In vitro antiplasmodial activity and cytotoxicity of nine plants traditionally used in Gabon

Aim of the study

As part of a project to identify new compounds active on malarial parasites, we tested the in vitro antiplasmodial activity of nine plants traditionally used to treat malaria symptoms in Haut-Ogooué Province, South-East Gabon.

Materials and methods

Dichloromethane and methanolic extracts of each plant were tested for their antiplasmodial activity on two chloroquine-resistant strains of Plasmodium falciparum (FCB and W2), based on lactate dehydrogenase activity. Cytotoxicity was assessed with the MTT test on MRC-5 human diploid embryonic lung cells.

Results

The methanolic extract of Staudtia gabonensis and the dichloromethane extract of Adhatoda latibracteata showed high antiplasmodial activity (IC₅₀ < 1 μg/ml) and low cytotoxicity, with selectivity indexes of about 58.25 and 16.43, respectively. The methanolic extract of Monodora myristica and the dichloromethane extract of Afromomum giganteum also showed promising activity (1 < IC₅₀ < 10 μg/ml) and low cytotoxicity, with selectivity indexes about 15.70 and 12.48, respectively. Dichloromethane extracts of Monodora myristica and Leonotis Africana showed moderate activity (10 < IC₅₀ < 40 μg/ml), with selectivity indexes about 6.07 and 28.89, respectively. Both extracts of Culcasia lancifolia had IC₅₀ values of 10-40 μg/ml but high cytotoxicity (selectivity indexes <2.77). The methanolic extract of Dorstenia klaineana had moderate antiplasmodial activity (IC₅₀ around 17 μg/ml) but strong cytotoxicity (0.43 μg/ml), giving a selectivity index of about 0.03.

Conclusions

Most extracts of nine selected plants traditionally used to treat malaria in Gabon had interesting antiplasmodial activity in vitro. This supports continued investigations of traditional medicines in the search for new antimalarial agents. The compounds responsible for the observed antiplasmodial effects are under investigation.     

Antiplasmodial activity of aporphine alkaloids and sesquiterpene lactones from Liriodendron tulipifera L.

Aim of the study

The objective of this study was to isolate and characterize the active constituents of the traditionally used antimalarial plant Liriodendron tulipifera by antiplasmodial-assay guided fractionation.

Materials and methods

Bark and leaves were extracted with solvents of increasing polarity. Fractions were generated using flash chromatography, counter current chromatography and preparative HPLC and subjected to in vitro antiplasmodial and cytotoxicity assays. Active fractions were subjected to further fractionation until pure compounds were isolated, for which the IC₅₀ values were calculated.

Results and discussion

Six known aporphine alkaloids, asimilobine (1), norushinsunine (2), norglaucine (3), liriodenine (4), anonaine (5) and oxoglaucine (6) were found to be responsible for the antiplasmodial activity of the bark. Leaves yielded two known sesquiterpene lactones, peroxyferolide (7) and lipiferolide (8) with antiplasmodial activity. The antiplasmodial activity of (2) (IC₅₀ = 29.6 μg/mL), (3) (IC₅₀ = 22.0 μg/mL), (6) (IC₅₀ = 9.1 μg/mL), (7) (IC₅₀ = 6.2 μg/mL) and (8) (IC₅₀ = 1.8 μg/mL) are reported for the first time.

Conclusion

This work supports the historical use of Liriodendron tulipifera as an antimalarial remedy of the United States and characterizes its antiplasmodial constituents.     

Evidence for a role of 5-HT1A receptor on antinociceptive action from Geissospermum vellosii

Ethnopharmacological relevance

Geissospermum vellosii is a tree widely found throughout the Amazonic forest and frequently used by the native population for painful disorders.

Aim of the study

The present study examined the antinociceptive effects of Geissospermum vellosii in behavioral models of nociception.

