Medicinal Plant Growth in Heavy Metals Contaminated Soils: Responses to Metal Stress and Induced Risks to Human Health

A near-infrared fluorescent probe for the detection of Cu2+ in Chinese herbal medicine and imaging in living cells

Copper is one of the common among the heavy metal pollution in Chinese herbal medicine (CHM). So, it is essential to develop rapid and accurate testing method to quantify the Cu2+ content in CHM. Herein, we prepared a coordination-based near-infrared fluorescent probe (NRh6G-FA) by introducing a hemicyanine dye in rhodamine 6G scaffold. NRh6G-FA had a high sensitivity, anti-interference performance, fast response (within 60 s), visualization (from light yellow to green) for Cu2+ and excellent sensing performance for the detection of Cu2+ at low concentrations (LOD = 0.225 μM). The most likely mechanism was verified on the basis of Job's plot, ESI-HRMS and DFT calculations. NRh6G-FA could be successfully applied for the detection and "naked eye" recognition of Cu2+ in CHM samples. Moreover, NRh6G-FA was used to visualize Cu2+ in living MCF-7 cells by confocal fluorescence imaging.

Variations in the biochemical characteristics of Lavandula sublepidota Rech.f. in response to the foliar enrichment of green-synthesized copper nano complexes from extract of neem and jujube

Copper (Cu) is an essential micronutrient in plant physiology and biochemistry. This article synthesized copper nano complexes (Cu-NCs) based on aqueous extracts of jujube and neem leaves. The effects of foliar application of Cu-jujube and Cu-neem Cu-NCs at concentrations of 0, 10, 25, and 50 mg L-1 on the bioactive compounds, antioxidant capacity, and essential oil of the Iranian native medicinal herb Lavandula sublepidota Rech. f. was investigated. The highest levels of flavonoids and polyphenols were observed in the plants treated with Cu-NCs at 25 mg L-1. However, no superiority was observed between the two types of Cu-NCs. Furthermore, 25 mg L-1 nCu-Z and nCu-N foliar application boosted essential oil yield (48 and 52%, respectively) over control. This suggests an ideal threshold beyond which toxicity was found. Similarly, the amount of commercially significant secondary metabolites increased at 25 mg L-1 CuNCs compared to 10 and 50 mg L-1 concentrations. The maximum antioxidant activity was found in extracts of lavender that had been treated with 25 mg L-1 CuNCs. When CuNCs were applied exogenously, the extracts' antibacterial activity (MIC μg mL-1) was substantially increased against the three pathogen strains. The results suggest that CuNCs demonstrate notably greater effectiveness, particularly at an ideal concentration of 25 mg L-1, in enhancing the production of essential oil and bioactive compounds in Lavandula sublepidota Rech. f. Therefore, these findings indicate the importance of the biosynthesis of NCs using plants and measuring the phytochemical changes of lavender plants.

Heterologous expression of ACC deaminase gene in Pelargonium graveolens showed elevated tolerance to chromium stress

An essential aromatic plant, Pelargonium graveolens, does not grow well in areas where chromium contamination is a problem. Because of oxidative stress and the collapse of the photosynthetic system, crops frequently sustain severe damage. The production of excess ethylene, known as stress ethylene, which is detrimental to plant growth, the formation of roots, and early senescence, is also increased by heavy metal exposure. The effectiveness of the 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase gene in transgenic Pelargonium graveolens under the control of CaMV 35S promoter was investigated to lessen the stress ethylene during chromium stress. Chromium was administered as potassium dichromate (K2Cr2O7) at four distinct concentrations (100 µM, 200 µM, 300 µM, and 500 µM) to transgenic and wild-type P. graveolens and stress-induced physiological changes were monitored. Transgenic P. graveolens demonstrated greater tolerance to chromium stress than wild-type P. graveolens, as evidenced by higher leaf-relative water content, chlorophyll content, CO2 absorption, transpiration rate, stomatal conductance, proline buildup, and antioxidant activity. The L1, L5, and L7, ACC deaminase-expressing transgenic lines also show a drop in ACC content during chromium stress, which subsequently lowered ethylene synthesis. Therefore, the reported transgenic P. graveolens lines having the ACC deaminase gene could be useful resources for growing in chromium-prone regions.

