Biological activities of extracts and isolated compounds from Bauhinia galpinii (Fabaceae) and Combretum vendae (Combretaceae) as potential antidiarrhoeal agents

Diarrhoea is one of the killer diseases resulting from the dehydration and loss of electrolytes through profuse and excessive excretion of loose stool. The pathoaetiologies include infections, intestinal inflammation, imbalanced intestinal oxidative homeostasis and altered motility. Treatment with oral rehydration therapy (ORT) is a key intervention especially in secretory diarrhoea as supportive therapy. Symptomatic and non-symptomatic therapies directed at treating the intestinal tissues are available. However, these conventional treatments are still not sufficient in curing diarrhoea due to their associated hazards such as the development and spread of drugresistant pathogens, changes in normal intestinal bacteria flora and potential chronic toxicity. Therapies targeted at intestinal tissue include antimotility and antisecretory agents have adverse effects such as addictiveness, constipation and fatal ischaemic colitis. Many ethnopharmacological and ethnobotanical therapies for treating diarrhoea exist among different cultures. The aims of this study were to evaluate the biological activities of plant extracts against some diarrhoeal pathophysiologies. A literature search in English of published articles and books that discussed ethnobotanical uses of medicinal plants in southern Africa was conducted. A list of 230 medicinal plants used in South African traditional medicines for treating diarrhoea and associated complications was created. The list included family, genus, species, biological activities and bioactive isolates as well as the remedies for diarrhoea. Twenty seven species were selected to evaluate for antimicrobial, antioxidant and anti-inflammatory activities. Safety of the plants was determined by determining the cytotoxicity of the crude extracts against Vero African green monkey kidney cell lines using a standard method. Motility effects of Bauhinia galpinii (BGE) and Combretum vendae (CVE) were determined by modulation of the contractility process of the isolated rat ileum induced by spasmogens. Phenolic compositions of the crude extract were determined using various standard methods and finally bioactivity guided isolation of antimicrobial and antioxidant compounds from BGE and CVE were carried out using open column chromatography. Identification and characterization of the isolated compounds was achieved by NMR, EI-MS and UV spectroscopy. The non-polar fractions had good antimicrobial activities with MIC ranged between 19 – 1250 μg/ml while the polar fraction had moderate antimicrobial activities with MIC ranged between 39 - >2500 μg/ml. In general the non-polar fractions had a higher antimicrobial activity. The crude extracts contained wide range phenolic compounds with a total phenolic (74.91±1.26 to 467.04±15.82 mg GAE/g plant material), and total flavonoids (11.27±3.37 to 176±5.96 mg EQ/g plant material). The antioxidant activities were concentrated and potentiated in the polar