Chemical composition and antimicrobial activity of the essential oils of four Ocimum species growing in Tanzania

Phytochemistry, Biological, and Pharmacological Properties of Abies alba Mill

Abies alba Mill. (Pinaceae), silver fir, is a widespread gymnosperm species in Europe, important for its ecological, economic, social, and cultural significance, as well as for its use for food and bioremediation purposes. The various parts of the plant (leaves, branches, cones, wood, bark) are also of pharmaceutical interest due to their composition of active compounds. In the last three decades, an impressive amount of research has been dedicated to this species. The variability of the chemical composition of essential oils (whether they come from leaves, oleoresin from branches, or other parts of the plant) is impressive, even in the case of specimens collected from the same geographical area. For essential oils prepared from needles or twigs and branches, limonene, β-pinene, α-pinene, camphene, β-phellandrene, and bornyl acetate are the leading compounds, although their wide variations seem to correspond to multiple chemotypes. Both bark and wood are rich in lignans and phenolic compounds. Matairesinol is apparently the dominant lignan in bark, and secoisolariciresinol and lariciresinol are the dominant ones in wood samples. Pharmacological studies with promising results have evaluated the antioxidant effect (mainly due to essential oils), but also the antimicrobial, antitumor, probiotic, antidiabetic, anti-steatosis, and anti-psoriatic activities.

Bornyl acetate: A promising agent in phytomedicine for inflammation and immune modulation

BACKGROUND

Bornyl acetate (BA), as a bicyclic monoterpene, is an active volatile component widely found in plants across the globe. BA can be used as essence and food flavor agent and is widely used in perfumes and food additives. It remains a key component in several proprietary Chinese medicines.

PURPOSE

This review summarized the pharmacological activity and research prospects of BA, making it the first of its kind to do so. Our aim is to provide a valuable resource for those pursuing research on BA.

METHODS

Databases including PubMed, Web of Science, and CNKI were used based on search formula "(bornyl acetate) NOT (review)" from 1967 to 2022. For the relevant knowledge of TCM, we quoted Chinese literature. Articles related to agriculture, industry, and economics were excluded.

RESULTS

BA showed rich pharmacological activities: It inhibits the NF-κB signal pathway via affecting the phosphorylation of IKB and the production of IKKs, inhibits the MAPK signal pathway via inhibiting the phosphorylation of ERK, JNK, and p38, down-regulates pro-inflammatory cytokines such as TNF-α, IL-1β, IL-6, up-regulates IL-11, reduces NO production, regulates immune response via up-regulating CD86⁺, decreases catecholamine secretion, and reduces tau protein phosphorylation. In addition to the pharmacological activities of BA, its toxicity and pharmacokinetics were also discussed in this paper.

CONCLUSION

BA has promising pharmacological properties, especially anti-inflammatory and immunomodulatory effects. It also has sedative properties and potential for use in aromatherapy. Compared to traditional NSAIDs, it has a more favorable safety profile while maintaining efficacy. BA has potential for developing novel drugs for treating various conditions.

In Vitro Anticancer and Antibacterial Activities of the Essential Oil of Forsskal’s Basil Growing in Extreme Environmental Conditions

Many species belonging to the genus Ocimum are used for aromatic, medicinal, and cosmetic purposes. The essential oil (OFEO) obtained by hydrodistillation of the flowering aerial parts of Forsskal’s Basil “Ocimum forskolei Benth” growing in extreme environmental conditions in Mecca Region, Saudi Arabia was analyzed by GC-MS. The main constituents were phenylpropanoids (methyl eugenol 55.65% and eugenol 11.66%), monoterpene (linalool 9.75%), and sesquiterpenes (germacrene D 3.72% and β-caryophyllene 2.57%). The OFEO was tested against MCF7, HT29, and HCT116 cancer cells and compared with normal fibroblast cells (MRC5). The MTT assay showed that HCT116 was more sensitive to OFEO (IC50 5.34 μg/mL), which reduced the number of HCT116 colonies at 6 μg/mL, while causing complete colony death at 12 and 24 μg/mL. Western Blotting and qRT-PCR were used to evaluate the level change of different proteins with respect to GAPDH. OFEO upregulated the apoptotic protein (caspase 3), and downregulated the cell proliferation proteins (AKT and pAKT), cell cycle arrest (PCNA, Cyclin D1), and the anti-apoptotic Bcl2 proteins. OFEO was also tested against reference strains of Gram-negative and Gram-positive bacteria including Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, and Staphylococcus aureus by using the well-diffusion and assessing their MICs, which ranged from 250 to 500 μg/mL.

Ecological Preferences and Diversity of Essential Oil Composition in Endangered Wild-Growing Populations of Sideritis sipylea Boiss. (Lamiaceae) of the East Aegean Islands (Greece): Evidencing Antioxidant Potential, Antimicrobial and Cytotoxic Activities

