Invasive Plants: Turning Enemies into Value

Occurrence, Pharmacological Properties, Toxic Effects, and Possibilities of Using Berries from Selected Invasive Plants

Invasive alien plants are typically associated with negative impacts on ecosystems and sometimes on health, but studies also describe their ethnomedicinal usage, particularly by indigenous communities. Given the existing limitations regarding a critical study on the berry-producing invasive plants, this study aims to provide scientific evidence and much-needed updated knowledge on the pharmacologically significant fruits of several berry-producing invasive alien plants. A list of 35 species from 16 families is provided, along with their characteristics, historical medicinal uses, updated biological activities, and available toxicity data. The definitions, terminology, and classification criteria used to describe alien species, specifically the invasive types, are also provided. Most of the berries of the described species exhibit remarkable antioxidant properties due to their abundance of highly reactive molecules, mainly polyphenols and carotenoids. Other biological activities, ranging from antimicrobial, anti-inflammatory, and anti-diabetic to anticancer and neuroprotective activities, have been identified. In contrast, quantitative toxicity issues have been poorly studied for berries from invasive plants. Hopefully, this work will serve as a starting point for further exploration of the molecules from berries of these plants in terms of drug discovery to advance various therapies or other applications.

From Threat to Opportunity: Harnessing the Invasive Carpobrotus edulis (L.) N.E.Br for Nutritional and Phytotherapeutic Valorization Amid Seasonal and Spatial Variability

Carpobrotus edulis (L.) N.E.Br. (Hottentot-fig) is a problematic invasive species found in coastal areas worldwide. Mechanical removal is a common control method, leaving the removed biomass available as a possible source of natural phytochemicals with prospective commercial applications. While the Hottentot-fig's vegetative organs have been studied previously, this work establishes for the first time a seasonal and spatial comparative analysis of its nutritional, chemical, and bioactivity profiles (in three locations over four seasons). Proximate and mineral contents were assessed, along with its phenolic composition and in vitro antioxidant and anti-inflammatory properties. Hottentot-fig's biomass offered a good supply of nutrients, mainly carbohydrates, proteins, and minerals, with a tendency for higher concentrations of the most relevant minerals and proteins in autumn and winter, and in plants from sites A (Ria de Alvor lagoon) and B (Ancão beach). The extracts were rich in polyphenolics, with higher levels in spring and summer, especially for luteolin-7-O-glucoside and salicylic and coumaric acids. The extracts were also effective antioxidants, with stronger radical scavenging activities in spring and summer, along with anti-inflammatory properties. Our results suggest that the usually discarded plant material of this invasive halophyte could be valuable as a source of natural products with potential biotechnological applications in the food and nutraceutical industries.

Screening antibiofilm activity of invasive plants growing at the Slope Merapi Mountain, Central Java, against Candida albicans

BACKGROUND

Candida albicans causes high-mortality candidiasis. Antifungal drug resistance demands the development of virulence factor-targeting drugs, particularly antibiofilm. This study screened the effects of five invasive plants growing in Indonesia (Mimosa pudica, Lantana camara, Acacia mangium, Ageratina riparia, and Mikania micrantha) against C. albicans biofilms. Antifungal activity, antiphospholipase activity, biofilm morphology of C. albicans, and cytotoxic capacity were also evaluated.

METHODS

Maceration was used to extract the plants, and the most active extract inhibiting the biofilms was fractionated using liquid-liquid fractionation. Antibiofilm activity was determined by a colorimetric assay, MTT. Antifungal activity was tested using the broth microdilution method. A phospholipase assay was performed using the egg-yolk agar method. Influence on the C. albicans morphology was assessed using scanning electron microscopy (SEM). The cytotoxic effect was carried out against Vero and HeLa cell lines.