fractions. The non-polar fractions had poor antioxidant activities with EC50 values ranging from 0.21±0.03 to 303.65±3.84 μg/ml for DPPH radical scavenging and 0.43±0.03 to 1709±91.44 μg/ml for ABTS radical scavenging. The crude extracts had selective COX-1 inhibitory activities ranging between 41.70 to 84.61% and had no COX-2 inhibitory activity. All the extracts tested had 15-LOX inhibitory capacity with LC50 values ranging between 0.86±0.27 and 111.44±37.28 μg/ml. The cytotoxicity results indicated a wide variation in toxic potential of the crude extracts with LC50 values ranging from 3.51 to 741.90μg/ml. The BGE extracts had dual activities as spasmolytic by stimulating the spontaneous contractility and also agonised contractions induced by spasmogens but it inhibited K+ induced contraction. CVE had spasmodic activities through a multiple mechanisms inhibiting contractions induced by spasmogens and K+ in a dosedependent manner. Several bioactive xompoundswere isolated from the Combretum vendee leaves, There were triterpenoids (ursol-12-en-28-oic acid, mixtures of corosolic acid and maslinic acid, and asiatic acid and arjunolic acid) as well as bibenzyls combretastatin B5-O-2’-β-D-glucopyranoside, combretastatin B1-O-2’-β-D glucopyranoside and a flavonoid (apigenin). From Bauhinia galpinii the following bioactive compounds were isolated and characterized: P-3 ethoxy sitosterol, one new flavone (5, 7, 4’ 5’ tetrahydroxy-2’-methoxyflavone (isoetin 2’-methyl ether) or 5, 7, 2’ 5’ tetrahydroxy-4’-methoxyflavone (isoetin 4’-methyl ether)), 3, 5, 7, 3’, 4’-pentahydroxyflavone and 3, 5, 7, 3’, 4’, 5’- hexahydroxyflavone, quercetin-3-O-β-galactopyranoside and myricetin-3-O-β-galactopyranoside. The extraction protocol used in this work potentiated the antimicrobial activities in the non-polar fractions while antioxidant activities were potentiated in the polar fractions. This indicated that using polar solvents as extractant for treating infectious diarrhoea may not be quite effective unless some other antidiarrhoeal mechanisms are involved. Therefore, mixture of organic solvent (ethanol) and water can be recommended for broad-based activity. Bauhinia galpinii extracts had a dual- mechanism of action (prokinetic and relaxant) on gastro-intestinal motility, depending on the prevalent patho-physiological condition and Combretum vendee mediated spasmolytic effects on isolated rat ileum through multiple inhibitions of a wide range of contractile stimuli. Hence, the presence of multiple acting spasmolytic activities in the plant extract might be contributing towards its effectiveness in treating diarrhoea and abdominal spasm. The uses of these plants in traditional medicine need to be monitored closely because of the selective inhibition of COX-1 and its associated GIT injury, and the high toxicity potential of some of the extracts. Further work evaluating the antidiarrhoea mechanisms, identification and isolation of bioactive compounds, sub-acute and acute toxicity of the plant extracts is recommended.Thesis (PhD)--University of Pretoria, 2012.Paraclinical Sciencesunrestricte

