African Traditional Medicinal Plants Research Articles

An imprecise probability approach-based determination of over-represented southern African plant genera and families used in ethnopharmacology

Ethnopharmacological relevanceThe analyses of patterns of over-representation of southern African traditional medicinal plants at the genus and family level provide information about the differences in plant use among southern African countries and disease categories. ‘Over-representation’ refers to the phenomenon whereby the proportion of plants belonging to a taxonomic group is higher in ethnobotanical pharmacopoeia than in the total flora. Aim of the studyThis study aimed to use the Imprecise Dirichlet Model (IDM) to analyse data from ten southern African countries to establish how over-represented medicinal plant families compare with over-represented genera, how over-represented medicinal taxa differ among countries in this region of Africa, and how over-represented taxa differ among six major disease categories. Materials and methodsFloral data for the total species composition of each country were obtained from online databases. Medicinal plant species lists were generated from published surveys, inventories, and books. IDM calculations were executed using the inverse of the cumulative beta probability density function in Microsoft Excel™. Python programming language source code was used to calculate Pearson correlation (r) values and Jaccard coefficients (J). ResultsNine of forty-two over-represented medicinal plant families in southern Africa (group 1) do not have over-represented genera. Seven of the forty genera with the highest margins of over-representation belong to under-represented families. Nineteen of the forty-two over-represented families have margins of over-representation smaller than the cumulative margins of their over-represented genera. Groups of countries with similar overall flora (J ≥ 0.333) are Botswana and Namibia (group 2), Malawi, Mozambique, Zambia and Zimbabwe (group 3). The families and genera with the highest margins of over-representation are Loganiaceae and Albizia in group 1, Combretaceae and Vachellia in group 2, Dioscoreaceae and Senna in group 3, and Sapotaceae and Solanum in group 4 (South Africa). The families and genera with the highest margins of over-representation across disease categories are Ebenaceae and Albizia, Canellaceae and Dicoma, Combretaceae and Pterocelastrus, Ebenaceae and Bersama, Francoaceae and Erythrina, and Aristolochiaceae and Strychnos for plants used in the treatment of STIs, febrile and mosquito-vector diseases, microbial infections, pain, skin conditions, and female sexual/reproductive problems, respectively. ConclusionsGenus-level calculations are more efficient in generating taxonomic lists that can be used for ethnopharmacological investigations due to the exclusion of under-represented genera. Limiting the size of geographical areas from which medicinal plant lists are sampled and targeting plants used to treat specific types of disease prevents the underestimation of niche over-represented taxa.

Antioxidant and angiotensin-converting enzyme inhibitory potential of South African traditional medicinal plants and plant-derived compounds

Antioxidant and angiotensin-converting enzyme inhibitory potential of South African traditional medicinal plants and plant-derived compounds

African Medicinal Plants Useful for Cognition and Memory: Therapeutic Implications for Alzheimer’s Disease

Alzheimer’s Disease (AD), a progressive neurodegenerative disorder linked to increasing age, is the primary cause of dementia in the world. Clinically, it is characterized by cognitive impairments, progressive memory deficits and diminished learning ability. Despite the comprehensive research in AD, none of the existing treatments prevents the onset and progression of the disease. The use of medicinal plants is a fundamental component of the African traditional healthcare system due to its accessibility and affordability in many parts of rural Africa. However, there is a dearth of an updated comprehensive compilation of potential medicinal plants from the African continent commonly used in the management of AD. The primary focus of the present article is to review evidence from selected African plants in experimental and preclinical studies which have promising prospects to be developed as novel therapeutic agents for the treatment of AD. To achieve this, major scientific databases such as Science Direct, Pubmed, Scopus, Web of Science and Google Scholar have been searched to investigate and gather information on African traditional medicinal plants useful for the treatment of cognitive deficits, memory impairments and AD. Our search results showed several commonly used medicinal plants and their possible mechanisms of action including inhibition of acetylcholinesterase activity, modification of Aβ processing, protection against oxidative stress and regulation of antioxidant enzymes activity. This review therefore provides a compilation of medicinal plants that could be further studied for their bioactive constituents; these may become safe, effective and novel therapeutic candidates for the treatment of AD.

