Fractionation and Antibacterial Evaluation of the Surface Compounds from the Leaves of Combretum zeyheri on Selected Pathogenic Bacteria.

Combretum zeyheri is traditionally used for the treatment of many infections, including bacterial infections. The aim of this study was to fractionate and evaluate antibacterial activity of the crude extract of C. zeyheri, as well as the surface compounds from the leaves of C. zeyheri, in two pathogenic bacteria, Staphylococcus aureus and Pseudomonas aeruginosa. The antibacterial activities of fractions obtained from chromatographic separations were determined using broth microdilution assay on the laboratory and clinical strains of S. aureus and P. aeruginosa. The fractionation of the compounds on the leaf surface yielded 262 fractions. The fractionated compounds with similar TLC profiles were pooled together to yield 47 pools. The extract and pooled fractions CZSC151154, CZSC155160, and CZSC209213 showed significant antibacterial activity with MIC values ranging from 12.5 µg/ml to 100 µg/ml. The clinical strain of S. aureus had MIC greater than 100 µg/ml for CZSC151154 and CZSC155160. The minimum bactericidal concentration values for these fractions were also in the range of 12.5 µg/ml to 100 µg/ml. The extract and fractions CZSC151154, CZSC155160, and CZSC209213 showed a concentration-dependent inhibition of growth in S. aureus. Analyses of the CZSC209213 pool by LC-MS showed the presence of nine compounds which are (3R,7R)-1,3,7-octanetriol, (-)-tortuosamine, 11-aminoundecanoic acid, 1-piperidinecarboxaldehyde, 3-hydroxy-4-isopropylbenzyl alcohol 3-glucoside, hydroxy-isocaproic acid, oleamide, palmitic amide, phytospingosine, and sphinganine. In conclusion, C. zeyheri leaf surface compounds exhibited antibacterial activity. The crude extract and the pooled fractions showed concentration-dependent inhibition of growth on S. aureus. Results from this study indicate the potential of C. zeyheri as a source of lead compounds that may be further developed into antibacterial drugs.

Evaluation of antimicrobial activity of chondrillasterol isolated from Vernonia adoensis (Asteraceae).

BACKGROUND: Bacteria have developed resistance to most of the current antibiotics. There is evidence suggesting that plant-derived compounds have a potential for interacting with biological processes. One of the plants commonly used in African ethnomedicine is Vernonia adoensis from the Asteraceae family. The leaves of the plant have been reported to have antimicrobial activity. Hence, the aim of this study was to isolate the bioactive compounds from the leaf extract and evaluate their antibacterial activity on Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. In addition, the effect of the isolated compound on biofilms of P. aeruginosa was determined. METHODS: Isolation of phytochemicals from the leaves of V. adoensis was done using column chromatography. Preparative TLC was used to further isolate mixed compounds in the fractions. Nuclear magnetic resonance spectroscopy and mass spectrometry was used to identify the isolated pure compounds. The broth microdilution assay was carried out to evaluate the antibacterial activity of the isolated compound on P. aeruginosa, S. aureus and K. pneumoniae. Crystal violet staining technique was used to evaluate the effect of the isolated compound on biofilms of P. aeruginosa. RESULTS: The compound isolated from V. adoensis was identified as chondrillasterol. Chondrillasterol exhibited 25, 38 and 65% inhibition of growth on S. aureus, K. pneumoniae and P. aeruginosa respectively. At 1.6 µg/mL chondrillasterol completely disrupted mature biofilm of P. aeruginosa while at 100 µg/mL the compound completely inhibited formation of biofilms of the bacteria. CONCLUSION: Chondrillasterol isolated from V. adoensis has antibacterial properties against S. aureus, K. pneumoniae and P. aeruginosa. The compound also has biofilm inhibition and disruption activity against P. aeruginosa biofilms. Thus, the active phytochemical could be a useful template for the development of new antimicrobial agents with both antibacterial and antibiofilm activity.

Cognitive-Enhancing Effect of a Hydroethanolic Extract of Crinum macowanii against Memory Impairment Induced by Aluminum Chloride in BALB/c Mice.

