Antidiabetic activity, glucose uptake stimulation and α-glucosidase inhibitory effect of Chrysophyllum cainito L. stem bark extract

Phycocyanin attenuates skeletal muscle damage and fatigue via modulation of Nrf2 and IRS-1/AKT/mTOR pathway in exercise-induced oxidative stress in rats

Prolonged strenuous exercise induces oxidative stress, leading to oxidative damage, skeletal muscle fatigue, and reduced exercise performance. The body compensates for oxidative stress through antioxidant actions, while related enzymes alone may not overcome excessive oxidative stress during prolonged strenuous exercise. Phycocyanin is an important antioxidant supplement derived from blue-green algae, which may be helpful in this type of situation. This study determined the effects of phycocyanin on exercise performance from prolonged strenuous exercise. Forty Sprague Dawley male rats were divided into 5 groups (n = 8 /group); Control group (C), Exercise group (E), and Exercise with supplement groups receiving low dose (Phycocyanin = 100 mg/kg BW; ELP) and high dose (Phycocyanin = 200 mg/kg BW; EHP) or vitamin C (Vitamin C = 200 mg/kg BW; VC). Phycocyanin was found to decrease oxidative damage markers, muscle fatigue, and muscle atrophy through the activated AKT/mTOR pathway. This was also found to have greater increases in antioxidants via Nrf2 signaling and increases ATP synthesis, GLUT4 transporters, and insulin signaling due to increased IRS-1/AKT signaling. In conclusion, phycocyanin was found to reduce oxidative damage and muscle atrophy, including an increase in insulin signaling in skeletal muscles leading to increased exercise performance in rats.

A novel approach to assessing the antioxidant and anti-diabetic potential of synthesized calcium carbonate nanoparticles using various extracts of Ailanthus altissima

Calcium carbonate nanoparticles (CaCO3) have been found to exhibit unique properties that show their potential to be used in various therapies. Green synthesis of CaCO3 has been progressively gaining ac-ceptance due to its cost-effectiveness and energy-efficient nature. In the current study, different extracts of Ailanthus altissima were used to synthesize the calcium carbonate nanoparticles the synthesis and characterization of CCNPs were confirmed by using Fourier Transform Infra-Red spectroscopy, UV-Vis spectroscopy, and Scanning Electron Microscopy (SEM). The antioxidant activities (hydrogen peroxide, phosphomolydbenum, and ferric reducing) of calcium carbonate nanoparticles were affirmed by a good range of percentages of inhibition against free radical scavenging. The antidebate assays of CCNPs were observed by in-vitro and in silico approaches in a range at various concentrations while maximum inhibition occurred. In conclusion, the current study depicted that conjugated CaCO3 with A. altissima has a good potential to cure oxidative stress and Type II diabetes and could be used in the future as biogenic nanomedicine for the treatment of other metabolic diseases.

Antidiabetic Properties of the Root Extracts of Dandelion (Taraxacum officinale) and Burdock (Arctium lappa)

Several preclinical studies suggest the potential of edible plants in controlling blood sugar levels and stabilizing diet. The goals of the study were to examine, analyze, and describe whether there are chemical compounds in dandelion and burdock roots that could have antidiabetic properties. The 70% ethyl alcohol and lyophilizate extracts (AE and LE, respectively), were used, and analyses were carried out on their total polysaccharide (TP), total phenolic content (TPC), tannin, and inulin. The antioxidant activity of extracts was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay, and hypoglycemic properties were based on α-amylase activity. Liquid chromatography-mass spectrometry was used for the tentative identification of the chemical components. Qualitative techniques confirmed the presence of inulin in both roots. Analysis of TPC, tannin content, DPPH assay, and α-amylase activity revealed higher values for burdock compared to dandelion. However, dandelion exhibited higher TP content. Burdock contained a small amount of tannin, whereas the tannin content in dandelion was insignificant. All LE consistently exhibited higher values in all analyses and assays for all roots compared to AE. Despite burdock root showing overall better results, it is uncertain whether these plants can be recommended as antidiabetic agents without in vivo studies.