Artemisia annua and Artemisia afra extracts exhibit strong bactericidal activity against Mycobacterium tuberculosis

Ethnopharmacological relevanceEmergence of drug-resistant and multidrug-resistant Mycobacterium tuberculosis (Mtb) strains is a major barrier to tuberculosis (TB) eradication, as it leads to longer treatment regimens and in many cases treatment failure. Thus, there is an urgent need to explore new TB drugs and combinations, in order to shorten TB treatment and improve outcomes. Here, we evaluated the potential of two Asian and African traditional medicinal plants, Artemisia annua, a natural source of artemisinin (AN), and Artemisia afra, as sources of novel antitubercular agents. Aim of the studyOur goal was to measure the activity of A. annua and A. afra extracts against Mtb as potential natural and inexpensive therapies for TB treatment, or as sources of compounds that could be further developed into effective treatments. Materials and methodsThe minimum inhibitory concentrations (MICs) of A. annua and A. afra dichloromethane extracts were determined, and concentrations above the MICs were used to evaluate their ability to kill Mtb and Mycobacterium abscessus in vitro. ResultsPrevious studies showed that A. annua and A. afra inhibit Mtb growth. Here, we show for the first time that Artemisia extracts have a strong bactericidal activity against Mtb. The killing effect of A. annua was much stronger than equivalent concentrations of pure AN, suggesting that A. annua extracts kill Mtb through a combination of AN and additional compounds. A. afra, which produces very little AN, displayed bactericidal activity against Mtb that was substantial but weaker than that of A. annua. In addition, we measured the activity of Artemisia extracts against Mycobacterium abscessus. Interestingly, we observed that while A. annua is not bactericidal, it inhibits growth of M. abscessus, highlighting the potential of this plant in combinatory therapies to treat M. abscessus infections. ConclusionOur results indicate that Artemisia extracts have an enormous potential for treatment of TB and M. abscessus infections, and that these plants contain bactericidal compounds in addition to AN. Combination of extracts with existing antibiotics may not only improve treatment outcomes but also reduce the emergence of resistance to other drugs.

Ameliorative effect of methanol stem extract of Parquetina nigrescens (Afzel) bullock on scopolamine-induced sub-chronic cognitive deficit in mice.

Background Parquetina nigrescens (Afzel) Bullock is a commonly used medicinal plant in African traditional medicine. The powdered roots and stems of the plant are taken with pap as a memory enhancer among the Yorubas of southwestern Nigeria. The mechanism by which scopolamine induces cognitive deficit mimics the pathogenesis of neurodegeneration in cognitive impairment. This study therefore, aimed at investigating the effect of the methanol stem extract of P. nigrescens on sub-chronically scopolamine-induced cognitive deficit in mice. Method Phytochemical screening was carried out on the extract using standard protocols. The oral median lethal dose (LD50) was estimated according to the Organisation for Economic Cooperation and Development (OECD) 425 limit test guideline. Doses of 250, 500, and 1000 mg/kg of the extract were used for the study. The elevated plus maze (EPM) and novel object recognition tests (NORT) were used to assess cognitive function. The brain tissue was assayed for the level of malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and acetylcholinesterase (AChE) activity. Results The plant extract contains phenolics, carbohydrates, tannins, saponins, and unsaturated sterols.The extract decreased the transfer latencies on days 7 and 8 against the scopolamine group in EPM and increased the discrimination index decreased by scopolamine in NORT. The methanol stem extract of P. nigrescens significantly (p ≤ 0.01) reduced MDA level; significantly (p ≤ 0.01) increased SOD activity; non-significantly increased GSH activity and the activity of AChE apeared not altered. Conclusion The methanol stem extract of P. nigrescens ameliorated sub-chronically scopolamine-induced cognitive deficit via antioxidant mechanism.

