Separation, Identification, and Antidiabetic Activity of Catechin Isolated from Arbutus unedo L. Plant Roots

Metabolomics and molecular networking approach for exploring the anti-diabetic activity of medicinal plants

Metabolomics and molecular networking approaches have expanded rapidly in the field of biological sciences and involve the systematic identification, visualization, and high-throughput characterization of bioactive metabolites in natural products using sophisticated mass spectrometry-based techniques. The popularity of natural products in pharmaceutical therapies has been influenced by medicinal plants with a long history of ethnobotany and a vast collection of bioactive compounds. Here, we selected four medicinal plants Cleistocalyx operculatus, Terminalia chebula, Ficus lacor, and Ficus semicordata, the biochemical characteristics of which remain unclear owing to the inherent complexity of their plant metabolites. In this study, we aimed to evaluate the potential of these aforementioned plant extracts in inhibiting the enzymatic activity of α-amylase and α-glucosidase, respectively, followed by the annotation of secondary metabolites. The methanol extract of Ficus semicordata exhibited the highest α-amylase inhibition with an IC50 of 46.8 ± 1.8 μg mL-1, whereas the water fraction of Terminalia chebula fruits demonstrated the most significant α-glucosidase inhibition with an IC50 value of 1.07 ± 0.01 μg mL-1. The metabolic profiling of plant extracts was analyzed through Liquid Chromatography-Mass Spectrometry (LC-HRMS) of the active fractions, resulting in the annotation of 32 secondary metabolites. Furthermore, we applied the Global Natural Product Social Molecular Networking (GNPS) platform to evaluate the MS/MS data of Terminalia chebula (bark), revealing that there were 205 and 160 individual ion species observed as nodes in the methanol and ethyl acetate fractions, respectively. Twenty-two metabolites were tentatively identified from the network map, of which 11 compounds were unidentified during manual annotation.

Qualitative and Quantitative Comparison of Aromatic Oil Components and Antifungal Effects of Cymbopogon flexuosus Obtained with Supercritical CO2, Microwave-Ultrasonic, Steam Distillation, and Hydrodistillation Extraction Techniques

Cymbopogon flexuosus is a highly valued botanical species with significant applications in the food and food supplement industries, medicine, and cosmetics. The effects of four extraction techniques, supercritical CO2, microwave-ultrasonic, steam distillation, and hydrodistillation techniques, on the yield, phytochemical constituents, and antifungal activity against nine fungal species of Cymbopogon flexuosus aromatic oil (AO) were explored in this investigation. Gas chromatography connected with a mass spectrometry apparatus was employed for the qualitative and quantitative analyses of the investigated plant AOs. In addition, using the broth microdilution method, minimum inhibitory concentrations (MICs) were calculated for several fungi species. The supercritical CO2 method gave the highest yield of AO (11.62 ± 0.03 (w/w)) followed by the microwave-ultrasonic method (1.55 ± 0.05% (w/w)) and the steam distillation method (1.24 ± 0.04% (w/w)), while the hydrodistillation methods gave the lowest yield (1.17 ± 0.01 (w/w)). In addition, eighteen molecules were specified in the AOs obtained with the supercritical CO2, microwave-ultrasonic, steam distillation, and hydrodistillation techniques, which constituted 99.36, 98.6, 98.21, and 98.31% (v/v) of the total oils, respectively. Additionally, linalyl acetate was the trending molecule in the microwave-ultrasonic and steam distillation methods, representing 24.61 and 24.34% (v/v), respectively, while geranial was the dominant molecule in the AOs extracted with the hydrodistillation and supercritical CO2 extraction techniques (27.01 and 25.6% (v/v), respectively). The antifungal screening results revealed that the tested C. flexuosus AOs have potential antifungal effects against all the screened fungi species. The antifungal effect of the AOs extracted with the steam distillation and microwave-ultrasonic methods was remarkable compared with that of the commercial antifungal drug Fluconazole. However, the AOs extracted with these two methods have a more potent antifungal effect against Candida parapsilosis than that of Fluconazole with MICs of 3.13 ± 0.01, 3.13 ± 0.01, and 6.25 ± 0.91 µg/mL, respectively. The same effects were also observed against Trichophyton rubrum with MICs of 6.25 ± 0.91 µg/mL, respectively. The results of this investigation demonstrated that the steam distillation and microwave-ultrasonic methods are promising processes for the extraction of C. flexuosus AO with a potent antifungal effect. This may be an advantage for the utilization of C. flexuosus AO over some antifungal synthetic agents commonly utilized as medicines, preservatives, food additives, cosmetics, and nutrient supplements.