Materials, methods and results

Oral administration of crude extract of Geissospermum vellosii or its dichloromethane fraction (1–100 mg/kg) inhibited formalin-induced inflammatory nociception and acetic acid-induced visceral nociception. The antinociceptive effect of Geissospermum vellosii was unrelated with motor dysfunctions. Furthermore, the alkaloid 12-metoxy-1-methyl-aspidospermidine (0.001–1 mg/kg), isolated from the dichloromethane fraction, also produced antinociception. The antinociception caused by the dichloromethane fraction was significantly attenuated by pre-treatment of mice with p-chlorophenylalanine methyl ester (PCPA, an inhibitor of serotonin synthesis, 100 mg/kg once a day for 4 consecutive days) and WAY-100635 (a 5-HT_1A receptor antagonist, 0.3 mg/kg). In contrast, dichloromethane fraction antinociception was not affected by pre-treatment of animals with ketanserin (a 5-HT₂ receptor antagonist, 0.3 mg/kg) or ondansetron (a 5-HT₃ receptor antagonist, 0.5 mg/kg).

Conclusions

Together, these results indicate that Geissospermum vellosii produces antinociception through an interaction with 5-HT_1A receptors. Furthermore, the alkaloid 12-metoxy-1-methyl-aspidospermidine contributes to the antinociceptive properties reported for Geissospermum vellosii.     

Antiplasmodial and cytotoxic activities of medicinal plants traditionally used in the village of Kiohima, Uganda

Aim of the study

In Uganda, malaria is the most common disease and Ugandan people largely rely on traditional medicine. In this context, we carried out an ethnobotanical study on the Kiohima village, located close to the Kibale National Park in South-Western Uganda and investigated in vitro the antiplasmodial and cytotoxic activities of selected medicinal plants.

Materials and methods

Seventy-five plants-using adults (men and women) were interviewed to find out their plant use. From these information, 48 plants used in traditional medicine were identified and according to their reported uses and to bibliographic data, several parts of 28 plants (leaves, barks, roots), were selected and collected for biological evaluations. These samples were dried, extracted with ethyl acetate and the crude extracts were assayed for in vitro antiplasmodial and cytotoxic activities at 10 μg/mL.

Results

One third of the screened plants showed a significant antiplasmodial activity with inhibition greater than 50% at 10 μg/mL.

Conclusion

These results may indicate a possible explanation of the use of some medicinal plant against malaria in the village of Kiohima and have also allowed to highlight a plant with potent antimalarial activity: Citropsis articulata root barks.     

Renaissance remedies: Antiplasmodial protostane triterpenoids from Alisma plantago-aquatica L. (Alismataceae)

Aim of the study

In a preliminary screen of extracts from plants used as antimalarial remedies used in Europe in the 16th and 17th, the ethyl acetate extract of Alisma plantago-aquatica L. (Alismataceae) was active against Plasmodium falciparum K1 strain with 77% growth inhibition at 4.9 μg/ml. The aim of this study was to isolate and identify the substances responsible for this antiplasmodial activity.

Materials and methods

With HPLC-based activity profiling in combination with HPLC hyphenated methods (HPLC-PDA, -MSn, HR-MS, and off-line microprobe NMR) the activity was assigned to time windows, and the substances contained therein were characterised chemically. The active compounds were isolated with semi-preparative HPLC and structures were elucidated with high resolution mass spectrometry, and 1D and 2D NMR spectroscopy.

Results

Four compounds were isolated and identified as protostane triterpenoids alisol A, alisol B 11-monoacetate, alisol B 23-monoacetate, and alisol G. Their IC₅₀s against Plasmodium falciparum ranged from 5.4 to 13.8 μM.

Conclusions

This is the first report of antiplasmodial activity from protostanes triterpenoids, and the first result of our ongoing project of screening for antiprotozoal natural products from remedies used in European renaissance medicine.     

New antiplasmodial alkaloids from Stephania rotunda

Ethnopharmacological relevance

Stephania rotunda Lour. (Menispermaceae) is a creeper growing in many countries of Asia and commonly found in the mountainous areas of Cambodia. As a folk medicine, it has been mainly used for the treatment of fever and malaria. The pharmacological activity is mostly due to alkaloids. Thus the aim of this study is to isolate new bioactive alkaloids from Stephania rotunda and to evaluate their in vitro antiplasmodial activity.

Materials and methods

Alkaloids were isolated and identified from dichloromethane and aqueous extracts using a combination of flash chromatography, high performance liquid chromatography, mass spectrometry and nuclear magnetic resonance. The purified compounds were tested for in vitro antiplasmodial activity on chloroquine-resistant W2 strain of Plasmodium falciparum.