Cola caricifolia (G.Don) K. Schum and Crotalaria retusa L. from Ivory Coast as sources of bioactive constituents

Cola caricifolia (G.Don) K. Schum and Crotalaria retusa L. are important plants in African traditional medicine used against a plethora of human ailments. In this study, phytochemical characterization and enzyme inhibitory assays were performed to assess the potential usefulness of C. caricifolia and C. retusa leaves extracts as source of bioactive constituents for potential industrial applications. The flavonoid content of C. caricifolia (22.27 mg rutin equivalent (RE)/g) was significantly higher (p<0.05) than C. retusa (12.45 mg RE/g) methanol extract. Inhibitory activity against acetylcholinesterase, butyrylcholinesterase, and tyrosinase were evaluated for all the extracts (ethyl acetate, methanol, and water), whereby the best activity recorded for the methanol extracts. Additionally, the methanol extracts of C. caricifolia and C. retusa showed significant antioxidant activity in the phosphomolybdenum, metal chelating, reducing power, and radical scavenging assays. Flavonoid glycosides and caffeoyl derivatives were the most abundant constituents in C. caricifolia. Crotalaria retusa contained several flavonoid glycosides with structures not described previously. One new compound, kaempferol-6-C-β-glucopyranoside-3-O-β-glucopyranosil-6-O-caffeoyl ester has been elucidated using spectroscopic method in the current study. Derivatives present in minor amount were tentatively identified as kaempferol glycosides. Overall phytochemical investigations allowed the identification of flavonoid O and C glycosides, caffeic acid derivatives, and phytosterols from both plant extracts while pyrrolizidine alkaloids were identified in C. retusa. Structural characteristics of the new isolated compounds along with the most abundant constituents of the two extracts were elucidated allowing the observation of some structural moieties related to the observed activity. These observations highlighted the potential use of these plants as a source of multi-directional biological agents that could lead to bioproducts development.

Indigenous knowledge codification of African traditional medicine: Inhibited by status quo based on secrecy?

This paper is located within global debates about the codification of indigenous knowledge (IK) practices vis-à-vis traditional medicine in Africa. Following a theoretical research based on an extensive literature review, the paper questions whether it is possible to codify all elements embedded in Africa’s indigenous knowledge practices in traditional medicine following that the medicine encompasses esoteric and non-esoteric elements. There is a persistent plea for the elements of Africa’s indigenous knowledge practices in traditional medicine to be codified and to desist from its status-quo phenomena of secrecy for posterity. Within Africa’s indigenous knowledge (IK) practices in traditional medicine are certain aspects that it may not be possible to codify. The non-esoteric aspect of African traditional medicine can be codified as it encompasses no secret, while the esoteric aspect may not be codified as it is considered to be secret for a select few traditional healers who exploit it for livelihood. The raison d’être for the examination stems from the notion that Africa’s indigenous knowledge practices in traditional medicine has a high livelihood potential, hence needs to be protected. Traditional healers have over generations fostered relationships with other groups, creating a complex web of high levels of cooperation, exchange and support that are essential for livelihood. Their fast erosion due to internal and external factors poses a serious threat to livelihood development in the subregion. The lack of codification of Africa’s indigenous knowledge practices in traditional medicine gives an urge to western pharmaceutical companies, who make huge profits from indigenous knowledge of medicinal plants. With further theoretical research, the paper exposes the esoteric and non-esoteric elements that encompass African traditional medicinal plants and the possible reasons why the status-quo based on secrecy persists within the esoteric aspects of the medicinal plant practices and how the status-quo may be uplifted within intellectual property rights (IPR) in the form of patent and other approaches for posterity.

