In-vitro antibacterial screening of methanol extracts of three combretum species against seven strains of methicillin resistant staphylococcus aureus (MRSA)

Background: Medicinal plants are valued as sources of natural compounds some of which are effective against several infectious diseases. Plants from the genus Combretum have been used traditionally in various African societies to treat variety of medical problems especially infectious diseases.Objective: In this study, we investigated the antibacterial activity of the methanol extracts from the leaves of three Combretum species namely Combretum hispidum, Combretum racemosum and Combretum platypterum against seven strains of methicillin resistant Staphylococcus aureus (MRSA) in vitro.Materials and methods: Methanol extract from Combretum hispidum, Combretum racemosum and Combretum platypterum were subjected to agar diffusion assay and broth micro-dilution test for the determination of antibacterial activity and minimum inhibitory concentration (MIC), all the extracts were tested against eight different strain of MRSA. Imipenem and ciprofloxacin were used as control.Results: Extract from Combretum racemosum leaves showed significant anti-MRSA activity with zone of inhibition as high as 37 mm and MIC values ranging from 0.16 - 1.25 mg/mL on all tested strains of MRSA. Extracts from the two other species did not exhibit any activity on all tested strain.Conclusion: Methanol extract from C. racemosum is highly effective against MRSA and it could be a potential source of newer antimicrobial agent against MRSA infections

In vitro antimicrobial activity of crude ethanol extracts and fractions of Terminalia catappa and Vitex doniana.

BACKGROUND: The spread of microorganisms resistant to some antimicrobial agents necessitates the need to search for novel and effective antimicrobial agents. In this study, the antimicrobial activity of Terminalid catappa Linn. (Combretaceae) and Vitex doniana Sweet. (Verbenaceae), two Nigerian medicinal plants used in folk medicines for the management of various ailments related to microbial infections were evaluated. OBJECTIVES: To evaluate the antimicrobial activity of the crude ethanol extracts and fractions of the leaves and stem bark of T. catappa and V. doniana. METHODOLOGY: Four crude ethanol extracts and 16 (n-hexane, ethylacetate, n-butanol and aqueous) fractions of leaves and stem bark of T. catappa and V doniana were evaluated for in vitro antimicrobial activity against fifteen (15) strains of bacteria and fungi. The antimicrobial activity was determined in a 96-well plate using a resazurin based broth microdilution method. Two standard antimicrobial drugs ampicillin and nystatin were included as positive control. RESULTS: The butanoL fraction of stem bark of T. catappa and ethanol crude extract of leaf of V don iana displayed the highest antibacterial activity with similar minimum inhibitory concentration (MIC) value of 93.75 microg/mL against S. aureus and B. subtilis. Furthermore, the ethyl acetate fraction of stem bark of T. catappa showed the highest antifungal activity with MIC of 187.5 microg/mL against A. sydowi. Amp icillin had MIC of 15.6 and 31.3 microg/mL against S. aureus and B. subtili, respectively while nystatin produced MIC of 3.9 microg/mL against A. sydowi. CONCLUSION: Termninalia catappa and Vitex doniana may serve as useful sources of plant derived antimicrobial agents.

In Vitro and In Vivo Antimalarial Activity of Ficus thonningii Blume (Moraceae) and Lophira alata Banks (Ochnaceae), Identified from the Ethnomedicine of the Nigerian Middle Belt.

Drug resistance in Plasmodium falciparum requires that new drugs must be developed. Plants are a potential source for drug discovery and development. Two plants that used to treat febrile illnesses in Nigeria were tested for in vitro and in vivo antimalarial activity and cytotoxicity in cancer cell lines. Methanol, hexane, and ethyl acetate leaf extracts of Ficus thonningii and Lophira alata were active in in vitro assays against P. falciparum NF54 (sensitive) and K1 (multiresistant) strains. Hexane extracts of F. thonningii and L. alata were the most effective extracts in in vitro assays with IC50 of 2.7 ± 1.6 µg/mL and 2.5 ± 0.3 µg/mL for NF54 and 10.4 ± 1.6 µg/mL and 2.5 ± 2.1 µg/mL for K1 strain. All extracts were nontoxic in cytotoxicity assays against KB human cell line with IC50 of over 20 µg/mL, demonstrating selectivity against P. falciparum. In vivo analysis shows that hexane extracts of both plants reduced parasitaemia. At the maximum dose tested, L. alata had a 74.4% reduction of parasitaemia while F. thonningii had a reduction of 84.5%, both extracts prolonged animal survival in mice infected with P. berghei NK65 when compared with vehicle treated controls. The antiplasmodial activity observed justifies the use of both plants in treating febrile conditions.

