Evaluation of Polyphenol Content and Antioxidant Capacity of Aqueous Extracts from Eight Medicinal Plants from Reunion Island: Protection against Oxidative Stress in Red Blood Cells and Preadipocytes

Evidence for the efficacy of anti-inflammatory plants used in Brazilian traditional medicine with ethnopharmacological relevance

ETHNOPHARMACOLOGICAL RELEVANCE

When exacerbated, inflammatory processes can culminate in physical and emotional disorders and, if not stopped, can be lethal. The high prevalence of inflammation has become a public health problem, and the need for new drugs to treat this pathology is imminent. The use of medicinal plants has emerged as an alternative, and a survey of data that corroborates its application in inflammatory diseases is the starting point. Furthermore, Brazil harbors a megadiversity, and the traditional use of plants is relevant and needs to be preserved and carefully explored for the discovery of new medicines.

AIM OF THE STUDY

This review sought to survey the medicinal plants traditionally used in Brazil for the treatment of inflammatory processes and to perform, in an integrative way, a data survey of these species and analysis of their phytochemical, pharmacological, and molecular approaches.

MATERIALS AND METHODS

Brazilian plants that are traditionally used for inflammation (ophthalmia, throat inflammation, orchitis, urinary tract inflammation, ear inflammation, and inflammation in general) are listed in the DATAPLAMT database. This database contains information on approximately 3400 native plants used by Brazilians, which were registered in specific documents produced until 1950. These inflammatory disorders were searched in scientific databases (PubMed/Medline, Scopus, Web of Science, Lilacs, Scielo, Virtual Health Library), with standardization of DECS/MESH descriptors for inflammation in English, Spanish, French, and Portuguese, without chronological limitations. For the inclusion criteria, all articles had to be of the evaluated plant species, without association of synthesized substances, and full articles free available in any of the four languages searched. Duplicated articles and those that were not freely available were excluded.

RESULTS

A total of 126 species were identified, culminating in 6181 articles in the search. After evaluation of the inclusion criteria, 172 articles representing 40 different species and 38 families were included in the study. Comparison of reproducibility in intra-species results became difficult because of the large number of extraction solvents tested and the wide diversity of evaluation models used. Although the number of in vitro and in vivo evaluations was high, only one clinical study was found (Abrus precatorius). In the phytochemical analyses, more than 225 compounds, mostly phenolic compounds, were identified.

CONCLUSION

This review allowed the grouping of preclinical and clinical studies of several Brazilian species traditionally used for the treatment of many types of inflammation, corroborating new searches for their pharmacological properties as a way to aid public health. Furthermore, the large number of plants that have not yet been studied has encouraged new research to revive traditional knowledge.

Antiseizure Activity of Mitragyna inermis in the Pentylenetetrazol-Induced Seizure Model in Mice: Involvement of Flavonoids and Alkaloids

Objective

This study aimed to investigate whether Mitragyna inermis (Willd.) Otto Kuntze organic and aqueous extracts are able to control seizures induced by pentylenetetrazol (PTZ) in mice based on flavonoid fingerprints and alkaloidal contents.

Materials and Methods

Ethanolic extract and decoction-derived fractions from roots, leaves, and stems were subjected to chromatographic fingerprinting using AlCl3 and screening for their antiseizure effects using PTZ-induced acute seizure model. From the fractions that showed potent bioactivities, plausible antiseizure alkaloids were isolated using thin layer chromatography, and their structures were elucidated using 1H NMR, 2D NMR, 13C NMR, and FAB-HR (+ve or -ve).

Results

All fractions, with the exception of the dichloromethane and hexane fractions, revealed remarkable flavonoid fingerprints. An acute PTZ-induced seizure test revealed that ethanolic extract of stem bark [500 mg/kg body weight (bw)], ethyl acetate extract of stem bark (500 mg/kg bw), and aqueous extract of leaves (300 mg/kg bw) significantly delayed the occurrence of hind limb tonic extension (HLTE); however, a non-significant delay was observed in the onset of first myoclonic jerk compared with control animals. Isolation yielded four main alkaloids: that are, pteropodine (1), isopteropodine (2), mitraphylline (3) and corynoxeine (4). Corynoxeine is a new compound derived from M. inermis.