The development and use of a drug-induced immunosuppressed rat-model to screen Phela for mechanism of immune stimulation

Ethnopharmacology relevancyPhela, is code name for a medicinal product made from four South African traditional medicinal plants (Clerodendrum glabrum E. Mey, Polianthes tuberosa (Linn.), Rotheca myricoides (Hochst.) Steane & Mabb. and Senna occidentalis (L.) Link). All these plants have established traditional use in a wide spectrum of diseases. Phela is under development for use as an immune booster in immunocompromised patients, which includes patients with the human immunodeficiency virus (HIV). Already several studies, both pre-clinical and clinical, have shown that Phela is a safe and effective immune booster. Despite some studies on the action of Phela, the mechanism of action by Phela is still not known. Understanding the mechanism of action will enable safer and effective use of the drug for the right indications. Unfortunately, there is no well characterized test-system for screening products for immune stimulant activity. Therefore, the objective of this study was to use Phela as the test article, to develop and validate a rat-model (test system) by which to screen medicines for immune stimulant activity. Material and methodsFirst, the batch of Phela used was authenticated by high performance liquid chromatography (HPLC) techniques; analytical methods for the immunosuppressant drugs, cyclosporine A (CsA), cyclophosphamide (CP) and dexamethasone (Dex) were developed and validated; and a slide-A-Lyzer dialysis was used to test for potential interactions in rat plasma of Phela with CsA, CP and Dex. Thereafter, using Sprague Dawley (SD) rats and in separate experiments, the effective dose of Phela in the study animals was determined in a dose ranging study with levamisole, a known immune stimulant as the positive control; the appropriate doses for immunosuppression by CsA, CP and Dex were determined; the time to reach ‘established immunosuppression’ with each drug was determined (it was also the time for intervention with Phela); and eventually, the effect of Phela on the immune system was tested separately for each drug induced immunosuppression. The immune system was monitored by observing for changes in plasma profiles of IL-2, IL-10, IgG, IgM, CD4 and CD8 cell counts at appropriate intervals, while in addition to function tests, the kidneys, liver, spleen, thymus, were weighed and examined for any pathology. ResultsThe chromatographic fingerprint certified this batch of Phela as similar to the authentic Phela. There was no significant interaction between Phela and CsA, CP and Dex. The effective dose of Phela was determined to be 15.4mg/kg/day. Phela led to a moderate increase in the immune parameters in the normal rats. Co-administration of Phela 15mg/kg/day orally for 21 days with CsA led to stoppage and reversal of the immunosppressive effects of CsA that were exhibited as increased IL-2, IL-10, CD4 and CD8 counts, implying that Phela stimulates the cell mediate immunity (CMI). For CP, Phela led to stoppage and reversal, though moderate, of CP-induced suppression of IL-10, IgM and IgG only, implying that Phela stimulates the humoral immunity (HI) too. Phela had no effect on Dex induced immunosuppression. Stimulation of the CMI means that Phela clinical testing programme should focus on diseases or disorders that compromise the CMI, e.g., HIV and TB. The stimulation of the HI immunity means that Phela may stimulate existing memory cells to produce antibodies. ConclusionThe present study has revealed Phela's mechanism of action as mainly by stimulation of the CMI, implying that the use of Phela as immune booster in HIV patients is appropriate; and that using Phela as the test product, a rat model for screening medicinal products for immune stimulation has been successfully developed and validated, with a hope that it will lead to the testing of other related medicinal products.

Antibacterial and synergistic studies of selected South African traditional medicinal plants

Antibacterial and synergistic studies of selected South African traditional medicinal plants

Antimicrobial activity of Albizia gummifera (J.F.Gmel.) C.A.Sm leaf extracts against four Salmonella serovars