Phytochemical profile, antioxidant, and wound healing activities of Echium amoenum (Boraginaceae)

Natural products' inflammatory and antioxidant properties have crucial roles in tissue repair and regeneration. This study aimed to investigate HPLC analysis, antioxidant activity, and wound-healing effect of Echium amoenum (EA) on rats. The EA was analysed for the determination of shikonin a derivative of naphthoquinone. In the wound healing assessment, forty Wistar rats were divided into five groups that were receiving the cream base, normal saline (NS), 1% silver sulfadiazine (SSD), and 5 and 10% EA cream (EAC). Shikonin was found in the EA extract. The average wound area on the 10th day was 0.71 ± 0.01, 0.86 ± 0.13, 0.58 ± 0.08, 0.53 ± 0.03 and 0.43 ± 0.04 cm2 for the cream base, NS, SSD, and 5 and 10% EAC, respectively. The collagen fibres were well formed and horizontally oriented in 5 and 10% EAC groups compared to other groups. EA cream was an effective treatment for wound healing in comparison with SSD.

Calcium Hexacyanoferrate Nanozyme Enhances Plant Stress Resistance by Oxidative Stress Alleviation and Heavy Metal Removal

Oxidative damage, exacerbated by the excessive accumulation of reactive oxygen species (ROS), profoundly inhibits both crop growth and yield. Herein, a biocompatible nanozyme, calcium hexacyanoferrate nanoparticles (CaHCF NPs), targeting ROS is developed, to mitigate oxidative damage and sequestrate heavy metal ions during plant growth. Uniquely, CaHCF NPs feature multifaced enzyme-like activities, involving superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase, thiol peroxidase, and ascorbate peroxidase, which enable them to neutralize excessive ROS. Furthermore, CaHCF NPs promote calcium-cadmium exchange process, diminishing the uptake of heavy metals. Importantly, 120 µg mL-1 of CaHCF NPs alleviate the inhibitory effects of hydrogen peroxide and cadmium chloride on Arabidopsis and tomato. The activities of SOD, POD, and CAT increase by 46.2%, 74.4%, and 48.3%, respectively, meanwhile the glutathione level rises by 72.4% in Arabidopsis under cadmium stress. Moreover, CaHCF NPs boost the expression of genes associated with antioxidation, heavy metal detoxification, nutrient transport, and stress resistance. These findings unveil the significant potential of nanoplatforms equipped with nanozymes in alleviating oxidative stress in plants, which not only regulate crop growth but also substantially ameliorate yield and quality, heralding a new era in agricultural nanotechnology.

Bioactive Profiling, Antibacterial Efficacy and Computational Modelling of Myrtus Communis Essential Oil (Morocco)

In the context of investigations into molecules of natural origin with biological activities. This study focuses on the development of Myrtus communis L., a medicinal plant found in the mountains of Morocco. The first, an analysis carried out on leaves using the inductively coupled plasma spectrometry technique, showed the almost total absence of heavy metals. Furthermore, we aim to identify the chemical composition of its essential oils by gas chromatography-mass spectrometry (GC/MS) analysis and assess its antibacterial efficacy in vitro and in silico. The average yield of essential oils was 0.9 %±0.06, and GC/MS analysis identified 35 constituents, with myrcene (27,38 %), limonene (16,51 %), α-pinene (7,32 %) being the major compounds. Remarkably, the essential oils displayed considerable antibacterial activity against various tested bacteria, including Escherichia coli (0.7 μL/mL), Escherichia pseudocoloides (2.8 μl/ml), Escherichia vekanda (2.8 μl/ml). Molecular docking has contributed to our understanding of the mechanism of antibacterial action of the main compounds in this essential oil.