Flower structure, anatomy, and sexuality of Chrysophyllum gonocarpum (Sapotaceae)

The Sapotaceae are a significant component of the humid forests of the Neotropics and have many species of economic interest. Chrysophyllum gonocarpum is one of them and its edible fruits have currently acquired a high commercial value. Since there are no studies that cover its floral anatomy and elucidate its sexual system, the objective of the present study is to describe these aspects based on field observations and a detailed anatomical analysis of their flowers. Conventional techniques of plant anatomy are implemented. The results indicate that the species presents cryptic dioecy, showing specimens with morphologically and functionally pistillate flowers (with reduced staminodes), and trees with morphologically hermaphrodite and functionally staminate flowers. In addition, data on floral nectaries and laticiferous are provided.

Chemical Constituents and Antidiabetic Activity of Dichloromethane Extract from Ficus carica Leaves

PURPOSE

To evaluate the dichloromethane extract of Ficus carica leaves (FCL) had a hypoglycemic impact in diabetic mice, as well as to identify the bioactive components in the extract and analyze their anti-hyperglycemia potential in HepG2 cells.

MATERIAL AND METHODS

The antidiabetic activity of dichloromethane extract of Ficus carica leaves was evaluated in diabetic mice induced by streptozotocin (STZ,100 mg/kg) combined with high-fat diet. The fasting blood glucose (FBG), blood lipids, oral glucose tolerance, glycated hemoglobin (HbA1c), and pathological change effects of the extract were measured after administering two doses of the extract (500 and 1000 mg/kg). On the other hand, we used column chromatography to isolate the dichloromethane extract, and we structurally identified the compounds based on ¹H NMR and ³C NMR spectra. The hypoglycemic activity of isolated compounds was investigated in palmitic acid (PA)-induced HepG2 cells.

RESULTS

FCL extract lowers blood glucose and improves blood lipids and the pancreatic β-cell also tend to recover whether the psoralen is removed or not. Meanwhile, three coumarins except psoralen were isolated from dichloromethane extract: 3,4-dihydropsoralen, umbelliferone and 7-hydroxyl-6-methylcoumarin. Psoralen and umbelliferone promoted glucose uptake in HepG2 cells.

DISCUSSION AND CONCLUSION

In vivo experiments, dichloromethane extract of FCL has potential antidiabetic activity, mainly by lowering blood glucose, improving blood lipids, glucose tolerance and repairing pancreatic islet damage, which justifies its use in the treatment of diabetes in Spanish folklore. Additionally, in vitro experiments, psoralen and umbelliferone demonstrated substantial glucose-lowering activity.

Antihyperglycemic activity of verbenone and L-arginine in nicotinamide-streptozotocin-induced diabetic mice: in vitro and in vivo studies

Background

Natural products are utilized globally for the management of diseases such as diabetes mellitus. Carrot seeds are ethnobotanically used in the management of diabetes mellitus. This study investigated the in vitro and in vivo antihyperglycemic activities of verbenone and L-arginine, which are compounds found in carrot seed.

Results

Verbenone, L-arginine, and their ratios combination expressed significantly in vitro α-amylase inhibitory activity with IC50 of 13.00, 12.69, and 13.30 µg/mL respectively compared with acarbose (IC50 = 12.64 µg/mL) and significant in vitro α-glucosidases inhibitory activity with IC50 of 29.01, 23.76 and 30.11 µg/mL respectively compared with acarbose (IC50 = 16.80 µg/mL). Furthermore, the compounds improved glucose uptake in yeast cells and inhibited haemoglobin glycation in vitro. In the in vivo study, the compounds significantly reduced the levels of blood glucose, the levels of liver total cholesterol, and liver triacylglycerol, the calculated cardiovascular indices, whereas the level of plasma high density lipoprotein (HDL) cholesterol was significantly elevated in all diabetic treated mice.

