The accumulation of metals, PAHs and alkyl PAHs in the roots of Echinacea purpurea

Phytochemistry, Mechanisms, and Preclinical Studies of Echinacea Extracts in Modulating Immune Responses to Bacterial and Viral Infections: A Comprehensive Review

BACKGROUND

Echinacea species, particularly Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida, are renowned for their immunomodulatory, antibacterial, and antiviral properties.

OBJECTIVES

This review explores the mechanisms by which echinacea herbal extracts modulate immune responses, focusing on their effects on both innate and adaptive immunity in bacterial and viral infections.

RESULTS

Key bioactive compounds, such as alkamides, caffeic acid derivatives, flavonoids, and polysaccharides, contribute to these effects. These compounds enhance immune cell activity, including macrophages and natural killer cells, stimulating cytokine production and phagocytosis. The antibacterial activity of echinacea against respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Legionella pneumophila) and skin pathogens (Staphylococcus aureus, Propionibacterium acnes) is reviewed, as well as its antiviral efficacy against viruses like herpes simplex, influenza, and rhinovirus. Echinacea's potential as a complementary treatment alongside conventional antibiotics and antivirals is discussed, particularly in the context of antibiotic resistance and emerging viral threats.

CONCLUSIONS

Challenges associated with variability in phytochemical content and the need for standardized extraction processes are also addressed. This review provides a comprehensive overview of echinacea's therapeutic potential and outlines future directions for research, including clinical trials and dosage optimization.

Transformation and degradation of tebuconazole and its metabolites in constructed wetlands with arbuscular mycorrhizal fungi colonization

Arbuscular mycorrhizal fungi (AMF) colonization has been used in constructed wetlands (CWs) to enhance treatment performance. However, its role in azole (fungicide) degradation and microbial community changes is not well understood. This study aims to explore the impact of AMF on the degradation of tebuconazole and its metabolites in CWs. Total organic carbon levels were consistently higher with the colonization of AMF (AMF+; 9.63- 16.37 mg/L) compared to without the colonization of AMF (AMF-; 8.79-14.48 mg/L) in CWs. Notably, tebuconazole removal was swift, occurring within one day in both treatments (p = 0.885), with removal efficiencies ranging from 94.10 % to 97.83 %. That's primarily due to rapid substrate absorption at the beginning, while degradation follows with a longer time. Four metabolites were reported in CWs first time: tebuconazole hydroxy, tebuconazole lactone, tebuconazole carboxy acid, and tebuconazole dechloro. AMF decreased the abundance of tebuconazole dechloro in the liquid phase, suggesting an inhibitory effect of AMF on dechlorination processes. Furthermore, tebuconazole carboxy acid and hydroxy were predominantly found in plant roots, with a higher abundance observed in AMF+ treatments. Metagenomic analysis highlighted an increasing abundance in bacterial community structure in favor of beneficial microorganisms (xanthomonadales, xanthomonadaceae, and lysobacter), along with a notable presence of functional genes like codA, NAD, and deaD in AMF+ treatments. These findings highlight the positive influence of AMF on tebuconazole stress resilience, microbial community modification, and the enhancement of bioremediation capabilities in CWs.

Asphalt dust influence on the distribution of polycyclic aromatic hydrocarbon in crankcase oil stains of a concrete, covered parking structure

Used crankcase oil is an important source of environmental polycyclic aromatic hydrocarbons (PAHs). Here, we use gas chromatography-mass spectrometry (GC-MS) to measure and compare the concentration of PAHs, including alkylated PAHs, in used oil against new and old oil stains and parking dust collected from a concrete, covered, open parking structure to understand the distribution of PAH in crankcase oil stains. PAH concentration in used oils ranges from 606 ng/mg to 1,592 ng/mg. The PAH distribution in used oil does not match that observed in parking oils stains, parking background, or parking dust. A comparison with PAH distributions in traffic related dusts extracted from the literature and dust collected from a neighboring open asphalt-paved parking suggests that covered parking dust includes substantial contributions from asphalt-paved parking dust, road dust, and/or coal tar dust. The parking dust is the most concentrated source of PAHs in the covered parking structure (PAHs up to 4,371 ng/mg), a small contribution of which can alter the distribution of PAHs in oil stains. Even with this contribution, we were able to observe a significant decrease of the ratio of low molecular weight PAHs to high molecular weight PAHs, and a significant increase in values of the phenanthrene/anthracene and fluoranthene/(fluoranthene + pyrene) ratios when oil stains age, suggesting biodegradation is an active attenuation process in covered, open parking structures.