Plants from the genus Sideritis (Lamiaceae) have been widely used in folk medicine for a long time and consequently are a focus of the scientific community. Despite this interest, explicit data about the essential oils (EOs) of the Endangered Sideritis sipylea have not been readily available to date. In this study, we investigated the ecological preferences of Greek S. sipylea and the chemical composition of the essential oils of wild-growing S. sipylea populations from two Greek islands (S1: Samos, S2: Lesvos); we explored concomitant associations with environmental factors; and we assessed their (i) antioxidant potential (two tests), (ii) antimicrobial activity against six microbial and two fungal strains, and (iii) cytotoxic effect in two human and one murine cell lines. We compiled an ecological profile in R based on all known Greek localities of S. sipylea, outlining for the first time its preferences regarding temperature (3.48 ± 1.53 °C to 30.70 ± 1.11 °C) and the precipitation regimes (5.92 ± 2.33 mm to 136 ± 11.43 mm) shaping its natural occurrence in the wild. The chemical analysis (42 compounds in total) confirmed the domination of monoterpene hydrocarbons in both samples (with quantitative and qualitative differences) and identified 12 new constituents reported in S. sipylea for the first time (e.g., Bicyclogermacrene and Cumacrene). Dominant compounds in S1 (39 constituents) were β-Myrcene (20.4%) followed by β-caryophyllene (11.8%), bicyclogermacrene (7.1%), β-pinene (6.3%), carvacrol (6.2%) and α-terpinene (6.1%), whereas in S2 (26 constituents) the main ones were α-pinene (37.3%), β-pinene (15.1%) and sabinene (12.1%), followed by β-caryophyllene (5.6%) and bicyclogermacrene (5.5%). The strong antioxidant capacity and cytotoxic activity of S. sipylea EOs are reported herein for the first time, while new insight is provided regarding their effect on bacterial and fungal strains (four ones originally tested herein). The biological activity analysis demonstrated variation among samples, with S2 being more potent than S1. Altogether, the results of the present study demonstrate the high biological potential of S. sipylea EOs with an interesting antioxidant capacity and antimicrobial and cytotoxic effects and reveal associations of natural chemodiversity with climatic factors.

A Comprehensive Review on the Biological, Agricultural and Pharmaceutical Properties of Secondary Metabolites Based-Plant Origin

Natural products are compounds produced by living organisms and can be divided into two main categories: primary (PMs) and secondary metabolites (SMs). Plant PMs are crucial for plant growth and reproduction since they are directly involved in living cell processes, whereas plant SMs are organic substances directly involved in plant defense and resistance. SMs are divided into three main groups: terpenoids, phenolics and nitrogen-containing compounds. The SMs contain a variety of biological capabilities that can be used as flavoring agents, food additives, plant-disease control, strengthen plant defenses against herbivores and, additionally, it can help plant cells to be better adapted to the physiological stress response. The current review is mainly focusing on certain key elements related to the significance, biosynthesis, classification, biochemical characterization and medical/pharmaceutical uses of the major categories of plant SMs. In addition, the usefulness of SMs in controlling plant diseases, boosting plant resistance and as potential natural, safe, eco-friendly substitutes for chemosynthetic pesticides were also reported in this review.

Sub-chronic toxicity of the aqueous leaf extract of Ocimum lamiifolium Hochst. ex Benth on biochemical parameters and histopathology of liver and kidney in rats: in vivo and in- silico toxicity studies

BACKGROUND

The aerial part of Ocimum lamiifolium is commonly used in Ethiopian traditional medicine. Although this plant is mostly used in traditional medicine, its safety profile has not been documented yet. The aim of this study was to assess the sub-chronic toxicity of O. lamiifolium aqueous extract in rats and to determine the toxicity profile of GC-MS identified bioactive compounds obtained from essential oil of O. lamiifolium using in silico toxicity methods.

METHODS

Eighty rats (40 male and 40 female) were randomly assigned to four groups of ten rats per sex/group. For 90 days, Groups I-III received 200, 400, and 600 mg/kg bw of aqueous extract of O. lamiifolium, respectively. Distilled water was given to Group IV (control). Clinical observations, food intake, and rat weight were all recorded during the experiment. In addition, several biochemical parameters, organ weight, and histology of the liver and kidney were all evaluated. For the in-silico toxicity study, GC-MS identified bioactive compounds in O. lamiifolium essential oil were obtained from published articles. The compounds two-dimensional structures were constructed using Chemdraw. The two-dimensional structures were converted into a simplified molecular input line entry system (SMILES) using the Swiss ADMET web tool. Furthermore, the toxicity parameters were predicted using the ProTox II server.

RESULTS

The administration of an aqueous extract of O. lamiifolium leaves significantly (p < 0.05) reduced the test animals' food intake and body weight gain. In the high dose (600 mg/kg bw) treated group, the serum alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase levels were significantly increased (p < 0.05). In female rats given 600 mg/kg bw of O. lamiifolium, the levels of serum urea were also increased. In addition, rats given 600 mg/kg bw had significantly lower blood glucose levels than the control group (p < 0.05). Doses up to 400 mg/kg bw didn't bring a significant change to the histology of the liver. However, in the high dose (600 mg/kg bw) treated group, some female rats' livers showed mild sinusoidal and central vein dilatation, as well as parenchymal necrosis. our findings showed that all compounds derived from the essential oil of O. lamiifolium showed no mutagenicity or cytotoxicity. However, 30% of the compounds tested were hepatotoxic, 20% carcinogenic, and 20% immunotoxin.

CONCLUSION

Our findings showed that oral administration of O. lamiifoliums aqueous extract up to a dose of 400 mg/kg bw is not toxic. However, high-dose (600 mg/kg bw) significantly affected the food consumption and weight gain of the experimental rats and the serum concentration of some liver and kidney enzymes were also significantly increased. Additionally, a considerable proportion of the tested compounds were predicted to be hepatotoxic, carcinogenic and immunotoxin. Furthermore, before employing O. lamiifolium preparations as drugs, a chronic toxicity research on the essential oil as well as its components that exhibited toxicity in the in-silico toxicity study is needed. Finally, use high doses of O. lamiifolium leaves with caution.