Biological activities of extracts and isolated compounds from Bauhinia galpinii (Fabaceae) and Combretum vendae (Combretaceae) as potential antidiarrhoeal agents

Diarrhoea is one of the killer diseases resulting from the dehydration and loss of electrolytes through profuse and excessive excretion of loose stool. The pathoaetiologies include infections, intestinal inflammation, imbalanced intestinal oxidative homeostasis and altered motility. Treatment with oral rehydration therapy (ORT) is a key intervention especially in secretory diarrhoea as supportive therapy. Symptomatic and non-symptomatic therapies directed at treating the intestinal tissues are available. However, these conventional treatments are still not sufficient in curing diarrhoea due to their associated hazards such as the development and spread of drugresistant pathogens, changes in normal intestinal bacteria flora and potential chronic toxicity. Therapies targeted at intestinal tissue include antimotility and antisecretory agents have adverse effects such as addictiveness, constipation and fatal ischaemic colitis. Many ethnopharmacological and ethnobotanical therapies for treating diarrhoea exist among different cultures. The aims of this study were to evaluate the biological activities of plant extracts against some diarrhoeal pathophysiologies. A literature search in English of published articles and books that discussed ethnobotanical uses of medicinal plants in southern Africa was conducted. A list of 230 medicinal plants used in South African traditional medicines for treating diarrhoea and associated complications was created. The list included family, genus, species, biological activities and bioactive isolates as well as the remedies for diarrhoea. Twenty seven species were selected to evaluate for antimicrobial, antioxidant and anti-inflammatory activities. Safety of the plants was determined by determining the cytotoxicity of the crude extracts against Vero African green monkey kidney cell lines using a standard method. Motility effects of Bauhinia galpinii (BGE) and 2500 μg/ml. In general the non-polar fractions had a higher antimicrobial activity. The crude extracts contained wide range phenolic compounds with a total phenolic (7 4.91 ±1.26 to 467.04±15.82 mg GAE/g plant material), and total flavonoids (11.27±3.37 to 176±5.96 mg EQ/g plant material). The antioxidant activities were concentrated and potentiated in the polar fractions. The non-polar fractions had poor antioxidant activities with EC50 values ranging from 0.21 ±0.03 to 303.65±3.84 μg/ml for DPPH radical scavenging and 0.43±0.03 to 1709±91.44 μg/ml for ABTS radical scavenging. The crude extracts had selective COX-1 inhibitory activities ranging between 41.70 to 84.61% and had no COX-2 inhibitory activity. All the extracts tested had 15-LOX inhibitory capacity with LC50 values ranging between 0.86±0.27 and 111.44±37.28 1-μg/ml. The cytotoxicity results indicated a wide variation in toxic potential of the crude extracts with LC50 values ranging from 3.51 to 741.901-μg/ml. The BGE extracts had dual activities as spasmolytic by stimulating the spontaneous contractility and also agonised contractions induced by spasmogens but it inhibited K+ induced contraction. CVE had spasmodic activities through a multiple mechanisms inhibiting contractions induced by spasmogens and K+ in a dosedependent manner. Several bioactive xompoundswere isolated from the <i<Combretum vendae leaves, There were triterpenoids (ursol-12-en-28-oic acid, mixtures of corosolic acid and maslinic acid, and asiatic acid and arjunolic acid) as well as bibenzyls combretastatin 85-0-2'-β-D-glucopyranoside, combretastatin 81-0-2'-β-Dglucopyranoside and a flavonoid (apigenin) .. From Bauhinia galpinii the following bioactive compounds were isolated and characterized: β-3 ethoxy sitosterol, one new flavone (5, 7, 4' 5' tetrahydroxy-2'-methoxyflavone (isoetin 2'-methyl ether) or 5, 7, 2' 5' tetrahydroxy-4'-methoxyflavone (isoetin 4'-methyl ether)), 3, 5, 7, 3', 4'-pentahydroxyflavone and 3, 5, 7, 3', 4', 5'hexahydroxyflavone, quercetin-3-0-β-galactopyranoside and myriceti n-3-0-β-galactopyranoside The extraction protocol used in this work potentiated the antimicrobial activities in the non-polar fractions while antioxidant activities were potentiated in the polar fractions. This indicated that using polar solvents as extractant for treating infectious diarrhoea may not be quite effective unless some other antidiarrhoeal mechanisms are involved. Therefore, mixture of organic solvent (ethanol) and water can be recommended for broad-based activity. Bauhinia galpinii extracts had a dual- mechanism of action (prokinetic and relaxant) on gastro-intestinal motility, depending on the prevalent patho-physiological condition and Combretum vendae mediated spasmolytic effects on isolated rat ileum through multiple inhibitions of a wide range of contractile stimuli. Hence, the presence of multiple acting spasmolytic activities in the plant extract might be contributing towards its effectiveness in treating diarrhoea and abdominal spasm. The uses of these plants in traditional medicine need to be monitored closely because of the selective inhibition of COX-1 and its associated GIT injury, and the high toxicity potential of some of the extracts. Further work evaluating the antidiarrhoea mechanisms, identification and isolation of bioactive compounds, sub-acute and acute toxicity of the plant extracts is recommended.Thesis (PhD)--University of Pretoria, 2013.Paraclinical Sciencesunrestricte

Evaluation of pharmacological activities, cytotoxicity and phenolic composition of four Maytenus species used in southern African traditional medicine to treat intestinal infections and diarrhoeal diseases

