A preliminary study of hypoglycemic activity of Lythrum salicaria

Antihyperglycemic Effect of the Aqueous Extract of Foeniculum vulgare in Normal and Streptozotocin-induced Diabetic Rats

BACKGROUND

Diabetes mellitus is associated with high blood glucose levels due to insulin shortcoming (insulinopenia) or defective insulin action. The objective of the study was to investigate the antidiabetic and antioxidant effects of Foeniculum vulgare in streptozotocin-induced diabetic rat.

METHODS

The effects of the leaves aqueous extract (LAE) of Foeniculum vulgare (F. vulgare) at a dose of 10 mg/kg on blood glucose levels were evaluated in normal and streptozotocin (STZ)- induced diabetic rats. Histopathological changes were also evaluated in liver in STZ-induced rats.

RESULTS

Single oral administration of F. vulgare LAE reduced blood glucose levels 6 h after administration in STZ diabetic rats (p<0.0001). Furthermore, blood glucose levels were decreased in both normal (p<0.05) and STZ diabetic rats (p<0.0001) after the fifteenth day of treatment. During this test, both groups did not show any significant change in their body weight. Moreover, this aqueous extract improved oral glucose tolerance in diabetic rats and revealed a positive effect on liver histology. On the other hand, the extract used in this experiment showed an inhibitory concentration (IC50) of 50% of free radicals with a concentration of 43±1.19 µg/ml. While the synthetic antioxidant (BHT) had an IC50 equal to 22.67±2.17µg /ml.

CONCLUSION

This study demonstrates the antihyperglycemic, hypoglycemic and antioxidant effects of the leaves of F. vulgare in normal and diabetic rats.

Isoorientin: A dietary flavone with the potential to ameliorate diverse metabolic complications

Isoorientin is a natural C-glucosyl flavone that is generating a lot of interest due to its multiple pharmacological activities. Increasing experimental data have shown that the robust antioxidant and anti-inflammatory properties of isoorientin remain important in ameliorating a number of metabolic complications. In fact, plants rich in isoorientin have demonstrated strong ameliorative properties against complications such as hyperglycemia, hyperlipidemia, and insulin resistance. However, while such evidence is accumulating, it has not been reviewed to better inform on the therapeutic potential of this flavone in improving human health. This review examines and extrapolates available literature on the potential beneficial or detrimental effects associated with the use of isoorientin in mitigating metabolic diseases, with a specific focus on diabetes, obesity, and insulin resistance, including associated complications. The discussion includes effective doses in various experimental settings and proposed molecular mechanisms by which isoorientin may exert its therapeutic effects. In addition, the protective effects of extracts of a number of isoorientin-rich plants against metabolic complications will be highlighted.

Lythrum salicaria L.-Underestimated medicinal plant from European traditional medicine. A review

ETHNOPHARMACOLOGICAL RELEVANCE

Purple loosestrife-Lythrum salicaria L. is a herbaceous perennial plant belonging to the Lythraceae family. It has been used for centuries in European traditional medicine. Despite Lythri herba being a pharmacopoeial plant material (Ph. Eur.), L. salicaria popularity as a medicinal plant has recently declined. The aim of the paper is to recall a traditional and historical use of L. salicaria and juxtapose it with comprehensive view on the current knowledge about its chemical composition and documented biological activities in order to bring back the interest into this valuable plant and indicate reasonable directions of future research and possible applications.

MATERIALS AND METHODS

Systematic survey of historical and ethnopharmacological literature was carried out using sources of European and American libraries. Pharmacological and phytochemical literature research was performed using Scopus, PubMed, Web of Science and Reaxys databases.

RESULTS

The review of historical sources from ancient times till 20th century revealed an outstanding position of L. salicaria in traditional medicine. The main applications indicated were gastrointestinal tract ailments (mainly dysentery and diarrhea) as well as different skin and mucosa affections. The current phytochemical studies have shown that polyphenols (C-glucosidic ellagitannins and C-glucosidic flavonoids) as well as heteropolysaccharides are dominating constituents, which probably determine the observed pharmacological effects. The extracts and some isolated compounds were shown to possess antidiarrheal, antimicrobial, anti-oxidant, anti-inflammatory and anti-diabetic activities.

CONCLUSIONS

The intrinsic literature overview conclusively demonstrates that L. salicaria L. used to be considered as an exceptionally effective remedy in European traditional medicine. Despite its unquestionable important position from unknown reasons its popularity has been weakened during the past few decades. Unfortunately the contemporary pharmacological research is still insufficient to support its thoroughly described traditional uses. The necessity of complex studies regarding modes of action, which would directly refer to L. salicaria main traditional applications-gastrointestinal tract ailments, is strongly underlined.