Study of the Chemical Composition of Rosa beggeriana Schrenk's Fruits and Leaves

Rosa species are widely used in folk medicine in different countries of Asia and Europe, but not all species are studied in-depth. For instance, Rosa beggeriana Schrenk, a plant which grows in Central Asia, Iran, and some parts of China, is little described in articles. Column and thin-layer chromatography methods were used to isolate biologically active substances. From a study of fruits and leaves of Rosa beggeriana Schrenk, a large number of compounds were identified, seven of which were isolated: 3β,23-dihydroxyurs-12-ene (1), β-sitosterol (2), betulin (3), (+)-catechin (4), lupeol (5), ethyl linoleate (6), and ethyl linolenoate (7). Their structures were elucidated by 1H, DEPT and 13C NMR spectroscopy, mass spectrometry, and GC-MS (gas chromatography-mass spectrometry). The study also identified the structures of organic compounds, including volatile esters and acids. Consequently, comprehensive data were acquired concerning the chemical constitution of said botanical specimen.

Effect of Wild Strawberry Tree and Hawthorn Extracts Fortification on Functional, Physicochemical, Microbiological, and Sensory Properties of Yogurt

The composition analyses and health-promoting properties (antioxidant capacity, antidiabetic, and antihypertensive properties) of wild fruit extracts and the effect of the incorporation of strawberry tree (STE) and hawthorn (HTE) extracts on the physicochemical, instrumental textural, microbiological, and sensory parameters of yogurts were evaluated. The incorporation of wild fruit extracts in yogurt increased antioxidant and antidiabetic properties (inhibition of digestive α-amylase, α-glucosidase, and lipase enzymatic activities) compared to the control, without decreasing their sensory quality or acceptance by consumers. The hawthorn yogurt (YHTE) showed the highest total phenolic content (TPC) and antioxidant capacity (ABTS and ORAC methods). Yogurts containing wild fruit extracts and dietary fiber achieved high overall acceptance scores (6.16-7.04) and showed stable physicochemical, textural, and microbiological properties. Therefore, the use of wild fruit extracts and inulin-type fructans as ingredients in yogurt manufacture stands as a first step towards the development of non-added sugar dairy foods for sustainable health.

A New Saponin (Zygo-albuside D) from Zygophyllum album Roots Triggers Apoptosis in Non-Small Cell Lung Carcinoma (A549 Cells) through CDK-2 Inhibition

Phytochemical study of the ethyl acetate root extract of Zygophyllum album has resulted in the isolation of a new saponin, Zygo-albuside D (1), along with two known compounds; (3-O-[β-D-quinovopyranosyl]-quinovic acid) (2), which is first reported in the root, and catechin (3), first reported in the genus. Their chemical structures were established by NMR and high-resolution mass spectrometry (HRMS). The new saponin (1) exhibited promising cytotoxicity with IC50 values of 3.5 and 5.52 μM on A549 and PC-3 cancer cell lines, respectively, compared to doxorubicin with IC50 values of 9.44 and 11.39 μM on A549 and PC-3 cancer cell lines, respectively. While it had an IC50 value of 46.8 μM against WISH cells. Investigating apoptosis-induction, compound 1 induced total apoptotic cell death in A549 lung cancer cells by 32-fold; 21.53% compared to 0.67% in the untreated control cells. Finally, it upregulated the pro-apoptotic genes and downregulated the antiapoptotic gene using gene expression levels. Compound 1 exhibited remarkable CDK-2 target inhibition by 96.2% with an IC50 value of 117.6 nM compared to Roscovitine. The molecular docking study further confirmed the binding affinity of compound 1 as CDK2 and Bcl2 inhibitors that led to apoptosis induction in A549 cancer cells. Hence, this study highlights the importance of compound 1 in the design of a new anticancer agent with specific mechanisms.