Cajachalcone: An Antimalarial Compound from Cajanus cajan Leaf Extract.

Cajanus cajan L, a member of the family Fabaceae, was identified from the Nigerian antimalarial ethnobotany as possessing antimalarial properties. The bioassay-guided fractionation of the crude methanol extract of C. cajan leaves was done in vitro using the multiresistant strain of Plasmodium falciparum (K1) in the parasite lactate dehydrogenase assay. Isolation of compound was achieved by a combination of chromatographic techniques, while the structure of the compound was elucidated by spectroscopy. This led to the identification of a cajachalcone, 2',6'-dihydroxy-4-methoxy chalcone, as the biologically active constituent from the ethyl acetate fraction. Cajachalcone had an IC50 value of 2.0 µ g/mL (7.4 µ M) and could be a lead for anti-malarial drug discovery.

Inhibitory activities of selected south west Nigerian medicinal plants against mycobacterium tuberculosis.

INTRODUCTION: Tuberculosis (TB), an infectious disease prevalent in the tropics especially in Africa and Asia is one of the highest causes of morbidity and mortality and a global concern. With increasing resistance of the pathogen, to existing antituberculosis drugs and the synergy between TB infection and acquired immune deficiency syndrome (AIDS), the need for development of new drugs to cope with the infection is urgent. OBJECTIVE: Extracts from 16 plants identified and selected from the ethnomedicine of the Ijebus in Southwestern Nigeria as remedies for tuberculosis were evaluated for activity against Mycobacterium tuberculosis, in vitro. METHODOLOGY: Plant extracts were screened against clinical isolate of Mycobacterium tuberculosis using agar plate method on Middlebrook 7H11 medium and observed for 12 weeks. RESULTS: The crude aqueous methanol extracts. showed varying degrees of activity at concentrations of 0.025 - 100 mg/mL. Ocimum grattisimum (leaf) demonstrated the highest activity with minimum inhibitory concentration (MIC) of 0.025 mg/mL. Two standard anti-tuberculosis drugs; rifampicin and isoniazid, included in the assay had MIC values of 0.01 mg/mL and 0.0005 mg/mL, respectively. CONCLUSION: The results of the study confirm the ethnopharmacological uses of some of the plants for TB indicating their potential as sources for the discovery of anti-tuberculosis drugs.

Alpha-amylase inhibitory activity of two Anthocleista species and in vivo rat model anti-diabetic activities of Anthocleista djalonensis extracts and fractions.