BACKGROUND: Microbial infections and resulting inflammation and oxidative stress are common pathogenesis of gastrointestinal tract (GIT) disorders. In South Africa, several species of the genus Maytenus are used in traditional medicine to treat various infectious diseases. Most of the previous work on this genus was focused on nonpolar extracts from the root and bark. In this study, leaf extracts of polar extracts of Maytenus peduncularis, Maytenus procumbens, Maytenus senegalensis and Maytenus undata were evaluated for antimicrobial, anti-inflammatory and antioxidant activities to determine their efficacy as therapeutic agents in GIT disorders. METHODS: Phenolic-enriched leaf extracts and fractions were prepared by extracting with acidified 70% methanol and solvent-solvent fractionation. The activities of the fractions against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Enterococcus faecalis as well as clinical isolates of Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans were determined using a serial microplate dilution method. Antioxidant activities were determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzthiazoline-6- sulphonic acid) (ABTS), hydroxyl (OH) radical scavenging and linoleic acid peroxidation inhibitory assays. The phenolic composition as well as the cytotoxicity against Vero cell lines of the crude extracts was evaluated using various standard protocols. RESULTS: The antimicrobial activities were concentrated in the non-polar fractions of hexane, dichloromethane and ethyl acetate (MICs 19–312 μg/ml). The crude extracts and polar fractions (butanol and water) had moderate to poor antimicrobial activity (MICs 312 to above 2500 μg/ml). The crude extracts and polar fractions had good antioxidant activity (EC50 values varied from 1.22 to 607 μg/ml, 1.71 to 312 μg/ml and 23 to 284 μg/ml for DPPH, ABTS and OH respectively. Linoleic acid peroxidation inhibition EC50 values of the crude extracts ranged between 27 and 39 μg/ml with relatively low toxicity against Vero cell lines (IC50 values 87 to 187 μg/ml). Fractionation of a crude extract with low activity could lead to fractions with more potent activity. CONCLUSION: This study justifies the traditional use of leaf crude extracts and fractions from these four plants to remedy gastrointestinal disorders resulting from infection, inflammation and oxidative stress complications. The study also provides rationale for the use of leaf extracts with same beneficial effects in place of unsustainable root and bark harvest.The South African Medical Research Councilhttp://www.biomedcentral.com/bmccomplementalternmedam201

Cytotoxic, antimicrobial, antioxidant, antilipoxygenase activities and phenolic composition of Ozoroa and Searsia species (Anacardiaceae) used in South African traditional medicine for treating diarrhoea

The safety and effectiveness of many of the medicinal plants used in traditional medicine by rural people with little or no access to allopathic drugs is yet to be evaluated. With this in mind, Ozoroa and Searsia (previously known as Rhus) species traditionally used in South Africa to treat microbial infections and gastrointestinal disorders were selected for in vitro evaluation of biological activities and cytotoxicity. Phenolic-enriched leaf extracts were prepared using mixture of 1% HCl acidified 70% acetone and n-hexane. The crude extractwas further fractionated with solvent of different polarities. Crude extracts and fractionswere tested against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecalis, Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans. In addition, the antioxidant potentialswere determined by DPPH, ABTS, hydroxyl radical scavenging and linoleic acid peroxidation inhibition. The cytotoxic activity of the crude extracts was assayed against Vero cells. The crude extract and the various fractions had good biological activities. The most noteworthy activity is the growth inhibition of the hexane and dichloromethane fractions with MIC values as low as 19 μg/ml. The ethyl acetate and butanol fractions had moderate to low antimicrobial activities with MICs ranging from 39 to 2500 μg/ml. The polar fractions were more active against the fungal pathogens compared with the non-polar fraction. In the DPPH antioxidant assays, the active compounds were concentrated in the polar fractions (IC50 of the crude extract ranged between 0.90 and 15.82 μg/ml). The ethyl acetate fraction was the most active (IC50 ranging between 0.84 and 7.92 μg/ml). Although thewater fraction was the most polar, the antioxidant activities were low due to the transfer of the active components into the ethyl acetate and butanol fractions. The crude extracts also had good linoleic acid peroxidation inhibition (LC50 ranging between 13.99 and 40.45 μg/ml). Crude extracts and fractions of the Ozoroa mucronata, O. paniculosa, Searsia leptodictya, S. pendulina, and S. pentheri species tested in this study had good activities relating to diarrhoea mechanisms of pharmacological relevance. However, use of phenolic-enriched crude extracts from these plants for diarrhoeal treatment or any other diseases need to be applied with caution as most of the plant extracts were reasonably toxic against Vero cell line. A next step in the possible application of these extracts to treat diarrhoea would be to identify the bioactive and toxic compounds.South African Medical Research Council (MRC).http;//www.elsevier.com/locate/sajb2015-11-30hb201

Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

ETHNOPHARMACOLOGICAL IMPORTANCE : Infections and gastrointestinal (GIT) disorders such as diarrhoea causes many problems in human health and animal production. Many Combretum species are used in traditional medicine to treat various diseases by rural people in Africa and Asia. Much of the work done to date on some species to validate their ethnopharmacological use was on the non-polar or intermediate polarity components. Many species are yet to be studied against relevant disease parameters using more polar extracts. AIMS : The polar components were extracted and fractionated by solvent-solvent fractionation to yield fractions of different polarities. The activity of these fractions on different parameters that could be involved in infectious and gastrointestinal track (GIT) disorders was investigated. The cytotoxic activities of the extracts were also determined to evaluate the potential of these extracts to combat diarrhoea in production animals. MATERIALS AND METHODS : Phenolic-enriched leaf extracts of Combretum bracteosum (Cob), Combretum padoides (Cop), Combretum vendae (Cov) and Combretum woodii (Cow) were obtained by extracting with a mixture of 70% acetone acidified with 1% HCl and n-hexane. The extract was sequentially treated by solvent-solvent fractionation with dichloromethane, ethyl acetate, and butanol to yield fractions with a large variation in polarity. The phenolic constituents of the extracts and fractions were determined using standard procedures. The antioxidant activities were determined using various standard methods. The minimum inhibitory concentrations (MICs) of the crude extracts and fractions against four bacterial and three fungal strains were assessed with a microplate serial dilution method. Cyclooxygenase (COX) and lipoxygenase (LOX) enzyme inhibitory assays and cytotoxicity studies against Vero cells were also carried out. RESULT : Some of the fractions had much higher antioxidant activity than the positive controls. The average EC50 values of the extracts for the DPPH and ABTS antioxidant assays were 0.21-12 μg/ml (Cop), 0.25-16 μg/ml (Cov), 0.33-9.41 μg/ml (Cow) and 4.97-85 μg/ml (Cob) respectively while the mean EC50 values for the positive controls ascorbic acid and trolox were 1.28-1.51 and 1.02-1.19 μg/ml respectively. All the crude extracts inhibited lipid peroxidation of linoleic acid by more than 80% at a concentration of 64 μg/ml. Even though some crude extracts had relatively low antimicrobial activity, fractions from these had high activity. Cop had the highest antibacterial activity with MICs ranging between 19-2500 μg/ml,followed by Cov with MICs ranging between 39-625 μg/ml. Cop also had the highest antifungal activity with MICs between 19-625 μg/ml. The MIC for Cow and Cov ranged from 19 to 1250 μg/ml. The extracts had no activity against COX 1 and 2 enzymes in the anti-inflammatory assay but had good lipoxygenase inhibition. The crude extracts had high concentrations of hydrolysable tannin (gallotannin). A good correlation (R2= 0.99) was found between the antioxidant activity and total tannin content indicating that, gallotannins may be responsible for the antioxidant activity. CONCLUSION : The results obtained in this study provided a scientific basis for the use of leaf extracts from these plant species to treatinfectious and GIT disorders. In general non-polar fractions had a high antimicrobial activity and polar fractions had a high antioxidant activity.South African Medical Research Council and the National Research Foundation (NRF), South Africa.http://www.elsevier.com/locate/jephb201

Clerodendrumic acid, a new Triterpenoid from Clerodendrum glabrum (Verbanaceae), and antimicrobial activities of fractions and constituents

One new triterpenoid, (3β,11α,19β)-3-(butanoyloxy)-11-hydroxytaraxast-20(30)-ene-23,28-dioic acid (clerodendrumic acid; 1) was isolated from the hexane extract of the leaves of Clerodendrum glabrum var. glabrum along with heptadecanoic acid (2). The structure of the new compound was elucidated by interpretation of its NMR (1D and 2D), MS, and IR data. Combined fractions C and D from the column chromatography of the hexane extract exhibited significant antifungal activities (average MIC of 0.10 mg/ml) against Candida albicans and Cryptococcus neoformans. C. albicans was relatively resistant to clerodendrumic acid (1; MIC 125 μg/ml) and was resistant to heptadecanoic acid (2; MIC 188 μg/ml). Both compounds had low antibacterial activities against two Gram-positive and two Gram-negative bacteria with average MIC values of 157 and 172 μg/ml, respectively. Compounds 1 and 2 were relatively nontoxic against monkey kidney Vero cells in vitro with IC50 values of 202.6 and 108.4 μg/ml, respectively.National Research Foundation (NRF) and the Netherlands Universities Foundation for International Cooperation (NUFFIC).http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1522-2675hb201

