Antiplasmodial activity of selected sudanese medicinal plants with emphasis on Acacia nilotica.

Twenty-two plant organs from eleven plants comprising five families were extracted and screened for antiplasmodial activity in vitro against Plasmodium falciparum 3D7 (chloroquine sensitive) and Dd2 (chloroquine resistant and pyrimethamine sensitive). Fifty nine percent of plant extracts from 22 extracts exerted activity on P. falciparum strain 3D7 with an IC(50) less than 50 microg/mL, whereas 43% of plant extracts showed an IC(50) value within 50 microg/mL on Dd2 strains. Plant extracts from Gardenia lutea, Haplophyllum tuberculatum, Cassia tora, Acacia nilotica and Aristolochia bracteolata possessed IC(50) values less than 5 microg/mL on both tested strains. Bioassay guided fractionation of A. nilotica revealed that the ethyl acetate extract possessed the highest activity (IC(50) = 1.5 microg/mL). Fraction 2 (R(f) = 0.75) prepared by preparative chromatography showed the highest activity on P. falciparum (IC(50) = 1.7 microg/mL). Phytochemical analysis indicated that the most active phase contained terpenoids and tannins and was devoid of alkaloids and saponins. The effect of plant extracts on lymphocyte proliferation showed low toxicity to the human cells. This plant has been subjected to long term clinical trials in folk medicine and is a promising plant.     

In vitro immunomodulating properties of selected Sudanese medicinal plants

Ethanolic extracts of 23 medicinal plants, commonly used in Sudanese folk medicines against infectious diseases, were investigated for their immunomodulating activity using luminol/lucigenin-based chemiluminescence assay. Preliminary screenings on whole blood oxidative burst activity showed inhibitory activities of 14 plant extracts, while only one plant, Balanites aegyptiaca fruits exhibited a proinflammatory activity. Further investigation was conducted by monitoring their effects on oxidative burst of isolated polymorphonuclear cells (PMNs) and mononuclear cells (MNCs) by using two different phagocytosis activators (serum opsonizing zymosan-A and PMA). Results obtained showed that the fruits and barks of Acacia nilotica, and leaves and barks of Khaya senegalensis, possess average inhibitory effects in the range of 70.7, 67.1, 69.5 and 67.4% on both types of phagocytes (PMNs and MNCs), respectively, at a 6.25 microg/mL concentration. Moderate inhibitory activity (52.2%) was exerted by the aerial parts of Xanthium brasilicum, while the rest of the plants showed only a weak inhibitory activity. The inhibition of oxidative burst activity was found to be irreversible in most of the extracts, except for Peganum harmala, Tephrosia apollinea, Tinospora bakis, and Vernonia amygdalina. Interestingly, the fruits of Balanites aegyptiaca exhibited a moderate proinflammatory effect (37-40.4% increases in ROS level compared to the control) at 25-100 microg/mL concentration in the case of whole blood along with PMNs phagocyte activity. The Tinospora bakis extract showed proinflammatory response at a low concentration (6.25 microg/mL) during activation with PMA. None of these extracts affected PMNs viability (90-98%) upon 2 h incubation, except of the ethanolic extracts of Acacia nilotica fruits and Balanites aegyptiaca barks.     

The potential antileishmanial activity of some Sudanese medicinal plants

A preliminary examination of the crude methanol extracts of eight plant species collected from Sudan, revealed that only three plant species had a considerable in vitro antileishmanial activity on Leishmania major promastigotes at a concentration < 0.5 µg/mL. The plants Azadirchta indica, Maytenus senegalensis and Eucalyptus globulus gave IC₅₀ values of 11.5, 55 and 78 µg/mL, respectively. Extracts of Pseudocedrela kotscifye and Balanites aegyptiaca had a moderate biological activity, whereas extracts of Sonchous cornatus, Khaya senegalensis and Tamarindus indica failed to exhibit any significant antileishmanial activity against L. major at concentrations <100 µg/mL. Liquid–liquid partitioning of the methanol extracts indicated that fractions of M. senegalensis in dichloromethane and ethyl acetate had the highest antileishmanial activity at 5 µg/mL; IC₅₀ values were 5.01 and 29.7 µg/mL, respectively. Preliminary phytochemical analysis of the dichloromethane fraction revealed terpenoids and traces of phenolic principles but no alkaloid, tannins or flavonoids were detected. As lymphocyte proliferation was inhibited by P. kotscifye and A. indica at higher concentrations (<50 µg/mL) in the presence of phytohaemagglutinin (PHA), M. senegalensis had no significant toxic effect whereas S. cornatus, T. indica and K. senegalensis had a stimulatory impact on lymphocyte cells. Copyright © 1998 John Wiley & Sons, Ltd.     