Conclusion

This study suggests that flavonoid fingerprints are tracers of M. inermis anticonvulsant ingredients. The stem bark ethanolic and ethyl acetate extracts and leaf aqueous extracts contain anticonvulsant bioactive principles that delay notifying the HLTE occurring in male naval medical research institute mice. Furthermore, alkaloidal contents also remain plausible bioactive anticonvulsant principles. All observations support the traditional use of M. inermis to manage epilepsy. However, further studies are needed to understand the effects of alkaloid fractions, flavonoids, and the isolated compounds as promising antiseizure agents derived from M. inermis in experimental animals.

Study of the Antibacterial Activity of Rich Polyphenolic Extracts Obtained from Cytisus scoparius against Foodborne Pathogens

Natural extracts containing high polyphenolic concentrations may act as good antimicrobials for their antibacterial and antibiofilm activity. The present research characterizes two hydro-organic extracts with high polyphenolic content, obtained from the shrub Cytisus scoparius as antipathogenic candidates. As a result of their own composition, both extracts, LE050 and PG050, have shown pronounced bioactivities with potential uses, especially in agricultural, livestock production, food manufacturing, and pharmaceutical industries. Polyphenolic compounds were extracted by using adjusted hydro-organic solvent mixtures. These extracts' in vitro antimicrobial activity was evaluated on Gram-positive and Gram-negative pathogenic bacteria, giving special attention to those involved in food contamination. Due to this, the biofilm dispersion was assessed on Listeria monocytogenes, Staphylococcus aureus and Pseudomonas aeruginosa. The extracts showed antimicrobial activity against the pathogenic species tested, presenting IC50 values between 0.625-20% v/v. Different behaviors have been detected between both extracts, probably linked to their distinct polyphenol composition, being LE050 extract the one with most promising bioactive applications. Finally, the results from the biofilm dispersion assays reveal that the extracts exhibit a good antibiofilm activity against the pathogenic bacteria tested.

Achyrocline satureioides as an adjuvant therapy for the management of mild viral respiratory infections in the context of COVID-19: Preliminary results of a randomized, placebo-controlled, and open-label clinical trial

We evaluated the impact of an Achyrocline satureioides inflorescence infusion on the clinical outcomes of viral respiratory infections, including those caused by SARS-CoV-2, in a monocentric, randomized, open-label, placebo-controlled clinical trial. Patients with symptoms of viral respiratory infection, including suspected cases of COVID-19, were included and assigned to receive either A. satureioides (n = 57) or Malus domestica (n = 67) infusions twice a day for 14 days. All participants were included before the RT-PCR results, performed using a nasopharyngeal swab. The patients were further divided into subgroups according to real-time polymerase chain reaction results: SARS-CoV-2-positive and SARS-CoV-2-negative subgroups for statistical analyses. We assessed clinical outcomes, such as the latency to resolution of cough, dyspnea, fever, sore throat, chest pain, smell and taste dysfunctions, diarrhea, nausea, abdominal pain, and loss of appetite; hospitalization; and mortality with questionnaires and medical records. The subjects that received early A. satureioides infusion showed a significant reduction in the average number of days with respiratory and neurological symptoms compared with the control group (M. domestica infusion). We conclude that A. satureioides is a safe agent and, in combination with standard care, improves viral respiratory infection symptoms, especially those related to COVID-19.

Procyanidins: A promising anti-diabetic agent with potential benefits on glucose metabolism and diabetes complications

Diabetes mellitus (DM) is a complex disease with alarming worldwide health implications and high mortality rates, largely due to its complications such as cardiovascular disease, nephropathy, neuropathy, and retinopathy. Recent research has shown that procyanidins (PC), a type of flavonoid, have strong antioxidant and free radical elimination effects, and may be useful in improving glucose metabolism, enhancing pancreatic islet cell activity, and decreasing the prevalence of DM complications. This review article presents a systematic search for peer-reviewed articles on the use of PC in the treatment of DM, without any language restrictions. The article also discusses the potential for PC to sensitise DM medications and improve their efficacy. Recent in vivo and in vitro studies have demonstrated promising results in improving the biological activity and bioavailability of PC for the treatment of DM. The article concludes by highlighting the potential for novel materials and targeted drug delivery methods to enhance the pharmacokinetics and bioactivity of PC, leading to the creation of safer and more effective anti-DM medications in the future.