Results

A new aporphine alkaloid named vireakine (2) along with two known alkaloids stephanine (1) and pseudopalmatine (8), described for the first time in Stephania rotunda, and together five known alkaloids tetrahydropalmatine (3), xylopinine (4), roemerine (5), cepharanthine (6) and palmatine (7) were isolated and identified. The structure of the new alkaloid was established on the basis of 1D and 2D NMR experiments and mass spectrometry. The compounds were evaluated for their in vitro antiplasmodial and cytotoxic activities. All tested compounds showed significant antiplasmodial activities with IC₅₀ ranged from 1.2 μM to 52.3 μM with a good selectivity index for pseudopalmatine with IC₅₀ of 2.8 μM against W2 strain of Plasmodium falciparum and IC₅₀>25 μM on K562S cells.

Conclusions

This study provides evidence to support the use of Stephania rotunda for the treatment of malaria and/or fever by the healers. Alkaloids of the tuber exhibited antiplasmodial activity and particularly cepharanthine and pseudopalmatine.     

Potent antiplasmodial extracts from Cameroonian Annonaceae

Aim of the study

In a search for new antimalarial leads, we have carried out a preliminary ethnopharmacological study with the aim of evaluating the in vitro antiplasmodial activity of extracts from thirteen Annonaceae species growing in Cameroon, and of assessing the acute toxicity of promising fractions in Swiss albino mice.

Materials and methods

Plants were selected on the basis of an ethnobotanical survey carried out in four sites in centre and south regions of Cameroon (Yaoundé neighbourhoods, Kon-Yambetta, Ngobayang and Mbalmayo) on Annonaceae plants locally used to treat malaria and related symptoms. The choice of the sites was mainly based on environmental factors enabling mosquito breeding, cosmopolitan areas regrouping people from different cultural origins, areas with limited access to health centers, and areas with people relying exclusively on traditional medical practices. Collected materials were extracted by maceration in 95% ethanol. The crude extract was partitioned using organic solvents and the fractions afforded were evaluated for antiplasmodial activity in culture against the W2 strain of Plasmodium falciparum. Promising fractions (methanol fractions) were assessed for their acute toxicity in Swiss albino mice.

Results

From the results achieved, 37 (31.3%) out of 118 extracts tested exhibited antiplasmodial activity, with IC₅₀ values ranging from 1.07 μg/ml to 9.03 μg/ml. Of the active extracts, 29 (78.4%) were methanol fractions, 21 (72.4%) of which inhibited the parasites with IC₅₀ < 5 μg/ml. The promising fractions proved to be safe through oral administration in mice.

Conclusions

The activities and toxicity profiles of methanol fractions indicate that they deserve to be further investigated in detail for antimalarial lead discovery.     

Analgesic effects and anti-inflammatory properties of the crude methanolic extract of Schwenckia americana Linn (Solanaceae)

Aim of the study

To evaluate analgesic effect and anti-inflammatory properties of Schwenckia americana (Solanaceae), a medicinal plant used for treating rheumatic pains and swelling in North-western Nigeria.

Materials and methods

Three doses (25 mg/kg, 50 mg/kg and 100 mg/kg) of the crude methanolic extract of Schwenkia americana were evaluated for analgesic and anti-inflammatory activities using acetic acid induced writhing test, formalin induced nociception, and formalin induced hind paw oedema in rats.

Results

All doses (25, 50, 100 mg/kg) of the extract tested were effective. The extract at the tested doses produced a percentage inhibition of the acetic acid induced abdominal constriction of (53.3, 58.0 and 86.7%), respectively. A percentage inhibition of the formalin induced nociception of 44.00, 56.04, and 56.04% (early phase) and 33.00, 36.63 and 59.71% (late phase) was also produced. The inhibition of oedema formation increased with increasing dosage from 25 to 100 mg/kg. The crude extract produced a statistically significant analgesic and anti-inflammatory activity comparable to the effect of standard drug (10 mg/kg Piroxicam).