Conclusion

The data revealed the in vitro antidiabetic activity of verbenone and L-arginine. Also, the compounds ameliorated hyperglycemia, hyperlipidemia and other diabetic-induced biochemical alterations in NAD-STZ-induced diabetic mice model.

Experimental Approaches to Diabetes Mellitus

One of the most common health problems today, diabetes is a serious, chronic, and complex disease characterized by high blood glucose levels. Nowadays, experimental diabetes models are being developed to study existing diabetes in depth, to improve diabetes medications, or to develop new medications. The protocols developed to date to create an experimental diabetes model are finalized in different time intervals and depending on various factors. With these models, which can be designed in vivo and in vitro, a picture similar to type 1 and type 2 diabetes can be created. In this review, we aimed to present the methodology, advantages, and disadvantages of all currently used experimental diabetes models in the light of current literature.

The Evolution of Pharmacological Activities Bouea macrophylla Griffith In Vivo and In Vitro Study: A Review

Bouea macrophylla Griffith (B. macrophylla) is one of the many herbal plants found in Asia, and its fruit is plum mango. This plant is rich in secondary metabolites, including flavonoids, tannins, polyphenolic compounds, and many others. Due to its bioactive components, plum mango has powerful antioxidants that have therapeutic benefits for many common ailments, including cardiovascular disease, diabetes, and cancer. This review describes the evolution of plum mango’s phytochemical properties and pharmacological activities including in vitro and in vivo studies. The pharmacological activities of B. macrophylla Griffith reviewed in this article are antioxidant, anticancer, antihyperglycemic, antimicrobial, and antiphotoaging. Each of these pharmacological activities described and studied the possible cellular and molecular mechanisms of action. Interestingly, plum mango seeds show good pharmacological activity where the seed is the part of the plant that is a waste product. This can be an advantage because of its economic value as a herbal medicine. Overall, the findings described in this review aim to allow this plant to be explored and utilized more widely, especially as a new drug discovery.

A review of alpha-glucosidase inhibitors from plants as potential candidates for the treatment of type-2 diabetes

Diabetes mellitus is a multifactorial global health disorder that is rising at an alarming rate. Cardiovascular diseases, kidney damage and neuropathy are the main cause of high mortality rates among individuals with diabetes. One effective therapeutic approach for controlling hyperglycemia associated with type-2 diabetes is to target alpha-amylase and alpha-glucosidase, enzymes that catalyzes starch hydrolysis in the intestine. At present, approved inhibitors for these enzymes are restricted to acarbose, miglitol and voglibose. Although these inhibitors retard glucose absorption, undesirable gastrointestinal side effects impede their application. Therefore, research efforts continue to seek novel inhibitors with improved efficacy and minimal side effects. Natural products of plant origin have been a valuable source of therapeutic agents with lesser toxicity and side effects. The anti-diabetic potential through alpha-glucosidase inhibition of plant-derived molecules are summarized in this review. Eight molecules (Taxumariene F, Akebonoic acid, Morusin, Rhaponticin, Procyanidin A2, Alaternin, Mulberrofuran K and Psoralidin) were selected as promising drug candidates and their pharmacokinetic properties and toxicity were discussed where available.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11101-021-09773-1.

Chrysophyllum cainito. L alleviates diabetic and complications by playing antioxidant, antiglycation, hypoglycemic roles and the chemical profile analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Chrysophyllum cainito L. (C. cainito) is a traditional folk medicine in tropical area which can be an alternative agent for diabetes mellitus. Although the antioxidant and antidiabetic activity of the extracts are reported, little is known on the antiglycation activity and effects on diabetic complications.

AIM OF THE STUDY

This work was aimed to investigate the chemical profile, antidiabetic, antioxidant activities of C. cainito. Especially, the antiglycation potential as well as the relationships between components and activities were evaluated.