Ocimum Species: A Review on Chemical Constituents and Antibacterial Activity

Infection by bacteria is one of the main problems in health. The use of commercial antibiotics is still one of the treatments to overcome these problems. However, high levels of consumption lead to antibiotic resistance. Several types of antibiotics have been reported to experience resistance. One solution that can be given is the use of natural antibacterial products. There have been many studies reporting the potential antibacterial activity of the Ocimum plant. Ocimum is known to be one of the medicinal plants that have been used traditionally by local people. This plant contains components of secondary metabolites such as phenolics, flavonoids, steroids, terpenoids, and alkaloids. Therefore, in this paper, we will discuss five types of Ocimum species, namely O. americanum, O. basilicum, O. gratissimum, O. campechianum, and O. sanctum. The five species are known to contain many chemical constituents and have good antibacterial activity against several pathogenic bacteria.

Dissecting dietary and semisynthetic volatile phenylpropenes: A compile of their distribution, food properties, health effects, metabolism and toxicities

Phenylpropenes represent a major subclass of plant volatiles, including eugenol, and (E)-anethole. They contribute to the flavor and aroma of many chief herbs and spices, to exert distinct notes in food, i.e., spicy anise- and clove-like to fruit. Asides from their culinary use, they appear to exert general health effects, whereas some effects are specific, e.g., eugenol being a natural local anesthetic. This review represents the most comprehensive overview of phenylpropenes with respect to their chemical structures, different health effects, and their food applications as flavor and food preservatives. Side effects and toxicities of these compounds represent the second main part of this review, as some were reported for certain metabolites generated inside the body. Several metabolic reactions mediating for phenylpropenes metabolism in rodents via cytochrome P450 (CYP450) and sulfotransferase (SULT) enzymes are presented being involved in their toxicities. Such effects can be lessened by influencing their pharmacokinetics through a matrix-derived combination effect via administration of herbal extracts containing SULT inhibitors, i.e., nevadensin in sweet basil. Moreover, structural modification of phenylpropanes appears to improve their effects and broaden their applications. Hence, such review capitalizing on phenylpropenes can help optimize their applications in nutraceuticals, cosmeceuticals, and food applications.

Antidiarrheal Effect of 80% Methanol Extract and Fractions of the Leaves of Ocimum lamiifolium in Swiss Albino Mice

Introduction

Worldwide, in children of under five years of age, diarrhea is responsible for more than 760,000 annual deaths. It is treated with both modern drugs and traditional medicinal plants, including O. lamiifolium. But the use of this plant as an antidiarrheal agent is not scientifically validated. Therefore, this study was aimed to evaluate antidiarrheal efficacy of the plant.

Method

The leaf powder was macerated by 80% methanol and then fractionated using n-hexane, n-butanol, and distilled water. Antidiarrheal activity was evaluated through different models (castor oil-induced diarrhea, enteropooling, and motility) using onset, number of wet feces, fluid content, weight and volume of intestinal content, and motility as test parameters by administering treatment doses to groups of mice. Group I received 10 mL/kg of the dissolving vehicle, Group II received either loperamide or atropine, and Groups III-V received extract doses of 100, 200, and 400 mg/kg, respectively. One-way ANOVA was used to analyze the data, followed by Tukey's post-hoc test.

Results

The crude extract exhibited a significant effect on the fluid content of feces at all tested doses. Additionally, the n-butanol and distilled water fractions revealed significant effects on onset of diarrhea at 400 mg/kg (p < 0.05), while the n-hexane fraction showed significant effects on number of wet feces, onset, and fluid content of feces at all tried doses. The crude extract and all the fractions (at 200 and 400 mg/kg) decreased the weight and volume of intestinal content significantly. Similarly, both the crude extract and distilled water fraction at 400 mg/kg as well as n-butanol and n-hexane fractions at 200 and 400 mg/kg showed meaningful differences on peristaltic index as compared to the negative control.

Conclusion

The results revealed that the leaf extract of O. lamiifolium has an antidiarrheal activity, which supports the traditional medical practice.

Effect of Germacrene-Rich Essential Oil of Parentucellia latifolia (L.) Caruel Collected in Central Sicily on the Growth of Microorganisms Inhabiting Historical Textiles

In the present study, the chemical composition of the essential oil from aerial parts of Parentucellia latifolia (L.) Caruel collected in Central Sicily was analyzed by gas chromatography and gas chromatography–mass spectrometry. The results showed the presence of sesquiterpene hydrocarbons, with germacrene D and germacrene B accounting, respectively, for 59.2% and 24.3% of the total oil. Different colonies of bacteria and fungi frequently affect cellulosic objects such as books stored in libraries and museums. The antibacterial and antifungal activity against some microorganisms infesting historical-artistic craftsmanship was determined, demonstrating that the essential oil was particularly active against Bacillus subtilis, Staphylococcus aureus, and Proteus vulgaris.

Physicochemical Properties, Antioxidant and Antimicrobial Activities of Ethiopian Sweet Basil (Ocimum basilicum L.) Leaf and Flower Oil Extracts

BACKGROUND

The occurrence of multidrug resistant pathogenic microbes has initiated the development of natural antimicrobial agents from plants. Oils from herbal sources have drawn scientific interest due to their potential source of bioactive compounds.