Conclusion

This study demonstrated the potential analgesic and anti-inflammatory properties of crude methanolic extract of Schwenkia americana thus justifying its traditional usage.     

In vitro antitrypanosomal and antileishmanial activity of plants used in Benin in traditional medicine and bio-guided fractionation of the most active extract

Ethnopharmacological relevance

The aim of the study was to evaluate the in vitro antitrypanosomal and antileishmanial activity of crude extracts of 10 plant species traditionally used in Benin to treat parasitic infections.

Materials and methods

For each species, dichloromethane, methanol and aqueous extracts were tested. Their antitrypanosomal and antileishmanial activities were evaluated in vitro on Trypanosoma brucei brucei (strain 427) (Tbb) and on promastigotes of Leishmania mexicana mexicana (MHOM/BZ/84/BEL46) (Lmm).

Results

The best growth inhibition was observed with the dichloromethane extracts of aerial parts of Acanthospermum hispidum DC. (Asteraceae) (IC₅₀ = 14.5 μg/ml on Tbb and 11.1 μg/ml on Lmm), twigs of Keetia leucantha (K. Krause) Bridson (syn. Plectronia leucantha Krause) (IC₅₀ = 5.8 μg/ml on Tbb), aerial parts of Byrsocarpus coccineus Schumach. & Thonn (syn. Rourea coccinea (Schumach. & Thonn.) Hook.f.) (IC₅₀ = 14.7 μg/ml on Tbb) and aerial parts of Carpolobia lutea G.Don. (IC₅₀ = 18.3 μg/ml on Tbb). All these extracts had a low cytotoxicity. It is not the case for the methanolic and water extracts of roots of Anchomanes difformis (Blume) Engl. (IC₅₀ = 14.7 and 13.8 μg/ml on Tbb) which were toxic at the same concentration range on WI38, human cells. A bio-guided fractionation of the most active extract of Keetia leucantha allowed to identify oleanolic acid and ursolic acid as responsible for the observed activities.

Conclusion

Our study gives some justification for antiparasitic activity of some investigated plants.     

Evaluation of an ethnopharmacologically selected Bhutanese medicinal plants for their major classes of phytochemicals and biological activities

Ethnopharmacological relevance

As many as 229 medicinal plants have been currently used in the Bhutanese Traditional Medicine (BTM) as a chief ingredient of polyherbal formulations and these plants have been individually indicated for treating various types of infections including malaria, tumor, and microbial. We have focused our study only on seven species of these plants.

Aim of the study

We aim to evaluate the antiplasmodial, antimicrobial, anti-Trypanosoma brucei rhodesiense and cytotoxicity activities of the seven medicinal plants of Bhutan selected using an ethno-directed bio-rational approach. This study creates a scientific basis for their use in the BTM and gives foundation for further phytochemical and biological evaluations which can result in the discovery of new drug lead compounds.

Materials and methods

A three stage process was conducted which consisted of: (1) an assessment of a pharmacopoeia and a formulary book of the BTM for their mode of plant uses; (2) selecting 25 anti-infective medicinal plants based on the five established criteria, collecting them, and screening for their major classes of phytochemicals using appropriate test protocols; and (3) finally analyzing the crude extracts of the seven medicinal plants, using the standard test protocols, for their antiplasmodial, antimicrobial, anti-Trypanosoma brucei rhodesiense and cytotoxicity activities as directed by the ethnopharmacological uses of each plant.

Results

Out of 25 medicinal plants screened for their major classes of phytochemicals, the majority contained tannins, alkaloids and flavonoids. Out of the seven plant species investigated for their biological activities, all seven of them exhibited mild antimicrobial properties, five plants gave significant in vitro antiplasmodial activities, two plants gave moderate anti-Trypanosoma brucei rhodesiense activity, and one plant showed mild cytotoxicity. Meconopsis simplicifolia showed the highest antiplasmodial activity with IC₅₀ values of 0.40 μg/ml against TM4/8.2 strain (a wild type chloroquine and antifolate sensitive strain) and 6.39 μg/ml against K1CB1 (multidrug resistant strain) strain. Significantly the extracts from this plant did not show any cytotoxicity.

