Hypotensive and spasmolytic activities of crude extract ofCyperus scariosus

Inhibition of Acetylcholinesterase with Novel 1, 3, 4, Oxadiazole Derivatives: A Kinetic, In Silico, and In Vitro Approach

Alzheimer's disease (AD) is a neurological disease that disturbs the memory, thinking skills, and behavior of the affected person. AD is a complex disease caused by the breakdown of acetylcholine via acetylcholinesterase (AChE). The present study aimed to assess the synthetic inhibitors of AChE that could be used to treat AD. For this purpose, synthetic compounds of oxadiazole derivatives (15-35) were evaluated and identified as promising inhibitors of AChE, exhibiting IC50 varying between 41.87 ± 0.67 and 1580.25 ± 0.7 μM. The kinetic parameters indicated that all the studied compounds bind to the allosteric site and decrease the efficiency of the AChE enzyme. In silico docking analysis showed that the majority of the compounds interact with the anionic subsite and Per-Arnt-Sim domain of AChE and are stabilized by various bonds including π-π and hydrogen bonding. The stability of the most potent compounds 16 and 17 with AChE interaction was confirmed by molecular dynamics simulations. Moreover, all compounds exhibited concentration-dependent calcium (Ca2+) antagonistic and spasmolytic activities. Among the whole series of oxadiazole derivatives, compounds 16 and 17 displayed the highest activities on spontaneous and potassium (K+)-induced contraction. Therefore, the AChE inhibitory potential, cytotoxicity safe profile, and Ca2+ antagonistic ability of these compounds make them potential therapeutic agents against AD and its associated problems in the future.

Anti-diabetic and spasmolytic potential of Farsetia hamiltonii Royle from Cholistan desert

ETHNOPHARMACOLOGICAL RELEVANCE

Folk herbal practitioners of the Cholistan desert claim Farsetia hamiltonii Royle (Brassicaceae) to treat diabetes, oxidative damages, diarrhea, fever, and abdominal cramps. The aim of this study was to scientifically find the potential of Farsetia hamiltonii in treating diabetes and gastrointestinal diseases.

MATERIALS AND METHODS

In vivo anti-diabetic activity of Farsetia hamiltonii was studied on alloxan induced diabetic rats to justify its traditional use. The in vitro antispasmodic activity on isolated tissues of rabbit jejunum was also evaluated. In addition, several enzyme inhibition studies (lipoxygenase, tyrosinase, acetylcholinesterase (AchE), carbonic II anhydrase and phosphodiesterase I) and antioxidant activity of plant extracts were also conducted.

RESULTS

In vivo experiments, Farsetia hamiltonii methanol extract (300 mg/kg) significantly lowered the fasting blood glucose (107.6 ± 1.249 mg/dL up to 4th day) comparable to positive control (Glibenclamide) throughout the study period. The in vitro antispasmodic activity on isolated tissues of rabbit jejunum on methanol extract showed concentration dependent (0.01-0.3 mg/ml) relaxation of spontaneous contractions with EC₅₀ value 0.011 µM and high K(+) (80 mM) induced contraction (0.01-0.1 mg/ml) with EC₅₀ value 0.066 mg/ml. Farsetia hamiltonii DCM and methanol extracts exhibited some antilipoxygenase activities while tyrosinase, acetylcholinesterase (AchE), carbonic II anhydrase, phosphodiesterase I, and antioxidant activity of plant extracts were not significant.

CONCLUSIONS

Our results validate the traditional use of Farsetia hamiltonii for the traditional therapeutic potential in treating diabetes and gastrointestinal diseases.

Studies on the chemical composition and possible mechanisms underlying the antispasmodic and bronchodilatory activities of the essential oil of Artemisia maritima L

This study describes the chemical composition of the essential oil of Artemisia maritima (Am.Oil) and the pharmacological basis for its medicinal use in gut and airways disorders. Twenty five compounds, composing 93.7% of the oil, were identified; among these, chrysanthenyl propionate and elixene were identified for the first time from any Artemisia species. The Am.Oil (0.3-1.0 mg/mL) suppressed spontaneous and high K(+) (80 mM)-induced contractions in isolated rabbit jejunum, suggestive of an antispasmodic effect mediated possibly through calcium channel blockade. The calcium channel blockade activity was confirmed when pre-treatment of the tissue with Am.Oil (0.01-0.03 mg/mL) shifted the Ca(++) concentration-response curves to the right, similar to verapamil and papaverine. In isolated tracheal strips, Am.Oil inhibited carbachol (CCh; 1 μM)-induced contractions more than that induced by K(+) and shifted the isoprenaline-induced inhibitory CRCs to the left, similar to papaverine, suggestive of potentiation, while, verapamil was more potent against K(+) than CCh-induced contractions and had no potentiating effect on isoprenaline-induced inhibitory CRCs. These data indicate that the Am.Oil exhibited spasmolytic and bronchodilator activities mediated possibly through dual blockade of calcium channels and phosphodiesterase, which provides the pharmacological basis to the medicinal use of Artemisia maritima in colic, diarrhea and possibly asthma.