OBJECTIVE

This study was aimed to examine the physicochemical and biological activities including antioxidant and antimicrobial potential of the oil extracted from basil leaves and flowers.

METHODS

The physicochemical properties of the oil extracts were measured based on oil yield, specific gravity, acid value, free fatty acids and peroxide values whilst the antioxidant activities were assessed by ascorbic acid, DPPH (2, 2- diphenyl-1-picrylhydrazyl), and hydrogen peroxide free radical scavenging activities. The antimicrobial experiment was conducted based on disc diffusion and broth dilution methods.

RESULTS

The result of antioxidant activity of Ocimum basilicum indicated significantly higher DPPH (86.45%) for leaf oil extract. The strongest antibacterial activity with maximum zone of inhibition (15.47 mm), minimum inhibitory concentration MIC (0.09 μg/ml), and corresponding minimum bactericidal concentration MBC (0.19 μg/ml) was exhibited by the flower oil extract against Staphylococcus aureus ATCC-25923. The strongest antifungal activity with maximum zone of inhibition (15.90 mm), MIC (0.125 μg/ml, the least value), and minimum fungicidal concentration MFC (0.09 μg/ml) were recorded for leaf oil against Candida albicans.

CONCLUSION

It can be concluded from the present study that the sweet basil flower and leaf oil extracts can be potential antioxidant, antibacterial, and antifungal agents.

Original Contributions to the Chemical Composition, Microbicidal, Virulence-Arresting and Antibiotic-Enhancing Activity of Essential Oils from Four Coniferous Species

This study aimed to establish the essential oil (EO) composition from young shoots of Picea abies, Larix decidua, Pseudotsuga menziesii, and Pinus nigra harvested from Romania and evaluate their antimicrobial and anti-virulence activity, as well as potential synergies with currently used antibiotics. The samples' EO average content varied between 0.62% and 1.02% (mL/100 g plant). The mono- and sesquiterpene hydrocarbons were dominant in the composition of the studied EOs. The antimicrobial activity revealed that the minimum inhibitory concentration (MIC) values for the tested EOs and some pure compounds known for their antimicrobial activity ranged from 6.25 to 100 µL/mL. The most intensive antimicrobial effect was obtained for the Pinus nigra EO, which exhibited the best synergistic effect with some antibiotics against Staphylococcus aureus strains (i.e., oxacillin, tetracycline, erythromycin and gentamycin). The subinhibitory concentrations (sMIC) of the coniferous EOs inhibited the expression of soluble virulence factors (DN-ase, lipase, lecithinase, hemolysins, caseinase and siderophore-like), their efficiency being similar to that of the tested pure compounds, and inhibited the rhl gene expression in Pseudomonas aeruginosa, suggesting their virulence-arresting drug potential.

Bacteriocin producing microbes with bactericidal activity against multidrug resistant pathogens

BACKGROUND

Bacteriocins are proteins or peptides synthesized by bacteria that show inhibitory or killing activities against various bacteria. Bacteriocins are mainly considered for effective alternatives to different commercial antibiotics, preservatives in the food and pharmaceutical industries.

OBJECTIVES

To screen and analyze novel bacteriocin-producing bacteria from the fermented food shidal for antibacterial activity against food pathogens and their molecular interactions studied through computationally.

METHODS

In this study, a strain Lactobacillus plantarum LA21 was isolated from the fermented food shidal identified based on morphological, biochemical, and 16S rDNA gene sequencing. The potent bacterium was subjected to improve bacteriocins production and characterized. Antimicrobial activity against drug-resistant bacteria and minimum inhibitory concentration (MIC) were determined. The bacteriocin was treated with proteolytic enzymes, and the mechanism of action on food pathogens was analyzed. Molecular docking studies were carried out as GLIDE module in the maestro tool of Schrodinger Software.

RESULTS

Bacteriocin was effective against pathogens such as Bacillus pumilus, Bacillus amyloliquefaciens, Staphylococcus aureus, and Listeria monocytogenes, with the most negligible MIC value was detected in L. monocytogenes. Furthermore, the depleted viability of bacterial cells indicated bacteriocin-induced cell lysis in L. monocytogenes via bactericidal activity. In addition, proteolytic enzyme digested bacteriocins revealed bacteriocin-like substances. Finally, molecular docking was performed to study the interactions between the targets and bacteriocins, results in relative intense contact with minimally 3 Å distance.

CONCLUSIONS

The characteristic features of these bacteriocin-like molecules revealed that L. plantarum LA21 is a novel bacteriocin-producing bacterial strain to prepare novel antimicrobial drugs, feed additives or preservatives for future use in livestock and food industries.

Authentication of holy basil using markers relating to a toxicology-relevant compound

Holy Basil—Ocimumtenuiflorum—is one of the popular new “superfoods” thought to act as an antioxidant and to reduce stress and anxiety. However, it is often surrogated with other Ocimum species differing in their chemical profiles that may even pose health risks to the consumers. Moreover, even specific chemotypes of Holy Basil itself can be toxicologically relevant, because they sometimes contain the carcinogen compound methyleugenol. Using DNA barcoding based on plastidic markers, O.tenuiflorum can be differentiated from other species of Ocimum. However, this approach is still suboptimal in handling larger sample numbers and in tracing chemotypes that accumulate methyleugenol. We have, therefore, designed a trait-related DNA barcode based on the enzyme eugenol O-methyltransferase (EOMT), responsible for the synthesis of methyleugenol. We show that a multiplex PCR combining trait-related and trait-independent markers can differentiate O.tenuiflorum from other Ocimum species and identify methyleugenol chemotypes of O.tenuiflorum, even in dried material sold as mixtures.