MATERIALS AND METHODS

The content of the primary components (polyphenols, flavonoids, steroids, and triterpenes), antioxidant, and hypoglycemic effects of ethanolic extracts from C. cainito leaves (CCE-1, 2, 3, 4) and stems (CSE-1, 2, 3, 4) were analyzed and detected. The chemical profiles of CCE-2 were characterized by HPLC-Q-TOF-MS/MS. The antiglycation and protection against oxidative stress effects were determined by in vitro assays. Relationship between bioactivities and components was analyzed by principal component analysis (PCA), heatmap analysis, and Pearson correlation analysis.

RESULTS

The composition was diverse between leaves and stem extracts with different activities. CCE-2 possessed the highest DPPH scavenging activity. CSE-2 displayed the highest ABTS scavenging activity and ferric reducing power. While CCE-3 showed the most effective inhibition on α-amylase and α-glucosidase activity (IC₅₀ 4.103 ± 0.332 μg/mL and 0.180 ± 0.006 mg/mL, respectively). PCA analysis showed that the most important variables in PC1 (60.7%) were total polyphenol and antioxidant activities. The hypoglycemic activity and contents of steroids showed important correlation. Advanced glycation end products formation was effectively inhibited by CCE-2 with myricetin 3-O-rhamnoside as the main constituent. CCE-3 displayed the highest protection effect against L02 cell line oxidation damage.

CONCLUSIONS

C. cainito leaves might be a promising candidate for antioxidant, hypoglycemic and antiglycation dietary supplement or potential agent against diabetes associated chronic diseases.

Protective rules of natural antioxidants against gamma-induced damage-A review

Phytochemicals accessible in food have demonstrated efficiency against impairment by gamma radiation. The review presented here is an attempt to show the pharmacological outline of the activity of the natural antioxidants and its primary action of molecular mechanism against the damage induced by gamma rays. This research focused on the results of the in vitro dosage of natural antioxidants relationship, and on the correlation of this information with the statistical variables. Moreover, it deliberated the natural compounds which could decrease the unwelcome impacts of gamma radiation and safeguard biological systems from radiation-stimulated genotoxicity. The outcomes indicated that natural compounds can be utilized as an adjunct to orthodox radiotherapy and cultivate it as an effectual drug for the clinical administration of ailments.

Chemical Composition, Antioxidant Potential, and Blood Glucose Lowering Effect of Aqueous Extract and Essential Oil of Thymus Serrulatus Hochst. Ex Benth

Thymus serrulatus, an endemic plant of Ethiopia, is traditionally used to cure various diseases and as a food ingredient. In the Ethiopian folk medicine, the decoction is orally taken as a remedy to treat diabetes and high blood pressure. The purpose of the present study was to evaluate the antioxidant and antihyperglycemic effects of the aqueous extract and of the essential oil of Thymus serrulatus. The chemical composition of the aqueous extract was determined by LC-MS and the essential oil was characterized by GC-MS analysis. Radical scavenging assays, namely scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH•), hydroxyl (•OH), and nitric oxide (•NO), were used as a first approach to screen the potential antioxidant abilities of the samples. Alpha-amylase and α-glucosidase inhibitory studies were also employed to evaluate the in vitro antihyperglycemic potential of the plant. The in vivo blood glucose lowering effect of the extracts was assessed using hypoglycemic activity and the oral glucose tolerance test in normal and in streptozotocin induced diabetic mice. When compared to the aqueous extract, the essential oil showed superior radical scavenging activity, particularly for •NO, as well as greater inhibitory potency against α-amylase and α-glucosidase (IC50 = 0.01 mg/ml and 0.11 mg/ml, respectively). Both tested samples showed a statistically significant antihyperglycemic effect. The aqueous extract at 600 mg/kg exerted maximum antihyperglycemic activity (44.14%), followed by the essential oil (30.82%). Body weight and glucose tolerance parameters were also improved by the samples both in normal and diabetic mice. The findings of this study support the hypothesis that aqueous extract and essential oil of T. serrulatus are promising therapeutic agents.

