Toxicological study on Glinus lotoides: a traditionally used taenicidal herb in Ethiopia

Extracts of five medicinal plants: Boscia angustifolia, Cissus quadrangularis, Securidaca longipedunculata, Stylosanthes erecta and Trichilia emetica, used traditionally in Malian traditional medicine were screened for in vitro antiplasmodial activity and GABA_A–benzodiazepine receptor binding activity. Four extracts showed significant antiplasmodial activities, with the dichloromethane extract of leaf of Securidaca longipedunculata being the most active (IC₅₀ of 7 μg/ml [95% CI: 5–9]). The dichloromethane extract of leaf of Trichilia emetica, in addition to its antiplasmodial activity (IC₅₀: 12 μg/ml [95% CI: 12–14]), exhibited a good binding activity to the GABA_A–benzodiazepine receptor, while water and methanol extracts of the same plant did not show any activity. A strong GABA_A-receptor complex binding activity was observed in the methanol extract of aerial part of Stylosanthes erecta. The results in this study justify some of the traditional indications of the plants investigated and may thus be candidates for Improved Traditional Medicines in Mali.     

Antitrypanosomal and antiplasmodial activity of medicinal plants from Côte d'Ivoire

The antitrypanosomal activity of 101 crude ethanol extracts derived from 88 medicinal plants from Côte d’Ivoire was determined in vitro using Trypanosoma brucei rhodesiense. Of those extracts 8 showed good activity (IC₅₀ values ≤8 μg/ml), 37 revealed a weak activity (IC₅₀ values between 25 and 8.1 μg/ml) and 56 did not show any activity at all (IC₅₀ values>25 μg/ml). The extracts of Enantia polycarpa (Annonaceae) and Trichilia emetica (Meliaceae) were the most promising ones. Their IC₅₀ values were 0.5 and 0.04 μg/ml, respectively, and the selectivity index 616 and 209, respectively. This is the first report of in vitro antitrypanosomal activity of these two plants. Their high activities render them candidates for the isolation of compounds which could develop into new lead structures for drug development programs against African trypanosomiasis. Seven of the tested extracts exhibited an antiplasmodial activity against K1 strain of Plasmodium falciparum with IC₅₀ values below 4 μg/ml. The highest activity was found for Enantia polycarpa stem bark with an IC₅₀ value of 0.126 μg/ml.     

Anti-inflammatory activity of Sedum kamtschaticum

Sedum kamtschaticum Fischer (Crassulaceae) has been used as a folk medicine in North-East Asia for treating inflammatory disorders. The present investigation was carried out to establish in vivo anti-inflammatory activity and cyclooxygenase-2 modulating activity of this plant material. The methanol extract of Sedum kamtschaticum significantly inhibited mouse croton oil-induced ear edema (24–47% inhibition at 50–400 mg/kg) and rat paw edema (24–30% inhibition at 400–800 mg/kg) by oral administration. Prednisolone (10 mg/kg) showed 54 and 36% inhibition in the same animal models, respectively. Sedum kamtschaticum also showed significant inhibitory activity against mouse ear edema induced by multiple treatment of phorbol ester for 3 days. In addition, Sedum kamtschaticum exhibited potent analgesic activity against mouse acetic acid-induced writhing (IC₅₀=125 mg/kg), while aspirin (200 mg/kg) showed 57% inhibition. Using lipopolysaccharide-treated RAW 264.7 cells, down-regulation of cyclooxygense-2 expression was found to be one of the cellular action mechanisms of anti-inflammation by Sedum kamtschaticum.     

Evaluation of ethnobotanically selected Benin medicinal plants for their in vitro antiplasmodial activity

Twenty extracts from nine Benin medicinal plants, traditionally used to treat malaria, were screened for in vitro antiplasmodial activity towards Plasmodium falciparum K1 chloroquine resistant and 3D7 chloroquine sensitive strains. All plants showed antiplasmodial activity below 10 μg/ml. Nine extracts exhibited IC₅₀ values below 5 μg/ml towards one or both of the two strains. The most active extract towards the sensitive 3D7 strain was the methanolic extract of Croton lobatus aerial part, with an IC₅₀ value of 0.38 μg/ml. The best inhibition of the growth of Plasmodium falciparum resistant K1 strain was observed with the methylene chloride extract of Hybanthus enneaspermus and with the methanolic extract of Croton lobatus roots (IC₅₀=2.57 and 2.80 μg/ml, respectively).     