Antimicrobial activity of selected Peruvian medicinal plants

The antimicrobial activity of 36 ethanol extracts from 24 plants, all of them currently used in the Peruvian traditional medicine for the treatment of several infectious and inflammatory disorders, was tested by means of the agar-well diffusion assay against four bacteria (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and four fungi (Candida albicans, Trichophyton mentagrophytes, Microsporum gypseum and Sporothrix schenckii). Twenty-five (69%) extracts showed some degree of antimicrobial activity against at least one microorganism. The plants with the greatest antimicrobial activity were Cestrum auriculatum L. Heritier (Solanaceae), Iryanthera lancifolia Ducke Suesseng (Myristicaceae), Lepechinia meyenii (Walp.) Epling (Lamiaceae) and Ophryosporus peruvianus (Gmelin) King & H. Rob. (Asteraceae).     

Antiplasmodial activity of extracts from seven medicinal plants used in malaria treatment in Cameroon

Aim of the study

In a search for new plant-derived biologically active compounds against malaria parasites, we have carried out an ethnopharmacological study to evaluate the susceptibility of cultured Plasmodium falciparum to extracts and fractions from seven Cameroonian medicinal plants used in malaria treatment. We have also explored the inhibition of the Plasmodium falciparum cysteine protease Falcipain-2.

Materials and methods

Plant materials were extracted by maceration in organic solvents, and subsequently partitioned or fractionated to afford test fractions. The susceptibility of erythrocytes and the W2 strain of Plasmodium falciparum to plant extracts was evaluated in culture. In addition, the ability of annonaceous extracts to inhibit recombinant cysteine protease Falcipain-2 was also assessed.

Results and discussion

The extracts showed no toxicity against erythrocytes. The majority of plant extracts were highly active against Plasmodium falciparumin vitro, with IC₅₀ values lower than 5 μg/ml. Annonaceous extracts (acetogenin-rich fractions and interface precipitates) exhibited the highest potency. Some of these extracts exhibited modest inhibition of Falcipain-2.

Conclusion

These results support continued investigation of components of traditional medicines as potential new antimalarial agents.     