Inhibition of Advanced Glycation End-Products by Tamarindus indica and Mitragyna inermis Extracts and Effects on Human Hepatocyte and Fibroblast Viability

Tamarindus indica and Mitragyna inermis are widely used by herbalists to cure diabetes mellitus. The aim of this study is to investigate the inhibitory potential of aqueous and various organic solvent fractions from both plants and some isolated compounds against advanced glycation end-products (AGEs). For this purpose, an in vitro BSA-fructose glycation model was used to evaluate the inhibition of AGE formation. Furthermore, the effects of the fractions on mouse fibroblast (NIH-3T3) and human hepatocyte (HepG2) survival were evaluated. The leaf, stem, and root fractions of both plants exhibited significant inhibition of AGEs formation. The IC₅₀ values appeared to be less than 250 µg/mL; however, all fractions presented no adverse effects on NIH-3T3 up to 500 µg/mL. Otherwise, our phytochemical investigation afforded the isolation of a secoiridoid from the Mitragyna genus named secoiridoid glucoside sweroside (1), along with three known quinovic acid glycosides: quinovic acid-3β-O-β-d-glucopyranoside (2), quinovic acid-3-O-β-d-6-deoxy-glucopyranoside, 28-O-β-d-glucopyranosyl ester (3), and quinovic acid 3-O-α-l-rhamnopyranosyl-(4→1)-β-d-glucopyranoside (4). In particular, 1-3 are compounds which have not previously been described in Mitragyna inermis roots. However, the isolated compounds did not exhibit AGE inhibitory activity. Further investigation on these potent antiglycation fractions may allow for the isolation of new antidiabetic drug candidates.

Quality Consistency of Herbal Products: Chemical Evaluation

The widespread utility of herbal products has been rising considerably worldwide, including both developed and developing countries, leading to the rapid growth of their availability in the United States and globally. This substantial increase in consumption of herbal products has witnessed the emergence of adverse effects upon oral administration of certain of these products, and thus has raised safety concerns. The adverse effects caused by the consumption of certain botanical medicines occur primarily as a result of the poor quality of plant raw materials or the finished products, which inherently may affect safety and/or efficacy. The poor quality of some herbal products can be attributed to a lack of proper quality assurance and quality control. A high demand for herbal products that surpasses production, combined with a desire for maximizing profits, along with a lack of rigorous quality control within some manufacturing facilities have led to the emergence of quality inconsistencies. The underlying causes for this involve the misidentification of plant species, or their substitution, adulteration, or contamination with harmful ingredients. Analytical assessments have revealed there to be frequent and significant compositional variations between marketed herbal products. The inconsistency of the quality of herbal products can be ascribed essentially to the inconsistency of the botanical raw material quality used to manufacture the products. Thus, the quality assurance and the quality control of the botanical raw materials is may contribute significantly to improving the quality and consistency of the quality of the end products. The current chapter focuses on the chemical evaluation of quality and consistency of herbal products, including botanical dietary supplements. Different techniques, instruments, applications, and methods used in identifying, quantifying, and generating chemical fingerprints and chemical profiles of the ingredients of the herbal products will be described. The strengths and weaknesses of the various techniques available will be addressed. Limitations of the other approaches including morphological or microscopic analysis and DNA-based analysis will be presented.

Estrogen receptors, ERK1/2 phosphorylation and reactive oxidizing species in red blood cells from patients with rheumatoid arthritis