ETHNOPHARMACOLOGICAL RELEVANCE: Anthocleista djalonensis (A. Chev) and Anthocleista vogelii Planch are plants being used in West Africa traditionally to treat various diseases such as malaria, hernia, hypertension, stomach aches, hemorrhoids, syphilis, and diabetes. Diabetes causes about 5% of all deaths globally each year. Chemotherapeutic agents such as biguanides, sulfonylureas, and thiozolidinediones are available for the treatment of diabetes, however, they have undesirable side effects. The need for newer, more effective and less toxic drugs is imperative and the biodiversity of Nigeria has a high potential for drug discovery based on plants used in the ethnomedicine. AIM OF THE STUDY: To investigate the leaves, stem bark and roots of these plants for their probable alpha-amylase inhibitory activities and establish their anti-diabetic activities. The overall goal is do bioassay-guided fractionation and isolation of active anti-diabetic compounds. MATERIALS AND METHODS: Powdered samples (leaves, stem bark and roots) macerated with 80% aqueous methanol were evaluated in vitro using alpha-amylase inhibitory assay while in vivo investigations were carried out on hyperglycemic rats. Diabetes was induced in albino rats by an intraperitoneal injection of alloxan monohydrate (80mg/kg). Plant extracts (1g/kg) were given orally for 7 days, while blood glucose levels were monitored using a one touch glucometer. The crude methanol extracts found to be most active were further partitioned into hexane and ethyl acetate fractions which were also tested in vivo on the diabetic animals. RESULTS: The leaves and stem bark crude methanol extracts of Anthocleista djalonensis gave comparable α-amylase inhibition of 73.66% and 72.90%, respectively which were quite higher than the 38.93% and 22.90% of the same plant parts given by Anthocleista vogelii. The crude stem bark extract of Anthocleista djalonensis exhibited significant peak blood glucose reduction on day 6 (72.59%, p<0.05) which was higher than the leaves or roots which gave 45.73% and 47.46% (p<0.05), respectively The stem bark ethyl acetate fraction of Anthocleista djalonensis gave reduction in blood glucose level of 60.86% (p<0.05). CONCLUSION: From our results, the leaves, stem bark and whole root of both plants exhibited α-amylase inhibitory activities with Anthocleista djalonensis also showing good anti-diabetic activities in vivo indicating that they contain active principles for the management of diabetes. There is justification for the use of the plants traditionally to manage diabetes.

Phytochemical and antimicrobial activities of the wild mango-Irvingia gabonensis extracts and fractions.

Crude methanol extracts obtained from the leaf, stem bark and root of the wild mango, Irvingia gabonensis, were screened for antimicrobial properties by agar well diffusion method at three different concentrations (100 mg/ml, 50 mg/ml and 25 mg/ml) against six human pathogenic microorganisms consisting of four bacteria and two fungi. The hexane, chloroform, ethyl acetate and methanol fractions of the leaf and root methanol extracts were also subjected to the same assay at concentrations of 100 mg/ml-5mg/ml. Gentamicin and Tioconazole were used as positive and methanol as negative controls. Significant inhibitory activities were exhibited by the leaf and root extracts. The crude methanol extract of the root displayed the highest activity at a concentration of 100 mg/ml. It had a diameter of zone of inhibition of 19.7mm while the reference drug had 19.3mm on Pseudomonas aeruginosa, the most sensitive bacteria. The fungi used in this study were also very sensitive to the leaf extract. All the active extracts and fractions exhibited concentration-dependent activities against all the test organisms. Diameter of zones of inhibition ranges from 10.0-30.0 mm. The stem bark was inactive against all the studied organisms. The most active fraction was the ethyl acetate soluble fraction of the leaf which showed a comparable antimicrobial activity against the organisms at concentrations 100 mg/ml and 50 mg/ml comparable to the reference standard drug Gentamicin and Tioconazole. The ethyl acetate soluble fractions of leaf and root were found to show the highest activity. At a concentration of 5 mg/ml, the root ethyl acetate fraction inhibited the growth of all the bacteria tested. The phytochemical screening of the plant materials revealed the presence oftannins, saponins, alkaloids and anthraquinones and the absence of cardiac glycosides. Thin layer chromatography indicated the presence of phenolic compounds.

Antiplasmodial compounds from Cassia siamea stem bark extract.

Cassia siamea L. (Fabaceae) was identified from the southwest Nigerian ethnobotany as a remedy for febrile illness. This led to the bioassay-guided fractionation of stem bark of the plant extract, using the parasite lactate dehydrogenase assay and multi-resistant strain of Plasmodium falciparum (K1) for assessing the in vitro antimalarial activity. Emodin and lupeol were isolated from the ethyl acetate fraction by a combination of chromatographic techniques. The structures of the compounds were determined by spectroscopy, co-spotting with authentic samples and comparison with literature data. Both compounds were found to be the active principles responsible for the antiplasmodial property with IC(50) values of 5 microg/mL, respectively.

Anti-inflammatory and antimicrobial activities of Hippocratea indica root bark and Poga oleosa fruits.