Anti-parasitic activity and cytotoxicity of selected medicinal plants from Kenya

Indigenous rural communities in the tropics manage parasitic diseases, like malaria and leishmaniasis, using herbal drugs. The efficacy, dosage, safety and active principles of most of the herbal preparations are not known. Extracts from 6 selected plant species, used as medicinal plants by indigenous local communities in Kenya, were screened for in vitro anti-plasmodial and anti-leishmanial activity, against 2 laboratory-adapted Plasmodium falciparum isolates (D6, CQ-sensitive and W2, CQ-resistant) and Leishmania major (IDU/KE/83 = NLB-144 strain), respectively. The methanol extract of Suregada zanzibariensis leaves exhibited good anti-plasmodial activity (IC₅₀ 4.66 ± 0.22 and 1.82 ± 0.07 μg/ml for D6 and W2, respectively). Similarly, the methanol extracts of Albizia coriaria (IC₅₀ 37.83 ± 2.11 μg/ml for D6) and Aspergillus racemosus (32.63 ± 2.68 and 33.95 ± 2.05 μg/ml for D6 and W2, respectively) had moderate anti-plasmodial activity. Acacia tortilis (IC₅₀ 85.73 ± 3.36 μg/ml for W2) and Albizia coriaria (IC₅₀ 71.17 ± 3.58 μg/ml for W2) methanol extracts and Aloe nyeriensis var kedongensis (IC₅₀ 87.70 ± 2.98 and 67.84 ± 2.12 μg/ml for D6 and W2, respectively) water extract exhibited mild anti-plasmodial activity. The rest of the extracts did not exhibit any anti-plasmodial activity. Although the leishmanicidal activity of extracts were lower than for pentosam (80%), reasonable activity was observed for Aloe nyeriensis methanol (68.4 ± 6.3%), Albizia coriara water (66.7 ± 5.0%), Maytenus putterlickoides methanol (60.0 ± 6.23%), Asparagus racemosus methanol and water (58.3 ± 8.22 and 56.8 ± 6.58%, respectively), Aloe nyeriensis water (53.3 ± 5.1%) and Acacia tortilis water (52.9 ± 6.55%) extracts at 1000 μg/ml. Leishmania major infected macrophages treated with methanol extracts of Suregada zanzibariensis and Aloe nyeriensis var kedongensis and Pentostam^® had infection rates of 28 ± 2.11, 30 ± 1.22 and 40 ± 3.69%, respectively at 1000 μg/ml, indicating better anti-leishmanial activity for the extracts. The methanol extract of Albizia coriara (44.0 ± 3.69%) and aqueous extracts of Asparagus racemosus (42 ± 3.84%) and Acacia tortilis (44 ± 5.59%) had similar activity to pentosam^®. Multiplication indices for Leishmania major amastigotes treated with methanol extracts of Albizia coriaria, Suregada zanzibariensis and Aloe nyeriensis var kedongensis, aqueous extract of Acacia tortilis and pentosam^® were 28.5 ± 1.43, 29.4 ± 2.15, 31.1 ± 2.22, 35.9 ± 3.49 and 44.0 ± 3.27%, respectively, at 1000 μg/ml, confirming better anti-leishmanial activity for the extracts. Aqueous extracts of Aloe nyeriensis (46.7 ± 3.28%) and Albizia coriaria (47.5 ± 3.21%) had similar activity level to pentosam^®. The plant extracts have better inhibitory activity while pentosam^® has better leishmanicidal activity. All extracts exhibited very low cytotoxicity (CC₅₀ > 500 μg/ml) against human embryonic lung fibroblast (HELF) cells. The investigations demonstrated the efficacy and safety of some extracts of plants that are used by rural indigenous communities for the treatment of parasitic diseases.     

Screening of selected Indian medicinal plants for acetylcholinesterase inhibitory activity

Seventy-six plant extracts including methanolic and successive water extracts from 37 Indian medicinal plants were investigated for acetylcholinesterase (AChE) inhibitory activity (in vitro). Results indicated that methanolic extracts to be more active than water extracts. The potent AChE inhibiting methanolic plant extracts included Withania somnifera (root), Semecarpus anacardium (stem bark), Embelia ribes (Root), Tinospora cordifolia (stem), Ficus religiosa (stem bark) and Nardostachys jatamansi (rhizome). The IC(50) values obtained for these extracts were 33.38, 16.74, 23.04, 38.36, 73.69 and 47.21mug/ml, respectively. These results partly substantiate the traditional use of these herbs for improvement of cognition.     

Antimicrobial activity of Ulopterol isolated from Toddalia asiatica (L.) Lam.: a traditional medicinal plant

Ethnopharmacological relevance

The leaves of Toddalia asiatica (L.) Lam. (Rutaceae) are widely used in folk medicine in India to treat various ailments like cough, malaria, indigestion, influenza lung diseases and rheumatism, fever, stomach ailments, cholera and diarrhea. In our earlier communication we have reported the antimicrobial study on the various extracts of the leaves and the isolation and identification of Flindersine, a quinolone alkaloid as the major active principle. In the present study, we report the antibacterial and antifungal activities of Ulopterol, a coumarin isolated as another major active antimicrobial principle.

Materials and methods

The leaves were successively extracted with hexane, chloroform, ethyl acetate, methanol and water. The extracts were studied for their antimicrobial activity against selected bacteria and fungi by using disc-diffusion method. The ethyl acetate extract which was found to possess highest antimicrobial activity was subjected to activity guided fractionation by column chromatography over silica gel. This resulted in the isolation of the coumarin, Ulopetrol, an active principle besides Flindersine which was reported by us earlier. The structure of the compound was elucidated using physical and spectroscopic data. Flindersine and Ulopterol were quantified by HPLC.