Inhibition of venom serine proteinase and metalloproteinase activities by Renealmia alpinia (Zingiberaceae) extracts: Comparison of wild and in vitro propagated plants

Ethnopharmacological relevance

The plant Renealmia alpinia has been used in folk medicine to treat snakebites in the northwest region of Colombia. In addition, it has been shown to neutralize edema-forming, hemorrhagic, lethal, and defibrin(ogen)ating activities of Bothrops asper venom. In this work, extracts of Renealmia alpinia obtained by micropropagation (in vitro) and from specimens collected in the wild were tested and compared in their capacity to inhibit enzymatic and toxic activities of a snake venom metalloproteinase isolated from Bothrops atrox (Batx-I) venom and a serine proteinase (Cdc SII) from Crotalus durissus cumanensis venom.

Materials and methods

We have investigated the inhibition capacity of Renealmia alpinia extracts on enzymatic and toxic actions of isolated toxins, a metalloproteinase and a serine proteinase. The protocols investigated included inhibition of proteolytic activity on azocasein, inhibition of proteolytic activity on fibrinogen, inhibition of pro-coagulant activity, inhibition of hemorrhagic activity and inhibition of edema-forming activity.

Results

Colorimetric assays detected the presence of terpenoids, flavonoids, tannins and coumarins in Renealmia alpinia extracts. Renealmia alpinia extracts inhibited the enzymatic, hemorrhagic and fibrinogenolytic activities of Batx-I. Extracts also inhibited coagulant, defibrin(ogen)ating and edema-forming activities of Cdc SII. Results highlight that Renealmia alpinia in vitro extract displayed comparable inhibitory capacity on venom proteinases that Renealmia alpinia wild extract. No alteration was observed in the electrophoretic pattern of venom proteinases after incubation with Renealmia alpinia extracts, thus excluding proteolytic degradation or protein denaturation/precipitation as a mechanism of inhibition.

Conclusions

Our results showed that Renealmia alpinia wild and in vitro extracts contain compounds that neutralize metallo- and serine proteinases present in snake venoms. The mechanism of inhibition is not related to proteolytic degradation of the enzymes nor protein aggregation, but is likely to depend on molecular interactions of secondary metabolites in the plant with these venom proteinases.     

Cytotoxicity of plants from Malaysia and Thailand used traditionally to treat cancer

The SRB cytotoxicity assay was used to screen extracts and isolated constituents of some traditional medicinal plants from Malaysia and Thailand against two human cancer cell lines, COR L23 lung cancer cell line and MCF7 breast cancer cell line and the non-cancer MCF5 cell line. Five out of the seven species tested, i.e. Thai Alpinia galanga, Alpinia officinarum, Cayratia japonica, Physalis minima, Tabernaemontana divaricata, exhibited interesting cytotoxicity activity and this is the first report of cytotoxicity from any Cayratia species. Following bioassay-guided fractionation, 1′-acetoxychavicol acetate (48 h exposure against COR L23 cells, IC₅₀ 7.8 μM against MCF7 cells, IC₅₀ 23.9 μM) was isolated as the major cytotoxic component of the Alpinia species, physalin F as the major cytotoxic component of Physalis minima (48 h exposure against COR L23 cells IC₅₀ 0.4 μM against MCF7 cells, IC₅₀ 0.59 μM). The Malaysian Alpinia galanga showed weak activity compared with the Thai sample and this was shown to be due to the relatively high amounts of 1′-acetoxychavicol acetate present in the Thai sample.     