The methanolic extracts of Hippocratea indica root bark and Poga oleosa fruits were investigated for anti-inflammatory and antimicrobial activities. Both extracts inhibited carrageenan-induced paw oedema significantly in rats in a dose-dependent manner in 4 h. H. indica inhibited oedema significantly at the minimal dose (125 mg/ml, p< 0.05) from 2 h onward, and gave 100% inhibition in 4 h. at 250 mg/kg. It was shown to be a more potent anti-inflammatory agent than P. oleosa. Also, H. indica extract exhibited greater antimicrobial activity against tested bacteria, with Staphylococcus aureus being the most susceptible bacterium (MIC, 16 mg/ml). Both plants were inactive against Candida albicans. These results confirm the anti-inflammatory and antibacterial activities of the two plants.

In vitro cytotoxicity studies of 20 plants used in Nigerian antimalarial ethnomedicine.

Twenty plants identified and selected from Southwest and Middle belt Nigerian antimalarial ethnopharmacology were evaluated for in vitro cytotoxicity using the brine shrimp lethality assay. The methanol extracts of 20 plant samples from 11 plant families were subjected to the assay. Of the studied plants, Lippia multiflora and Morinda lucida bark were found to be cytotoxic, with LC(50) values of 1.1 and 2.6 microg/ml, respectively. The least toxic plant extract was Bridelia micrantha (LC(50) value >9.0 x 10(6) microg/ml). Most of the plants were found to be relatively non-toxic.

A phytotherapeutic approach to Nigerian anti-HIV and immunomodulatory drug discovery.

Effective therapies for management of HIV infection are top priority due to the high rate of morbidity and mortality of the disease, globally and this has assumed devastating dimension in the African continent. In Nigeria, many patients use herbal remedies for the management of HIV/AIDS, without sufficient scientific proof that they possess anti-HIV activity. In this report, the role of the tropical rainforest plants, identified through ethnomedical approach, as a source of antiviral and immunomodulating agents is highlighted. Some plant derived antiviral and immunomodulatory agents are briefly discussed. An outline of in vitro antiviral and immunomodulatory assays that can be adapted to the Nigerian environment is given. The urgent need to identify and evaluate the medicinal plants in the Nigerian biodiversity reputedly used for management of viral infections is also emphasized.

Efficacy of herbal remedies used by herbalists in Oyo State Nigeria for treatment of Plasmodium falciparum infections--a survey and an observation.

In the course of evaluating the contribution of phytomedicine to possible drug discovery of antimalarial drugs, an ethnomedical survey of specialized children traditional clinics was done. In the observational multi center study, efficacy of eight different herbal remedies, each consisting of 3-8 ingredients and administered by herbalists were investigated in clients enrolled in the six traditional clinics in Oyo (urban center) and Otu (rural center) of Oyo State, Nigeria. The clients, aged between six months and fifteen years with clinical symptoms of malaria were enrolled in the clinics of the herbalists, as their usual practice. Oral informed consents were obtained from their parents or guardians. Microscopic diagnosis of malaria infection was used to evaluate parasitaemia and validate efficacy of herbal remedies. Results of the analysis showed that, of the 163 clients of the herbalists, only 62 (30 from Oyo, 32 from Otu) had microscopically confirmed P. falciparum infection. Only results from 54 clients (29/30 (Oyo) and 25/32 (Otu) with P. falciparum infection could be evaluated. Plasmodium falciparum infection in 88% (23/29) of clients from Oyo responded to treatment with the herbal remedies while cure rate in clients from Otu was 42% (13/25). Parasite densities ranged from 171 to 53,613 parasites/microl blood and 87 to 36,209 parasites/microl blood in patients from Oyo and Otu respectively. The herbalists administered the remedies and Gossypium arboreum, Anarcadium occidentalis, Citrus medica, Phyllanthus amarus and Lippia multiflora were the main ingredients in the efficacious remedies. The herbalists gave detailed descriptions of each of the 8 herbal remedies proffered. The results confirm the efficacy of two of the eight herbal remedies, thereby validating the role of ethnomedicine as a possible source for the discovery of new chemotherapeutic agents in the treatment of P. falciparum malaria.

In vitro and in vivo antimalarial studies of Striga hermonthica and Tapinanthus sessilifolius extracts.