Evaluation of cytotoxic and apoptotic effects of the extracts and phenolic compounds of Astragalus globosus Vahl and Astragalus breviflorus DC

Astragalus L. is a genus member of the Fabaceae family, representing about 3,000 species all over the world and 380 species in Turkey. Astragalus species have been used in traditional medicine for many years. Astragalus globosus Vahl, known as "top geven", is a dwarf, scapose, perennial herb, Astragalus breviflorus DC., known as "yünlü geven", is an extremely spiny dwarf shrub. These endemic species grow in the Turkish cities of Erzurum, Kars, and Van. This is the first phytochemical and cytotoxic investigation of Astragalus globosus Vahl and Astragalus breviflorus DC. The main extracts and sub-fractions from the plants were evaluated for in vitro cytotoxic and apoptotic activities. The IC₅₀ values of dichloromethane, n-butanol, and water extracts of the aerial parts of A. globosus against the MCF-7 cell line were determined as 28.39, 868.60, and 1753.00 µg/mL. The values for the MDA-MB-231 cell line were 264.00, 620.30, and 1300.50 µg/mL, respectively. From A. globosus, the following were isolated: a flavone glycoside, diosmetin-7-O-rutinoside (1); and two flavonol glycosides, isorhamnetin-3-O-rutinoside (2) and quercetin-3-O-galactoside (3). From A. breviflorus, two phenolic acids, caffeic acid (4) and chlorogenic acid (5), and a flavan-3-ol, catechin (6), were isolated. Diosmetin-7-O-rutinoside was isolated from Astragalus species for the first time and showed the highest cytotoxic activities on the MCF-7 and MDA-MB-231 breast cancer cell lines with IC₅₀ values of 13.65 and 12.89 μg/mL, respectively. Moreover, we observed that diosmin exerts cytotoxic effects by causing cell necrosis.

Characterization, antibacterial, antioxidant, antidiabetic, and anti-inflammatory activities of green synthesized silver nanoparticles using Phragmanthera austroarabica A. G. Mill and J. A. Nyberg extract

Introduction

Diabetes mellitus is a chronic metabolic disorder that exhibited great expansion all over the world. It is becoming an epidemic disease adding a major burden to the health care system, particularly in developing countries.

Methods

The plant under investigation in the current study Phragmanthera austroarabica A. G. Mill and J. A. Nyberg is traditionally used in Saudi Arabia for the treatment of diabetes mellitus. The methanolic extract (200 mg/kg) of the plant and pure gallic acid (40 mg/kg), a major metabolite of the plant, as well as their silver nanoparticle formulae (AgNPs) were evaluated for their antidiabetic activity.

Results and Discussion

The results showed a decrease in body fat, obesity, an improvement in lipid profiles, normalization of hyperglycemia, insulin resistance, and hyperinsulinemia, and an improvement in liver tissue structure and function. However, the results obtained from AgNPs for both extract and the pure gallic acid were better in most measured parameters. Additionally, the activity of both the crude extract of the plant and its AgNPs were evaluated against a number of gram-positive, gram-negative bacteria and fungi. Although the activity of the crude extract ranged from moderate to weak or even non-active, the AgNPs of the plant extract clearly enhanced the antimicrobial activity. AgNPs of the extract demonstrated remarkable activity, especially against the Gram-negative pathogens Proteus vulgaris (MIC 2.5 μg/ml) and Pseudomonas aeruginosa (MIC 5 μg/ml). Furthermore, a promising antimicrobial activity was shown against the Gram-positive pathogen Streptococcus mutants (MIC 1.25 μg/ml).