Biological activity and microscopic characterization of Lythrum salicaria L

Background

There are several plants have been used worldwide in the folk medicine with high incidence for treatment of human disorders, of which Lythrum salicaria belongs to the Lythraceae family has traditionally reputation for some medicinal usage and recently many biological and pharmacological activity of the plant have been studied.

Methods

In this study, microscopic characterizations of the aerial parts of the plant were determined. Moreover, the plant extract (aqueous methanol 80%) was subjected to an anti-diabetic activity test (in a rat model of streptozocin induced diabetes), anti-Helicobacter pylori (using disc diffusion method) along with antioxidant activity against DPPH (stable free radical) tests. Besides, total flavonoids, phenols, tannins, as well as polysaccharides contents have been assessed using spectroscopic methods.

Results

The microscopic properties of the plant fragments revealed anomocytic stomata, conical shape trichomes, and abundant spherical pollen grains as a characteristic pattern for the aerial parts of the plant. The extract of the plant at concentration of 15 g/kg showed mild lowering activity on blood glucose level to 12.6% and 7.3% after 2 and 3 h of administration. Additionally, clinically isolated H. pylori strain was inhibited with the plant extract at concentration of 500 mg/mL (zone of inhibition: 17 ± 0.08 mm). Moreover, IC₅₀ values for DPPH inhibition of the plant extract, vitamin E, BHA were examined as 13.5, 14.2, and 7.8 μg/mL, respectively. Total flavonoids, phenols, tannin, and polysaccharides contents of the extract were successfully evaluated as 5.8 ± 0.4 μg QE/mg EXT, 331 ± 3.7 μg GAE/mg EXT, 340 ± 2.3 μg TAE/mg EXT, 21 ± 0.2 μg GE/mg EXT, respectively.

Conclusions

The results suggested that L. salicaria has low anti-diabetic and anti-Helicobacter pylori effects, but high antioxidant activity, just the same as positive standard (vitamin E), which might be attributed to the high content of phenolic compounds in the extract.

C-glucosidic ellagitannins from Lythri herba (European Pharmacopoeia): chromatographic profile and structure determination

INTRODUCTION

Lythri herba, a pharmacopoeial plant material (European Pharmacopoea), is obtained from flowering parts of purple loosestrife (Lythrum salicaria L.). Although extracts from this plant material have been proven to possess some interesting biological activities and its pharmacopoeial standardisation is based on total tannin content determination, the phytochemical characterisation of this main group of compounds has not yet been fully conducted.

OBJECTIVE

To isolate ellagitannins from Lythri herba, determine their structures and develop chromatographic methods for their qualitative analysis.

RESULTS

Five C-glucosidic ellagitannins - monomeric- vescalagin and castalagin together with new dimeric structures - salicarinins A-C, composed of vescalagin and stachyurin, vescalagin and casuarinin, castalagin and casuarinin units connected via formation of valoneoyl group, were isolated using column chromatography and preparative HPLC. Structures were determined according to (1) H and (13) C-NMR (one- and two-dimensional), electrospray ionisation-time of flight (ESI-TOF), electrospray ionisation-ion trap (ESI-MS(n) ) and circular dichroism (CD) spectra, together with acidic hydrolysis products analysis. HPTLC on RP-18 modified plates and HPLC-DAD-MS(n) on RP-18 column methods were developed for separation of the five main ellagitannins.

Lythrum hyssopifolia (lesser loosestrife) poisoning of sheep in Victoria

OBJECTIVE

To document an ovine disease attributed to the consumption of Lythrum hyssopifolia (lesser loosestrife).

PROCEDURES

Historical and histological review of field and experimental cases.

RESULTS

1-20% mortality occurred in sheep flocks grazing paddocks where L. hyssopifolia was the predominant green vegetation. Well-documented disease outbreaks occurred in summer on nine farms across Victoria between 1974 and 2002. Liver damage occurred in all nine outbreaks, with kidney damage in at least eight. Hepatocyte necrosis was usually zonal to midzonal (zone 2) in the liver samples from four farms and periacinar (zone 3) in those from three farms, but some livers showed only single-cell necrosis. Multinucleate hepatocytes near necrotic areas were a feature in six cases. Proximal tubular epithelium appeared to be the primary renal target and brown granules were often present in renal tubules. Biochemical and histological evidence of liver and kidney damage was obtained from two sheep experimentally pen-fed harvested L. hyssopifolia.

CONCLUSION

Chemicals in L. hyssopifolia are toxic to ovine hepatocytes and renal tubular epithelial cells.