Antidiabetic effect of Sophora pachycarpa seeds extract in streptozotocin-induced diabetic mice: a statistical evaluation

Undoubtedly, identification of the chemical composition of organic extracts or secondary metabolites of plant materials and evaluation of their potential bioactivity are among the main objectives of natural products-based investigations. In the present study, we report the chemical composition and antidiabetic activity of Sophora pachycarpa (Family Fabaceae) seeds extract (SPE) for the first time. First, the plant seeds were macerated in ethanol. The extract was subjected to analysis on a gas chromatography-mass spectrometry (GC-MS) system to identify the chemical composition. In vivo assay was run to evaluate the antidiabetic activity of the extract. Forty mice were divided into four groups, namely healthy mice, untreated diabetic mice, diabetic mice treated with metformin and diabetic mice treated with SPE. The antidiabetic activity of SPE was analyzed using three statistical methods, namely analysis of variance, K-means, and principal component analysis. According to GC-MS analysis, alkaloids of sophoridine, oleic acid, linoleic acid, and n-hexadecanoic acid were among the most abundant constituent components of SPE. The extract also exhibited a notable antidiabetic activity and remarkably decreased the levels of alkaline phosphatase (ALP), serum glutamic pyruvic transaminase (SGPT), and serum glutamic oxaloacetic transaminase (SGOT) enzymes. The statistical analyses revealed there are no significant differences between the ability of SPE and metformin in the regulation of fasting blood sugar level and liver enzymes (ALP, SGPT, and SGOT). A quinolizidine alkaloid, namely sophoridine, along with fatty acids, viz oleic, linoleic, and n-hexadecanoic acid, were characterized as the major compounds in S. tachycardia seeds extract. The plant extract was also found as a potent agent to reduce blood glucose and liver enzymes.

Hypoglycemic activity of Origanum vulgare L. and its main chemical constituents identified with HPLC-ESI-QTOF-MS

Origanum vulgare L. (O. vulgare) is an important medicine food homology in diabetes. The present study aimed to assess the hypoglycemic effect of the leaf extract of O. vulgare in HepG2 and HepG2-GFP-CYP2E1 (E47) cells, and disclose its potential active components by the HPLC-ESI-QTOF-MS method. Firstly, we evaluated the anti-diabetic capacity of the leaf extract of O. vulgare through inhibition of α-glucosidase activity, promotion of glucose uptake, inhibition of glycosylation and relieving of oxidative stress. Secondly, the promoter activity, the mRNA and protein expression of PEPCK and SREBP-1c, and the expression of CPY2E1 and GLUT2 in the O. vulgare mediated anti-diabetic capacity were analyzed in HepG2 and E47 cells. Finally, HPLC-ESI-QTOF-MS analysis was performed to identify the herb's main components under 280 nm irradiation. In vitro assays demonstrated that the extract inhibited α-glucosidase activity, promoted glucose uptake, inhibited glycosylation and relieved oxidative stress, which suggested that O. vulgare leaf extract has a strong hypoglycemic capacity. Moreover, mechanistic analysis also showed that the extract decreased the promoter activity and the mRNA and protein expression of PEPCK and SREBP-1c. In addition, the extract inhibited the expression of CPY2E1 and enhanced the expression of GLUT2. Moreover, the UV chromatogram at 280 nm showed six main peaks, identified as amburoside A (or 4-(3',4'-dihydroxybenzoyloxymethyl) phenyl O-β-d-glucopyranoside), luteolin 7-O-glucuronide, apigenin 7-O-glucuronide, rosmarinic acid, lithospermic acid and a novel compound, demethylbenzolignanoid, based on accurate MS data. This work supported the ethnopharmacological usage of O. vulgare as an antidiabetic herbal medicine or dietary supplement and identified its main phenolic compounds.