Pharmacological basis for the use of Borago officinalis in gastrointestinal, respiratory and cardiovascular disorders

AIM OF THE STUDY

In this study, we investigated the crude extract of Borago officinalis leaves (Bo.Cr) for its antispasmodic, bronchodilator, vasodilator and cardio-depressant activities to rationalize some of the traditional uses.

MATERIALS AND METHODS

Bo.Cr was studied using different isolated tissue preparations including rabbit jejunum, trachea, aorta, and guinea-pig atria.

RESULTS

Bo.Cr which was tested positive for flavonoids, coumarins, sterols and tannins produced a concentration-dependent relaxation of spontaneous and K+ (80mM)-induced contractions in isolated rabbit jejunum preparations, suggestive of Ca++ antagonist effect, which was confirmed when pretreatment of the tissue with Bo.Cr produced a rightward shift in the Ca++ concentration-response curves like that caused by verapamil. In rabbit tracheal preparations, Bo.Cr relaxed the carbachol (1microM) and K+-induced contractions. Verapamil also produced non-specific inhibitory effect. In rabbit aorta preparations, Bo.Cr exhibited vasodilator effect against phenylephrine and K+-induced contractions similar to verapamil. When tested in guinea-pig atria, Bo.Cr caused inhibition of both atrial force and rate of contractions.

CONCLUSIONS

These results suggest that the spasmolytic effects of Bo.Cr are mediated possibly through Ca++ antagonist mechanism, which might explain the traditional use of Borago officinalis in hyperactive gastrointestinal, respiratory and cardiovascular disorders.

Blood pressure lowering effect of olive is mediated through calcium channel blockade

Olive (Olea europea) is used in traditional medicine as a remedy for hypertension. The aqueous-methanolic crude extract of O. europea fruit (OeF.Cr) was studied in anaesthetized rats and its possible mechanism was elucidated using isolated cardiovascular preparations. Intravenous administration of OeF.Cr produced a dose-dependent (30-100 mg/kg) fall in arterial blood pressure in normotensive anaesthetized rats. This effect remained unaltered in atropinized animals. In the in vitro studies OeF.Cr (0.1-3.0 mg/ml) inhibited spontaneously beating guinea-pig atria. Moreover, it relaxed K+ and/or phenylephrine-induced contractions of rabbit aortic preparations over a dose range of 0.1-3.0 mg/ml, suggesting calcium channel blockade (CCB). The CCB effect was confirmed when pretreatment of the vascular preparations with OeF.Cr produced a dose-dependent rightward shift of the Ca2+ dose-response curves, similar to verapamil. These results suggest that the blood pressure lowering effect of olive is mediated through CCB, justifying its use in hypertension.

Studies on spasmogenic and spasmolytic activities ofCalendula officinalisflowers

The aqueous-ethanol extract of Calendula officinalis flowers (Co.Cr) was studied for its possible spasmolytic and spasmogenic effects in isolated gut preparations. In rabbit jejunum, Co.Cr caused a dose-dependent (0.03-3.0 mg/mL) relaxation of spontaneous and K+-induced contractions, suggestive of calcium channel blockade (CCB). In a few preparations, a mild non-reproducible spasmogenic effect was observed at lower doses, followed by relaxation. The CCB effect was confirmed when pretreatment of the jejunum preparations with Co.Cr produced a dose-dependent rightward shift in the Ca(++) dose-response curves, similar to that of verapamil. Activity-directed fractionation revealed that the spasmolytic activity of the plant was concentrated in its organic fractions. The aqueous fraction exhibited a marked atropine sensitive spasmogenic effect but was found to be devoid of any spasmolytic effect. These data indicate that the crude extract of Calendula officinalis flowers contains both spasmolytic and spasmogenic constituents, exhibiting these effects through calcium channel blocking and cholinergic activities and this study provides a scientific base for its traditional use in abdominal cramps and constipation.