Crinum macowanii is a bulbous plant indigenous to many parts of Southern Africa. Extracts of C. macowanii have gained interest since the discovery of various alkaloids, few of which possess acetylcholinesterase inhibitory activity. The present study was performed to evaluate the effect of a crude hydroethanolic extract of C. macowanii against aluminum chloride-induced memory impairment in mice using the Morris water maze and the novel object recognition task. C. macowanii (10, 20, and 40 mg/kg p.o) was administered daily for five weeks, while donepezil (3 mg/kg p.o) was used as the positive control. C. macowanii at a dosage of 40 mg/kg showed a significantly lower escape latency than the negative control (P < 0.0001) and was found to be comparable to donepezil 3 mg/kg in the Morris water maze test. C. macowanii at 40 mg/kg exhibited a significantly higher discrimination index than aluminum chloride-treated mice in the novel object recognition task. The results may support the usefulness of C. macowanii in the management of dementia and related illnesses.

Effects of a hydroethanolic extract of Boophone disticha bulb on anxiety-related behaviour in naive BALB/c mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Boophone disticha is one of the most important medicinal bulbs of Southern Africa. Previous in vitro studies have shown that it's crude ethanolic extracts and some alkaloidal phytoconstituents possesses high affinity for the serotonin transporter protein (SERT) and serotonin receptor 1a (5HT1a) which are both implicated in the pathogenesis and treatment of anxiety disorders. However, there are no in vivo studies that validates the anxiolytic actions of the plant. AIM OF THE STUDY: This study was therefore set to determine the anxiolytic-like activity of an orally administered hydroethanolic extract of B. disticha bulbs in naive mice using the behavioural tests of anxiety. MATERIALS AND METHODS: Naïve adult male BALB/c mice were randomly placed into five treatment groups (n=6-10): vehicle control (10ml/kg 0.9% NaCl), positive control (1mg/kg diazepam) and the hydroethanolic extract of B. disticha (10, 25 and 40mg/kg p.o.). Souk test, elevared plus maze and open field tests were used to evaluate the anxiolytic-like activity of the B. disticha extract. RESULTS: Diazepam-treated mice exhibited higher number of sector visits and line crossings in the ST, rearings in the OF and head dips in the EPM than the control (p<0.05). B. disticha extract treated groups expressed higher sector visits at 10mg/kg, and, unprotected head dips at 25mg/kg in the ST, as well as, open arm time entries at 10mg/kg dose, and unprotected head dips at all doses in the EPM than the control group (p<0.05). The 25mg/kg B. disticha dose group exhibited highest anxiolytic-like activity in both the ST and OF, while the 10mg/kg was most active in the EPM. CONCLUSION: The extract of B. disticha exerted good anxiolytic-like activity in both the ST and OF at medium dose (25mg/kg), while the low dose (10mg/kg) showed prominent anxiolytic-like activity in the EPM.

Pattern and Epidemiology of Poisoning in the East African Region: A Literature Review.

The establishment and strengthening of poisons centres was identified as a regional priority at the first African regional meeting on the Strategic Approach to International Chemicals Management (SAICM) in June 2006. At this meeting, the possibility of a subregional poisons centre, that is, a centre in one country serving multiple countries, was suggested. The WHO Headquarters following consultation with counterparts at the WHO Regional Office for Africa (AFRO) and the SAICM Africa Regional Focal Point successfully submitted a proposal to the SAICM Quick Start Programme (QSP) Trust Fund Committee for a feasibility study into a subregional poisons centre in the Eastern Africa subregion. However, before such a study could be conducted it was deemed necessary to carry out a literature review on the patterns and epidemiology of poisoning in this region so as to inform the feasibility study. The current paper presents the results of this literature review. The literature search was done in the months of June and July 2012 by two independent reviewers with no language or publication date restrictions using defined search terms on PUBMED. After screening, the eventual selection of articles for review and inclusion in this study was done by a third reviewer.

A promising poison information centre model for Africa.