Results

Ulopterol showed activity against the bacteria viz. Staphylococcus epidermidis, Enterobacter aerogenes, Shigella flexneri, Klebsiella pneumoniae (ESBL-3967), Escherichia coli (ESBL-3984) and fungi viz. Aspergillus flavus, Candida krusei and Botrytis cinerea. Quantification by HPLC showed the content of Flindersine and Ulopterol to be 0.361% and 0.266% respectively on dry weight basis of the leaves.

Conclusions

Ethyl acetate extract (successive extraction) contained Ulopterol, a coumarin, besides Flindersine, a quinolone alkaloid, as a major active principle in the antimicrobial studies. This is the first report of the antimicrobial activity of Ulopterol and also its first report from the plant.     

Immunomodulatory potential of Enicostema axillare (Lam.) A. Raynal, a traditional medicinal plant

Ethnopharmacological relevance

Enicostema axillare (Lam.) A. Raynal., (Gentianaceae) has been used in traditional Indian system of medicine as depurative and for the treatment of psoriasis, intermittent fever and cancer. Ethnobotanical survey conducted in Theni District indicated a high consensus for this plant as blood purifier and to treat dermatopathy and venereal infections. The present study evaluated the immunomodulatory activity of the methanol extract of Enicostema axillare.

Materials and methods

In vivo immunomodulatory activity of Enicostema axillare methanol extract (100 and 200 mg/kg b.w) was evaluated by assessing its effect on the total and differential leukocyte count, organ weight, hemaggultinating antibody titer, plaque forming cells, quantitative hemolysis of SRBC and delayed type hypersensitivity. Sheep red blood cells (SRBC, 5 × 10⁸ cells/0.1 mL) were used to immunize the animals. In vitro immunomodulatory potential of the extract was studied using peritoneal macrophages by evaluating its effects on NBT reduction, NO production and cytokine release.

Results

The animals treated with Enicostema axillare methanol extract showed a significant (P ≤ 0.05) increase in weight of the thymus and spleen. The total leukocyte and lymphocyte count was increased significantly (P < 0.005) by the treatment. There was no significant alteration in neutrophil count. A dose dependent increase in antibody titer value was observed. A decreased response to DTH reaction induced by SRBC was recorded. A potential phagocytic response was seen on treatment with the extracts at 10 and 25 μg/mL. The extract inhibited the release of pro-inflammatory cytokines and production of NO significantly in a dose dependent manner.

Conclusion

These findings suggested that the methanol extract of Enicostema axillare acted on both humoral and cell mediated immune functions and decreased the release of pro-inflammatory cytokines in the peritoneal macrophages.     

In vitro antiplasmodial activity of selected Luo and Kuria medicinal plants

Ethnopharmacological relevance

Drug resistance in malaria is a recurring subject that threatens public health globally. There is an urgent need to seek new antimalarial agents. This study seeking new antimalarials from medicinal plants is guided by ethnobotany.

Materials and methods

Medicinal plants of the Luo and Kuria ethnic groups of Kenya with high usage reports were screened in vitro for their antiplasmodial activity using the SYBR Green I fluorescence assay (MSF assay).

Results

The IC50's for drugs and total plant extracts ranged from 0.01217 to 10.679 mg/ml. Extracts were more active on chloroquine sensitive than resistant Plasmodium falciparum strains. Tylosema fassoglense, Ageratum conyzoides and Ocimum kilimandscharicum exhibited promising results. Plectranthus barbatus did not show activity.

Conclusion

Ethnobotanical knowledge was sufficiently reliable for identifying plant extracts with antiplasmodial activity.     

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).     

Antibacterial and antifungal activity of Flindersine isolated from the traditional medicinal plant, Toddalia asiatica (L.) Lam.

Aim of the study

The leaves and root of Toddalia asiatica (L.) Lam. (Rutaceae) are widely used as a folk medicine in India. Hexane, chloroform, ethyl acetate, methanol and water extracts of Toddalia asiatica leaves and isolated compound Flindersine were tested against bacteria and fungi.