Presence of cholinergic and calcium channel blocking activities explains the traditional use of Hibiscus rosasinensis in constipation and diarrhoea

The aqueous-ethanolic extract of the aerial parts of Hibiscus rosasinensis Linn. (Malvaceae) was studied for the possible presence of spasmogenic and spasmolytic constituents to rationalize its traditional use in gastrointestinal disorders. The crude extract (Hr.Cr) caused a concentration-dependent (1-10mg/mL) spasmogenic effect in isolated guinea-pig ileum, which was blocked in the presence of atropine (0.1 microM). In spontaneously contracting rabbit jejunum, the plant extract exhibited a weak stimulatory effect at lower doses (0.03-0.30 mg/mL) followed by an inhibitory effect at higher doses (1.0-3.0mg/mL). Pretreatment of the tissues with atropine blocked the stimulatory effect resulting in the potentiation of the spasmolytic effect. Hr.Cr (0.03-1.0mg/mL) also showed an inhibitory effect on K(+) (80 mM)-induced contractions. The calcium channel blocking activity was confirmed when Hr.Cr shifted the Ca(2+) concentration-response curves to the right, similar to verapamil. Activity-directed fractionation revealed that the spasmolytic component(s) was separated in the ethyl acetate, while the spasmogenic in the petroleum ether fraction. The aqueous fraction exhibited a combination of weak spasmogenic and spasmolytic effects. These data indicate that the crude extract contains spasmogenic and spasmolytic constituents mediating their effect through cholinergic receptors activation and blockade of Ca(2+) influx, respectively, which may explain its traditional use in constipation and diarrhoea.

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 microM), 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.

Withanolides, a new class of natural cholinesterase inhibitors with calcium antagonistic properties

The withanolides 1-3 and 4-5 isolated from Ajuga bracteosa and Withania somnifera, respectively, inhibited acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholinesterase (BChE, EC 3.1.1.8) enzymes in a concentration-dependent fashion with IC50 values ranging between 20.5 and 49,2 microm and 29.0 and 85.2 microm for AChE and BChE, respectively. Lineweaver-Burk as well as Dixon plots and their secondary replots indicated that compounds 1, 3, and 5 are the linear mixed-type inhibitors of AChE, while 2 and 4 are non-competitive inhibitors of AChE with K(i) values ranging between 20.0 and 45.0 microm. All compounds were found to be non-competitive inhibitors of BChE with K(i) values ranging between 27.7 and 90.6 microm. Molecular docking study revealed that all the ligands are completely buried inside the aromatic gorge of AChE, while compounds 1, 3, and 5 extend up to the catalytic triad. A comparison of the docking results showed that all ligands generally adopt the same binding mode and lie parallel to the surface of the gorge. The superposition of the docked structures demonstrated that the non-flexible skeleton of the ligands always penetrates the aromatic gorge through the six-membered ring A, allowing their simultaneous interaction with more than one subsite of the active center. The affinity of ligands with AChE was found to be the cumulative effects of number of hydrophobic contacts and hydrogen bonding. Furthermore, all compounds also displayed dose-dependent (0.005-1.0 mg/mL) spasmolytic and Ca2+ antagonistic potentials in isolated rabbit jejunum preparations, compound 4 being the most active with an ED50 value of 0.09 +/- 0.001 mg/mL and 0.22 +/- 0.01 microg/mL on spontaneous and K+ -induced contractions, respectively. The cholinesterase inhibitory potential along with calcium antagonistic ability and safe profile in human neutrophil viability assay could make compounds 1-5 possible drug candidates for further study to treat Alzheimer's disease and associated problems.

Juliflorine: A potent natural peripheral anionic-site-binding inhibitor of acetylcholinesterase with calcium-channel blocking potential, a leading candidate for Alzheimer’s disease therapy

The alkaloid juliflorine (1) from Prosopis juliflora inhibited acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholinesterase (BChE, EC 3.1.1.8) enzymes in a concentration-dependent fashion with IC50 values 0.42 and 0.12 microM, respectively. Lineweaver-Burk as well as Dixon plots and their secondary replots indicated that the nature of inhibition was purely of non-competitive type with Ki values 0.4 and 0.1 microM, against AChE and BChE, respectively. By molecular docking studies compound 1 was found to be ideally spaced inside the aromatic gorge of AChE with rings A/B remaining at the top and rings C/D penetrating deep into the gorge, that might be due to the greater hydrophobicity of rings C/D as compared to rings A/B, allowing their simultaneous interaction with the peripheral anionic and quaternary ammonium-binding sites. The 1-AChE complex was found to be stabilized by hydrophobic contacts, hydrogen bonding, and pi-pi stacking between the compound 1 and amino acid residues of the aromatic gorge of AChE. Amino acid residues Tyr70, Asp72, Tyr121, Trp279, and Tyr334 of the peripheral anionic site (PAS) of AChE were found to be exclusively involved in the hydrophobic contacts with compound 1 that might be responsible for the competitive mode of inhibition. Compound 1 also showed dose-dependent (30-500 microg/mL) spasmolytic and Ca2+-channel blocking activities in isolated rabbit jejunum preparations. The cholinesterase inhibitory potential along with calcium-channel blocking activity of compound 1 and safe profile in human neutrophils viable assay could make it a possible drug candidate for Alzheimer's disease.