In the past few decades, non-typhoidal serovars of Salmonella have gained resistance to several classes of antibiotics including third generation Cephalosporins and Fluoroquinolones. There has also been an increase in the number of infections caused by antimicrobial resistant Salmonella serotypes including Salmonella Typhimurium DT 104 which is resistant to at least five antimicrobial agents. Therefore, the aim of this study was to investigate Albizia gummifera (Fabaceae), a native tree species of Africa that has been used extensively in African traditional medicine for the treatment of stomach infection, skin diseases and malaria for antimicrobial activity against four Salmonella serovars. Dichloromethane, methanol and acetone leaf extracts of A. gummifera were screened for antimicrobial activity against Salmonella Typhimurium, S. Enteritidis, S. Dublin, and S. Gallinarum using the microplate dilution method. The minimal inhibitory concentration (MIC) of the extracts ranged between 0.125 and 1mg/ml, while minimal bactericidal concentrations (MBC) ranged between 0.25 and >2.00mg/ml. The best activity was exhibited by the methanol extract against all the tested strains. The mutagenic and cytotoxic potential of the most active methanol extract were also determined. The extract was not mutagenic in the Ames tester strains TA98 and TA100 with and without metabolic activation. However, the methanol extract was cytotoxic to both Human hepatocellular carcinoma (C3A) and Madin-Darby Bovine kidney (MDBK) cell lines. The results obtained in this study validate in part the use of this plant in African traditional medicine for the treatment of stomach infection.

Psychopharmacological potentials of methanol leaf extract of Securinega virosa Roxb (Ex Willd) Baill. in mice.

Schizophrenia is a highly disabling chronic psychiatric illness. The existing antipsychotic agents are associated with untoward effects and drug interactions leading to the intensification of search for newer agents with better efficacy and safety profile. Securinega virosa is a commonly used medicinal plant in African traditional medicine. The decoction of the leaves of the plant in combination with other plants is used in the management of mental illness. In this study, we evaluate the antipsychotic potential of the methanol leaf extract (25, 50 and 100 mg kg(-1)) of the plant using apomorphine-induced stereotypic climbing behavior and swim-induced grooming tests, all in mice. The CNS depressant effect was also evaluated using ketamine-induced sleep test mice. The extract at the highest dose tested (100 mg kg(-1)) significantly reduced the apomorphine (1 mg kg(-1))-induced stereotypic climbing behavior after 30 min. Similarly, haloperidol (2 mg kg(-1)), the standard agent significantly (p<0.001) decreased the mean climbing behavior. In the swim-induced grooming test, the extract significantly (p<0.01) and dose-dependently decreased the total grooming time. Similarly, haloperidol (2 mg kg(-1)) significantly (p<0.001) decreased the mean grooming activity. The extract significantly increased the total ketamine-induced sleep duration at doses of 50 and 100 mg kg(-1). These findings suggest that the extract possesses antipsychotic and sedative potentials and lend credence to the ethnomedical use of the leaves of the plant in the management of mental illness.

English

Securinega virosa is a commonly used medicinal plant in African traditional medicine in the management of epilepsy. In an attempt to isolate and characterize the bioactive principles responsible for the anticonvulsant property, the crude methanol root bark extract of the plant was exhaustively partitioned into petroleum ether, chloroform, ethyl acetate and n-butanol. The anticonvulsant potential of the n-butanol fraction (75, 150 and 300 mg/kg) was evaluated using maximal electroshock (MES) test in chicks, strychnine, picrotoxin, 4-aminopyridine and pentylenetetrazole-induced seizures in mice. The fraction did not protect the chicks against tonic-hind limb extension due to MES. Similarly, the fraction did not afford significant protection against seizures induced by strychnine, aminopyridine and picrotoxin contrary to the observations of protections in the crude extract, against pentylenetetrazole-induced seizure, the fraction afforded 66.67% protection and significantly (P&lt;0.01) delayed the onset of seizure in unprotected animals. Column chromatographic separation of the n-butanol fraction yielded three major sub-fractions which were subjected to anticonvulsant screening using pentylenetetrazol (PTZ)-induced seizure. The anticonvulsant potential of the n-butanol fraction was retained in the more polar sub-fractions. The findings of this study suggest that the n-butanol fraction Securinega virosa root bark contains bioactive principle(s) that possess anticonvulsant activities which may be beneficial against absence seizure. This lends further credence to the ethnomedicinal claim of the use of the root of S. virosa in the management of epilepsy. &nbsp; Key words: Securinega virosa, epilepsy, seizure, maximal electroshock, pentyleneterazole, picrotoxin, 4-aminopyridine, strychnine.