Polycyclic aromatic hydrocarbon (PAH) accumulation in selected medicinal plants: a mini review

The use of plant-based products in healthcare systems has experienced a tremendous rise leading to a substantial increase in global demand. However, the quality and effectiveness of such plant-based treatments are often affected due to contamination of various pollutants including polycyclic aromatic hydrocarbons (PAHs). Like other plants, medicinal plants also uptake and accumulate PAHs when exposed to a contaminated environment. The consumption of such medicinal plants and/or plant-based products causes negative effects on health rather than providing any therapeutic advantages. Unfortunately, research focusing on PAH accumulation in medicinal plants has received very limited attention. This review discusses a sizable number of literature regarding the concentration of sixteen priority PAH pollutants as recognised by the US Environmental Protection Agency (USEPA) in different medicinal plants. The review also highlights the risk assessment of cancer associated with some medicinal plants in terms of benzo[a]pyrene (BaP) equivalent concentrations.

Molecular Defensive Mechanism of Echinacea purpurea (L.) Moench against PAH Contaminations

The understanding of the molecular defensive mechanism of Echinacea purpurea (L.) Moench against polycyclic aromatic hydrocarbon (PAH) contamination plays a key role in the further improvement of phytoremediation efficiency. Here, the responses of E. purpurea to a defined mixture of phenanthrene (PHE) and pyrene (PYR) at different concentrations or a natural mixture from an oilfield site with a history of several decades were studied based on transcriptomics sequencing and widely targeted metabolomics approaches. The results showed that upon 60-day PAH exposure, the growth of E. purpurea in terms of biomass (p < 0.01) and leaf area per plant (p < 0.05) was negatively correlated with total PAH concentration and significantly reduced at high PAH level. The majority of genes were switched on and metabolites were accumulated after exposure to PHE + PYR, but a larger set of genes (3964) or metabolites (208) showed a response to a natural PAH mixture in E. purpurea. The expression of genes involved in the pathways, such as chlorophyll cycle and degradation, circadian rhythm, jasmonic acid signaling, and starch and sucrose metabolism, was remarkably regulated, enhancing the ability of E. purpurea to adapt to PAH exposure. Tightly associated with transcriptional regulation, metabolites mainly including sugars and secondary metabolites, especially those produced via the phenylpropanoid pathway, such as coumarins, flavonoids, and their derivatives, were increased to fortify the adaptation of E. purpurea to PAH contamination. These results suggest that E. purpurea has a positive defense mechanism against PAHs, which opens new avenues for the research of phytoremediation mechanism and improvement of phytoremediation efficiency via a mechanism-based strategy.

Remediation of petroleum hydrocarbon contaminated soil using hydrocarbonoclastic rhizobacteria, applied through Azadirachta indica rhizosphere

Crude oil/petroleum hydrocarbons (PHs) are major pollutants worldwide. In the present study, three bacterial isolates -Pseudomonas aeruginosa BB-BE3, P. aeruginosa BBBJ, and Gordonia amicalis BB-DAC were selected for their efficient hydrocarbon degradation and plant growth promotion (PGP) abilities. All three isolates were positive for siderophore production, phosphate solubilization, and IAA production, even in the presence of crude oil. The rhizoremediation ability was validated through pot trials where all three isolates promoted the growth of the Azadirachta indica plant in crude oil-contaminated soils. Treatment with the combination of the plant (A. indica) and bacteria, i.e., Pseudomonas aeruginosa BB-BE3; P. aeruginosa BBBJ; Gordonia amicalis BB-DAC showed 95.71, 93.28, and 89.88% removal of TPHs respectively, while the treatment with the plant (only) resulted in 13.44% removal of TPHs whereas, in the control (Sterile bulk soil + Crude oil), the hydrocarbon removal percentage was only 5.87%. The plant tissues were analyzed for catalase (CAT) and peroxidase (POX) activities, and the plants augmented with bacterial strains had significantly low CAT and POX activities as compared to uninoculated control. Therefore, the results suggest that the A. indica plant, in symbiotic association with these hydrocarbonoclastic rhizobacteria, could be used for bioremediation of crude oil-polluted soil.