Antispasmodic and hypotensive effects of Ferula asafoetida gum extract

The effects of Ferula asafoetida gum extract on the contractile responses of the isolated guinea-pig ileum induced by acetylcholine, histamine and KCl, and on the mean arterial blood pressure of rat were investigated. In the presence of extract (3 mg/ml), the average amplitude of spontaneous contractions of the isolated guinea-pig ileum was decreased to 54 +/- 7% of control. Exposure of the precontracted ileum by acetylcholine (10 microM) to Ferula asafoetida gum extract caused relaxation in a concentration-dependent manner. Similar relaxatory effect of the extract was observed on the precontracted ileum by histamine (10 microM) and KCl (28 mM). However, when the preparations were preincubated with indomethacin (100 nM) and different antagonists, such as propranolol (1 microM), atropine (100 nM), chlorpheniramine (25 nM) then were contracted with KCl, exposure to the extract (3 mg/ml) did not cause any relaxation. Furthermore, Ferula asafoetida gum extract (0.3-2.2 mg/100g body weight) significantly reduced the mean arterial blood pressure in anaesthetised rats. It might be concluded that the relaxant compounds in Ferula asafoetida gum extract interfere with a variety of muscarinic, adrenergic and histaminic receptor activities or with the mobilisation of calcium ions required for smooth muscle contraction non-specificly.

Structure and spasmolytic activity of eucalyptanoic acid from Eucalyptus camaldulensis var. obtusa and synthesis of its active derivative from oleanolic acid

A new triterpenoid acid named eucalyptanoic acid (1) has been isolated from the fresh uncrushed leaves of Eucalyptus camaldulensis var. obtusa along with two known constituents, beta-sitosterol (2) and betulinic acid (3). The structure of 1 has been established as 3beta-hydroxyolean-9(11),12-dien-28-oic acid through spectral studies including 1D and 2D NMR. 1 and its acetyl (1a) and acetylmethyl (1b) derivatives were tested for spasmolytic activity. 1b was found to be the most active spasmolytic, mediated through blockade of calcium influx at 1 mg/mL. In the present study 1b was also prepared starting from oleanolic acid (4). Acetylation of 4 gave 4a, which on methylation afforded 4b. Reaction of 4b with N-bromosuccinimide (NBS) furnished 1b. Hence 4 may be regarded as the biogenetic precursor of 1. Compounds 4 and 4a were found inactive at 1 mg/mL, while 4b was moderately active in showing spasmolytic activity.

Triterpenoids from the leaves of Psidium guajava

Two triterpenoids, 20beta-acetoxy-2alpha,3beta-dihydroxyurs-12-en-28-oic acid (guavanoic acid, 3), and 2alpha,3beta-dihydroxy-24-p-z-coumaroyloxyurs-12-en-28-oic acid (guavacoumaric acid, 7), along with six known compounds 2alpha-hydroxyursolic acid (1), jacoumaric acid (2), isoneriucoumaric acid (4), asiatic acid (5), ilelatifol D (6) and beta-sitosterol-3-O-beta-D-glucopyranoside (8), have been isolated from the leaves of Psidium guajava. Their structures were determined through spectroscopic methods. Compound 5 showed dose-dependent (10-500 microg/ml) spasmolytic activity in spontaneously contracting isolated rabbit jejunum preparations.

Spasmolytic constituents from Eucalyptus camaldulensis var. obtusa leaves

Phytochemical studies on the leaves of Eucalyptus camaldulensis var. obtusa have resulted in the isolation of a new triterpenoid camaldulin (3beta-formyloxyurs-11-en-28,13beta-olide) (1) along with ursolic acid lactone acetate (2), ursolic acid lactone (3), betulinic acid (4), and beta-sitosterol 3-O-beta-D-glucopyranoside (5). The structures were assigned on the basis of 1D and 2D NMR studies. Compounds 1-3 were tested for spasmolytic activity and were found to possess calcium antagonist activity.