Molecular docking analysis and evaluation of the antibacterial and antioxidant activities of the constituents of Ocimum cufodontii

Ocimum cufodontii ((Lanza) A.J.Paton) has been traditionally used in Ethiopia against bacteria. The extracts of the leaves and roots of O. cufodontii after silica gel column chromatography furnished compounds 1–5, compounds 3 and 4 are new natural products. The oil from the hydro-distillation of the leaves, after analyzed with GC–MS, has led to the identification of β-caryophyllene as a principal component, suggesting the essential oil as medicine and spices to enhance the taste of food. The constituents of O. cufodontii were assessed for their antibacterial activity against E. coli, K. pneumonia, S. typhymurium and S. aureus. The best activity was displayed against S. aureus by the hexane extract of the roots, compound 4, and the essential oil with an inhibition zone of 17, 15, and 19 mm, respectively. Molecular docking analysis revealed that compound 1 has better docking efficiency and forms hydrophobic interactions with five amino acids (ARG192, PHE196, GLU185, GLU193, and LYS189). This suggests that the compounds may act as potential inhibitors of DNA gyrase. The constituents were also assessed for their antioxidant activities using DPPH, ferric thicyanate and ferric reducing power assay. The hexane extracts of the roots inhibited the DPPH radical and peroxide formation by 90.5 and 83%, respectively, suggesting the potential of the extract as an antioxidant. Furthermore, the hexane extract of the roots of O. cufodontii exhibited the maximum reducing power compared with the EtOAc and methanol extracts. Hence, the activity displayed herein indicated as the plant has great potential as a remedy for diseases caused by bacteria and radicals.

Strong and nonspecific synergistic antibacterial/antibiofilm impact of nano-silver biosynthesized and decorated with active ingredients of Oscimum basilicum L

In this study, Ocimum basilicum (a proven broad spectrum medicinal plant for broad-spectrum pharmacological activities) leaf extract was used as conjugates for the fabrication of silver nanoparticles (AgNP). Color change of the reaction mixture and UV-Visible spectrophotometry indicated the fabrication of silver nanoparticles, further X-ray diffraction (XRD) crystallography, scanning electron microscopy (SEM), transmission electron microscopic images (TEM), and Selected area electron diffraction (SAED) confirms the purity, monodispersity, and morphology including size (22.4 nm) and conjugated functional group of Ocimum basilicum. The conjugation of functional OH, N-O, and C=O groups was confirmed by Fourier-transform infrared spectroscopy (FT-IR). The engineered AgNP have shown significantly efficient antibacterial and antibiofilm activities (92.7% biofilm inhibition) on diverse clinical strains and thus showed its potential for use in clinical applications.

Antioxidant and Antibacterial Activities of the Essential Oil of Moroccan Tetraclinis articulata (Vahl) Masters

The purpose of this study is to evaluate and compare the antioxidant and antibacterial activities of essential oil isolated from Tetraclinis articulata (Vahl) leaves, Masters originating in Morocco (Benslimane Region, Atlantic-influenced plain). The analysis of the major compounds of essential oil was performed by gas chromatography and mass spectrometry, and this oil is dominated by bornyl acetate (35.05%), camphor (11.17%), and α-pinene (10.84%). The antioxidant properties were evaluated by the test of the radical trap 2,2-diphényl-1-picrylhydrazyl (DPPH), and the antimicrobial activity of T. articulata essential oil was tested against clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli which have been inhibited from the 25 μg/mL.

Antimicrobial Terpenoids as a Potential Substitute in Overcoming Antimicrobial Resistance

There was a golden era where everyone thought that microbes can no longer establish threat to humans but the time has come where microbes are proposing strong resistance against the majority of antimicrobials. Over the years, the inappropriate use and easy availability of antimicrobials have made antimicrobial resistance (AMR) to emerge as the world's third leading cause of death. Microorganisms over the time span have acquired resistance through various mechanisms such as efflux pump, transfer through plasmids causing mutation, changing antimicrobial site of action, or modifying the antimicrobial which will lead to become AMR as the main cause of death worldwide by 2030. In order to overcome the emerging resistance against majority of antimicrobials, there is a need to uncover drugs from plants because they have proved to be effective antimicrobials due to the presence of secondary metabolites such as terpenoids. Terpenoids abundant in nature are produced in response to microbial attack have huge potential against various microorganisms through diverse mechanisms such as membrane disruption, anti-quorum sensing, inhibition of protein synthesis and ATP. New approaches like combination therapy of terpenoids and antimicrobials have increased the potency of treatment against various multidrug resistant microorganisms by showing synergism to each other.

A Systematic Review of the Effects of Satureja Khuzestanica Jamzad and Zataria Multiflora Boiss against Pseudomonas Aeruginosa

BACKGROUND

The use of antibiotics is common, but its excessive or improper use leads to antibiotic resistance. Consequently, scientists have been interested in exploring traditional medicine to identify a new source of anti-bacterial agents. The present study aimed to conduct a systematic review to determine the anti-bacterial activity of Satureja Khuzestanica Jamzad (SKJ) and Zataria Multiflora Boiss (ZM) essential oils against Pseudomonas Aeruginosa in vitro.