Soil initial bacterial diversity and nutrient availability determine the rate of xenobiotic biodegradation

Understanding the relative importance of soil microbial diversity, plants and nutrient management is crucial to implement an effective bioremediation approach to xenobiotics-contaminated soils. To date, knowledge on the interactive effects of soil microbiome, plant and nutrient supply on influencing biodegradation potential of soils remains limited. In this study, we evaluated the individual and interactive effects of soil initial bacterial diversity, nutrient amendments (organic and inorganic) and plant presence on the biodegradation rate of pyrene, a polycyclic aromatic hydrocarbon. Initial bacterial diversity had a strong positive impact on soil biodegradation potential, with soil harbouring higher bacterial diversity showing ~ 2 times higher degradation rates than soils with lower bacterial diversity. Both organic and inorganic nutrient amendments consistently improved the degradation rate in lower diversity soils and had negative (inorganic) to neutral (organic) effect in higher diversity soils. Interestingly, plant presence/type did not show any significant effect on the degradation rate in most of the treatments. Structural equation modelling demonstrated that initial bacterial diversity had a prominent role in driving pyrene biodegradation rates. We provide novel evidence that suggests that soil initial microbial diversity, and nutrient amendments should be explicitly considered in the design and employment of bioremediation management strategies for restoring natural habitats disturbed by organic pollutants.

Influence of carbon-containing and mineral sorbents on the toxicity of soil contaminated with benzo[a]pyrene during phytotesting

Benzo[a]pyrene (BaP) is a member of polycyclic aromatic hydrocarbons known for high persistency and toxicity. Technologies of BaP sorption through solid matrixes have received relatively more attention. The present study was devoted to the phytotesting investigations of two different groups of sorbents, such as carbonaceous, including biochar and granulated activated carbon (GAC), and mineral, including tripoli and diatomite. Evaluation of the BaP removing efficiency was carried out using the phytotesting method with spring barley in Haplic Chernozem contaminated with different levels of contamination (200 and 400 μg kg^-1 BaP). The sorbents' efficiency for BaP remediation was estimated in the sorbents doses from 0.5 to 2.5% per kg of soil. It was shown that biochar and GAC decreased the soil toxicity class to a greater extent than mineral sorbents ones. The effect intensified with an increase in applying sorbents doses. The optimal dose of carbonaceous sorbents into the soil contaminated with 200 µg kg^-1 was 1%, decreasing the BaP content up 57-59% in the soil. Simultaneously, the optimal dose of the mineral sorbents was found to be 1.5%, which decreased the BaP content in the soil up 41-48%. Increasing the BaP contamination level up to 400 µg kg^-1 showed the necessity of a sorbent dose increasing. In these conditions, among all applied sorbents, only 2% GAC could reduce the soil toxicity class to the normal level up to 0.91-1.10. It was shown that BaP tended to migrate from the soil to the roots and further into the vegetative part of barley.

Selection of Endophytic Strains for Enhanced Bacteria-Assisted Phytoremediation of Organic Pollutants Posing a Public Health Hazard