RESULTS

M. pudica extracts showed the most potent antifungal efficacy with minimum inhibitory concentration (MIC) of 15.62 µg/mL and 7.81 µg/mL for aerial parts and roots, respectively. At high concentrations (500 µg/mL and 250 µg/mL), ethanol extract of M. pudica aerial parts strongly inhibited the phospholipase activity. Ethyl-acetate fraction of M. pudica aerial parts demonstrated the most potent antibiofilm activity against 24 h old biofilm of C. albicans with an inhibitory concentration (53.89%) of 62.5 µg/mL showed no cytotoxicity in both Vero and HeLa cells. This fraction affected the morphology of C. albicans and contained promising compounds for inhibiting the 24 h old biofilm of C. albicans.

CONCLUSIONS

Invasive M. pudica plant inhibited the growth of planktonic C. albicans cells and its ethyl acetate fraction decreased the metabolic activity of C. albicans biofilms. This result demonstrates the potential of invasive M. pudica plant to reduce biofilm-associated candida infection.

Advancing environmental design with phytoremediation of brownfield soils using spontaneous invasive plants

Compared to traditional mechanical brownfield remediation strategies, phytoremediation as a sustainable and low-impact solution, yielding long-term soil chemical improvement. As a common part of many local plant communities, spontaneous invasive plants have advantages over native species in growth speed and resource-use efficiency and are many are effective on degrading or removing chemical soil pollutants. This research presents a methodology for using spontaneous invasive plants as the agent of phytoremediation for brownfield remediation is an innovative component of ecological restoration and design. This research explores s conceptual and applicable model of using spontaneous invasive plants in the phytoremediation of brownfield soil for environmental design practice. This research summarizes five parameters (Soil Drought Level, Soil Salinity, Soil Nutrients, Soil Metal Pollution, and Soil pH) and their classification standards. Based on the five parameters, a series of experiments were designed to examine 5 spontaneous invasive species' tolerance and performance to different soil conditions. Taking the research results as a data base, this research developed a conceptual model of selecting suitable spontaneous invasive plants for brownfield phytoremediation by overlaying the soil condition data and plants' tolerance data. Using a brownfield site in Boston metropolitan region as a case study, the research tested the feasibility and rationality of this model. The results propose a novel approach and materials for general environmental remediation of contaminated soil by involving spontaneous invasive plants. It also transforms the abstract phytoremediation knowledge and data to an applicable model which integrates and visualizes the requirements of scientific plant selection, design aesthetic, and ecosystem factors to help the environmental design process in brownfield remediation.

Phytochemical profile and antioxidant capacity, α-amylase and α-glucosidase inhibitory activities of Oxalis pes-caprae extracts in alloxan-induced diabetic mice

Diabetes and its complications are closely correlated with chronic hyperglycemia, causing severe oxidative stress and leading to glycation reaction with formation of advanced glycation end products. However, medicinal plants are still a source of inspiration for the discovery of new treatments of several diseases, including diabetes. The present study was aimed to evaluate the antioxidant and antidiabetic properties of Oxalis pes-caprae flowers extract in alloxan-induced diabetic mice. The phytochemical and antioxidant activities of both aqueous and methanolic extracts were assessed by in-vitro testing such as free radical scavenging assays (DPPH and ABTS⁺), ferrous ions (Fe²⁺) chelating activity and reducing power assay. Additionally, the detection of Amadori products and advanced glycation end products was used to determine the antiglycation potential. α-glucosidase and α-amylase inhibitory assessment was employed to determine the antidiabetic effect, while alloxan-induced diabetic mice were used to measure the in-vivo activities of antioxidants and carbohydrates enzymes. The effect of the methanolic extract on body weight and blood glucose level of extract-treated diabetic mice were also investigated. Among the tested extract, the methanolic extract was the richest in phenolic compounds which is directly related with their remarkable antioxidant, enzyme inhibitory and antiglycation activity. The oral administration of the two doses of Oxalis pes-caprae flowers (150 mg/kg and 250 mg/kg) daily for 3 weeks resulted in hypoglycemic effect compared to the reference drug, glibenclamide (10 mg/kg). Furthermore, the extract was shown to significantly increase the activities of antioxidants and glycolysis enzymes in the liver, kidney and spleen of diabetic mice, compared to diabetic control group. Therefore, Oxalis pes-caprae extract effectively exhibited hypoglycemic and antidiabetic effects as indicated by in-vitro and in-vivo studies, confirming the protective effects on hyperglycemia and oxidative damage.