Conclusions

These findings provide the scientific basis for the use of seven medicinal plants in the BTM for the treatment of malaria, microbial infections, infectious fevers, and the Trypanosoma brucei rhodesiense infection. The results also form a good preliminary basis for the prioritization of candidate plant species for further in-depth phytochemical and pharmacological investigations toward our quest to unearth lead antiparasitic, anticancer and antimicrobial compounds.     

Anti-inflammatory effect of a methanolic extract of leaves of Dregea volubilis

Aim of study

The aim of this study was to establish the anti-inflammatory activity of the methanolic extract of Dregea volubilis leaves (MEDV) with its fractions and to delineate the possible mechanism of action for MEDV.

Materials and methods

The anti-inflammatory activities of MEDV along with its petroleum ether and chloroform fractions were evaluated in a carrageenan induced model of acute inflammation. The effect of MEDV on lipopolysaccharide induced production of nitric oxide (NO) in macrophages was also studied.

Results

MEDV (100, 200 and 400 mg/kg body weight) significantly reduced carrageenan induced paw edema; chloroform fraction was most potent (66%, p < 0.001). MEDV was non-toxic up to 125 μg/ml in mouse peritoneal macrophages wherein it (0-100 μg/ml) reduced lipopolysaccharide induced NO production.

Conclusion

MEDV possesses significant anti-inflammatory activity. Chloroform fraction of MEDV showed best anti-inflammatory activity.     

Identification and pharmacological characterization of the anti-inflammatory principal of the leaves of dwarf elder (Sambucus ebulus L.)

Aim of the study

The performed investigations aimed on the identification of the anti-inflammatory principal of extracts of leaves of Sambucus ebulus L. (dwarf elder) in order to rationalize the traditional use of this plant for the treatment of chronically inflammatory diseases.

Materials and methods

Dwarf elder leaf extract was subjected to activity guided fractionation using inhibition of TNFα induced expression of vascular cell adhesion molecule 1 (VCAM-1) on the surface of human umbilical vein endothelial cells (HUVECs) as monitoring tool (positive control: parthenolide 10 μM, VCAM-1 expression (% of control): 5.35 ± 0.38%).

Results

Bio-guided isolation resulted in identification of ursolic acid as anti-inflammatory principal. Besides its inhibitory effects against TNFα induced expression of VCAM-1 (IC₅₀ 6.25 μM), ursolic acid inhibits also TNFα induced expression of ICAM-1 (IC₅₀ value between 3.13 and 6.25 μM) (positive control: parthenolide 10 μM, ICAM-1 expression (% of control): 38.89 ± 16.6%). Toxic effects of ursolic acid on HUVECs can be drastically reduced using an enriched extract instead of the pure compound.

Conclusions

Our findings suggest an additional mechanism of the anti-inflammatory activity of ursolic acid by demonstrating its ability to inhibit TNFα-stimulated expression of VCAM-1 and ICAM-1 and support the traditional use of extracts and preparations of Sambucus ebulus L., rich in ursolic acid, for the treatment of chronically inflammatory processes.     

Activation of M3 muscarinic receptor and Ca²⁺ influx by crude fraction from Crotonis Fructus in isolated rabbit jejunum

Ethnopharmacological relevance

Crotonis Fructus is the mature fruit of Croton tiglium L. (Euphorbiaceae), which has been used in traditional Chinese medicine for the treatment of gastrointestinal (GI) diseases, such as constipation, abdominal pain, peptic ulcer, and intestinal inflammation for thousands of years. The aim of this study was to investigate the pharmacological effect of extracts and fractions from Crotonis Fructus on GI tract.

Materials and methods

The activities of methanol extract and fractions from Crotonis Fructus on the smooth muscle contractions were evaluated using isolated rabbit jejunum model.

Results

The results suggest that the n-BuOH and H₂O fractions showed spasmolytic activity, while the MeOH extract, PE and EtOAc fractions exerted spasmogenic effect. Moreover, bioassay-guided fractionation verified that the EtOAc fraction was more potent than others, followed by PE fraction and methanol extract. Additionally, atropine (10 μM), 4-DAMP (10 μM) and verapamil (0.1 μM) produced a significant inhibition of contractions caused by EtOAc fraction, while either hexamethonium (10 μM) or methoctramine (10 μM) was inactive. Additionally, a HPLC fingerprint of EtOAc fraction was appraised to ensure its chemical consistency and the main component has been identified as phorbol 12-acetate-13-tiglate.