INTRODUCTION: The burden of poisoning exposures in Africa is a significant public health concern, yet only ten African countries have poisons information centres. The establishment of poisons centres was subsequently identified as a priority. This article focuses on workshop discussions with international multi-sector stakeholders in Eastern Africa regarding the possibility of a sub-regional poisons centre serving multiple countries. METHODS: The project was led by an independent consultant under the guidance of an international steering group. Steering group members provided input at international multi-stakeholder meetings and during monthly teleconferences. RESULTS: Participants of the stakeholder meetings agreed that the establishment of a sub-regional poisons centre in Eastern Africa was necessary and feasible. Virtual collaboration is possible due to recent technological developments, and the overall suggestion was for countries to establish their own poisons centres and to network and coordinate these centres through a network hub. CONCLUSION: A number of benefits might result from such a poisons centre network hub, including: (1) Improved cooperation between countries on poisoning problems; (2) Harmonisation and strengthening of research and surveillance; (3) Common standards and best practices e.g. regulating chemicals, data management, and staff training; and (4) Greater bargaining power to secure resources. Further investigation is needed to identify the most suitable location for the network hub, the activities it should fulfil, and the availability of specialists in poisons information who could become members of the hub.

INTRODUCTION: La charge que représentent les expositions à l'empoisonnement en Afrique est une préoccupation de santé publique importante, et pourtant, seuls une dizaine de pays africains sont dotés de centres d'information antipoison. La création de centres antipoison a donc été identifiée comme une priorité. Cet article se concentre sur les discussions de l'atelier organisé avec les parties prenantes multisectorielles internationales en Afrique de l'Est concernant la possibilité de la création d'un centre antipoison sous-régional desservant plusieurs pays. MÉTHODES: Le projet a été mené par un consultant indépendant, sous la direction d'un groupe de pilotage international. Les membres du groupe de pilotage ont apporté leur contribution lors de réunions internationales multipartites et de téléconférences mensuelles. RÉSULTATS: Les participants des réunions des parties prenantes ont convenu que la mise en place d'un centre antipoison sous-régional en Afrique de l'Est était nécessaire et faisable. La collaboration virtuelle est possible grâce aux récents développements technologiques, et la suggestion générale était que les pays établissent leurs propres centres antipoison et mettent en réseau et coordonnent ces centres par le biais d'une tête de réseau. CONCLUSION: Une telle tête de réseau de centres antipoison pourrait présenter un certain nombre d'avantages, notamment: (1) Une amélioration de la coopération entre les pays sur les problèmes d'empoisonnement; (2) Une harmonisation et un renforcement de la recherche et de la surveillance; (3) Des normes communes et des meilleures pratiques, par exemple la réglementation des produits chimiques, la gestion des données et la formation du personnel; (4) Une meilleure position de négociation pour obtenir des ressources. Une enquête plus approfondie est nécessaire pour identifier l'emplacement le plus approprié pour la tête de réseau, les activités qu'elle devra remplir et la disponibilité de spécialistes en information antipoison qui pourraient participer à cette tête de réseau.

Antiamnesic Effects of a Hydroethanolic Extract of Crinum macowanii on Scopolamine-Induced Memory Impairment in Mice.

Crinum macowanii has been found to contain alkaloids that have activity against acetylcholinesterase enzyme in vitro. The present study was undertaken to investigate the in vivo ability of hydroethanolic crude extract of Crinum macowanii to ameliorate memory impairment induced by scopolamine. Thirty-six male Balb/c mice weighing around 25-35 g were employed in the present investigation. Y-maze and novel object recognition apparatus served as the exteroceptive behavioural models, and scopolamine-induced amnesia served as the interoceptive behavioural model. C. macowanii (10, 20, and 40 mg/kg p.o.) was administered in single doses to the mice. Donepezil (3 mg/kg p.o.) was used as a positive control agent. C. macowanii extract reversed the amnesia induced by scopolamine as indicated by a dose-dependent increase in spontaneous alternation performance in the Y-maze task. C. macowanii 40 mg/kg showed significant activity (p < 0.05 versus negative control), comparable to that of the positive control. C. macowanii also showed memory-enhancing activity against scopolamine-induced memory deficits in the long-term memory novel object recognition performance as indicated by a dose-dependent increase in the discrimination index. The results indicate that the hydroethanolic extract of C. macowanii may be a useful memory restorative mediator in the treatment of cognitive disorders such as Alzheimer's disease.

Spasmogenic effects of Sclerocarya birrea stem bark aqueous extract on rat isolated uterine horns.