Ethnopharmacological Survey of Plants Used in the Traditional Treatment of Gastrointestinal Pain, Inflammation and Diarrhea in Africa: Future Perspectives for Integration into Modern Medicine.

Simple SummaryThis review provides an inventory of numerous plant species used as traditional remedies for pain and diarrhea in Africa. Africa can emulate advances in traditional Chinese medicine through research, commercialization, teaching traditional medicine in medical schools, and incorporating botanical products in treating veterinary and human patients. Prioritized research of plant species with proven folklore in treating pain and diarrhea using high throughput screening to identify and test bioactive compounds to verify their effectiveness, mechanisms of action and safety and translational research are needed to facilitate these advances and the integration of traditional African botanical preparations for treating pain and gastrointestinal disorders into western medicine.There is a growing need to find the most appropriate and effective treatment options for a variety of painful syndromes, including conditions affecting the gastrointestinal tract, for treating both veterinary and human patients. The most successful regimen may come through integrated therapies including combining current and novel western drugs with acupuncture and botanical therapies or their derivatives. There is an extensive history and use of plants in African traditional medicine. In this review, we have highlighted botanical remedies used for treatment of pain, diarrheas and inflammation in traditional veterinary and human health care in Africa. These preparations are promising sources of new compounds comprised of flavonoids, bioflavanones, xanthones, terpenoids, sterols and glycosides as well as compound formulas and supplements for future use in multimodal treatment approaches to chronic pain, gastrointestinal disorders and inflammation. The advancement of plant therapies and their derivative compounds will require the identification and validation of compounds having specific anti-nociceptive neuromodulatory and/or anti-inflammatory effects. In particular, there is need for the identification of the presence of compounds that affect purinergic, GABA, glutamate, TRP, opioid and cannabinoid receptors, serotonergic and chloride channel systems through bioactivity-guided, high-throughput screening and biotesting. This will create new frontiers for obtaining novel compounds and herbal supplements to relieve pain and gastrointestinal disorders, and suppress inflammation.

Traditional Medicines in Africa: An Appraisal of Ten Potent African Medicinal Plants

The use of medicinal plants as a fundamental component of the African traditional healthcare system is perhaps the oldest and the most assorted of all therapeutic systems. In many parts of rural Africa, traditional healers prescribing medicinal plants are the most easily accessible and affordable health resource available to the local community and at times the only therapy that subsists. Nonetheless, there is still a paucity of updated comprehensive compilation of promising medicinal plants from the African continent. The major focus of the present review is to provide an updated overview of 10 promising medicinal plants from the African biodiversity which have short- as well as long-term potential to be developed as future phytopharmaceuticals to treat and/or manage panoply of infectious and chronic conditions. In this endeavour, key scientific databases have been probed to investigate trends in the rapidly increasing number of scientific publications on African traditional medicinal plants. Within the framework of enhancing the significance of traditional African medicinal plants, aspects such as traditional use, phytochemical profile, in vitro, in vivo, and clinical studies and also future challenges pertaining to the use of these plants have been explored.

Evaluation of Traditional Medicines I: Identification of Phela Using Different Chromatographic Techniques

