Foliar-applied nano-cerium dioxide differentially affect morpho-physiological traits and essential oil profile of Salvia mirzayanii Rech. f. & Esfand under drought stress and post-stress recovery conditions.

Drought stress is known to diminish the growth and yield of plants by altering the physiological, biochemical and molecular processes, thus threatening food security worldwide. Nanoparticles (NPs) have emerged as an effective strategy to raise plant productivity under current rapid environmental challenges. However, there is little literature on mechanisms underlying the beneficial role of re-watering in drought-stressed plants treated with NPs. In this study, the effects of cerium dioxide nanoparticles [(CeO2 NPs), 0 (control), 125, 250, 500, and 1000 mL L-1] were investigated on morpho-physiological and phytochemical traits of Salvia mirzayanii plants under different drought stress intensities [(25%, 50%, 75%, and 100% (control) of field capacity (FC) moisture] and post-stress re-watering (recovery) in a three-way factorial arrangement based on randomized complete block design. Uptake and accumulation of CeO2 NPs in the leaf tissue of plant samples were confirmed using SEM and EDX techniques. The results of ANOVA demonstrated that growth and physio-phytochemical traits were significantly (p < 0.05) affected by individual treatment and/or their double and triple interactions. Exposure to various levels of CeO2 NPs during drought stress mitigated the adverse effects of stress on growth parameters (e.g., plant height, shoot and root dry weights, and root length) and photosynthetic pigments (chlorophyll a and b) content compared to the respective controls in varying degrees. However, proline and essential oil content were increased in drought-stressed plants, and tended to decrease during the period of recovery. Before re-watering, the antioxidant enzymes, CAT, POD, and SOD, activity in leaf tissues was increased with the increase of drought stress intensity upon both treated and non-treated CeO2 NPs conditions. However, the three-way interaction results demonstrated that recovery after drought stress following CeO2 NPs application particularly 1000 mL L-1 decreased the activity of antioxidant enzymes compared to the controls. Based on GC and GC-MS analysis, all essential oil samples predominantly composed of oxygenated monoterpenes and sesquiterpenes including Decane, Spathulenol, Octane, α-Terpinyl acetate, Hexyl isovalerate, Dodecane, Butanoic acid, Linalool, δ-Cadinene, Muurolol, α-Cadinol, Eudesm-7(11)-en-4-ol, which significantly (p < 0.05) changed under different experimental treatments. The recovery after stress, however, increased only the content of δ-Cadinene in plants from severe drought stress upon foliar application of 1000 mL L-1 CeO2 NPs compared to the non-recovery period. Conclusively, integrative use of CeO2 NPs and re-watering after drought stress could be an encouraging and eco-friendly strategy to improve both drought tolerance, growth and pyhtochemical contents in S. mirzayanii plants.

Chemical composition and biological effects of three different types (tear, paste, and mass) of bitter Ferula assa-foetida Linn. gum.

Ferula assa-foetida gum oleoresin (FAGO) is traditionally used for treatment of different ailments. The subject of this article was to evaluate the chemical composition and antibacterial effects of the different types of bitter FAGO essential oils in the natural habitat of Southwest Iran. α-pinene (38.2%), and (Z)-propenyl sec-butyl disulfide (12.4%) were the main components of F. assa-foetida tear type essential oil, with high antibacterial, anti-biofilm and cytotoxic activities, followed by paste and mass types, respectively. α-pinene (27.8%), and (Z)-propenyl-sec-butyl disulfide (24.2%) were identified as main components of paste type. α-pinene (33.4%), ß-pinene (16.3%), and (Z)-propenyl sec-butyl disulfide (16.1%) were the main components of asafoetida mass type gum oleoresin essential oil. FAGO essential oil specially tear one could serve as suitable candidate for further studies.

Usnea sp.: Antimicrobial potential, bioactive compounds, ethnopharmacological uses and other pharmacological properties; a review article.