ETHNOPHARMACOLOGICAL RELEVANCE: Sclerocarya birrea (Anacardiaceae), popularly known as "marula", is used as a traditional remedy for allegedly treating dysmenorrhoea and a host of other ailments such as malaria, fever, diarrhoea, dysentery, stomach disorders, headaches and to facilitate childbirth. This study investigated the pharmacological effects of S. birrea extract (SBE) on isolated, spontaneously-contracting uterine horns of healthy, young adult, female Wistar rats. MATERIALS AND METHODS: One kilogramme of S. birrea fresh stem bark was identified and authenticated. The bark was air-dried at room temperature (26 ± 1°C) for two weeks. The dried stem bark was milled and macerated in 2.5l of distilled water for 48 h and filtered. A rotary evaporator was used to concentrate the aqueous extract by drying it at 60 ± 1°C. Freeze-drying gave 61.3g/kg (i.e., 6.13% yield) of a dark-brown, powdery, crude extract. Rat isolated uterine horns were mounted in 25-ml Iworx tissue organ-baths containing De Jalon׳s physiological solution, and exposed to graded concentrations of SBE (25, 50, 100, 200, 300, 400mg/ml/kg). The effects of SBE and atropine, oxytocin, verapamil, indomethacin, acetylcholine, serotonin, cimetidine and histamine on the isolated uterine muscles, were recorded using LabScribe2 software. RESULTS: The aqueous stem bark extract of S. birrea produced significant (p<0.05) concentration-dependent contractions of the uterine horn muscle preparation reaching a maximum at the 300 mg/ml dose. SBE mimicked and potentiated uterine muscle contractile effects of oxytocin (0.5-5 µU/ml) and acetylcholine (0.1-3 µg/ml). Pre-incubation of tissues with atropine (1-3 µg/ml), non-significantly (p>0.05) inhibited SBE-induced contractions on uterine muscles. Verapamil (2 µg/ml), indomethacin and -p-tosyl-l-phenylalanine-chloromethyl-ketone (TPCK) inhibited the contractile effects of SBE (25-400mg/ml/kg), suggesting possible calcium-mediated mechanism of action for SBE and possible COX-enzyme inhibition. Pre-incubating tissues with histamine (10(-8)-10(-5)M) resulted in relaxation of the uterus, while cimetidine potentiated the contractile effects of SBE. Serotonin potentiated the contractile effects of SBE. CONCLUSION: These results indicate that SBE causes contraction on uterine smooth muscles possibly through its effects on oxytocin, acetylcholine and serotonin receptors. As a result SBE should not be used by patients suffering from dysmenorrhoea as it can worsen it or pregnant patients as it can result in miscarriage/abortion.

Cardiovascular effects of Boophone disticha aqueous ethanolic extract on early maternally separated BALB/C mice.

ETHNOPHARMACOLOGICAL RELEVANCE: There are a number of reports from traditional medical practice in Zimbabwe and neighboring countries and few in vitro studies suggesting an effect with extracts of Boophone disticha in some forms of anxiety disorder. AIM OF THE STUDY: In order to validate the use of Boophone disticha in treatment of anxiety, this study was set to determine the effects of the plant extracts on blood pressure (BP) and heart rate (HR) in adult BALB/c mice subjected to repeated early maternal separation (MS) stress. MATERIALS AND METHODS: To test whether early life stress increases anxiety in mice, non-invasive tail cuff method was used to examine the autonomic nervous system activity by assessing cardiovascular reactivity and response to acute mixing stress (AMS) and restraint stress (RS) in adult mice subjected to early postnatal stress as compared to control. AMS-induced cardiovascular response was then evaluated in adult MS mice treated with Boophone disticha as compared to vehicle and diazepam. RESULTS: Comparisons of the BP and HR measurements indicated that MS significantly reduced AMS-induced HR responses in BALB/c mice when compared with control. Boophone disticha treatment significantly reduced AMS-induced BP response in BALB/c MS mice as compared to vehicle and diazepam treatments. CONCLUSIONS: Our findings demonstrate for the first time that postnatal stress can induce short-term changes in the sensitivity of the cardiovascular system to subsequent stress which can be reduced by treatment with a freeze dried aqueous ethanolic extract of Boophone disticha.

Acute oral toxicity and neurobehavioural toxicological effects of hydroethanolic extract of Boophone disticha in rats.