The hypoglycaemic activity of the aqueous extract of Stachytarpheta angustifolia (Verbanaceae) in normoglycaemic and alloxan-induced diabetic rats

The hypoglycaemic activity of the aqueous extract of Stachytarpheta angustifolia (Verbanaceae) was studied in normoglycaemic and alloxan-induced diabetic rats. The extract was administered orally to the rats and blood glucose level was monitored for 7 h. Results indicate that the aqueous extract (750 mg kg(-1)) produced a significant blood glucose reduction in both normoglycaemic and alloxan-induced diabetic rats (p < 0.05). The present result therefore appears to support the use of the plant aqueous extract for the management of type 2 diabetes by traditional medical practitioners in Northern Nigeria. The mechanism of action of the aqueous extract needs to be studied.

Effect of Salvia officinalis L. leaves on serum glucose and insulin in healthy and streptozotocin-induced diabetic rats

The leaves of sage (Salvia officinalis L., Lamiaceae) are reported to have a wide range of biological activities, such as anti-bacterial, fungistatic, virustatic, astringent, eupeptic and anti-hydrotic effects. To determine the hypoglycaemic effect of sage leaves, we investigated the effects of essential oil and methanolic effect of the plant on healthy and streptozotocin-induced diabetic rats. The animals were made diabetic using by streptozotocin (70 mg/kg, i.p.). The methanolic extract (100, 250, 400 and 500 mg/kg) and essential oil (0.042, 0.125, 0.2 and 0.4 ml/kg) were injected intraperitoneally. The control groups were administered water and sunflower oil as vehicles of methanolic extract and essential oil, respectively. Blood samples were obtained from retro-orbital sinus before administration and 1, 3 and 5 h after administrations. The serum glucose was measured by the enzymatic method of glucose oxidase. The results showed that the essential oil of sage did not change serum glucose, while the plant extract significantly decreased serum glucose in diabetic rats in 3h without effect on insulin releasing from the pancreas but not in healthy rats. Also, the LD(50) of the methanolic extract is measured (4000 mg/kg, i.p.). The present data indicate that sage extract has hypoglycaemic effect on diabetic animals and the plant should be considered in future therapeutic researches.

Hypoglycaemic activity ofRetama raetam in rats

The purpose of this study was to determine the underlying mechanism of the hypoglycaemic activity of an aqueous extract perfusion of Retama raetam (RR) in normal and streptozotocin-induced diabetic rats. The aqueous extract was administered intravenously and the blood glucose changes were determined within 4 h after starting the treatment. Plasma insulin concentrations and glycosuria were determined. The aqueous RR extract at a dose of 10 mg[sol ]kg[sol ]h produced a significant decrease in blood glucose levels in normal rats (p < 0.001) and an even more marked decrease in diabetic rats (p < 0.001). This hypoglycaemic effect might be due to an extra-pancreatic action of the aqueous extract of RR, since the basal plasma insulin concentrations were unchanged after RR treatment. A potent increase of glycosuria was observed both in normal and diabetic rats (p < 0.001). It is concluded that an aqueous extract perfusion of RR caused a potent inhibition of renal glucose reabsorption. This renal effect is at least one mechanism to explain the observed hypoglycaemic activity of this plant in normal and diabetic rats.

Phlorizin-like effect of Fraxinus excelsior in normal and diabetic rats

The purpose of this study was to determine the underlying mechanism of the hypoglycaemic activity of the aqueous extract perfusion of Fraxinus excelsior L. (FE) in normal and streptozotocin-induced diabetic rats. The aqueous extract was administered intravenously and the blood glucose changes were determined within four hours after starting the treatment. Plasma insulin concentrations and glycosuria were determined. The aqueous extract at a dose of 10 mg/kg/h produced a significant decrease in blood glucose levels in normal rats (P < 0.001) and even more in diabetic rats (P < 0.001). This hypoglycaemic effect might be due to an extra-pancreatic action of the aqueous extract of FE, since the basal plasma insulin concentrations were unchanged after FE treatment. A potent increase of glycosuria was observed both in normal and diabetic rats (P < 0.001). We conclude that aqueous extract perfusion of FE caused a potent inhibition of renal glucose reabsorption. This renal effect might be at least one mechanism explaining the observed hypoglycaemic activity of this plant in normal and diabetic rats.

Studies on the in vitro and in vivo hypoglycemic activities of some medicinal plants used in treatment of diabetes in Jordanian traditional medicine

Ferula persica, Paronychia argentea, and Pistacia atlantica are three of the plants widely recommended by the herbalists and used for their hypoglycemic activity in Jordan. Aqueous extracts of these plants were tested in vitro for their alpha amylase inhibitory activity and in vivo for their hypoglycemic activity in normoglycemic and streptozocin-induced hyperglycemic rats. Although the three plants were advocated for their hypoglycemic effects in Jordanian traditional herbal medicine; none of them showed significant hypoglycemic activity compared to the untreated animals. Paronychia argentea and Pistacia atlantica showed significant alpha amylase inhibitory activity while Ferula persica did not demonstrate any alpha amylase inhibitory activity. The main conclusion of this work was the concern over the unjustified claims of the uses of some herbal medicine in Jordan and possibly in other countries.