Anthropogenic activities generate a high quantity of organic pollutants, which have an impact on human health and cause adverse environmental effects. Monitoring of many hazardous contaminations is subject to legal regulations, but some substances such as therapeutic agents, personal care products, hormones, and derivatives of common organic compounds are currently not included in these regulations. Classical methods of removal of organic pollutants involve economically challenging processes. In this regard, remediation with biological agents can be an alternative. For in situ decontamination, the plant-based approach called phytoremediation can be used. However, the main disadvantages of this method are the limited accumulation capacity of plants, sensitivity to the action of high concentrations of hazardous pollutants, and no possibility of using pollutants for growth. To overcome these drawbacks and additionally increase the efficiency of the process, an integrated technology of bacteria-assisted phytoremediation is being used recently. For the system to work, it is necessary to properly select partners, especially endophytes for specific plants, based on the knowledge of their metabolic abilities and plant colonization capacity. The best approach that allows broad recognition of all relationships occurring in a complex community of endophytic bacteria and its variability under the influence of various factors can be obtained using culture-independent techniques. However, for practical application, culture-based techniques have priority.

Disturbed phospholipid metabolism by three polycyclic aromatic hydrocarbons in Oryza sativa

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in soils that can be readily absorbed by crops, affecting growth and development. Phospholipids (PLs) are essential components of cell membrane and can indicate cellular responses to various organic pollutants. However, the detailed molecular mechanism of phospholipid metabolism based regulation employed by crops in response to PAHs stresses remains elusive. This study characterized the accumulation patterns of representative PAHs, namely phenanthrene (PHEN), pyrene (PY), and benzo[a]pyrene (BaP) in rice (Oryza sativa). Crop's responses to PAHs via the regulation of phospholipid metabolism were also explored. PHEN exhibited the highest accumulation in both roots and shoots, followed by PY and BaP, despite PY exhibited much greater phytotoxicity than the other two PAHs. The exposure to 10-500 μg/L PY resulted in downregulations of the phospholipase A₂ genes PLA₂-3, PLA₂-4, and PLA₂-6 (to 19% of the control without exposure) and phospholipase C genes PLC-1, PLC-2, and PLC-4 (to 50% of the control), consistent with the changes in phospholipase activity. The contents of typical PLs, including phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and phosphatidic acid also decreased to a greater extent than those in the PHEN- and BaP-exposed groups. These were the major reasons for the relatively high phytotoxicity of PY, in terms of growth inhibition and cell membrane damage. These findings provide a more comprehensive understanding of crop responses to PAHs and provide insights into risk assessment of soil PAH contamination, which hold potentials in improving food safety and quality worldwide.

Effects of benzo[a]pyrene toxicity on morphology and ultrastructure of Hordeum sativum

Many studies have been devoted to investigation of toxic benzo(a)pyrene (BaP) compound, but studies involving changes at the cellular level are insufficient to understand the mechanisms of polycyclic aromatic hydrocarbons (PAHs) effect on plants. To study the toxicity of BaP, a model vegetation experiment was conducted on cultivation of spring barley (Hordeum sativum distichum) on artificially polluted BaP soil at different concentrations. The article discusses the intake of BaP from the soil into the plant and its effect on the organismic and cellular levels of plant organization. The BaP content in the organs of spring barley was determined by the method of saponification. With an increase in the concentration of BaP in the soil, its content in plants also rises, which leads to inhibition of growth processes. The BaP content in the green part of Hordeum sativum increased from 0.3 µg kg^-1 in control soil up to 2.6 µg kg^-1 and 16.8 µg kg^-1 under 20 and 400 ng/g BaP applying in soil, as well as in roots: 0.9 µg kg^-1, 7.7 µg kg^-1, 42.8 µg kg^-1, respectively. Using light and electron microscopy, changes in the tissues and cells of plants were found and it was established that accumulation of BaP in plant tissues caused varying degrees of ultrastructural damage depending on the concentration of pollutant. BaP had the greatest effect on the root, significant changes were found in it both at histological and cytological levels, while changes in the leaves were observed only at the cytological level. The results provide significant information about the mechanism of action of BaP on agricultural plants.