PHELA is a herbal mixture of four African traditional medicinal plants that has been used for decades in wasting conditions and is now being developed by the Medical Research Council (MRC) as an immune booster for patients with compromised immune system. A chromatographic fingerprint of PHELA was needed for quality control purposes. Here, a comprehensive method for fingerprinting of PHELA using different chromatographic techniques is described. It involved extraction of the PHELA by either acidic or a simple 'salting-out' method, followed by Thin Layer Chromatography (TLC) analysis and/or preparative Column Chromatography (CC). The products were thereafter analyzed by High Performance Liquid Chromatography with UV-detector (HPLC-UV), HPLC with fluorescence-detector (HPLC-FL) and Gas-Chromatography with a Mass Selective Detector spectrometer (GC-MSD). The fingerprints were successfully used to differentiate PHELA from another common herbal product made from Hypericum perforatum (St. John's Wort), thereby illustrating its high potential for use in fingerprinting of PHELA and in differentiating it from other herbal medicines. By validating the different chromatographic techniques on the standardized extraction methods, this approach will enable wide application in quality control of PHELA using acceptable procedures, thereby promoting effective monitoring of the finished product in all countries where it will be used.

Evaluation of Traditional Medicines II: The Use of Metabolite Peak-Kinetics to Monitor PHELA in Rat Plasma.

PHELA is a herbal mixture of four African traditional medicinal plants that is under development by the Medical Research Council (MRC) for use as an immune stimulant in immune compromised individuals. Before major in vivo investigations could be conducted, there was a need to establish a plasma marker for concentration monitoring of PHELA. Chromatographic separation was achieved using a C18 RP column (250 mm × 4.6 mm × 5 µm), 70% acetonitrile in water and fluorescent detection. Three groups of rats (n=5) were administered with PHELA (15.4 mg/kg) and one rat from each group was sacrificed at 1, 2, 4, 6 and 8 hours. Surprisingly, on the HPLC analysis, none of the marker peaks of spiked plasma were detectable in the plasma of treated animals. Instead, a new peak was observed at 9.2 minutes, which implied that it was a metabolite of PHELA. Using peak area per unit plasma volume (PK-area/L), the relevant pharmacokinetic parameters were derived. The metabolite's half-life was 3.47±0.35 hours and reached maximum concentration at 4.67 ± 1.15 hrs. It was estimated that with once daily dosing of PHELA, the concentration at steady state (Css) would be 47.52 ± 5.94 PK-area/L with no drug accumulation (Acc index =.009 ± 0.004). In conclusion, the use of peak area per unit volume to derive pharmacokinetics of unknown compounds (Peak-kinetics) and to confirm ingestion of PHELA were demonstrated with a hope that they may appeal to those experiencing similar problems with monitoring of herbal products of which little is known.

Interactions between Phytochemical Components of Sutherlandia Frutescens and the Antiretroviral, Atazanavir In Vitro: Implications for Absorption and Metabolism

African traditional medicinal plants, such as Sutherlandia frutescens have the potential to interact pharmacokinetically with the protease inhibitor class of antiretrovirals, thereby impacting on their safety and efficacy. The effects of extracts and phytochemical components of Sutherlandia frutescens, on the in vitro absorption and metabolism of the protease inhibitor, atazanavir were thus investigated. Aqueous and methanolic extracts of Sutherlandia frutescens were prepared by freeze-drying of hot water and methanol decoctions of Sutherlandia frutescens plant material respectively, whilst crude triterpenoid glycoside and flavonol glycoside fractions were isolated by solvent extraction and subsequent column chromatography. Atazanavir was quantitated in the absence or presence of these compounds as well as commercially available purported constituents of Sutherlandia frutescens, namely, L-canavanine, L-GABA and D-pinitol, after a one hour co-incubation in Caco-2 cell monolayers and human liver microsomes. The triterpenoid and flavonol glycoside fractions were found to be present in the aqueous and methanolic extracts of Sutherlandia frutescens and were shown to contain the sutherlandiosides and sutherlandins known to be present in Sutherlandia frutescens. The aqueous extract and D-pinitol significantly reduced atazanavir accumulation by Caco-2 cells, implying a decrease in atazanavir absorption, whilst the opposite was true for the triterpenoid glycoside fraction. Both the aqueous and methanolic extracts inhibited atazanavir metabolism in human liver microsomes, whilst enhanced atazanavir metabolism was exhibited by the triterpenoid glycoside fraction. The extracts and phytochemical components of Sutherlandia frutescens influenced the accumulation of atazanavir by Caco-2 cells and also affected ATV metabolism in human liver microsomes. These interactions may have important implications on the absorption and metabolism and thus the overall oral bioavailability of atazanavir.