Effects of leaf aqueous extract of Bidens pilosa (Asteraceae) on KCl- and norepinephrine-induced contractions of rat aorta

The effect of leaf aqueous extract of Bidens pilosa Linn. on KCl- and norepinephrine-induced contractions of rat aortic strips was studied. In aortic strips with endothelium intact, contractions induced using 60 mM KCl and 10(-5) M norepinephrine were dose-dependently relaxed by the extract, a more significant effect being seen with norepinephrine-induced contractions. Following mechanical damage to the aortic endothelium, inhibition of contractions was more prominent (105%) with the norepinephrine-induced contractions compared with KCl-induced contractions (15%) when the maximal dose (8 mg/ml) of the extract was used. The results suggest that the relaxation effect of the extract may be due to the blockade of the influx of extracellular Ca2+ into the cell.

The antiplatelet aggregatory activity of Acacia nilotica is due to blockade of calcium influx through membrane calcium channels

1. The extract of Acacia nilotica (A. nilotica) blocked platelet aggregation mediated by platelet agonists, arachidonic acid (0.75 mM), ADP (4.3 microM), platelet activating factor (800 nM) and collagen (638 nM) in a dose-dependent manner. 2. The extract (0.21-1.4 mg/ml) blocked the platelet aggregation induced by Ca2+ ionophore, A-23187 (6 microM), in a dose-dependent manner, indicating that the Ca2+ influx is involved in aggregation. 3. The plant extract also inhibited aggregation in platelets pretreated with phorbol, 12-myristate, 13-acetate (196 nM) alone or in combination with ADP (4.3 microM), indicating an effect on protein kinase C. 4. These results indicate that the antiplatelet aggregatory activity of the extract of A. nilotica is mainly due to blockade of Ca2+ channels, although evidence also suggests the involvement of protein kinase C.

Studies on protective effect of Cyperus scariosus extract on acetaminophen and CCl4-induced hepatotoxicity

1. The hepatoprotective activity of aqueous-methanolic extract of Cyperus scariosus (Cyperaceae) was investigated against acetaminophen and CCl4-induced hepatic damage. 2. Acetaminophen produced 100% mortality at a dose of 1 g/kg in mice while pretreatment of animals with plant extract (500 mg/kg) reduced the death rate to 30%. 3. Acetaminophen at a dose of 640 mg/kg produced liver damage in rats as manifested by the rise in serum levels of alkaline phosphatase (ALP), glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) to 430 +/- 68, 867 +/- 305 and 732 +/- 212 IU/l (n = 10) respectively, compared to respective control values of 202 +/- 36, 59 +/- 14 and 38 +/- 7. 4. Pretreatment of rats with plant extract (500 mg/kg) significantly lowered (P < 0.05) the respective serum ALP; GOT and GPT levels to 192 +/- 31, 63 +/- 9 and 35 +/- 8. 5. The hepatotoxic dose of CCl4 (1.5 ml/kg; orally) raised serum ALP, GOT and GPT levels to 328 +/- 30, 493 +/- 102 and 357 +/- 109 IU/l (n = 10) respectively, compared to respective control values of 177 +/- 21, 106 +/- 15 and 47 +/- 12. 6. The same dose of plant extract (500 mg/kg) was able to significantly prevent (P < 0.05) CCl4-induced rise in serum enzymes and the estimated values of ALP, GOT and GPT were 220 +/- 30, 207 +/- 95 and 75 +/- 38, respectively. 7. The plant extract also prevented CCl4-induced prolongation in pentobarbital sleeping time confirming hepatoprotectivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Preventive and curative effects of Artemisia absinthium on acetaminophen and CCl4-induced hepatotoxicity

1. Effect of aqueous-methanolic extract of Artemisia absinthium (Compositae) was investigated against acetaminophen- and CCl4-induced hepatic damage. 2. Acetaminophen produced 100% mortality at the dose of 1 g/kg in mice while pretreatment of animals with plant extract (500 mg/kg) reduced the death rate to 20%. 3. Pretreatment of rats with plant extract (500 mg/kg, orally twice daily for two days) prevented (P < 0.01) the acetaminophen (640 mg/kg) as well as CCl4 (1.5 ml/kg)-induced rise in serum transaminases (GOT and GPT). 4. Post-treatment with three successive doses of extract (500 mg/kg, 6 hr) restricted the hepatic damage induced by acetaminophen (P < 0.01) but CCl4-induced hepatotoxicity was not altered (P > 0.05). 5. Plant extract (500 mg/kg) caused significant prolongation (P < 0.05) in pentobarbital (75 mg/kg)-induced sleep as well as increased strychnine-induced lethality in mice suggestive of inhibitory effect on microsomal drug metabolizing enzymes (MDME). 6. These results indicate that the crude extract of Artemisia absinthium exhibits hepatoprotective action partly through MDME inhibitory action and validates the traditional use of plant in hepatic damage.