Invasiveness, Monitoring and Control of Hakea sericea: A Systematic Review

Solutions for ecological and economic problems posed by Hakea sericea invasions rely on scientific knowledge. We conducted a systematic review to analyze and synthesize the past and current scientific knowledge concerning H. sericea invasion processes and mechanisms, as well as monitoring and control techniques. We used ISI Web of Science, Scopus, and CAPES Periodicals to look for publications on the ecological and environmental factors involved in H. sericea establishment (question 1); responses of H. sericea to fire in native and invaded ecosystems (question 2); and H. sericea monitoring and control methods (question 3). We identified 207 publications, 47.4% of which related to question 1, mainly from Australia and South Africa, with an increasing trend in the number of publications on monitoring and modeling. The traits identified in our systematic review, such as adaptations to dystrophic environments, drought resistance, sclerophylly, low transpiration rates, high nutrient use efficiency, stomatal conductance and photosynthetic rates, strong serotiny, proteoid roots and high post-fire seed survival and seedling recruitment, highlighted that H. sericea is a successful invader species due to its long adaptive history mediated by an arsenal of ecophysiological mechanisms that place it at a superior competitive level, especially in fire-prone ecosystems. Integrated cost-effective control methods in selected areas and the incorporation of information on the temporal invasion dynamics can significantly improve invasion control and mitigate H. sericea impacts while maintaining the supply of ecosystem services in invaded areas.

Valorization of Invasive Plant Extracts against the Bispecies Biofilm Staphylococcus aureus-Candida albicans by a Bioguided Molecular Networking Screening

Invasive plants efficiently colonize non-native territories, suggesting a great production of bioactive metabolites which could be effective antibiofilm weapons. Our study aimed to look for original molecules able to inhibit bispecies biofilm formed by S. aureus and C. albicans. Extracts from five invasive macrophytes (Ludwigia peploides, Ludwigia grandiflora, Myriophyllum aquaticum, Lagarosiphon major and Egeria densa) were prepared and tested in vitro against 24 h old bispecies biofilms using a crystal violet staining (CVS) assay. The activities of the extracts reducing the biofilm total biomass by 50% or more were comparatively analyzed against each microbial species forming the biofilm by flow cytometry (FCM) and scanning electron microscopy. Extracts active against both species were fractionated. Obtained fractions were analyzed by UHPLC-MS/MS and evaluated by the CVS assay. Chemical and biological data were combined into a bioactivity-based molecular networking (BBMN) to identify active compounds. The aerial stem extract of L. grandiflora showed the highest antibiofilm activity (>50% inhibition at 50 µg∙mL−1). The biological, chemical and BBMN investigations of its fractions highlighted nine ions correlated with the antibiofilm activity. The most correlated compound, identified as betulinic acid (BA), inhibited bispecies biofilms regardless of the three tested couples of strains (ATCC strains: >40% inhibition, clinical isolates: ≈27% inhibition), confirming its antibiofilm interest.