Chrysophyllum cainito stem bark extract induces apoptosis in Human hepatocarcinoma HepG2 cells through ROS-mediated mitochondrial pathway

Hepatocellular carcinoma is the most common type of primary liver cancer in humans. This study aimed to demonstrate anticancer properties of an aqueous extract from Chrysophyllum cainito stem bark (CE) and its underlying mechanisms. Our MTT assay results showed that CE significantly reduced human hepatocellular carcinoma (HepG2) cell viability with the IC₅₀of 100 µg/mL, while human dermal primary fibroblast (HDFa) cells showed less susceptibility in every concentration tested. Determined by Annexin V staining, the proportion of apoptotic HepG2 cells increased in a dose-dependent fashion after 24 hour-exposure of CE. The results from Western blot analysis confirmed that CE reduced procaspase-3, suggesting apoptosis by activating caspase-3 cleavage. Using the DCFH-DA and DiOC6 fluorescent probes, it was found that CE significantly stimulated the generation of reactive oxygen species (ROS) and reduced mitochondrial membrane potential (Δψ_m), respectively. According to cell cycle analysis, CE (100 µg/mL) profoundly increased the percentage of cells in the sub-G1 phase, indicating cell apoptosis. These data suggest that CE induces apoptosis and cell death in human hepatocellular carcinoma via generation of intracellular ROS and disruption of Δψm. This is the first demonstration of the anticancer activity with proposed underlying mechanism of CE in liver cancer cells.

A colorimetric method for screening α-glucosidase inhibitors from flavonoids using 3,3',5,5'-tetramethylbenzidine as a chromogenic probe

A facile and novel colorimetric method for screening of α-glucosidase inhibitors (AGIs) from flavonoids using 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic probe is proposed. This method is based on the colorimetric detection of ascorbic acid (AA) through the TMB oxidation reaction catalyzed by horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H₂O₂). In the TMB/H₂O₂/HRP system, HRP catalyzes the oxidation of H₂O₂ to ‧OH radical which oxidizes TMB to blue-colored oxidized TMB (oxTMB). In the presence of AA, the production of ‧OH radical is suppressed and causes the decrease of oxTMB, resulting in the fading of the blue color and the decrease of absorbance at 652 nm. Based on this, the existence of AA can be facilely identified. In the 2-O-α-d-glucopyranosyl-l-ascorbic acid (AA-2 G)/α-glucosidase (α-Glu) system, the produced AA inhibits the oxidation of TMB to blue-colored oxTMB. In the presence of AGIs, the production of AA is inhibited, which inhibits the reduction of oxTMB, resulting in a blue color recovery and an increase of the absorbance at 652 nm. Based on this, the colorimetric method is developed for screening of AGIs from 7 flavonoids.

Evaluation of the alpha-amylase inhibitory activity of Nepalese medicinal plants used in the treatment of diabetes mellitus

Background

α-Amylase catalyses the hydrolysis of starch and ultimately producing glucose. Controlling the catalytic activity of this enzyme reduces glucose production in the postprandial stage, which could be a therapeutic benefit for people with diabetes. This study was conducted to evaluate α-amylase inhibition for utilizing the crude extracts of some medicinal plants traditionally used in Nepal for the treatment of diabetes and its related complications.

Methods

Microtiter plate approach has been used to assess inhibitory activities of in vitro α-amylase of methanolic extracts of thirty-two medicinal plants. A starch tolerance test was used in rats to investigate the in vivo study of the methanolic extract concerning glibenclamide as the positive control.

Results

Acacia catechu, Dioscorea bulbifera, and Swertia chirata exhibited inhibitory activity against α-amylase and with IC50 values; 49.9, 296.1, and 413.5 μg/mL, respectively. Kinetics study revealed that all the extracts displayed a mixed type of inhibition pattern, with Ki values ranging from 26.6–204.2 μg/mL. Free radical scavenging activity was again re-examined and found prominent in extracts of A. catechu. Likewise, A. catechu and S. chirata showed significant reduction of blood glucose concentration up to 30 min after oral dose of 250 mg/kg (F (4, 20) = 4.1, p = .048), and (F (4, 20) = 4.1, p = .036), respectively.