The antimalarial activities of the methanol extracts of Striga hermonthica (whole plant) and Tapinanthus sessilifolius (leaves), commonly used in Northern Nigeria for the treatment of malaria, were evaluated. In the in vitro antiplasmodial analysis, the extracts of T. sessilifolius and S. hermonthica utilized in the study, displayed mild to weak activities with IC50 values of 200.5 and 274.8 microg/ml respectively. This was investigated, using the multidrug resistant Plasmodium falciparum, K1 strain, in the parasite lactate dehydrogenase assay. The murine model in vivo antimalarial activity of the tested extracts, using chloroquine-sensitive Plasmodium berghei (ANKA P1), in the 4-day suppressive test, showed that both plants had intrinsic antimalarial properties, that were dose-dependent. At a dose of 400mg/kg weight of mice, extract of S. hermonthica exhibited a higher intrinsic antimalarial activity (68.5 % suppression) than that of T. sessilifolius (51.3 %). Chloroquine, the standard reference drug, had an average suppression of 78.0 % at a dose of 10 mg/kg weight of mice while normal saline was used as control. Preliminary phytochemical screening of the extracts indicated the presence ofsaponins, tannins, flavonoids, volatile oils and cardiac glycosides.

Antimicrobial and cytotoxicity evaluation of Buchholzia coriacea stem bark.

Fractions prepared from the methanol extract of Buchholzia coriacea stem bark exhibited a high concentration-dependent antibacterial and antifungal activity compared to the standard antibiotics, ampicillin and tioconazole. In the brine shrimp lethality (BSL) assay, the methanol extract was found to be non-toxic with an LC(50) of 1031 microg/ml. The two main compounds present in the most active fraction were isolated and identified as lupeol and beta-sitosterol.

Cultural categorization of febrile illnesses in correlation with herbal remedies used for treatment in Southwestern Nigeria.

The ethnographic study was conducted in two communities in Oyo State in Southwestern Nigeria. The study sites consisted of a rural and an urban local government area located in the tropical rain forest zone of Nigeria. The study was designed to obtain information on febrile illnesses and herbal remedies for treatment with the aim of identifying potential antimalarial drugs. The study revealed that fever is a general term for describing illnesses associated with elevated body temperature. The indigenous Yoruba ethnic population has categorized fever based on symptoms and causes. The present communication is the result of focus group discussion and semi-structured questionnaire administered to traditional healers, herb sellers, elders and mothers. This was on types of fevers, symptoms and causes of febrile illnesses. The investigation also included use of traditional herbs in the prevention and treatment of the illnesses in the two communities.A total of 514 respondents were interviewed. This was made up of 266 (51.8%) from Atiba local government area (LGA), an urban centre while 248 (48.2%) respondents were interviewed from Itesiwaju LGA, a rural community. The LGAs are located in Oyo State of Nigeria. The respondents proffered 12 types of febrile illnesses in a multiple response answering system in Yoruba language. The most common ones (direct translation into English) were: yellow fever (39.1%), typhoid (34.8%), ordinary (28.8%), rainy season (20.8%) and headache (10.5%) fevers, respectively. Perceived causes of each of the febrile illnesses included stress, mosquito bites, unclean water, rains and over exposure to the sun. Methods of fever prevention were mainly with the use of herbal decoctions, powdered herbs, orthodox medications and maintenance of proper hygiene. Of a total of 112 different herbal remedies used in the treatment of the febrile illnesses compiled from the study, 25 recipes are presented. Recipes consisted of 2-7 ingredients. Oral decoctions (84%), oral powders (63%), use as soaps and creams (40%) in a multiple response system, were the most prevalent routes of administration of prepared herbs used in the treatment of the fevers. Boiling in water or alcohol was the most common method used in the preparation of the remedies. The four most frequently mentioned (multiple response system) plants in the Southwest ethnobotany for fevers were Azadirachta indica (87.5%), Mangifera indica (75.0%), Morinda lucida (68.8%) and Citrus medica (68.8%).

Antibacterial and antifungal activities of Quassia undulata and Quassia amara extracts in vitro.

