recurvus and N. canaliculatus (average MICs 256, 267 and 299 µg/mL, respectively). The lowest MIC value among extracts was obtained for N. canaliculatus against L. elongiosporus (MIC 64 µg/mL).

In vitro antimicrobial activity of plants used in traditional medicine in Gurage and Silti Zones, south central Ethiopia.

BACKGROUND: To overcome the escalating problems associated with infectious diseases and drug resistance, discovery of new antimicrobials is crucial. The present study aimed to carry out in vitro antimicrobial analysis of 15 medicinal plant species selected according to their traditional medicinal uses in Gurage and Silti Zones, south central Ethiopia. METHODS: Ethanol extracts of various plant parts were investigated for their antimicrobial activity against 20 bacterial and one yeast strains. The minimum inhibitory concentration (MIC) was determined by broth microdilution method. RESULTS: Asparagus africanus, Guizotia schimperi, Lippia adoensis var. adoensis and Premna schimperi were active against Candida albicans, Enterococcus faecalis and Staphylococcus aureus at a concentration of 512 µg/ml or lower. Strong antibacterial activity (MIC≥128 µg/ml) was observed for G. schimperi extract against 17 resistant and sensitive Staphylococcus strains, at a concentration comparable to standard antibiotics. Moreover, this extract showed higher antibacterial activity for the test against S. aureus ATCC 33591, ATCC 33592, SA3 and SA5 strains (128-256 µg/ml) than oxacillin (512 µg/ml). CONCLUSIONS: The study revealed in vitro antibacterial activity of plants used in folk medicine in south central Ethiopia. The usefulness of these plants, in particular of G. schimperi, should be confirmed through further phytochemical and toxicity analyses.

Composition and Antimicrobial Activity of Euphrasia rostkoviana Hayne Essential Oil.

Eyebright, Euphrasia rostkoviana Hayne (Scrophulariaceae), is a medicinal plant traditionally used in Europe for the treatment of various health disorders, especially as eyewash to treat eye ailments such as conjunctivitis and blepharitis that can be associated with bacterial infections. Some Euphrasia species have been previously reported to contain essential oil. However, the composition and bioactivity of E. rostkoviana oil are unknown. Therefore, in this study, we investigated the chemical composition and antimicrobial activity of the eyebright essential oil against some organisms associated with eye infections: Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, and Candida albicans. GC-MS analysis revealed more than 70 constituents, with n-hexadecanoic acid (18.47%) as the main constituent followed by thymol (7.97%), myristic acid (4.71%), linalool (4.65%), and anethole (4.09%). The essential oil showed antimicrobial effect against all organisms tested with the exception of P. aeruginosa. The best activity was observed against all Gram-positive bacteria tested with the minimum inhibitory concentrations of 512 µg/mL. This is the first report on the chemical composition of E. rostkoviana essential oil and its antimicrobial activity.

In Vitro Antistaphylococcal Effects of Embelia schimperi Extracts and Their Component Embelin with Oxacillin and Tetracycline.

Bacterial infections are in less-developed countries traditionally treated by remedies prepared from medicinal plants. Embelia schimperi (Vatke) is a plant used as a taenicide or disinfectant in Ethiopia, very often taken mixed with another plant species. In the present study, we examined two extracts prepared from seeds and twigs with leaves of E. schimperi and its main present secondary metabolite embelin for their antibacterial combinatory effect with oxacillin and tetracycline against sensitive and resistant Staphylococcus aureus strains. Minimum inhibitory concentrations were determined through the broth microdilution method, whereas the combinatory effect was evaluated through fractional inhibitory concentration sum (ΣFIC) indices. Results show many positive interactions and synergy occurring in embelin and oxacillin combinations against 4 out of 9 strains (ΣFIC 0.203-0.477) and for embelin and tetracycline combination against 3 out of 9 strains (ΣFIC 0.400-0.496). Moreover, the resistance to oxacillin has been overcome in 2 strains and to tetracycline in 3 strains. According to our knowledge, this is the first study showing antimicrobial combinatory effect of E. schimperi as well as of embelin. These findings can be used for the further research targeted on the development of new antistaphylococcal agents.