Conclusions

These data indicate that the regulatory effect of EtOAc fraction on GI motility are medicated via the activation of M3 muscarinic receptor and Ca²⁺ influx through L-type Ca²⁺ channel. These provide a scientific basis for the traditional use of Crotonis Fructus in GI disorders.     

Cytotoxic, apoptotic and anti-α-glucosidase activities of 3,4-di-O-caffeoyl quinic acid, an antioxidant isolated from the polyphenolic-rich extract of Elephantopus mollis Kunth

Ethnopharmacological relevance

The decoction of the whole plant of Elephantopus mollis Kunth. is traditionally consumed to treat various free radical-mediated diseases including cancer and diabetes.

Aim of the study

This study was initiated to determine whether the most effective antioxidant compound isolated from the whole plant of Elephantopus mollis can also contribute to its claimed traditional values as anticancer and antidiabetes agents.

Materials and methods

An active antiradical phenolic compound (3,4-di-O-caffeoyl quinic acid) was isolated from the methanol extract (with the highest in polyphenolic content) and their antioxidant activities were compared using four different assays, that are DPPH, FRAP, metal chelating, and β-carotene bleaching tests. The compound was also evaluated for its cytotoxic activity, apoptotic induction and anti-glucosidase efficacies using methylene blue, DeadEnd™ assay and α-glucosidase assays, respectively.

Results

The compound acted as a greater primary antioxidant than its methanol extract, by having higher ferric reducing activity (EC₅₀ 2.18 ± 0.05 μg/ml), β-carotene bleaching activity (EC₅₀ 23.85 ± 0.65 μg/ml) and DPPH scavenging activity (EC₅₀ 68.91 ± 5.44 μg/ml), whereas the methanol extract exhibited higher secondary antioxidant activity as a metal chelator with lower EC₅₀ value (49.39 ± 3.68 μg/ml) than the compound. Cytotoxicity screening of this compound exhibited a remarkable dose-dependent inhibitory effect on NCI-H23 (human lung adenocarcinoma) cell lines (EC₅₀ 3.26 ± 0.35 μg/ml) and was found to be apoptotic in nature based on a clear indication of DNA fragmentation. This compound also displayed a concentration-dependent α-glucosidase inhibition with EC₅₀ 241.80 ± 14.29 μg/ml.

Conclusions

The findings indicate the major role of 3,4-di-O-caffeoyl quinic acid to antioxidant capacities of Elephantopus mollis extracts. The compound also exerted apoptosis-mediated cytotoxicity and α-glucosidase inhibitory effects and is thus a promising non toxic agent in treating cancer and type 2 diabetes mellitus.     

Plants used by native Amazonian groups from the Nanay River (Peru) for the treatment of malaria

Aim of the study

In order to evaluate the antimalarial potential of traditional remedies used in Peru, Indigenous and Mestizo populations from the river Nanay in Loreto were interviewed about traditional medication for the treatment of malaria.

Materials and methods

The survey took place on six villages and led to the collection of 59 plants. 35 hydro-alcoholic extractions were performed on the 21 most cited plants. The extracts were then tested for antiplasmodial activity in vitro on Plasmodium falciparum chloroquine resistant strain (FCR-3), and ferriprotoporphyrin inhibition test was also performed in order to assume pharmacological properties.

Results

Extracts from 9 plants on twenty-one tested (Abuta rufescens, Ayapana lanceolata, Capsiandra angustifolia, Citrus limon, Citrus paradise, Minquartia guianensis, Potalia resinífera, Scoparia dulcis, and Physalis angulata) displayed an interesting antiplasmodial activity (IC₅₀ < 10 μg/ml) and 16 remedies were active on the ferriprotoporphyrin inhibition test.

Conclusions

The results give scientific validation to the traditional medical knowledge of the Amerindian and Mestizo populations from Loreto and exhibit a source of potentially active plants.     