Comparative pharmacokinetic study of paeoniflorin after oral administration of decoction of Radix Paeoniae Rubra and Radix Paeoniae Alba in rats

An investigation was designed and conducted to compare the pharmacokinetics difference of paeoniflorin after oral administration of the extracts of Radix Paeoniae Rubra and Radix Paeoniae Alba to rats on separate occasions. Quantification of paeoniflorin in rat plasma was achieved using a simple and rapid HPLC method for pharmacokinetic study. After oral administration of decoctions of Radix Paeoniae Rubra and Radix Paeoniae Alba, paeoniflorin was absorbed and reached a maximum concentration of 3.69 ± 1.46 and 1.46 ± 0.29 (p < 0.05) μg/ml at 1.67 ± 0.43 and 0.80 ± 0.35 h (p < 0.05), respectively. Compared to the AUC (18.85 ± 7.54 μg h/ml) after oral administration of the paeoniflorin solution, a smaller AUC (10.61 ± 1.51 μg h/ml, p < 0.05) and a larger AUC (24.89 ± 7.41 μg h/ml) of paeoniflorin after oral administration of the decoctions of Radix Paeoniae Alba and Radix Paeoniae Rubra were obtained, respectively. There were statistically significant differences in pharmacokinetic parameters of paeoniflorin including the t_max, C_max, AUC, t_1/2, CL, and V_d among the animals orally administered the decoctions of Radix Paeoniae Rubra and Radix Paeoniae Alba. In particular, the parameters of t_max, C_max, and AUC of paeoniflorin were remarkably increased (P < 0.05, P < 0.001) when oral administering paeoniflorin in the decoctions of Radix Paeoniae Rubra, but t_1/2, V_d, and CL were decreased (P < 0.05 or P < 0.01), in comparison of the decoction of Radix Paeoniae Alba.     

Hypoglycemic effect of Acosmium panamense bark on streptozotocin diabetic rats

The hypoglycemic effects of water and butanolic extracts prepared from the bark of Acosmium panamense (Fabaceae) were studied in diabetic rats (streptozotocin (STZ)-induced). Oral application of water extracts at doses of 20 and 200 mg/kg and of butanol extracts at doses of 20 and 100 mg/kg significantly lowered the plasma glucose levels in diabetic rats within 3 h. Glibenclamide was used as reference and showed similar hypoglycemic effect like the extracts.

Three structurally new compounds were isolated from the plant and shown to be the main constituents in both extracts.     

Medicinal plants from nepal: evaluation as inhibitors of leukotriene biosynthesis

The methanolic extracts of 25 different Nepalese medicinal plants were tested for their activity to inhibit the biosynthesis of leukotriene B₄ in bovine polymorphonuclear leukocytes. The selected indigenous plants are used in traditional herb remedies to treat inflammatory diseases such as asthma, bronchitis, rheumatism, and skin disorders presumed to be mediated by leukotrienes. The leaves of Zanthoxylum nepalensis were shown to be the most potent inhibitor with an IC₅₀ value of 11 μg/ml. The extracts obtained from Astercantha longifolia and Hedychium ellipticum also exhibited potent inhibitory action with IC₅₀ values of 20 and 22 μg/ml, respectively.     

Inhibition of sustained repetitive firing in cultured hippocampal neurons by an aqueous fraction isolated from Delphinium denudatum

In this report we investigated the effects of the aqueous fraction (AF) isolated from Delphinium denudatum on sustained repetitive firing in cultured neonatal rat hippocampal pyramidal neurons. Blockade of SRF is one of the basic mechanisms of antiepileptic drugs (AED) at the cellular level.

The effects of aqueous fraction (0.2–0.6 mg/ml) were compared with the prototype antiepileptic drug, phenytoin (PHT). Using the whole cell current-clamp technique, sustained repetitive firing was elicited in neurons by a depolarizing pulse of 500 ms duration, 0.3 Hz and 0.1–0.6 nA current strength. Similar to phenytoin, aqueous fraction reduced the number of action potentials (AP) per pulse in a concentration-dependent manner until no action potentials were elicited for the remainder of the pulse. There was a corresponding use-dependent reduction in amplitude and V_max (velocity of upstroke) of action potentials. The V_max and amplitude of the first action potential was not affected by phenytoin, while aqueous fraction exhibited concentration-dependent reduction. At 0.6 mg/ml aqueous fraction reduced V_max to 58–63% and amplitude to 16–20% of the control values. The blockade of sustained repetitive firing by aqueous fraction was reversed with hyperpolarization of membrane potential (−65 to −75 mV) while depolarization of membrane potential (−53 to −48 mV) potentiated the block.