Conclusions

Enzymatic assay for α-amylase inhibition using extracts was successfully evaluated. Also, the in-vitro and in-vivo study model revealed that medicinal plants could be a potent source of α-amylase inhibition. So, they could serve as potential candidates for future drug development strategies for curing diabetes with minimal or no adverse side effects.

Chrysophyllum cainito: A Tropical Fruit with Multiple Health Benefits

Chrysophyllum cainito is a tropical fruit tree with multiple benefits to human health. C. cainito possesses strong antioxidant properties either in vitro or in vivo. Extracts from the leaves, stem bark, fruits, peel, pulp, or seed of C. cainito are promising candidates in traditional medicine for curing diabetes and fighting against bacterial, fungal, and viral infections. C. cainito leaf extract alone or in a complex formula exhibits anti-inflammatory responses by reducing hypersensitivity, acts as inflammatory markers, and has antinociceptive effects. The leaf extract also increases wound healing speed and assists in regulating fat uptake. In addition, the C. cainito fruit shows anticancer activity against osteosarcoma. In conclusion, the aerial parts of C. cainito have strong beneficial biological effects on human health.

Reduction of blood glucose by plant extracts and their use in the treatment of diabetes mellitus; discrepancies in effectiveness between animal and human studies

ETHNOPHARMACOLOGICAL RELEVANCE

The global problem of diabetes, together with the limited access of large numbers of patients to conventional antidiabetic medicines, continues to drive the search for new agents. Ancient Asian systems such as traditional Chinese medicine, Japanese Kampo medicine, and Indian Ayurvedic medicine, as well as African traditional medicine and many others have identified numerous plants reported anecdotally to treat diabetes; there are probably more than 800 such plants for which there is scientific evidence for their activity, mostly from studies using various models of diabetes in experimental animals.

AIM OF THE REVIEW

Rather than a comprehensive coverage of the literature, this article aims to identify discrepancies between findings in animal and human studies, and to highlight some of the problems in developing plant extract-based medicines that lower blood glucose in patients with diabetes, as well as to suggest potential ways forward.

METHODS

In addition to searching the 2018 PubMed literature using the terms 'extract AND blood glucose, a search of the whole literature was conducted using the terms 'plant extracts' AND 'blood glucose' AND 'diabetes' AND 'double blind' with 'clinical trials' as a filter. A third search using PubMed and Medline was undertaken for systematic reviews and meta-analyses investigating the effects of plant extracts on blood glucose/glycosylated haemoglobin in patients with relevant metabolic pathologies.

FINDINGS

Despite numerous animal studies demonstrating the effects of plant extracts on blood glucose, few randomised, double-blind, placebo-controlled trials have been conducted to confirm efficacy in treating humans with diabetes; there have been only a small number of systematic reviews with meta-analyses of clinical studies. Qualitative and quantitative discrepancies between animal and human clinical studies in some cases were marked; the factors contributing to this included variations in the products among different studies, the doses used, differences between animal models and the human disease, and the impact of concomitant therapy in patients, as well as differences in the duration of treatment, and the fact that treatment in animals may begin before or very soon after the induction of diabetes.

CONCLUSION

The potential afforded by natural products has not yet been realised in the context of treating diabetes mellitus. A systematic, coordinated, international effort is required to achieve the goal of providing anti-diabetic treatments derived from medicinal plants.

Antidiabetic and hypolipidemic efficacy of skin and seed extracts of Momordica cymbalaria on alloxan induced diabetic model in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Momordica cymbalaria, a wild vegetable belongs to the Cucurbitaceae family, has long been used as a food and a remedy for diabetes mellitus in the Asian native medicinal system.