Vasorelaxation by extracts of Casimiroa spp. in rat resistance vessels and pharmacological study of cellular mechanisms

Aim of the study

Casimiroa spp. are Mexican plants traditionally used for treatment of hypertension. To study their antihypertensive action, we determined the arterial dilatation induced by extracts from leaves and seeds of Casimiroa calderoniae F. Chiang & Medrano, Casimiroa edulis Llave et Lex, and Casimiroa pubescens Ramirez.

Materials and methods

The vascular effects of Casimiroa spp. extracts were investigated on rat caudal and aortic arteries. In addition, the extracts were characterized by HPLC using heraclenol, isopimpinellin, heraclenin and phellopterin as external standards. The methanolic extract of Casimiroa pubescens seeds (Cp12) was also studied by H-NMR and LC-MS (ESI-TOF) for the determination of casimiroin and zapotin.

Results

The hexanic and methanolic extracts of Casimiroa spp. (20 μg/ml) showed vasorelaxation in arterial tissues precontracted by phenylephrine (0.5 μM); the extracts from seeds always caused a greater relaxation in comparison to those from leaves. The most active were the methanolic seed extracts of Casimiroa edulis (Ce8) and Casimiroa pubescens (Cp12). To study the pharmacological mechanisms of vasodilatation we used various inhibitors selective to different receptor subtypes or intracellular enzymes. The vasorelaxant effect of Ce8 (20 μg/ml) remained unaffected by the pretreatment with pyrilamine (10 μM), an antagonist of histamine H₁ receptors, but was inhibited by atropine (0.1 μM), a muscarinic receptor antagonist. Therefore, to determine muscarinic receptor subtypes, we used pirenzepine (1 μM), a selective inhibitor of M₁ receptor, and 4-diphenylacetoxyl-N-methylpiperidine methiodide (DAMP, 0.01 μM), a selective inhibitor of M₃ receptor. Only the latter reduced the vasodilatation by Ce8 and Cp12. To investigate the role of the nitric oxide synthase (NOS), we used N^G-nitro-l-arginine methyl ester (l-NAME, 10 μM), a selective NOS inhibitor, which decreased the dilatation induced by Ce8 and Cp12. Finally, we studied the action of (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) (ODQ, 3 μM), a selective guanylyl cyclase inhibitor, which inhibited the dilatation by Casimiroa extracts.

Conclusion

The data show that methanolic seed extracts of Casimiroa edulis (Ce8) and Casimiroa pubescens (Cp12) induce vasorelaxation by M₃ receptor through the activation of cGMP-dependent NO signaling. These results support the traditional use of Casimiroa decoctions for antihypertensive treatments in the Mexican ethnomedicine.     

Proliferative effects of five traditional Nigerian medicinal plant extracts on human breast and bone cancer cell lines

Ethnopharmacological relevance

The medicinal plants Hunteria umbellata (HUL), Cola lepidota (CCL), Persea americana leaf (PAL), Root bark of Persea americana (RPA) and Plukenetia conophora (PCL) are used in Nigerian traditional medicine for the treatment of cancer and cancer related diseases.

Aim of the study

To scientifically evaluate the cell proliferative and apoptotic effects of the plants extracts using breast and osteocarcinoma cell lines, and also to identify the possible components via LC-MS to have a kind of chemical fingerprint.

Materials and methods

The antiproliferative and apoptotic effects of methanolic extracts (10 μg/ml) of the five medicinal plants were subjected to in vitro evaluation using four cancer cell lines (breast-MCF-7 and BT-20; Osteocarcinoma-MG-63 and Saos-2) measured by flow cytometry. Non-tumorigenic controls MCF-12A and primary isolated osteoblasts (POB) were chosen to eliminate negative influence on healthy tissue.

Results

Of the five extracts RPA demonstrated a significant (P < 0.05) anti-proliferative activity against estrogen receptor positive breast cancer cell lines (MCF-7). The proliferative phase was decreased by 18%, whereas, a significant increase in cell proliferation (about 27%) was observed for RPA at a concentration of 10 μg/ml. PCL, CCL, HUL and PAL did not show marked inhibition of the proliferation of cell line MCF-7.