The results suggest that aqueous fraction blocks sustained repetitive firing in hippocampal neurons in a use-dependent and voltage-dependent manner similar to phenytoin. However, unlike phenytoin, which interacts preferably with the inactive state of the Na⁺ channel, the compounds present in aqueous fraction apparently also interact with the resting state of the Na⁺ channels as suggested by dose-dependent reduction of V_max and amplitude of first AP. We conclude that aqueous fraction contains potent anticonvulsant compounds.     

Effects of alkaloids of Himatanthus lancifolius (Muell. Arg.) Woodson, Apocynaceae, on smooth muscle responsiveness

Himatanthus lancifolius, popularly known as “agoniada” in Brazil, is largely used in folk medicine against asthma, dysmenorrhea and as an emenagogue and abortive. This study reveals the effects of an alkaloid rich fraction (AlkF) obtained from the bark of Himatanthus lancifolius in vascular and non-vascular smooth muscle responsiveness. Incubation of AlkF (3–30 μg/ml) during 15 min generates a concentration-related and fully reversible reduction in maximal contractile responses evoked by acetylcholine and phenylephrine in rat jejune and aorta preparations, respectively. Exposition of endothelium-denuded pre-contracted rat aorta rings to AlkF results in a complete relaxation, with EC₅₀ of 22.2 (16.2–28.2 μg/ml). AlkF is also able to induce a concentration-related rightward shift of cumulative concentration curves for calcium in uterus and aorta rings maintained in depolarizing nutritive solution. Moreover, addition of AlkF in calcium-free solution also reduces, in a concentration-dependent manner, the ability of caffeine and phenylephrine to contract aorta rings. This study reveals that the bark of Himatanthus lancifolius possesses one or more indole alkaloids able to alter non-vascular and vascular smooth muscle responsiveness, an event that may involve the blocking of calcium entry or changes on intracellular calcium utilization or mobilization.     

Tanshinone inhibits intimal hyperplasia in the ligated carotid artery in mice

The hypoglycemic effects of water, ethanolic and butanolic extracts prepared from the root of Malmea depressa (Baill) R.E. Fries. (Annonaceae) were studied in diabetic rats (streptozotocin induced). Oral application of water extracts at doses of 40 and 80 mg/kg, ethanolic (112 mg/kg) and butanolic (80 mg/kg) extracts significantly lowered the plasma glucose levels in diabetic rats within three hours. Glibenclamide and metformin were used as references and showed similar hypoglycemic effects like the extracts. The three extracts have a similar chemical composition (HPLC analysis).     

Isolation and anticomplement activity of compounds from Dendropanax morbifera

Dendropanax morbifera Leveille (Araliaceae) is used in Korea for a variety of disease, such as migraine headache and dysmenorrheal. A new polyacetylene (1) and six known compounds (2–7) were isolated from the leaves of this plant by conventional chromatographic techniques. The structure of the new polyacetylene (1) was determined as (9Z,16S)-16-hydroxy-9,17-octadecadiene-12,14-diynoic acid by spectroscopic means including 2D NMR, which comprised the determination of a chiral by modified Mosher’s ester method. Compounds 1–7 were investigated in vitro for their anticomplement activity against the classical pathway of the complement system. Of these, compound 1 showed significant anticomplement activity with 50% inhibitory concentration (IC₅₀) value of 56.98 μM, whereas compounds 2–7 were inactive.     