METHODS

A comprehensive literature search for studies published on SKJ and ZM was carried out. Various keywords (S. Khuzestanica, Marzeh-e-Khuzestani, Z. Multiflora, Z. Multiflora Boiss; avishan-e-shirazi, shirazi thyme, thymol, carvacrol; P. aeruginosa, Iran, antibacterial effect; traditional medicine, phytomedicine, herbal medicine) were used to search both international and Iranian databases (Google Scholar, Science Direct, Web of Science, MEDLINE; PubMed, Scopus, Cochrane Library, Academic Search; Journal Storage, Magiran, Irandoc, Scientific Information Database (SID), and IranMedex). The selected articles were published during 2000-2017 and were written in English or Persian.

RESULTS

Seventeen articles were included in the review. The main ingredients of SKJ and ZM plants were carvacrol and thymol. The potential anti-bacterial activity of essential oils from these plants was confirmed. The carvacrol content, as the major active ingredient of SKJ was between 38.33-97.89%. The major ingredients of ZM were carvacrol (16.8-82.7%) followed by thymol (25.70-64.87%). The minimum inhibitory concentration (MIC) value of SKJ and ZM essential oils against bacterial strains was in the range of 0.31-450 and 2-8,000 μg/mL, respectively.

CONCLUSION

The present review study confirmed the anti-bacterial activity of SKJ and ZM, particularly against Pseudomonas in vitro.

Chemical composition and antimicrobial activities of essential oil from Wedelia urticifolia growing wild in Hunan Province, China

The essential oil obtained from Wedelia urticifolia growing in Hunan Province, China, was analyzed for the first time by capillary GC and GC-MS. A total of 67 constituents, representing 98.68% in essential oil were identified. The major constituents of the oil were: α-pinene (8.85%), limonene (6.38%), carvacrol (6.15%), caryophyllene (6.08%), spathulenol (5.49%), sabinene (5.36%), camphor (4.34%). Antimicrobial potential of oil against bacterial strains (Pseudomonas aeruginosa, Escherichia coli and Bacillus subtilis, and Staphylococcus aureus), yeast strains (Hansenula anomala and Saccharomy cescerevisiae) and molds (Aspergillus niger, Chaetomium globosum, Mucor racemosus, and Monascus anka) was determined by disc diffusion method and broth micro dilution method, respectively. The oil exhibited promising antimicrobial effect as a diameter of zones of inhibition (16.8-24.9 mm). Minimum inhibitory concentration values of oil were ranged 62.5-1000 μg/mL.

Combinations of Plant Essential Oil Based Terpene Compounds as Larvicidal and Adulticidal Agent against Aedes aegypti (Diptera: Culicidae)

Insecticidal plant-based compound(s)in combinations may show synergistic or antagonistic interactions against insect pest. Considering the rapid spread of the Aedes borne diseases and increasing resistance among Aedes population against conventional insecticides, twenty-eight combinations of plant essential oil-based terpene compounds were prepared and tested against larval and adult stages ofAedes aegypti. Initially five plant essential oils (EOs) were assessed for their larvicidal and adulticidal efficacy and two of their major compounds from each EO were identified from GC-MS results. Identified major compounds namely Diallyldisulfide, Diallyltrisulfide, Carvone, Limonene, Eugenol, Methyl Eugenol, Eucalyptol, Eudesmol and α-pinene were purchased and tested individually against A. aegypti. Binary combinations of these compounds were then prepared using sub-lethal doses, tested and their synergistic and antagonistic effects were determined. The best larvicidal compositions were obtained while Limonene was mixed with Diallyldisulfide and the best adulticidal composition was obtained while Carvone was mixed with Limonene. Commercially used synthetic larvicide "Temephos" and adulticide "Malathion" were tested individually and in binary combinations with the terpene compounds. The results revealed that the combination of Temephos and Diallyldisulfide and combination of Malathion and Eudesmol were the most effective combination. These effective combinations bear potential prospect to be used against Aedes aegypti.

Oviposition deterrent activity of basil plants and their essentials oils against Tuta absoluta (Lepidoptera: Gelechiidae)

The leafminer Tuta absoluta Meyrick (Lepidoptera: Gelechiidae) is one of the most important pests of tomato, reducing crop yields by up to 100% in greenhouses and fields, in several countries globally. Because synthetic insecticides lead to resistance and have adverse effects on natural enemies and the health of producers, alternative control methods are needed. In this study, we assessed the oviposition-deterring effect of basil plants, Ocimum gratissimum L. and O. basilicum L. (Lamiaceae), using dual-choice behavioural assays performed in flight tunnels. We found that both plants significantly reduced T. absoluta oviposition behaviour on a tomato plant located nearby. To evaluate the potential effect of basil volatile organic compounds, we formulated essential oils of both plant species in paraffin oil, and observed a similar oviposition-deterring effect. Gas chromatography analyses detected 18 constituents in these essential oils which the major constituents included thymol (33.3%), p-cymene (20.4%), γ-terpinene (16.9%), myrcene (3.9%) in O. gratissimum and estragol (73.8%), linalool (8.6%), β-elemene (2.9%) and E-β-ocimene (2.6%) in O. basilicum. Twenty and 33 compounds were identified of the volatiles collected on O. gratissimum and O. basilicum plants, respectively. The main components include the following: p-cymene (33.5%), γ-terpinene (23.6%), α-terpinene (7.2%), α-thujene (6.7%) and E-α-bergamotene (38.9%) in O. gratissimum, and methyl eugenol (26.1%), E-β-ocimene (17.7%), and linalool (9.4%) in O. basilicum. Four compounds (α-pinene, β-pinene, Myrcene, Limonene) were common in essential oils and plants. Our results suggest the valuable potential of basil and associated essential oils as a component of integrated management strategies against the tomato leafminer.