Cassava (Manihot esculenta Crantz): A Systematic Review for the Pharmacological Activities, Traditional Uses, Nutritional Values, and Phytochemistry

Cassava (Manihot esculenta Crantz) is considered one of the essential tuber crops, serving as a dietary staple food for various populations. This systematic review provides a comprehensive summary of the nutritional and therapeutic properties of cassava, which is an important dietary staple and traditional medicine. The review aims to evaluate and summarize the phytochemical components of cassava and their association with pharmacological activities, traditional uses, and nutritional importance in global food crises. To collect all relevant information, electronic databases; Cochrane Library, PubMed, Scopus, Web of Science, Google Scholar, and Preprint Platforms were searched for studies on cassava from inception until October 2022. A total of 1582 studies were screened, while only 34 were included in this review. The results of the review indicate that cassava has diverse pharmacological activities, including anti-bacterial, anti-cancer, anti-diabetic, anti-diarrheal, anti-inflammatory, hypocholesterolemic effects, and wound healing properties. However, more studies that aim to isolate the phytochemicals in cassava extracts and evaluate their pharmacological property are necessary to further validate their medical and nutritional values.

Mineral contents, antimicrobial profile, acute and chronic toxicity of the aqueous extract of Moroccan Thymus vulgaris in rodents

Moroccan flora is rich in plants used in traditional medicine, but the further scientific investigation is necessary. The aim of the research was to evaluate the nutritional content and antimicrobial activity of Moroccan Thymus vulgaris, as well as its possible acute and chronic toxicological effects on rodents. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) was used to determine the mineral content. The antimicrobial activity was determined using a well-diffusion test, a minimum inhibitory concentration (MIC), and a minimum bactericidal/fungicidal concentration (MBC/MFC) assay. Acute and chronic toxicity studies were conducted in vivo on mice and rats, respectively. Following that, haematological, serum-biochemistry, and histological investigations were performed. Moroccan Thyme was shown to be a source of numerous minerals which are necessary for health promotion. All antimicrobial testing, disc diffusion, MIC, and MBC tests revealed that thyme had potent antibacterial activity against all microorganisms tested. Staphylococcus aureus was the most susceptible bacterium, followed by Salmonella enterica and Escherichia coli. Additionally, thyme exhibited great antifungal efficacy against Candida albicans. The acute toxicity results indicated that the aqueous extract of T. vulgaris is almost non-toxic when taken orally. According to the chronic toxicity study, the extract is generally safe when taken orally over an extended period of time. The biochemical and haematological characteristics of the serum and blood were within acceptable limits, and histological examination revealed no abnormalities. In conclusion, the findings of this investigation, confirm the antimicrobial efficacy of the aqueous extract of Moroccan T. vulgaris and its safety for experimental animals.

Antidiabetic Potential of Commonly Available Fruit Plants in Bangladesh: Updates on Prospective Phytochemicals and Their Reported MoAs

Diabetes mellitus is a life-threatening disorder affecting people of all ages and adversely disrupts their daily functions. Despite the availability of numerous synthetic-antidiabetic medications and insulin, the demand for the development of novel antidiabetic medications is increasing due to the adverse effects and growth of resistance to commercial drugs in the long-term usage. Hence, antidiabetic phytochemicals isolated from fruit plants can be a very nifty option to develop life-saving novel antidiabetic therapeutics, employing several pathways and MoAs (mechanism of actions). This review focuses on the antidiabetic potential of commonly available Bangladeshi fruits and other plant parts, such as seeds, fruit peals, leaves, and roots, along with isolated phytochemicals from these phytosources based on lab findings and mechanism of actions. Several fruits, such as orange, lemon, amla, tamarind, and others, can produce remarkable antidiabetic actions and can be dietary alternatives to antidiabetic therapies. Besides, isolated phytochemicals from these plants, such as swertisin, quercetin, rutin, naringenin, and other prospective phytochemicals, also demonstrated their candidacy for further exploration to be established as antidiabetic leads. Thus, it can be considered that fruits are one of the most valuable gifts of plants packed with a wide spectrum of bioactive phytochemicals and are widely consumed as dietary items and medicinal therapies in different civilizations and cultures. This review will provide a better understanding of diabetes management by consuming fruits and other plant parts as well as deliver innovative hints for the researchers to develop novel drugs from these plant parts and/or their phytochemicals.