In vitro and in vivo anthelmintic activity of crude extracts of Coriandrum sativum against Haemonchus contortus

In vitro anthelmintic activities of crude aqueous and hydro-alcoholic extracts of the seeds of Coriandrum sativum (Apiaceae) were investigated on the egg and adult nematode parasite Haemonchus contortus. The aqueous extract of Coriandrum sativum was also investigated for in vivo anthelmintic activity in sheep infected with Haemonchus contortus. Both extract types of Coriandrum sativum inhibited hatching of eggs completely at a concentration less than 0.5 mg/ml. ED₅₀ of aqueous extract of Coriandrum sativum was 0.12 mg/ml while that of hydro-alcoholic extract was 0.18 mg/ml. There was no statistically significant difference between aqueous and hydro-alcoholic extracts (p > 0.05). The hydro-alcoholic extract showed better in vitro activity against adult parasites than the aqueous one. For the in vivo study, 24 sheep artificially infected with Haemonchus contortus were randomly divided into four groups of six animals each. The first two groups were treated with crude aqueous extract of Coriandrum sativum at 0.45 and 0.9 g/kg dose levels, the third group with albendazole at 3.8 mg/kg and the last group was left untreated. Efficacy was tested by faecal egg count reduction (FECR) and total worm count reduction (TWCR). On day 2 post treatment, significant FECR was detected in groups treated with higher dose of Coriandrum sativum (p < 0.05) and albendazole (p < 0.001). On days 7 and 14 post treatment, significant FECR was not detected for both doses of Coriandrum sativum (p > 0.05). Significant (p < 0.05) TWCR was detected only for higher dose of Coriandrum sativum compared to the untreated group. Reduction in male worms was higher than female worms. Treatment with both doses of Coriandrum sativum did not help the animals improve or maintain their PCV while those treated with albendazole showed significant increase in PCV (p < 0.05).     

Hepatotoxic effect of (+)usnic acid from Usnea siamensis Wainio in rats, isolated rat hepatocytes and isolated rat liver mitochondria

Hepatotoxic effect of (+)usnic acid, the active constituent of Usnea siamensis Wainio was studied in rats, isolated rat hepatocytes and isolated rat liver mitochondria. In rats, after treatment with high dose of (+)usnic acid (200 mg/kg per day, i.p.) for 5 days, there was no significant change in serum transaminase activity (serum AST, ALT) while the electron micrographs showed apparent morphological damage of mitochondria and endoplasmic reticulum. (+)Usnic acid at high dose (1 mM) as well as carbon tetrachloride (CCl₄, the reference hepatotoxin) induced loss of cell membrane integrity in isolated rat hepatocytes by increasing the release of cellular transaminases (AST, ALT). Increase in lipid peroxidation, decrease in glutathione (GSH) content and increase in aniline hydroxylase activity (CYP 2E1) were also found. Combination of (+)usnic acid and CCl₄ showed the additive results. (+)Usnic acid (0.15–6 μM) possessed uncoupling activity in isolated rat liver mitochondria. It stimulated respiration by mitochondria respiring with glutamate plus malate or succinate as substrates and activated ATPase activity. Increasing concentration of (+)usnic acid (>6 μM) exhibited loss of respiratory control and ATP synthesis. In conclusion, hepatotoxic effect of high dose (+)usnic acid may involve its reactive metabolite(s), causing loss of integrity of membrane like structures, resulting in destruction of mitochondrial respiration and oxidative phosphorylation.     

Inhibition of the pro-inflammatory mediators' production and anti-inflammatory effect of the iridoid scrovalentinoside

We have studied scrovalentinoside, an iridoid with anti-inflammatory properties isolated from Scrophularia auriculata ssp. pseudoauriculata, as an anti-inflammatory agent in different experimental models of delayed-type hypersensitivity. We found that scrovalentinoside reduced the edema induced by oxazolone at 0.5 mg/ear and sheep red blood cells at 10 mg/kg. The observed effect occurred during the last phase or inflammatory response; during the earlier phase or induction of the delayed-type hypersensitivity reaction, no significant activity was noted. Thus, scrovalentinoside reduced both the edema and cell infiltration in vivo and reduced lymphocyte proliferation in vitro, affecting the cycle principally during the first 48 h. Whereas cells stimulated with phytohemagglutinin changed from the G₀/G₁ phase to the S and G₂/M phases, when these same cells were treated with scrovalentinoside (100 μM), they remained in the G₀/G₁ phase. Finally, scrovalentinoside inhibited the production of the pro-inflammatory mediators’ TNF-, IFN-γ, IL-1β, IL-2, IL-4, LTB₄, and NO, but had no effect on the production of the anti-inflammatory cytokine IL-10.     

