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.

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.