AIM OF THE STUDY

This study aims to evaluate the efficacy of ethanolic extract of skin (EESK) and methanolic extract of seed (MESE) of M. cymbalaria (MC), for their hypoglycemic and hypolipidemic effects in alloxan induced diabetic rats.

MATERIALS AND METHODS

The diabetes induced rats were given skin and seed extracts at doses 250 and 500 mg/kg b.w. p.o. for 28 days. Alloxan monohydrate (120 mg/kg) was used to induce diabetes mellitus. Daily food and water intake were assessed. Blood glucose levels and body weights were measured every 7 days throughout the experiment. Antioxidant assays, different biochemical and glycemic parameters were evaluated. Histopathological studies on pancreas, liver and kidney were also studied.

RESULTS

Treatment of EESK and MESE showed dose significant decrease in fasting blood glucose level (FBG) in experimental diabetic animals with significant reduction in food and water intake and increase in body weight. Findings confirmed the hypoglycemic and hypolipidemic effects of EESK and MESE in the experimental groups. The impaired glucose tolerance and altered activities of the hepatic enzymes such as AST, ALT and ALP levels of diabetic rats were significantly improved by the administration of EESK and MESE. Oral treatment with MC extract for 28 days demonstrated significant protective effects on the lipid profile, biochemical parameters and antioxidant levels. Besides, biochemical findings were supported by histopathological investigations.

CONCLUSION

These results suggest that the treatment with EESK and MESE of MC at a dose of 500 mg/kg b.w. have better protective effects against hyperglycemia, hyperlipidemia and oxidative stress generated during diabetes justifying the use of the plant in traditional systems of medicine.

Addition of Olive Leaf Extract (OLE) for Producing Fortified Fresh Pasteurized Milk with An Extended Shelf Life

An olive leaf extract (OLE) has been tested in vitro for its antibacterial activity and ability to inhibit α-glucosidase enzyme. OLE was also evaluated for its potential, when added to pasteurized milk, to preserve nutritional parameters and to limit microbial growth, thus prolonging shelf life. In vitro assays demonstrated a strong antibacterial efficacy of OLE mainly against Bacillus cereus and the capacity to inhibit α-glucosidase enzyme (IC₅₀) when used at 0.2 mg oleuropein/mL. The milk fortification with OLE at 3.6 mg of oleuropein/mL of milk reduced total mesophilic bacteria at undetectable level after 6 d (expiration date) and by 1 log CFU/mL after 10 d. Moreover, OLE addition at 1.44 and 3.6 mg of oleuropein/mL of milk significantly reduced fat and lactose losses up to 10 d. The results motivate the use of the OLE to make a new functional milk with an extended shelf life.

Hypoglycemic Activity of Tilia americana, Borago officinalis, Chenopodium nuttalliae, and Piper sanctum on Wistar Rats

Diabetes mellitus (DM) is considered the epidemic of the 21st century. Traditional medicine uses plants to treat DM; many of these have hypoglycemic effects in both animal models and diabetic patients. Our objective was to evaluate the hypoglycemic activity of Tilia americana, Borago officinalis, Chenopodium nuttalliae, and Piper sanctum on diabetic rats. The methanolic extracts of the plants under study were obtained by Soxhlet extraction. Toxicity was evaluated on Artemia salina; the antioxidant potential was evaluated using the DPPH technique. Hypoglycemic capacity at doses of 250 and 500 mg/kg was tested on Wistar rats with diabetes induced by alloxan (120 mg/kg). The toxicity on A. salina was null for the extracts of B. officinalis and P. sanctum, moderate for T. americana, and highly toxic for C. nuttalliae. The relevant extract of T. americana var. mexicana showed antioxidant activity. Three plants of the studied plants showed hypoglycemic activity: Tilia Americana (p = 0.0142), Borago officinalis (p = 0.0112), and Piper sanctum (p = 0.0078); P. sanctum was the one that showed the greatest reduction in glucose levels at a lower dose.