Guaianolide Derivatives from the Invasive Xanthium spinosum L.: Evaluation of Their Allelopathic Potential

Ziniolide, xantholide B (11α-dihydroziniolide), and 11β-dihydroziniolide, three sesquiterpene lactones with 12,8-guaianolide skeletons, were identified as volatile metabolites from the roots of Xanthium spinosum L., an invasive plant harvested in Corsica. Essential oil, as well as hydrosol and hexane extracts, showed the presence of guaianolide analogues. The study highlights an analytical strategy involving column chromatography, GC-FID, GC-MS, NMR (1D and 2D), and the hemi-synthesis approach, to identify compounds with incomplete or even missing spectral data from the literature. Among them, we reported the 1H- and 13C-NMR data of 11β-dihydroziniolide, which was observed as a natural product for the first time. As secondary metabolites were frequently involved in the dynamic of the dispersion of weed species, the allelopathic effects of X. spinosum root's volatile metabolites were assessed on seed germination and seedling growth (leek and radish). Essential oil, as well as hydrosol- and microwave-assisted extracts inhibited germination and seedling growth; root metabolite phytotoxicity was demonstrated. Nevertheless, the phytotoxicity of root metabolites was demonstrated with a more marked selectivity to the benefit of the monocotyledonous species compared to the dicotyledonous species. Ziniolide derivatives seem to be strongly involved in allelopathic interactions and could be the key to understanding the invasive mechanisms of weed.

From wandering weeds to pharmacy: An insight into traditional uses, phytochemicals and pharmacology of genus Chromolaena (Asteraceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Chromolaena species, of the Asteraceae family, are distributed across the tropical and the temperate regions of Africa, the Americas, southern Asia, and Australia. Despite "falling out of favour" among the people because of their "weedy" nature, Chromolaena species have indisputable long medicinal history in the treatment of malaria, nasal congestion, inflammation, eye disorders, asthma, cough, flu, headache, and cold.

AIM OF THE REVIEW

The aim of this review is to systematically summarize the current knowledge on ethnopharmacology, phytochemistry, pharmacology, toxicology, and real-time scientific applications of the genus Chromolaena after its re-classification from genus Eupatorium, as well as to proffer integrated approaches in maximizing their therapeutic values despite their "weedy" nature.

MATERIALS AND METHODS

First, the current species in the genus were verified by "The Plant List" (http://www.theplantlist.org) and "Royal Botanic Gardens, Kew/Missouri Botanical Garden" (http://mpns.kew.org/mpns-portal/). Second, the relevant information on each of the identified species was gathered from following databases: Google Scholar, Online Wiley library, ScienceDirect, SciFinder, Scopus, PubMed. Scientific literature was searched from inception till August 2021.

RESULTS

More than 190 phytochemicals have been isolated and identified from 27 species of the genus, including flavonoids, alkaloids, triterpenoids, diterpenoids, sesquiterpenoids, steroids, fatty acids, and coumarins among others. Pharmacological investigations, both in vitro and in vivo, have shown that the extracts and the compounds have antimicrobial, anticancer, antioxidant, insecticidal, anti-inflammatory, and anti-diabetic activities among others.

CONCLUSIONS

Many species of genus have potential therapeutic values, and hence they are more than "wandering" weeds. In addition, there is growing interest in the real-time scientific applications of the genus in the production of pharmacological polyherbal products, and this should serve as a stimulus to strategically develop integrated control approaches for preserving these species, with a view of maximizing their therapeutic values and reducing their cost of eradication.

Exploring the Phytochemicals of Acacia melanoxylon R. Br

Invasive species are currently a world menace to the environment, although the study of their chemistry may provide a means for their future beneficial use. From a study of Portuguese Acacia melanoxylon R. Br. five known compounds were isolated: lupeol, 3β-Z-coumaroyl lupeol, 3β-E-coumaroyl lupeol (dioslupecin A), kolavic acid 15-methyl ester and vomifoliol (blumenol A). Their structures were elucidated by 1D and 2D NMR spectroscopy and mass spectrometry, and as a result some corrections are made to their previous 13C NMR assignments. Cytotoxicity of 3β-E-coumaroyl lupeol (dioslupecin A) and kolavic acid 15-methyl ester was evaluated against HCT116 human colorectal cancer cells although biological activity was not evident.