In vitro antiplasmodial activity of extracts of Argentinian plants

Fifteen extracts from nine selected Argentine medicinal plants were tested for their antiplasmodial activity in vitro by assessing their ability to inhibit the uptake of [3H]-hypoxanthine into the Plasmodium falciparum K1 pyrimethamine/chloroquine resistant strain. The methanol extract of Satureja parvifolia showed good antiplasmodial activity (IC₅₀ 3 μg/ml). Inhibition of the growth of P. falciparum was also observed with aqueous extracts of Buddleja globosa and S. parvifolia.     

Antidiabetic effect of a leaf extract from Gymnema sylvestre in non-insulin-dependent diabetes mellitus patients

The effectiveness of GS₄, an extract from the leaves of Gymnema sylvestre, in controlling hyperglycaemia was investigated in 22 Type 2 diabetic patients on conventional oral anti-hyperglycaemic agents. GS₄ (400 mg/day) was administered for 18–20 months as a supplement to the conventional oral drugs. During GS₄ supplementation, the patients showed a significant reduction in blood glucose, glycosylated haemoglobin and glycosylated plasma proteins, and conventional drug dosage could be decreased. Five of the 22 diabetic patients were able to discontinue their conventional drug and maintain their blood glucose homeostasis with GS₄ alone. These data suggest that the beta cells may be regenerated/repaired in Type 2 diabetic patients on GS₄ supplementation. This is supported by the appearance of raised insulin levels in the serum of patients after GS₄ supplementation.     

Antispasmodic and blood pressure lowering effects of Valeriana wallichii are mediated through K+ channel activation

Crude extract of Valeriana wallichii rhizome (Vw.Cr) and its fractions were studied for possible antispasmodic and blood pressure lowering activities to rationalize some of the folkloric uses. In rabbit jejunum preparations, Vw.Cr (0.1–3.0 mg/mL) caused relaxation of spontaneous contractions. When tested against high K⁺ (80 mM)-induced contractions it produced weak inhibitory effect, while caused complete relaxation of the contractions induced by low K⁺ (20 mM). In the presence of glibenclamide (3 μM), the inhibitory effect of low K⁺ was shifted to the right, similar to that produced by cromakalim while, verapamil caused no differentiation in its inhibitory effect against low and high K⁺-induced contractions. In guinea pig ileum, the plant extract produced similar results as in rabbit jejunum. Intravenous administration of Vw.Cr, produced fall in arterial blood pressure in normotensive anaesthetized rats and this effect was partially blocked by glibenclamide. In rabbit aortic preparations, plant extract also caused a selective and glibenclamide-sensitive relaxation of low K⁺ (20 mM)-induced contractions. Activity-directed fractionation studies revealed that the observed activity was distributed both in the chloroform and aqueous fractions. These results indicate that the antispasmodic and hypotensive effects of Valeriana wallichii are mediated possibly through K_ATP channel activation, which justify its use in gastrointestinal and cardiovascular disorders.     

Diuretic activity of some Withania aristata Ait. fractions

We previously reported on the significant dose-dependent diuretic effects produced in laboratory rats by hot water infusions and methanol extracts of Withania aristata Ait., where notable increases were observed in the excretion of water and sodium, with an interesting potassium-saving effect. The present study gives the results of the diuretic effects in rats of the hexane, dichloromethane, ethyl acetate, butanol and methanol–water fractions of the previously studied methanol extract.

Water excretion rate, pH, density, conductivity and content of Na⁺, K⁺ and Cl⁻ were measured in the urine of the rats when subjected to hypersaline conditions. Of the above fractions, the methanol:water extract (100 mg/kg) showed the most interesting diuretic activity (25%; ^**p < 0.01), which suggested that increase in the polarity of the extracting solvent led to an increase in the concentration of the polar compounds responsible for the diuretic effect. These data, together with previous results on the aqueous and methanol extracts, reaffirm assertions made regarding the effectiveness of the extracts of this plant against urinary pathologies in the Canary Islands folk medicine.