Red blood cells (RBCs) are recognized to be important pathogenetic determinants in several human cardiovascular diseases (CVD). Undergoing to functional alterations when submitted to risk factors, RBCs modify their own intracellular signaling and the redox balance, shift their status from antioxidant defense to pro-oxidant agents, become a potent atherogenic stimulus playing a key role in the dysregulation of the vascular homeostasis favoring the developing and progression of CVD. Rheumatoid arthritis (RA) is a chronic autoimmune disease associated with a significantly increased risk of cardiovascular mortality with a prevalence from two to five more likely in woman, mainly attributed to accelerated atherosclerosis. The purpose of this study was to correlate the RA disease activity and the RBCs functional characteristics. Thirty-two women (aged more than 18 years) with RA, and 25 age-matched healthy women were included in this study. The disease activity, measured as the number of swollen and painful joints (DAS-28), was correlated with 1) the expression of RBCs estrogen receptors, which modulate the RBC intracellular signaling, 2) the activation of the estrogen-linked kinase ERK_½, which is a key regulator of RBC adhesion and survival, and 3) the levels of inflammatory- and oxidative stress-related biomarkers, such as the acute-phase reactants, the antioxidant capacity of plasma, the reactive oxidizing species formation and 3-nitrotyrosine. All the biomarkers were evaluated in RA patients at baseline and 6 months after treatment with disease-modifying anti-rheumatic drugs (DMARDs). We found, for the first times, that in RA patients 1) the DAS-28 correlated with RBC ER-α expression, and did not correlate with total antioxidant capacity of plasma; 2) the RBC ER-α expression correlated with systemic inflammatory biomarkers and oxidative stress parameters, as well as ERK_½ phosphorylation; and 3) the DMARDs treatments improved the clinical condition measured by DAS-28 score decrease, although the RBCs appeared to be more prone to pro-oxidant status associated to the expression of survival molecules. These findings represent an important advance in the study of RA determinants favoring the developing of CVD, because strongly suggest that RBCs could also participate in the vascular homeostasis through fine modulation of an intracellular signal linked to the ER-α.

Identification and Quantification of Key Phytochemicals, Phytohormones, and Antioxidant Properties in Coccinia grandis during Fruit Ripening

Coccinia grandis contains secondary metabolites, such as flavonoids, phenolic acids, terpenoids, alkaloids, sterols, and glycosides, which are known to have in vitro antioxidant, antidiabetic, anti-inflammatory, and antidyslipidemic activities. C. grandis fruits change dramatically during ripening, and the differences in the phytochemicals contribute to various uses. This study reports the phytochemical compounds and antioxidant activities during ripening of C. grandis for the first time. Characterizations were conducted on the physiologically active substances in C. grandis fruits at three ripening stages, and a total of 25 peaks were identified. Key phytochemicals in the ripening stages of C. grandis were identified, and the major substances that contributed to antioxidant properties were selected and quantitatively analyzed. Although the concentration of tiliroside increased during aging, hydroxycinnamic acid (chlorogenic and p-coumaric acids), flavonols (rutin), and triterpenes (cucurbitacins B and D) with antioxidant effects decreased. Therefore, phenolic compounds and cucurbitacins dominate immature C. grandis quantitatively. Regarding phytohormones, the gibberellin A4 content decreased as the fruits matured, but indoleacetic acid and salicylic acid increased with fruit maturity. The antioxidant capacities determined by DPPH and ABTS consistently decreased with increasing maturity. Accordingly, the extracts of immature C. grandis fruits have high levels of bioactive compounds and can be used to develop food additives and health supplements.

Aqueous Extract of Psiloxylon mauritianum, Rich in Gallic Acid, Prevents Obesity and Associated Deleterious Effects in Zebrafish

Obesity has reached epidemic proportions, and its prevalence tripled worldwide between 1975 and 2016, especially in Reunion Island, a French overseas region. Psiloxylon mauritianum, an endemic medicinal plant from Reunion Island registered in the French pharmacopeia, has recently gained interest in combating metabolic disorders because of its traditional lipid-lowering and “anti-diabetic” use. However, scientific data are lacking regarding its toxicity and its real benefits on metabolic diseases. In this study, we aim to determine the toxicity of an aqueous extract of P. mauritianum on zebrafish eleutheroembryos following the OECD toxicity assay (Organization for Economic Cooperation and Development, guidelines 36). After defining a non-toxic dose, we determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) that this extract is rich in gallic acid but contains also caffeoylquinic acid, kaempferol and quercetin, as well as their respective derivatives. We also showed that the non-toxic dose exhibits lipid-lowering effects in a high-fat-diet zebrafish larvae model. In a next step, we demonstrated its preventive effects on body weight gain, hyperglycemia and liver steatosis in a diet-induced obesity model (DIO) performed in adults. It also limited the deleterious effects of overfeeding on the central nervous system (i.e., cerebral oxidative stress, blood-brain barrier breakdown, neuro-inflammation and blunted neurogenesis). Interestingly, adult DIO fish treated with P. mauritianum display normal feeding behavior but higher feces production. This indicates that the “anti-weight-gain” effect is probably due to the action of P. mauritianum on the intestinal lipid absorption and/or on the microbiota, leading to the increase in feces production. Therefore, in our experimental conditions, the aqueous extract of P. mauritianum exhibited “anti-weight-gain” properties, which prevented the development of obesity and its deleterious effects at the peripheral and central levels. These effects should be further investigated in preclinical models of obese/diabetic mice, as well as the impact of P. mauritianum on the gut microbiota.