Central depressant activity of butanol fraction of Securinega virosa root bark in mice

Ethnopharmacological relevanceSecurinega virosa is a commonly used medicinal plant in African traditional medicine in the management of epilepsy and mental illness. Previous studies in our laboratory showed that the crude methanol root bark extract of the plant possesses significant behavioral effect in laboratory animals. In an attempt to isolate and characterize the biological principles responsible for the observed activity, this study is aimed at evaluating the central depressant activity of the butanol fraction of the methanol root bark extract of Securinega virosa. Materials and methodsThe medial lethal dose of the butanol fraction was estimated using the method of Lorke. Preliminary phytochemical screening was conducted on the butanol fraction using standard protocol. The behavioral effect of the butanol fraction (75, 150 and 300mg/kg) was evaluated using diazepam induced sleep test, hole-board test, beam walking assay, staircase test, open field test and elevated plus maze assay, all in mice. ResultsThe median lethal dose of the butanol fraction was estimated to be 1256.9mg/kg. The preliminary phytochemical screening revealed the presence of tannins, saponins, alkaloids, flavonoids, cardiac glycosides, similar to those found in the crude methanol extract. The butanol fraction significantly (P<0.001) reduced the mean onset of sleep in mice and doubled the mean duration of sleep in mice at the dose of 75mg/kg. The butanol fraction and diazepam (0.5mg/kg) significantly (P<0.01–0.001) reduced the number of head dips in the hole-board test suggesting sedative effect. The sedative effect of the butanol fraction was further corroborated by its significant (P<0.01–0.001) reduction of the number of step climbed and rearing in the staircase test. The butanol fraction did not significantly increase the time taken to complete the task and number of foot slips in the beam walking assay, suggesting that it does not induce significant motor coordination deficit. Diazepam (2mg/kg), the standard agent used significantly (P<0.01) increased the number of foot slips. In the open field test, the butanol fraction significantly reduced the number of square crossed as well as the number of rearing. However, the butanol fraction did not significantly alter the behavior of mice in the elevated plus maze assay, while diazepam (0.5mg/kg) significantly (P<0.05) increased the time spent in the open arm and reduced the number of closed arm entry. ConclusionThe findings of this study suggest that the butanol fraction of Securinega virosa root bark contains some bioactive principles that are sedative in nature.

Validating the in vitro antimicrobial activity of Artemisia afra in polyherbal combinations to treat respiratory infections

Artemisia afra is one of the most widely used medicinal plants in African traditional medicine and is commonly administered in polyherbal combinations to treat respiratory infections. Focussing on plant volatiles, the aim of this study was to provide scientific evidence for the antimicrobial activity of A. afra (principle plant) in combination with essential oils from three medicinal aromatic plants; Agathosma betulina, Eucalyptus globulus and Osmitopsis asteriscoides. In vitro minimum inhibitory concentration (MIC) assays were undertaken on four pathogens ( Enterococcus faecalis ATCC 29212, Moraxella catarrhalis ATCC 23246, Klebsiella pneumoniae NCTC 9633 and Cryptococcus neoformans ATCC 90112) to determine antimicrobial efficacy of the oils and their combinations. The fractional inhibitory concentration (FIC) and isobolograms were used to interpret pharmacodynamic interactions such as synergy, antagonism or additive profiles. The antimicrobial activity of the individual oils mostly displayed moderate activity. Predominantly, additive interactions were noted. The most prominent synergistic interaction (FIC value of 0.5) was observed when A. afra was combined with O. asteriscoides in the 8:2 ratio (eight parts A. afra with two parts O. asteriscoides) against C. neoformans. No antagonistic interactions were evident.

Antimicrobial interactions between medicinal plants in African traditional medicine

Antimicrobial interactions between medicinal plants in African traditional medicine