Conclusion

These results give suggestive evidence that the plant extracts exhibit some correlation between the claimed ethnomedicinal uses and the cell proliferative activity. RPA extract includes chemical compounds with estrogen-like activity and validates its potential use as anticancer agent, particularly against breast carcinoma; provided important information potentially helpful in drug designing and discovery. Further studies will involve the isolation of anti tumour compounds in RPA by LC-MS and detailed mechanism of anticancer activities.     

Relaxant effects of Artemisia ludoviciana on isolated rat smooth muscle tissues

Ethnopharmacological relevance

Artemisia ludoviciana spp. mexicana (Willd. Ex.) Spring D.D. Keck (Asteraceae), known as “estafiate” is employed for the treatment of diarrhea, dysentery, parasites, abdominal pain, vomiting, stomach ache, and also as antispasmodic agent. The aim of the present study was to evaluate the relaxant effect of hexanic (HEAl), dichloromethanic (DEAl) and methanolic (MEAl) extracts on isolated trachea, ileum and aorta rat rings, and to establish the tracheo-relaxant mode of action of DEAl.

Materials and methods

All extracts were investigated based on their capacity of to inhibit the rat ileum spontaneous contraction, to relax contraction induced by noradrenaline (0.1 μM) on endothelium-intact and endothelium-denuded thoracic aorta rat rings, and also to inhibit contraction provoked by carbachol (1 μM) on rat trachea.

Results

Organic extracts had no spasmolytic action on ileum strips compared to positive control (papaverine, p < 0.05). On the other hand, all extracts induced a significant concentration- and partial endothelium-dependent vasorelaxant activity. Extracts also showed significant relaxant effect on pre-contracted tracheal tissue in a concentration-dependent manner. In last two experiments, DEAl was the most potent and efficient extract; however, it was less potent than papaverine and theophylline, used as positive controls (p < 0.05). In tracheal preparation, DEAl shifted to the right, in a parallel manner, the concentration-response curves induced by carbachol (p < 0.05). Also, DEAl induced a significant relaxant effect on the contraction produced by potassium chloride (KCl, 80 mM). Pre-incubation with 1-H-[1,2,4]-oxadiazolo-[4,3a]-quinoxalin-1-one (ODQ, 10 μM), indomethacin (10 μM), N_ω-nitro-l-arginine methyl ester (l-NAME, 10 μM), glibenclamide (10 μM) and 2-aminopyridine (2-AP, 100 μM) did not modify the DEAl-relaxant curves.

Conclusions

Functional experiments suggest that the most active extract, DEAl, induced its relaxant effect by possible muscarinic receptors antagonism and calcium channel blockade in tracheal rings. On the other hand, significant vasorelaxant activity showed by DEAl is partially endothelium-dependent. Finally, spasmolytic activity induced by the extracts in the rat ileum was not significant, which suggests that the antidiarrheic effect of the plant is related to antimicrobial and antiparasitic properties previously described.     

Neuroprotective effect of Momordica charantia in global cerebral ischemia and reperfusion induced neuronal damage in diabetic mice

Ethnopharmacological relevance

Momordica charantia L. (Cucurbitaceae) fruits have been used traditionally for centuries, especially for treating diabetes and associated complications.

Aim of the study

The present study was performed to evaluate neuroprotective effect of lyophilized M. charantia fruit juice against global cerebral ischemia and reperfusion induced neuronal injury in diabetic mice.

Materials and methods

Global cerebral ischemia induced by occluding both common carotid arteries for 10 min followed by 24 h reperfusion was used to induce neuronal injury. Ischemia-reperfusion induced neuronal injury was evaluated in terms of cerebral infarct size, generation of free radicals measured as thiobarbaturic acid reactive substances (TBARS), and neurological functions measured as short term memory and motor activity.

Results

The cerebral oxidative stress and damage, and neurological deficits were dose dependently attenuated by pre-treatment with the lyophilized M. charantia juice (200-800 mg/kg, p.o., o.d.). Moreover, M. charantia also exhibited dose dependent antihyperglycemic activity in diabetic mice.

Conclusions

These results suggest that M. charantia has potent neuroprotective activity against global cerebral ischemia-reperfusion induced neuronal injury and consequent neurological deficits in diabetic mice.