Biochar as a partner of plants and beneficial microorganisms to assist in-situ bioremediation of heavy metal contaminated soil

Synergistic remediation of heavy metal (HM) contaminated soil using beneficial microorganisms (BM) and plants is a common and effective in situ bioremediation method. However, the shortcomings of this approach are the low colonisation of BM under high levels of heavy metal stress (HMS) and the poor state of plant growth. Previous studies have overlooked the potential of biochar to mitigate the above problems and aid in-situ remediation. Therefore, this paper describes the characteristics and physicochemical properties of biochar. It is proposed that biochar enhances plant resistance to HMS and aids in situ bioremediation by increasing colonisation of BM and HM stability. On this basis, the paper focuses on the following possible mechanisms: specific biochar-derived organic matter regulates the transport of HMs in plants and promotes mycorrhizal colonisation via the abscisic acid signalling pathway and the karrikin signalling pathway; promotes the growth-promoting pathway of indole-3-acetic acid and increases expression of the nodule-initiating gene NIN; improvement of soil HM stability by ion exchange, electrostatic adsorption, redox and complex precipitation mechanisms. And this paper summarizes guidelines on how to use biochar-assisted remediation based on current research for reference. Finally, the paper identifies research gaps in biochar in the direction of promoting beneficial microbial symbiotic mechanisms, recognition and function of organic molecules, and factors affecting practical applications.

Phytotoxicity of metal-organic framework MOF-74(Co) nanoparticles to pea seedlings

Metal-organic framework (MOF) materials have unique structure and fantastic properties for wide-ranging applications. Pilot studies highlighted the toxicity and potential threats of MOF materials to the environment. In this study, we revealed the phytotoxicity of MOF-74(Co) nanoparticles (NPs) and their inhibitory effects on the photosynthesis of pea seedlings (Pisum sativum L.). MOF-74(Co) NPs have limited influences on the germination of pea seeds, but distinct environmental effects of MOF-74(Co) NPs were found in pea seedlings. The root length of pea seedlings, fresh weight and dry weight decreased by 50.0%, 29.2% and 36.4%, respectively, compared with the control group, when the material concentration was greater than 100 mg L-1. The net photosynthetic rate decreased by 48% and the intercellular CO2 concentration increased by 183% upon exposure to MOF-74(Co) NPs. Mechanistically, MOF-74(Co) exposure led to Co uptake in pea seedlings; the increases were 223% for the root, 267% for the stem and 6562% for the leaves, respectively, when the MOF-74(Co) NP concentration was 10 mg L-1. The released Co ions from MOF-74(Co) NPs caused oxidative damage to leaves and induced damage to the acceptor side of photosynthesis system II. Our results indicated that the environmental toxicity of MOF materials was largely regulated by the metal centers. MOF materials with nontoxic metal elements are desirable for future applications.

Impact of Heavy Metal Pollution in the Environment on the Metabolic Profile of Medicinal Plants and Their Therapeutic Potential

The paper provides a comprehensive examination of heavy metal stress on medicinal plants, focusing on its impact on antioxidant capacity and biosynthetic pathways critical to their therapeutic potential. It explores the complex relationship between heavy metals and the physiological and biochemical responses of medicinal plants, highlighting how metal stress disrupts biosynthetic pathways, altering concentrations of secondary metabolites. This disruption may compromise the overall quality and efficacy of medicinal plants, requiring a holistic understanding of its cumulative impacts. Furthermore, the study discusses the potential of targeted genetic editing to enhance plant resilience against heavy metal stress by manipulating genes associated with antioxidant defenses. This approach represents a promising frontier in safeguarding medicinal plants in metal-contaminated environments. Additionally, the research investigates the role of phytohormone signaling in plant adaptive mechanisms to heavy metal stress, revealing its influence on biochemical and physiological responses, thereby adding complexity to plant adaptation. The study underscores the importance of innovative technologies and global cooperation in protecting medicinal plants' therapeutic potential and highlights the need for mitigation strategies to address heavy metal contamination effectively.

Heavy metals in onion (Allium cepa L.) and environmental and health risks

This study aimed to determine heavy metal content in soil and selected cultivars of onion. Cd content in soil exceeded the limit 2.43 times. Bioavailable forms of Pb and Cd in soil exceeded the critical value 5.9 times and 1.9 times, respectively. Analysed cultivars were not bioaccumulators of monitored heavy metals. However, Pb and Cd content in cultivars Nanas F1, Kappa and Daytona F1 exceeded the maximum limit set by the EU regulation. For Pb this was also the case for the Spirith cultivar. Based on health risk assessment it could be concluded that moderate consumption of onions from the studied localities does not pose a risk to consumers.