Seasonality effects on chemical composition, antibacterial activity and essential oil yield of three species of Nectandra

In this study, we aimed to determine whether seasonality affects the content, chemical composition, and antimicrobial activity of essential oils (EOs) from the leaves of three species of Nectandra (Nectandra megapotamica, Nectandra grandiflora, and Nectandra lanceolata) native to the Atlantic rainforest, Sao Paulo state, Brazil. In addition, we identified the compounds potentially related to the antimicrobial activity. Leaves were randomly collected in the middle of winter (August), spring (November), summer (February), and autumn (May). The influence of seasonality on the content and chemical composition of EOs from the Nectandra species was evident in this study. The EOs from N. lanceolata and N. grandiflora were characterized by similarities in the chemical composition and had a higher relative proportion of oxygenated sesquiterpenes. N. megapotamica presented a different chemical profile, with plenty of monoterpenic and sesquiterpenic hydrocarbons. Changes in the EO chemical profile because of seasonality were shown by the similarities between the EOs obtained in spring and autumn and the differences between the EOs obtained in summer and winter. The EO from the leaves of N. megapotamica harvested in winter and spring showed the highest control of the growth of Escherichia coli, and this antimicrobial action can be related to the monoterpenes α-pinene and β-pinene as well as myrcene and limonene. The minimum inhibitory concentration (MIC) of the EO from the leaves of N. lanceolata harvested in summer and autumn was lower against the gram-positive bacterium Staphylococcus aureus and can be related to the sesquiterpene hydrocarbons isobicyclogermacrenal, epi-zizanone, and germacrene B.

Antibacterial and Antifungal Activities of Spices

Infectious diseases caused by pathogens and food poisoning caused by spoilage microorganisms are threatening human health all over the world. The efficacies of some antimicrobial agents, which are currently used to extend shelf-life and increase the safety of food products in food industry and to inhibit disease-causing microorganisms in medicine, have been weakened by microbial resistance. Therefore, new antimicrobial agents that could overcome this resistance need to be discovered. Many spices-such as clove, oregano, thyme, cinnamon, and cumin-possessed significant antibacterial and antifungal activities against food spoilage bacteria like Bacillus subtilis and Pseudomonas fluorescens, pathogens like Staphylococcus aureus and Vibrio parahaemolyticus, harmful fungi like Aspergillus flavus, even antibiotic resistant microorganisms such as methicillin resistant Staphylococcus aureus. Therefore, spices have a great potential to be developed as new and safe antimicrobial agents. This review summarizes scientific studies on the antibacterial and antifungal activities of several spices and their derivatives.

Characterization and Antibacterial Potential of Lactic Acid Bacterium Pediococcus pentosaceus 4I1 Isolated from Freshwater Fish Zacco koreanus

This study was undertaken to characterize a lactic acid bacterium 4I1, isolated from the freshwater fish, Zacco koreanus. Morphological, biochemical, and molecular characterization of 4I1 revealed it to be Pediococcus pentosaceus 4I1. The cell free supernatant (CFS) of P. pentosaceus 4I1 exhibited significant (p < 0.05) antibacterial effects (inhibition zone diameters: 16.5-20.4 mm) against tested foodborne pathogenic bacteria with MIC and MBC values of 250-500 and 500-1,000 μg/mL, respectively. Further, antibacterial action of CFS of P. pentosaceus 4I1 against two selected bacteria Staphylococcus aureus KCTC-1621 and Escherichia coli O157:H7 was determined in subsequent assays. The CFS of P. pentosaceus 4I1 revealed its antibacterial action against S. aureus KCTC-1621 and E. coli O157:H7 on membrane integrity as confirmed by a reduction in cell viability, increased potassium ion release (900 and 800 mmol/L), reduced absorption at 260-nm (3.99 and 3.77 OD), and increased relative electrical conductivity (9.9 and 9.7%), respectively. Gas chromatography-mass spectrometry (GC-MS) analysis of the CFS of P. pentosaceus 4I1 resulted in the identification of seven major compounds, which included amino acids, fatty acids and organic acids. Scanning electron microscopic-based morphological analysis further confirmed the antibacterial effect of CFS of P. pentosaceus 4I1 against S. aureus KCTC-1621 and E. coli O157:H7. In addition, the CFS of P. Pentosaceus 4I1 displayed potent inhibitory effects on biofilms formation by S. aureus KCTC-1621 and E. coli O157:H7. The study indicates the CFS of P. pentosaceus 4I1 offers an alternative means of controlling foodborne pathogens.

Antimicrobial Properties of Plant Essential Oils against Human Pathogens and Their Mode of Action: An Updated Review

A wide range of medicinal and aromatic plants (MAPs) have been explored for their essential oils in the past few decades. Essential oils are complex volatile compounds, synthesized naturally in different plant parts during the process of secondary metabolism. Essential oils have great potential in the field of biomedicine as they effectively destroy several bacterial, fungal, and viral pathogens. The presence of different types of aldehydes, phenolics, terpenes, and other antimicrobial compounds means that the essential oils are effective against a diverse range of pathogens. The reactivity of essential oil depends upon the nature, composition, and orientation of its functional groups. The aim of this article is to review the antimicrobial potential of essential oils secreted from MAPs and their possible mechanisms of action against human pathogens. This comprehensive review will benefit researchers who wish to explore the potential of essential oils in the development of novel broad-spectrum key molecules against a broad range of drug-resistant pathogenic microbes.