Use of Strawberry Tree (Arbutus unedo) as a Source of Functional Fractions with Biological Activities

Arbutus unedo, commonly named 'strawberry tree' (ST), is a Mediterranean native plant that represents a relevant source of biologically active fractions and compounds. ST fruits, traditionally used with culinary and medicinal purposes, along with other components (leaves, roots, honeys, etc.), have been subjected to varied extraction procedures to obtain enriched and bioactive products. This work reviewed the scientific literature, searching for studies that evaluated the potential health implications of ST fractions and attending to the tested biological activities (antioxidant, antiproliferative, hypoglycemic, immune-modulatory, antihypertensive, antimicrobial, etc.), the part of the tree, the experimental model, the specific bioactive compounds and the selected extraction protocol. Furthermore, the strengths and weaknesses of the current state of the published evidence were critically analysed. Although in vitro results demonstrated the potential of ST fractions, further research is encouraged in order to obtain in vivo evidence (animal and clinical studies), assess additional activities (hypocholesterolemic, microbiome-modulatory), maximize the use of advanced extraction technologies, purify and isolate specific bioactive compounds and broaden the analysis investigating phenolic and non-phenolic molecules and their bioavailability.

Comparative Metabolite Fingerprinting of Four Different Cinnamon Species Analyzed via UPLC-MS and GC-MS and Chemometric Tools

The present study aimed to assess metabolites heterogeneity among four major Cinnamomum species, including true cinnamon (Cinnamomum verum) and less explored species (C. cassia, C. iners, and C. tamala). UPLC-MS led to the annotation of 74 secondary metabolites belonging to different classes, including phenolic acids, tannins, flavonoids, and lignans. A new proanthocyanidin was identified for the first time in C. tamala, along with several glycosylated flavonoid and dicarboxylic fatty acids reported for the first time in cinnamon. Multivariate data analyses revealed, for cinnamates, an abundance in C. verum versus procyandins, dihydro-coumaroylglycosides, and coumarin in C. cassia. A total of 51 primary metabolites were detected using GC-MS analysis encompassing different classes, viz. sugars, fatty acids, and sugar alcohols, with true cinnamon from Malaysia suggested as a good sugar source for diabetic patients. Glycerol in C. tamala, erythritol in C. iners, and glucose and fructose in C. verum from Malaysia were major metabolites contributing to the discrimination among species.

In Silico Approaches to Identify Polyphenol Compounds as α-Glucosidase and α-Amylase Inhibitors against Type-II Diabetes

Type-II diabetes mellitus (T2DM) results from a combination of genetic and lifestyle factors, and the prevalence of T2DM is increasing worldwide. Clinically, both α-glucosidase and α-amylase enzymes inhibitors can suppress peaks of postprandial glucose with surplus adverse effects, leading to efforts devoted to urgently seeking new anti-diabetes drugs from natural sources for delayed starch digestion. This review attempts to explore 10 families e.g., Bignoniaceae, Ericaceae, Dryopteridaceae, Campanulaceae, Geraniaceae, Euphorbiaceae, Rubiaceae, Acanthaceae, Rutaceae, and Moraceae as medicinal plants, and folk and herb medicines for lowering blood glucose level, or alternative anti-diabetic natural products. Many natural products have been studied in silico, in vitro, and in vivo assays to restrain hyperglycemia. In addition, natural products, and particularly polyphenols, possess diverse structures for exploring them as inhibitors of α-glucosidase and α-amylase. Interestingly, an in silico discovery approach using natural compounds via virtual screening could directly target α-glucosidase and α-amylase enzymes through Monte Carto molecular modeling. Autodock, MOE-Dock, Biovia Discovery Studio, PyMOL, and Accelrys have been used to discover new candidates as inhibitors or activators. While docking score, binding energy (Kcal/mol), the number of hydrogen bonds, or interactions with critical amino acid residues have been taken into concerning the reliability of software for validation of enzymatic analysis, in vitro cell assay and in vivo animal tests are required to obtain leads, hits, and candidates in drug discovery and development.