Human Health Risk Assessment of Arsenic and Other Metals in Herbal Products Containing St. John's Wort in the Metropolitan Area of Mexico City

Consumption of St. John's wort plant is high worldwide due to its various medicinal properties. However, herbal products containing St. John's wort may be contaminated with toxic metals. This is often related to contamination of both water and the atmosphere, lack of proper cultivation methods, and inadequate plant storage conditions, as well as a lack of stricter sanitary supervision. A safety assessment of copper (Cu), lead (Pb), cadmium (Cd) and arsenic (As) content in 23 products containing St. John's wort (pharmaceutical herbal products, food supplements and traditional herbal remedies) sold in the metropolitan area of Mexico City was conducted. The analysis of metals was determined using a graphite-furnace atomic absorption spectrometer. All herbal products were contaminated with Cu, Pb, Cd and As. The pharmaceutical herbal items showed less contamination by metals. The daily human intake (DHI) values for Pb exceeded the permissible limits in the group of traditional herbal remedies. The DHI calculation for As exceeded the permitted intake values for all items in the group of traditional herbal remedies, five food supplements and one pharmaceutical herbal product. The hazard indicator calculation of the non-carcinogenic cumulative risk values for traditional herbal remedies was greater than 1, suggesting a risk to human health.

Human Health Risk Assessment to the Consumption of Medicinal Plants with Melliferous Potential from the Romanian South-Eastern Region

This study presents the impact on human health by consuming medicinal herbs with high melliferous potential (HMPs) from botanical areas with different pollution levels. First, the bioaccumulation of the plants' parts has been determined. The study assessed the potential health risks associated with the ingestion of various mineral species (macroelements-K, Ca, Mg, Na; microelements-Fe, Mn, Cu, Zn, and one trace element Cd) from three types of HMPs (Sambucus nigra (SnL), Hypericum perforatum (Hp), and Tilia tomentosa (Tt)). The average concentrations of these elements were not similar even in the same type of HMPs. Nevertheless, all samples contained detectable levels of the studied elements. The average concentrations of the studied elements were very low (significantly lower than the legal limit set by the WHO). The study's findings indicated that the potential health risks associated with ingesting the elements in HMPs were within acceptable limits for children and adults. The hazard quotient (HQ) for Fe, Mn, Cu, Zn, and Cd and the hazard index (HI) for the minerals from HMPs were significantly lower than the acceptable limit (HQ and HI = 1). Similarly, the carcinogenic risk for chemical substances (Riskccs) were lower than or close to the acceptable limit (1 × 10^-4).

Current Trends for Lavender (Lavandula angustifolia Mill.) Crops and Products with Emphasis on Essential Oil Quality

Lavender is in the research spotlight due to its increasing economic importance, while market demand is expected to continue to grow. Among the hundreds of essential-oil-bearing plants, Lavandula angustifolia Mill. remains one of the most valuable. This paper explores the lavender chain timeline from crop to products, examining the expanding knowledge on the characteristics, phytochemical profile and functional potential of lavender that could lead to new products and uses. Lavender crops can be expanded without competing for productive land, instead using marginal, contaminated or unproductive land. A novel cultivation trend proposes leveraging agri-background biodiversity, arbuscular mycorrhiza and the natural enemies of pests for healthy crops. Together with breeding efforts targeting highly performant genotypes with complex volatile profiles coupled with resistance to specific biotic (particularly Phytoplasma) and abiotic (salt, heavy metals) stressors, industry could have a steady supply of high-quality raw material. Besides the expansion of the uses of essential oil in cosmetics, pharmaceuticals, food and environmental and agri-applications, novel channels have appeared for the use of the solid by-product, which is rich in polyphenols and polysaccharides; these channels have the potential to create additional streams of value. The stabilization and optimization of techno-functional delivery systems through the encapsulation of essential oil can extend shelf-life and enhance biological activity efficiency.