The Essential Oil Compositions of Ocimum basilicum from Three Different Regions: Nepal, Tajikistan, and Yemen

The aerial parts of Ocimum basilicum L. were collected from four different geographical locations, Sindhuli and Biratnagar (Nepal), Chormaghzak village (Tajikistan), and Sana'a (Yemen). The essential oils were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry. A cluster analysis of 179 essential oil compositions revealed six major chemotypes: Linalool, eugenol, estragole, methyl eugenol, 1,8-cineole, and geraniol. All four of the basil oils in this study were of the linalool-rich variety. Some of the basil oils were screened for bioactivity including antimicrobial, cytotoxicity in human cancer cells, brine shrimp lethality, nematicidal, larvicidal, insecticidal, and antioxidant. The basil oils in this study were not notably antibacterial, cytotoxic, antioxidant, nor nematicidal, but were active in the brine shrimp lethality test, and did show larvicidal and insecticidal activities.

Protective Effect of Ocimum basilicum Essential Oil Against Acetic Acid-Induced Colitis in Rats

Ocimum basilicum L has been traditionally used for the treatment of inflammatory bowel disease in Iran. This study investigates the ameliorative effect of Ocimum basilicum essential oil on an acetic acid-induced colitis model in rats. Ocimum basilicum essential oil with 2 doses (200 and 400 μL/kg) significantly ameliorated wet weight/length ratio of colonic tissue compared to the control group. Higher doses of essential oil (200 and 400 μL/kg) significantly reduced ulcer severity, ulcer area, and ulcer index. On the other hand, histological examination revealed the diminution of total colitis index as a marker for inflammatory cell infiltration in the colonic segments of rats treated with Ocimum basilicum essential oil (200 and 400 μL/kg). The increased level of myeloperoxidase was significantly decreased after the treatment with the essential oil (200 and 400 μL/kg). These results suggest that Ocimum basilicum exhibits protective effect against acetic acid-induced colitis.

Fern-synthesized nanoparticles in the fight against malaria: LC/MS analysis of Pteridium aquilinum leaf extract and biosynthesis of silver nanoparticles with high mosquitocidal and antiplasmodial activity

Malaria remains a major public health problem due to the emergence and spread of Plasmodium falciparum strains resistant to chloroquine. There is an urgent need to investigate new and effective sources of antimalarial drugs. This research proposed a novel method of fern-mediated synthesis of silver nanoparticles (AgNP) using a cheap plant extract of Pteridium aquilinum, acting as a reducing and capping agent. AgNP were characterized by UV-vis spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Phytochemical analysis of P. aquilinum leaf extract revealed the presence of phenols, alkaloids, tannins, flavonoids, proteins, carbohydrates, saponins, glycosides, steroids, and triterpenoids. LC/MS analysis identified at least 19 compounds, namely pterosin, hydroquinone, hydroxy-acetophenone, hydroxy-cinnamic acid, 5, 7-dihydroxy-4-methyl coumarin, trans-cinnamic acid, apiole, quercetin 3-glucoside, hydroxy-L-proline, hypaphorine, khellol glucoside, umbelliferose, violaxanthin, ergotamine tartrate, palmatine chloride, deacylgymnemic acid, methyl laurate, and palmitoyl acetate. In DPPH scavenging assays, the IC50 value of the P. aquilinum leaf extract was 10.04 μg/ml, while IC50 of BHT and rutin were 7.93 and 6.35 μg/ml. In mosquitocidal assays, LC50 of P. aquilinum leaf extract against Anopheles stephensi larvae and pupae were 220.44 ppm (larva I), 254.12 ppm (II), 302.32 ppm (III), 395.12 ppm (IV), and 502.20 ppm (pupa). LC50 of P. aquilinum-synthesized AgNP were 7.48 ppm (I), 10.68 ppm (II), 13.77 ppm (III), 18.45 ppm (IV), and 31.51 ppm (pupa). In the field, the application of P. aquilinum extract and AgNP (10 × LC50) led to 100 % larval reduction after 72 h. Both the P. aquilinum extract and AgNP reduced longevity and fecundity of An. stephensi adults. Smoke toxicity experiments conducted against An. stephensi adults showed that P. aquilinum leaf-, stem-, and root-based coils evoked mortality rates comparable to the permethrin-based positive control (57, 50, 41, and 49 %, respectively). Furthermore, the antiplasmodial activity of P. aquilinum leaf extract and green-synthesized AgNP was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of P. falciparum. IC50 of P. aquilinum were 62.04 μg/ml (CQ-s) and 71.16 μg/ml (CQ-r); P. aquilinum-synthesized AgNP achieved IC50 of 78.12 μg/ml (CQ-s) and 88.34 μg/ml (CQ-r). Overall, our results highlighted that fern-synthesized AgNP could be candidated as a new tool against chloroquine-resistant P. falciparum and different developmental instars of its primary vector An. stephensi. Further research on nanosynthesis routed by the LC/MS-identified constituents is ongoing.