Materials and methods

Antibacterial and antifungal activities were tested against bacteria and fungi using disc-diffusion method and minimum inhibitory concentrations (MICs). The compound was confirmed using X-ray crystallography technique.

Results

Antibacterial and antifungal activities were observed in ethyl acetate extract. One active principle Flindersine (2,6-dihydro-2,2-dimethyl-5H-pyrano [3,2-c] quinoline-5-one-9cl) was isolated from the ethyl acetate extract. The MIC values of the compound against bacteria Bacillus subtilis (31.25 μg/ml), Staphylococcus aureus (62.5 μg/ml), Staphylococcus epidermidis (62.5 μg/ml), Enterococcus faecalis (31.25 μg/ml), Pseudomonas aeruginosa (250 μg/ml), Acinetobacter baumannii (125 μg/ml) and fungi Trichophyton rubrum 57 (62.5 μg/ml), Trichophyton mentagrophytes (62.5 μg/ml), Trichophyton simii (62.5 μg/ml), Epidermophyton floccosum (62.5 μg/ml), Magnaporthe grisea (250 μg/ml) and Candida albicans (250 μg/ml) were determined.

Conclusions

Ethyl acetate extract showed promising antibacterial and antifungal activity and isolated compound Flindersine showed moderate activity against bacteria and fungi.     

Investigations on antimycobacterial activity of some Ethiopian medicinal plants.

Fifteen crude extracts prepared from seven Ethiopian medicinal plants used to treat various infectious diseases were assessed for their ability to inhibit the growth of Mycobacterium tuberculosis. A preliminary screening of the crude extracts against M. tuberculosis typus humanus (ATCC 27294) was done by dilution assay using L?wenstein-Jensen medium. None of the tested extracts except the acetone fraction obtained from the stem bark of Combretum molle (R. Br. ex G. Don.) Engl & Diels (Combretaceae) showed significant inhibitory action against this strain. The acetone fraction of the stem bark of C. molle caused complete inhibition at concentrations higher than 1 mg/mL. Phytochemical analysis of the bioactive fraction led to the isolation of a major tannin and two oleanane-type pentacyclic triterpene glycosides. The tannin was identified as the ellagitannin, punicalagin, whilst the saponins were characterized as arjunglucoside (also called 4-epi-sericoside) and sericoside. All the pure compounds were further tested against the ATCC strain. Punicalagin was found to inhibit totally growth of the ATCC and also of a patient strain, which was fully sensitive to the standard antituberculosis drugs, at concentrations higher than 600 microg/mL and 1.2 mg/mL, respectively. On the other hand, the saponins failed to show any action on the ATCC strain. It appears that our findings are the first report of tannins exhibiting antimycobacterial activity.     

Antimalarial activity of extracts of Malaysian medicinal plants.

In vitro and in vivo studies revealed that Malaysian medicinal plants, Piper sarmentosum, Andrographis paniculata and Tinospora crispa produced considerable antimalarial effects. Chloroform extract in vitro did show better effect than the methanol extract. The chloroform extract showed complete parasite growth inhibition as low as 0.05 mg/ml drug dose within 24 h incubation period (Andrographis paniculata) as compared to methanol extract of drug dose of 2.5 mg/ml but under incubation time of 48 h of the same plant spesies. In vivo activity of Andrographis paniculata also demonstrated higher antimalarial effect than other two plant species.     

Investigation of the effects of selected medicinal plants on experimental thrombosis

Six medicinal plants indigenous to Africa were evaluated for their activity on experimental thrombosis in mice. Of the plants screened, the extract of Commiphora molmol exhibited the strongest antithrombotic activity, while the extract of Ageratum conyzoides showed no marked activity. This study established the antithrombotic effect of the extracts of Azadiractha indica, Bridelia ferruginea, Commiphora molmol, Garcinia kola and Curcuma longa. Copyright © 1999 John Wiley & Sons, Ltd.     

Screening of Rwandese medicinal plants for anti-trichomonas activity.

A series of 30 medicinal plants used in Rwandese traditional medicine has been screened for anti-trichomonas activity against the protozoan Trichomonas vaginalis. Seventeen plants showed anti-trichomonas activity.