Hypericum lanceolatum Lam. Medicinal Plant: Potential Toxicity and Therapeutic Effects Based on a Zebrafish Model

Hypericum lanceolatum Lam. (H. lanceolatum) is a traditional medicinal plant from Reunion Island used for its pleiotropic effects mainly related to its antioxidant activity. The present work aimed to 1) determine the potential toxicity of the plant aqueous extract in vivo and 2) investigate its putative biological properties using several zebrafish models of oxidative stress, regeneration, estrogenicity, neurogenesis and metabolic disorders. First, we characterized the polyphenolic composition by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and identified chlorogenic acid isomers, quercetin and kaempferol derivatives as the major compounds. We then evaluated for the first time the toxicity of an aqueous extract of H. lanceolatum and determined a maximum non-toxic concentration (MNTC) in zebrafish eleutheroembryos from 0 to 96 hpf following OECD (Organization for Economic Cooperation and Development) guidelines. This MNTC test was also determined on hatched eleutheroembryos after 2 days of treatment (from 3 to 5 dpf). In our study, the anti-estrogenic effects of H. lanceolatum are supported by the data from the EASZY assay. In a tail amputation model, we showed that H. lanceolatum at its MNTC displays antioxidant properties, favors immune cell recruitment and tissue regeneration. Our results also highlighted its beneficial effects in metabolic disorders. Indeed, H. lanceolatum efficiently reduces lipid accumulation and body mass index in overfed larva- and adult-models, respectively. In addition, we show that H. lanceolatum did not improve fasting blood glucose levels in a hyperglycemic zebrafish model but surprisingly inhibited neurogenesis impairment observed in diabetic conditions. In conclusion, our study highlights the antioxidant, pro-regenerative, anti-lipid accumulation and pro-neurogenic effects of H. lanceolatum in vivo and supports the use of this traditional medicinal plant as a potential alternative in the prevention and/or treatment of metabolic disorders.

Protective Effects of Medicinal Plant Decoctions on Macrophages in the Context of Atherosclerosis

Atherosclerosis is a hallmark of most cardiovascular diseases. The implication of macrophages in this pathology is widely documented, notably for their contribution to lipid accumulation within the arterial wall, associated with oxidative stress and inflammation processes. In order to prevent or limit the atherosclerosis damage, nutritional approaches and medicinal plant-based therapies need to be considered. In Reunion Island, medicinal plant-based beverages are traditionally used for their antioxidant, lipid-lowering and anti-inflammatory properties. The aim of our study was to assess the protective effects of eight medicinal plant decoctions in an in vitro model of RAW 264.7 murine macrophages exposed to pro-atherogenic conditions (oxidized low-density lipoproteins—ox-LDL—E. coli Lipopolysaccharides—LPS). The impact of polyphenol-rich medicinal plant decoctions on cell viability was evaluated by Neutral Red assay. Fluorescent ox-LDL uptake was assessed by flow cytometry and confocal microscopy. Activation of NF-κB was evaluated by quantification of secreted alkaline phosphatase in RAW-Blue™ macrophages. Our results show that medicinal plant decoctions limited the cytotoxicity induced by ox-LDL on macrophages. Flow cytometry analysis in macrophages demonstrated that medicinal plant decoctions from S. cumini and P. mauritianum decreased ox-LDL uptake and accumulation by more than 70%. In addition, medicinal plant decoctions also inhibited NF-κB pathway activation in the presence of pro-inflammatory concentrations of E. coli LPS. Our data suggest that medicinal plant decoctions exert protective effects on ox-LDL-induced cytotoxicity and limited macrophage lipid uptake. Moreover, herbal preparations displayed anti-inflammatory properties on macrophages that can be of interest for limiting the atherosclerotic process.