ETHNOPHARMACOLOGICAL RELEVANCE: Usnea sp. is a fruticose thalli lichen with interesting medicinal properties. Since ancient times, Usnea sp. has been used in traditional medicine worldwide to treat various diseases. The broad scientific studies on this lichen have proved its multidirectional biological effect, such as antimicrobial activity, which is attributed to its usnic acid content. PURPOSE: The main aim of this review is to provide an up-to-date overview of the antimicrobial activities of Usnea sp., including the traditional and medicinal uses, and a critical evaluation of the presented data. Also, the mechanism of this type of action will be explained. METHODS: To prepare this manuscript, the information was extracted from scientific databases (Pubmed, ScienceDirect, Wiley, Springer, and Google Scholar), books, and theses. The available scientific information was critically analysed. RESULTS: Analysis of the scientific literature regarding traditional uses and bioactivity research showed that Usnea sp. extracts exhibit high antibacterial activity. The Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, and Mycobacterium tuberculosis) and aquatic oomycetous fungi were the most sensitive Usnea sp. extracts. Moderate activity against Malassezia furfur and dermatophytes was observed, as well. Gram-negative bacteria, yeast, and fungi were more frequently resistant to Usnea sp. extracts (included Escherichia coli, Candida sp., Saccharomyces cerevisiae, and Aspergillus sp.). The antiviral activity of Usnea sp. was limited. CONCLUSION: The results show that the use of Usnea sp. in traditional medicine can be scientifically documented. Studies show that usnic acid is the active compound present in Usnea sp. extracts. This compound, which has a high antibacterial and cytotoxic activity, exists in large quantities in low-polarity extracts, and low concentration in these of high-polarity. Usnea sp. extracts contain compounds other than usnic acid as well with biological effects. Usnea barbata is a species that has been employed in modern-day cosmetic and pharmaceutical preparations. The information presented in the review can be considered as a source of knowledge about the Usnea sp. It presents research on biological properties reported for different species of Usnea genus and thus can facilitate their use in medicine.

Mentha piperita essential oils loaded in a chitosan nanogel with inhibitory effect on biofilm formation against S. mutans on the dental surface.

Mentha piperita essential oils (MPEO) were loaded into chitosan nanogel to use as antibiofilm agent against Streptococcus mutans and to protect its dental plaque. Chitosan nanoparticles (CsNPs) were prepared by sol-gel method using linking bridge of tripolyphosphate (TPP). Physiological properties of MPEO-CNs were assessed by FTIR, SEM/EDX, DLS and zeta potential. Release kinetics, MIC and MBC were determined for MPEO-CNs. Expression of biofilm-associated genes including 8 genes: grfB, C and D, brpA, spaP, gbpB, relA and vicR was investigated at the presence of sub-MIC of MPEO-CNs. Most abundant bioactive compounds of MPEO were l-menthol (45.05%) and l-menthal (17.53%). SEM/EDX exhibited successful entrapment of MPEO into CsNPs followed by the changes in abundance of elemental peaks. A signal at 1737 cm-1 on chitosan spectrum was attributed to the carboxylic (CO) groups overlapped by MPEO incorporation. A new signal at 2361 cm-1 was assigned to electrostatic interactions of amine groups in chitosan with phosphoric units of TPP within the MPEO-chitosan. MPEO incorporation into porous nanogel decreased monodispersity of the nanoparticles and then raises z-average. Maximum release of MPEO was about 50% during 360 h in a hydroalcoholic solvent at ambient temperature. The adherence of bacterial cells showed high sensitivity to the nanoformulation of MPEO compared with unloaded chitosan-nanogel. Antibiofilm inhibition of S. mutans occurred in 50 and 400 µg/mL for MPEO-CNs and unloaded-nanogel, respectively. Among biofilm synthesis genes, gtfB, gtfC, gtfD were slightly affected by MPEO-CNs treatment, while gbpB, spaP, brpA, relA, and vicR genes underwent significant down-regulation in the presence of both unloaded-nanogel and MPEO-loaded-nanogel. This study demonstrated that the MPEO-CNs promised an efficient nanoformulation with the greatest inhibitory action against some glycosyltransferase genes (gtfB, C and D) as important enzymes involved in extracellular polymers. Finally, the results concluded that MPEO-CNs have a potential use as antibiofilm agent in toothpaste or mouth washing formulations.