Extracts of Quassia undulata and Quassia amara (Simaroubaceae) were screened for in vitro antibacterial and antifungal properties respectively. A total of eight extracts, comprising hexane and methanol extracts of the leaves and stems of each of the two plants were investigated. At a concentration of 5 mg/ml all eight extracts exhibited marked antibacterial and antifungal activities in most cases higher than the standard reference drugs included in the study. The extracts inhibited the growth of Escherichia coli, Streptococcus faecalis, Stapylococcus aureus and Aspergillus niger, even when the standard reference drugs utilized in the study did not. Quassia amara leaf methanol extract singularly exhibited the highest activities in both assays, which included the use of six clinical strains of bacteria and five fungi. The agar cup (10 mm diameter) diffussion and broth dilution techniques were used in both assays, utilising eleven human pathogenic microorganisms. Ampicillin and tioconazole were also included in the assay as reference compounds, while methanol was used as control. Diameter of zones of inhibition ranged between 11.0-29.0 mm for the tested extracts/drugs. All the extracts have shown impressive activities against the commonly encountered microorganisms and have thus confirmed the folklore uses of the plants in the African ethnomedicine.

In vivo antimalarial activities of Quassia amara and Quassia undulata plant extracts in mice.

Extracts obtained from two Nigerian Simaroubaceae plants, Quassia amara L. and Quassia undulata (Giull and Perr) D. Dietr were screened for antimalarial properties using a total of six extracts. The plant extracts showed significant antimalarial activities in the 4 day suppressive in vivo antimalarial assay in mice inoculated with red blood cells parasitized with Plasmodium berghei berghei. Plant extracts were studied at 100 mg and 200 mg per kg body weight mouse per day, respectively. At a concentration of 100 mg/kg of mouse, Q. amara leaf hexane extract had the highest suppressive activity with a parasite density of 0.16 +/- 0.001%. Q. amara leaf methanol extract had an outstanding activity; of 0.05 +/- 0.03% at 200 mg/kg. Chloroquine (10 mg/kg, positive control) had a suppressive activity of 0.34 +/- 0.02 in the same assay on day 4.

Preliminary antifungal and cytotoxicity studies of extracts of Ritchiea capparoides var. longipedicellata.

Crude extracts obtained from the leaves, stem bark and roots of Ritchiea capparoides var. longipedicellata were screened for in vitro antifungal activity using the agar tube dilution method. The leaf hexane, leaf methanol, stem bark methanol and root methanol extracts were tested using ten clinical strains of fungi at a concentration of 200 and 400 microg/ml, respectively. At 400 microg/ml, all four extracts inhibited the growth of six of the ten test fungi used in the study. Inhibition of the growth of Aspergillus niger by the extracts was also seen but the activity was low and the leaf hexane and root methanol extracts inhibited the growth of Drechslera rostrata. Only the leaf hexane extract was active against Curvularia lunata, while the growth of Candida albicans was not inhibited by any of the extracts. The inhibition of growth of almost all the microorganisms decreased at 200 microg, griseofulvin was included as a reference compound and methanol as the control. Preliminary cytotoxicity tests were done with the four extracts using the larvae of the brine shrimp, Artemia saline. The extracts were however found to be relatively non-toxic as each extract had an LD50 value greater than 1000 microg/ml.

Studies on the seed oils of Parkia biglobosa and Parkia bicolor.

The seed oils of Parkia biglobosa and Parkia bicolor (Mimosaceae) have been analysed for their possible edible utility and to provide some physical data on both oils. The fatty acid composition of the oils was identified. Six major fatty acids were identified in the oil of P. bicolor while five were identified in that of P. biglobosa by Gas Chromatography (GC) and Gas Chromatography-Mass Spectroscopy (GC-MS). The two oils contained five similar fatty acids in almost the same ratios. Arachidic acid was the most abundant fatty acids (greater than forty per cent) in both oils. Other fatty acids in the oils were behenic, stearic, palmitic and linoleic acids. The sixth fatty acid in P. bicolor was an odd number of carbon atom and un unsaturated fatty acid (C20H37COOH) named bicolargic acid. The oils were also found to be non toxic.