An Insight into Phytochemical, Pharmacological, and Nutritional Properties of Arbutus unedo L. from Morocco

Arbutus unedo L. (Ericaceae) is an evergreen shrub widely distributed in the Mediterranean region, particularly through the Moroccan forests. It is an important medicinal plant of great scientific interest due to its nutritional, pharmacological, and chemical properties. The objective of this review is to provide insights into traditional medicinal uses and phytochemical and pharmacological properties of A. unedo from Morocco. In Morocco, the plant has been used as a traditional medicine to treat several pathological conditions. Many phytochemical compounds have been reported in the plant, of which vitamins, carotenoids, flavonoids, polyphenols, tannins, and their derivatives are the most prevalent. Leaves and fruits of A. unedo contain the most significant number of phytochemicals among the species. Furthermore, researchers have demonstrated that A. unedo exhibited antioxidant, anticancer, antibacterial, antidiabetic, antiaggregant, and antihypertensive activities due to the presence of many biochemical compounds with health-promoting properties. According to different toxicity tests, the use of A. unedo is devoid of any significant side effects and/or toxicity. Despite its nutraceutical and health-promoting properties, Moroccan A. unedo remains underexploited mainly, and most of its traditional uses have not yet undergone scientific evidence-based research; therefore, improved knowledge about the potential value of the plant would allow understanding of its biological activity based on its phytochemical compounds that may contribute to the species preservation and valorization.

Ethnobotanical Survey of Medicinal Plants Used by Traditional Healers to Treat Diabetes in the Taza Region of Morocco

Type 2 diabetes is one of the noncommunicable diseases that is becoming a pandemic in Africa. In Morocco, traditional healers have started to use herbal medicines for the treatment of diabetes either individually or in combination with food. The current study aimed to perform an ethnobiological survey of antidiabetic plants use in the Taza region of Morocco. A total of 193 traditional healers were interviewed using a semistructured questionnaire. Data collected were analyzed utilizing the use value (UV), fidelity level (FL), and relative frequency citation (RFC) indices. Forty-six plant species belonging to 28 families were recorded for the treatment of diabetes in the Taza region of Morocco. The most frequently cited plant species are Salvia officinalis, Marrubium vulgare, and Ajuga iva. Lamiaceae, Asteraceae, and Fabaceae were the most reported families. Leaves are the most used part of plants to prepare drugs, the decoction is the preferred mode of preparation, and remedies are often administered orally. Interestingly, Cytisus battandieri, Urginea maritima, Plantago ovata, and Ziziphus jujuba were reported as new medicinal plants used to treat diabetes in the Taza region of Morocco. People in the Taza region still rely on indigenous plants for their basic healthcare needs. Further research should be carried out to validate the antidiabetic effect of the newly reported plant species. This validation can be investigated by the determination of bioactive compounds and evaluation of their in vitro and in vivo antidiabetic effects.

Metabolomic profiling to reveal the therapeutic potency of Posidonia oceanica nanoparticles in diabetic rats

Posidonia oceanica is a sea grass belonging to the family Posidoniaceae, which stands out as a substantial reservoir of bioactive compounds. In this study, the secondary metabolites of the P. oceanica rhizome were annotated using UPLC-HRESI-MS/MS, revealing 86 compounds including simple phenolic acids, flavonoids, and their sulphated conjugates. Moreover, the P. oceanica butanol extract exhibited substantial antioxidant and antidiabetic effects in vitro. Thus, a reliable, robust drug delivery system was developed through the encapsulation of P. oceanica extract in gelatin nanoparticles to protect active constituents, control their release and enhance their therapeutic activity. To confirm these achievements, untargeted GC-MS metabolomics analysis together with biochemical evaluation was employed to investigate the in vivo anti-diabetic potential of the P. oceanica nano-extract. The results of this study demonstrated that the P. oceanica gelatin nanoparticle formulation reduced the serum fasting blood glucose level significantly (p < 0.05) in addition to improving the insulin level, together with the elevation of glucose transporter 4 levels. Besides, multivariate/univariate analyses of the GC-MS metabolomic dataset revealed several dysregulated metabolites in diabetic rats, which were restored to normalized levels after treatment with the P. oceanica gelatin nanoparticle formulation. These metabolites mainly originate from the metabolism of amino acids, fatty acids and carbohydrates, indicating that this type of delivery was more effective than the plain extract in regulating these altered metabolic processes. Overall, this study provides novel insight for the potential of P. oceanica butanol extract encapsulated in gelatin nanoparticles as a promising and effective antidiabetic therapy.