Chemical composition, cytotoxic effect and antimicrobial activity of Stachys koelzii Rech.f. essential oil against periodontal pathogen Prevotella intermedia.

Prevotella intermedia is associated with periodontal diseases and endodontic infections. Periodontitis can be suppressed by utilizing the antiseptics, which target the infectious bacteria. The member of Stachys sp. has been used traditionally in the form of decoction or infusion for management of infectious diseases. The subject of this article was to evaluate the chemical composition, antimicrobial and cytotoxic effect of Stachys koelzii essential oil and its main components against Prevotella intermedia. GC-FID and GC-MS analysis were used to determine the chemical composition. The antimicrobial effects of S. koelzii essential oil was evaluated by micro-broth dilution assay. Time kill curve assays, leakage of cytoplasmic materials and anti-biofilm effects were determined. Its cytotoxic effect was evaluated by MTT assay. Essential oil with main components of α-pinene, trans-caryophyllene and 1,8-cineole inhibited P. intermedia with MIC and MBC values of 0.1 and 0.2 mg/mL. Its biofilm formation was higher than α-pinene, followed by trans-caryophyllene and 1,8-cineole. Essential oil and its main components increased the leakage of cytoplasmic components. Essential oil showed cytotoxic effect on HeLa cell lines with IC50 0.06 mg/mL. The cytotoxic effect of α-pinene on healthy cell lines was higher than essential oil. S. koelzii essential oil can be used in mouthwash formulations and its efficacy should be evaluated in large clinical studies.

INVESTIGATION ON CHEMICAL COMPOSITION, ANTIMICROBIAL, ANTIOXIDANT, AND CYTOTOXIC PROPERTIES OF ESSENTIAL OIL FROM DRACOCEPHALUM KOTSCHYI BOISS.

BACKGROUND: Dracocephalum kotschyi Boiss is a herb with wide-spread applications. Lorestan traditional healers have applied it for the treatment of rheumatoid diseases and stomach disorders. MATERIALS AND METHODS: Hydrodistillation process was used for essential oil extraction, the extracted essential oil was then analyzed through combination of capillary GC-FID, GC-MS and RI. The in vitro antimicrobial, antioxidant and cytotoxic activities of this essential oil were examined. Results indicate that the essential oil has a broad range of anti-microbial activity against all of the tested microorganisms. RESULTS: The 50% of cytotoxic concentrations was 26.4 µg/ml and 4266.7 µg/ml for Hela cells and human lymphocytes, respectively. The oil cytotoxicity against the human tumor cell line was far higher than the amount required for human healthy cells. Conversely, the essential oil's IC50 value of 49.2 µg/ml in the DPPH assay, could be regarded as its strong antioxidant potential. CONCLUSION: According to the data obtained, it can be concluded that D. kotschyi essential oil could be applied as a safe antibacterial and antioxidant agent for food and pharmaceutical purposes.

Inhibition of the mevalonate pathway enhances carvacrol biosynthesis and DXR gene expression in shoot cultures of Satureja khuzistanica Jamzad.

Carvacrol is a major component of Satureja khuzistanica Jamzad (≤90%) that has significant antimicrobial and antioxidant properties. Considering the specific capabilities of S. khuzistanica to produce highly pure carvacrol, this plant is an important potential source of carvacrol that could address the abundant consumption and increasing demand for this monoterpene in current world markets. This research was performed to better understand the process of biosynthesis and accumulation of carvacrol in S. khuzistanica. Tests were performed on shoot cultures of S. khuzistanica in Linsmaier-Skoog (LS) medium treated with different concentrations of fosmidomycin (an inhibitor of the non-mevalonate pathway) and mevinolin (an inhibitor of the mevalonate pathway) for 21 days at the following concentrations: 0, 10, 25, 50, 75 and 100 µM. The present study demonstrated that the MEP pathway is the major pathway that provides IPP for the biosynthesis of carvacrol, and the expression and activity levels of the DXR enzyme have a critical effect on carvacrol biosynthesis. Surprisingly, Mevinolin at concentrations of 75 and 100 µM increased the carvacrol content and the DXR activity and gene expression in S. khuzistanica plantlets.