Phylogenetic analysis of hyperaccumulator plant species for heavy metals and polycyclic aromatic hydrocarbons

Increasing concentration of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) in the soil may impose a serious threat to living organisms due to their toxicity and the ability to accumulate in plant tissues. The present review focuses on the phylogenetic relationships, sources, biotransformation and accumulation potential of hyperaccumulators for the priority HMs and PAHs. This review provides an opportunity to reveal the role of hyperaccumulators in removal of HMs and PAHs from soils, to understand the relationships between pollutants and their influence on the environment and to find potential plant species for soil remediation. The phylogenetic analysis results showed that the hyperaccumulators of some chemicals (Co, Cu, Mn, Ni, Zn, Cd) are clustered on the evolutionary tree and that the ability to hyperaccumulate different pollutants can be correlated either positively (Cd-Zn, Pb-Zn, Co-Cu, Cd-Pb) or negatively (Cu-PAHs, Co-Cd, Co-PAHs, Ni-PAHs, Cu-Ni, Mn-PAHs). Further research needs to be extended on the focus of commercializing the techniques including the native hyperaccumulators to remediate the highly contaminated soils.

Difference in the rhizosphere microbiome of Melia azedarach during removal of benzo(a)pyrene from cadmium co-contaminated soil

Benzo(a)pyrene (BaP) is a highly persistent biohazard polyaromatic hydrocarbon and often reported to be present in soils co-contaminated with heavy metals. The present study explains the rhizodegradation of BaP using bacterial consortium in the rhizosphere of Melia azedarach, along with a change in taxonomical and functional properties of the rhizosphere microbiome. The relative abundance of most dominant phylum Proteobacteria was 2% higher with BaP, while in the presence of both BaP and Cd, its abundance was 2.2% lower. Functional metagenome analysis also revealed the shifting of microbial community and functional gene abundance in the favor of xenobiotic compound degradation upon augmentation of bacterial consortium. Interestingly, upon the addition of BaP the range of functional abundance for genes of PAH degradation (0.165-0.19%), was found to be decreasing. However, augmentation of a bacterial consortium led to an increase in its abundance including genes for degradation of benzoate (0.55-0.64%), toluene (0.2-0.22%), naphthalene (0.25-0.295%) irrespective of the addition of BaP and Cd. Moreover, under greenhouse condition, the application of M. azedarach-bacterial consortium enhanced the degradation of BaP in the rhizosphere (88%) after 60 days, significantly higher than degradation in bulk soil (68.22%). The analysis also showed an increase in degradation of BaP by 15% with plant-native microbe association than in bulk soil. Therefore, the association of M. azedarach-bacterial consortium enhanced the degradation of BaP in soil along with the taxonomical and functional attributes of the rhizosphere microbiome.

Improving growth properties and phytochemical compounds of Echinacea purpurea (L.) medicinal plant using novel nitrogen slow release fertilizer under greenhouse conditions

Medicinal plant production is most important than other agricultural plants due to their phytochemical compounds effects on human health. Paying attention to plant nutrition requirement is so important. In order to assess the effect of nitrate (NO₃⁻) dosage supplies from two types of fertilizers on growth and phytochemical properties of Echinacea purpurea rhizomata cum radicibus, an experiment with completely simple design was carried out under greenhouse conditions. Two types of fertilizers (new invented nitrogen (N) slow release fertilizer and urea chemical fertilizer) at three dosages (50, 100, and 150 mM) were applied. Plant growth parameters and total phenolic (TPC), total flavonoids (TFC), polysaccarides content, essential oil content, caffeic acid derivatives, and anti-radical scavenging activities of E. purpurea were assessed. The results showed the significant (p ≤ 0.01) differences among treatments, both in growth and phytochemical properties. Using of N slow release, especially in 150 mM dosage, significantly increased all the plant growth and phytochemical properties. The dried E. purpurea rhizomata cum radicibus contained more caftaric acid (max 12.56 mg g⁻¹ DW) and chicoric acid (max 7.56 mg g⁻¹ DW) than other derivatives. Despite the impact of heavy metals on yield and growth of E. purpurea, the concentration of all heavy metals and micronutrients (boron (B), cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), and zinc (Zn)) in studied soil and fertilizer samples was less than United States Environmental Protection Agency (USEPA) limits of contamination. Based on the results, using of N slow release fertilizers can improve phytochemical properties of the plant due to its polymeric structure and can be a suitable substitution of chemical fertilizers, especially in medicinal plants growth.