The potential of P. oceanica butanol extract encapsulated in gelatin nanoparticles as a promising and effective antidiabetic therapy has been investigated via metabolomics.

Antidiabetic Effects of Flavan-3-ols and Their Microbial Metabolites

Diet is one of the pillars in the prevention and management of diabetes mellitus. Particularly, eating patterns characterized by a high consumption of foods such as fruits or vegetables and beverages such as coffee and tea could influence the development and progression of type 2 diabetes. Flavonoids, whose intake has been inversely associated with numerous negative health outcomes in the last few years, are a common constituent of these food items. Therefore, they could contribute to the observed positive effects of certain dietary habits in individuals with type 2 diabetes. Of all the different flavonoid subclasses, flavan-3-ols are consumed the most in the European region. However, a large proportion of the ingested flavan-3-ols is not absorbed. Therefore, the flavan-3-ols enter the large intestine where they become available to the colonic bacteria and are metabolized by the microbiota. For this reason, in addition to the parent compounds, the colonic metabolites of flavan-3-ols could take part in the prevention and management of diabetes. The aim of this review is to present the available literature on the effect of both the parent flavan-3-ol compounds found in different food sources as well as the specific microbial metabolites of diabetes in order to better understand their potential role in the prevention and treatment of the disease.

Arbutus unedo L., (Ericaceae) inhibits intestinal glucose absorption and improves glucose tolerance in rodents

ETHNOPHARMACOLOGICAL RELEVANCE

Arbutus unedo L., (Ericaceae) is one of the most traditional plants commonly used to treat diabetes in people living in Eastern Morocco region particularly in Taza and Beni Mellal.

AIM OF THE STUDY

The aim of the study was to find if there is a scientific support to the ethnopharmacological relevance use of Arbutus unedo L., roots bark (AU) to treat diabetes.

MATERIALS AND METHODS

We studied the effects of crude aqueous extract of AU on intestinal glucose absorption using short-circuit current technique in vitro and oral glucose tolerance test in vivo.

RESULTS

The aqueous extract of AU (10 µg/mL to 1 mg/mL) induced concentration-dependent inhibition of sodium-dependent glucose transport across isolated mouse jejunum. The maximal inhibition was obtained with 1 mg/mL, which exhibited more than 80% of the Phloridzin inhibition with an IC₅₀ close to 216 µg/mL. A 6-week AU ingestion (2 g/(kg day)), improved oral glucose tolerance as efficiently as metformin (300 mg/(kg day)). Arbutus unedo L. and metformin also reduced body weight.

CONCLUSIONS

Arbutus unedo L. roots bark aqueous extract directly inhibited the electrogenic intestinal absorption of glucose in vitro. In addition it improved oral glucose tolerance and lowered body weight in rats after chronic oral administration in vivo. These results add a scientific support to the ethnopharmacological relevance use of Arbutus unedo L. roots bark to treat diabetes.

Comprehensive Investigation of the Effects of Brewing Conditions in Sample Preparation of Green Tea Infusions

Chemical and biological investigation of green tea has been generally performed while using different infusions that are prepared without consideration of the effects of sample preparation conditions. In this study, for the first time, the effects of green tea brewing conditions on the antioxidant activity and chemical profiles of metabolome and catechin compounds were examined at 60 °C and 95 °C for a period of 5-300 min. The antioxidant capacities of the tea infusions, which were assessed as per 2,2-diphenyl-1-picryl-hydrazyl hydrate (DPPH) radical scavenging activity, depended more on temperature than time. Metabolomics study that was based on ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF/MS) revealed that the metabolic profiles, including 33 differential metabolites, were significantly changed by temperature and time, with the effects of time being more evident at 95 °C starting after 30 min. Infusions that were brewed at 95 °C for greater than 30 min yielded distinct profiles in the hierarchical clustering analysis. The quantification of eight catechins by UHPLC-QqQ/MS showed that the total catechin level peaked at 95 °C brewing at 10 min, after which the levels of four epi-forms of catechins decreased and those of four non-epi-forms increased, implying the epimerization of catechins over time. These results suggest that the brewing conditions for sample preparation of green tea should be put into careful consideration in studies where green tea extracts are applied as aqueous infusions.