Inhibition of endogenous glucose production accounts for hypoglycemic effect of Spergularia purpurea in streptozotocin mice

The purpose of this study was to determine the underlying mechanism of the hypoglycemic activity of the aqueous extract perfusion of Spergularia purpurea (SP) in diabetic mice and streptozotocin-induced diabetic rats. The aqueous extract was administered intravenously and the blood glucose levels were determined within 4 hours after starting the treatment. Plasma insulin concentrations and endogenous glucose production were also determined. The aqueous extract at a dose of 10 mg/kg produced a significant decrease in blood glucose levels in normal rats (P < 0.05), and even more in diabetic rats (P < 0.001). This hypoglycemic effect might be due to an extra-pancreatic action of the aqueous extract of SP, since the basal plasma insulin concentrations were unchanged after SP treatment. In diabetic mice, a similar effect was observed and the results showed that aqueous extract of SP caused a potent inhibitor effect on basal endogenous glucose production (p < 0.001). We conclude that aqueous extract perfusion of SP inhibits endogenous glucose production in mice. This inhibition is at least one mechanism explaining the observed hypoglycemic activity of this plant in diabetic animals.

Hypoglycemic effect of Suaeda fruticosa in streptozotocin-induced diabetic rats

The purpose of this study was to examine the hypoglycemic activity of the aqueous extract of the aerial part of Suaeda fruticosa (SF) in normal and streptozotocin-induced diabetic rats. The aqueous extract was administered intravenously (i.v.) and the blood glucose changes were determined within 4 h after starting the treatment. Plasma insulin, cholesterol and triglycerides levels were also determined. The aqueous extract at a dose of 192 mg/kg produced a significant decrease in blood glucose levels in normal rats (P < 0.05), and even more in diabetic rats (P < 0.001). This hypoglycemic effect might be due to an extra-pancreatic action of the aqueous extract of SF, since that the levels of plasma insulin were unchanged between the values before and after treatment. In the other hand, the effect of the aqueous extract on the plasma cholesterol were also significant in both normal and diabetic rats (P < 0.05). But, there is no significant effect of SF on plasma triglycerides in both groups. In order to characterize the active principle(s), which could be responsible for the therapeutic effect, preliminary phytochemical analysis of the aqueous extract of the plant has been investigated.

Hypoglycaemic effect of spergularia purpurea in normal and streptozotocin-induced diabetic rats

Single and repeated oral administration of the water extracts of Spergularia purpurea (SP) at a dose of 10 mg/kg were tested on hypoglycaemic activity in normal and streptozotocin-induced diabetic rats. In normal rats, the water extract of SP decreased significantly the plasma glucose levels 4 h after single oral administration (P<0.01), and one week after repeated oral administration (P<0.05). A significant decrease of plasma glucose levels was observed 6 h after a single oral administration of the water extract of S. purpurea in severe hyperglycaemic rats (n=6) from 22.78+/-0.60 to 11.21+/-0.49 mmol/l (P<0.001). On other hand, water extract of S. purpurea normalised plasma glucose levels after two weeks of repeated oral administration in diabetic rats; 24.05+/-1.16 versus 7.18+/-0.51 mmol/l (P<0.001) at the start and 2 weeks after water extract administration, respectively. We conclude that the water extract of SP induces hypoglycaemic activity when administered orally in normal and STZ diabetic rats. In order to determine the active principle (s) responsible of the hypoglycaemic effect, preliminary phytochemical analysis of the water extract has been investigated.

Natural products with hypoglycemic, hypotensive, hypocholesterolemic, antiatherosclerotic and antithrombotic activities

This article reviews compounds of botanical origin which are capable of lowering plasma levels of glucose and cholesterol and blood pressure, as well as compounds inhibiting atherosclerosis and thrombosis. Hypoglycemic natural products comprise flavonoids, xanthones, triterpenoids, alkaloids, glycosides, alkyldisulfides, aminobutyric acid derivatives, guanidine, polysaccharides and peptides. Hypotensive compounds include flavonoids, diterpenes, alkaloids, glycosides, polysaccharides and proteins. Among natural products with hypocholesterolemic activity are beta-carotene, lycopene, cycloartenol, beta-sitosterol, sitostanol, saponin, soybean protein, indoles, dietary fiber, propionate, mevinolin (beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor) and polysaccharides. Heparins, flavonoids, tocotrienols, beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitors (statins), garlic compounds and fungal proteases exert antithrombotic action. Statins and garlic compounds also possess antiatherosclerotic activity.