Boophone disticha (B. disticha) has been used systemically in traditional medical practice in Zimbabwe and neighbouring countries for the management of various central nervous system conditions including hysteria. Abuse of the plant by teenagers in Zimbabwe for its claimed hallucinogenic effects has also been reported, with the advent of serious toxicity in some cases. In the present work, we describe the acute toxicity and neurotoxicological effects of a freeze dried hydro-ethanolic plant extract of the bulb of B. disticha. Thirty-three adult (6-12 weeks old), non-pregnant female Sprague Dawley rats were used for the oral LD(50) estimation. Animals were given doses of 50, 120, 240, 360, 500 and 700 mg/kg and were observed using a modified Functional Observation Battery (FOB) for behavioural toxicity. The estimated oral LD(50) of the plant extract was between 120 and 240 mg/kg. For doses of 240 mg/kg and less, signs of toxicity began approximately 10 minutes after gavage, and the most prominent initial signs were head tremors (at 50 mg/kg) and body tremors, severe body tremors(>360 mg/kg) followed by convulsions. Generally, symptoms of toxicity lasted approximately 2 hours for doses of 240 mg/kg and less; and 3 hours for doses over 240 mg/kg for animals that survived. These results point to a rapid gastrointestinal absorption of the active principles in the plant extract. The most prominent neurotoxicological effects were increased flaccid limb paralysis and spastic hind-limb paralysis. Tachypnoea was noted at low doses and higher doses produced laboured breathing. The retropulsion observed with higher doses could indicate the reported hallucinogenic effects of the plant extract.

Drug information in Zimbabwe: 1990-1999.

OBJECTIVE: To assess the utilisation and development of the Zimbabwe Drug And Toxicology Information Service (DATIS) SETTING: The national drug and poisons information centre in Harare, Zimbabwe. METHOD: A survey of records at the Zimbabwe national Drug and Toxicology Information Service (DaTIS) for the period January 1990 to December 1999 was conducted and compared to a previous review. MAIN OUTCOME MEASURES: Average annual reporting rate, distribution of service users and report categories RESULTS: The mean (SD) reporting rate was 142.9 (81.6) p.a. with an increasing trend. Most contacts came from the capital city (67%). Pharmacists (40%) predominated in requests for drug information (DI), which comprised about three-quarters of reports, whereas toxicological enquiries mostly came from physicians (49%). Therapeutic categories mentioned most in DI reports were systemic anti-infective (24%) and nervous system agents (20.4%). Pesticides (28%) predominated in toxicology requests followed by pharmaceuticals (21%), largely nervous system (36%) and antiparasitic agents (23%). CONCLUSION: Compared to the previous decade, use of DaTIS had not grown significantly due to perceived resource constraints, lack of local political and institutional support and divided loyalty of staff. The drug and poison information components serves two distinct user populations with separate needs. Development plans for both DaTIS and other drug information services in Africa need to be realistic taking into account the resource constraints and local political and institutional support.

Toxicoepidemiology in Zimbabwe: pesticide poisoning admissions to major hospitals.

BACKGROUND: Acute pesticide poisoning (APP) is a well-recognized cause of morbidity and mortality but is not well described in developing countries. We describe the toxicoepidemiology of APP in Zimbabwe. METHODS: All cases of APP admitted to eight major referral hospitals in Zimbabwe from January 1998 to December 1999 (inclusive) were identified using ICD-9 codes and ward registers and relevant information recorded on a standard data collection sheet. RESULTS: There were a total of 914 single pesticide exposures. Almost half (49.1%) resulted from oral exposure to rodenticides, 42.2% from anticholinesterase-type pesticides (AChTP), mostly organophosphates (OP) that were responsible for over 90% of admissions from AChTP. Accidental and deliberate self-poisoning (27.1% and 58.6%, respectively) accounted for most cases with only eight homicides. The case fatality rate (CFR) in deaths/100 admissions was 6.8 [62 deaths; 95% Confidence Interval (CI) 5.2-8.6] and was significantly higher in males (9.4) than females (4.1) (CI for difference in proportions; 2.0-8.5). In addition, the CFR for deliberate self-poisoning (DSP), 6.5 deaths/100 admissions, was also significantly higher than that for accidental poisoning (0.8 deaths/100 admissions) (CI for difference in proportions 3.2-7.9). Organophosphates were implicated in 70.9% of all fatalities, with over 20% resulting from oral exposure to rat poison (RP). CONCLUSION: Organophosphates and rat poison (RP) are the leading causes of APP admissions to major referral hospitals in Zimbabwe, with most of the admissions being the result of deliberate self-poisoning. Greater control in the sale and use of these products could help prevent significant morbidity and mortality.