Isolation and characterization of two acaricidal compounds from Calpurnia aurea subsp. aurea (Fabaceae) leaf extract

The menace caused by ticks and tick-borne diseases is a major limitation to the livestock industry in Africa. The high costs and non-availability of synthetic, chemical acaricides to resource-limited farmers, resistance of ticks to available acaricides and residue problems in meat and milk consumed by humans further complicate matters. The use of plant extracts as a possible source of new acaricides has received much interest in the last decade. In our endeavour to discover natural acaricidal compounds, tick toxicant bioassays were conducted and the chloroform fraction of Calpurnia aurea ethanol leaf extract had good acaricidal activity. Further purification of the fraction revealed two flavonoids, isolated from C. aurea for the first time. These flavonoids were characterized as apigenin-7-O-β-d-glycoside and isorhoifolin by means of NMR spectroscopic and mass spectrometry analysis. Isorhoifolin was the most potent compound (LC50 = 0.65 mg/ml), was not cytotoxic and should be further investigated for its potential as an acaricidal agent.The Technology Innovation Agency in conjunction with the Council for Scientific and Industrial Research, University of Pretoria and the Schlumberger Faculty for the Future Foundation.http://link.springer.com/journal/104932019-07-01hj2018Paraclinical Science

Evaluation of several tree species for activity against salmonella

Handling and consumption of contaminated foods (meat, milk and eggs) are considered a major source of infection in humans. This public health risk reinforces the need for close monitoring and collaboration between public health and veterinary authorities to mitigate the risk at the humananimal interface necessary for health and food security. Gastroenteritis that is not self-limiting is mostly treated with a wide range of antibiotics. The indiscriminate use of these antibiotics has resulted in the upsurge of resistant and multiresistant strains of bacteria. This complicates treatment, especially in patients with human immunodeficiency virus (HIV) infection, necessitating the search for novel, cheaper, safer and efficacious antibacterial products. Recent in vitro studies have revealed that indigenous South African plants possess antimicrobial properties against gastrointestinal disorders and diarrhoea-causing organisms. In a preliminary screening, the antibacterial activities of acetone, ethanol, methanol and water extracts of the leaves were determined using a two-fold serial microdilution method against a range of pathogenic bacteria (Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus, Escherichia coli, Salmonella Typhimurium and Pseudomonas aeruginosa). The plant species investigated were Protorhus longifolia, Searsia leptodictya, Carissa macrocarpa, Combretum bracteosum, Kirkia wilmsii, Loxostylis alata, Brachychiton acerifolium, Brachychiton bidwillii, Noltea africana and Blighia unijugata. All the extracts had activity against at least one of the test organisms over an incubation period of 24 hours. The average MIC values of the plant extracts against the different bacteria ranged from 0.2 mg/ml to 1.4 mg/ml. The Gram-positive bacteria (S. aureus, B. cereus and E. faecalis) were more susceptible to the plant extracts than the Gramnegative bacteria (E. coli, S. Typhimurium and P. aeruginosa). P. longifolia and L. alata extracts were the most active against nearly all the bacteria tested with MIC values as low as 0.02 mg/ml. L. alata was selected for further work to isolate compounds active against Salmonella species.Poster presented at the University of Pretoria, Faculty of Veterinary Science Faculty Day, September 07, 2017, Pretoria, South Africa.Includes bibliographical referencesab201

Ultrastructure changes induced by the phloroglucinol derivative agrimol G isolated from Leucosidea sericea in Haemonchus contortus

Plant extracts used for the treatment of helminth infections in sheep are an alternative to chemical anthelmintic drugs. Previous studies have reported the anthelmintic activity of acetone leaf extracts of Leucosidea sericea. For this study, we evaluate the ultrastructure changes induced by the acetone leaf extract of L. sericea and the component agrimol G (AG) that was isolated for the first time on adult haemonchus parasites. Adult haemonchus parasites harvested from sheep were incubated with the plant extract and AG for 3 h and evaluated by both scanning and transmission electron microscopy in comparison and in combination with albendazole or ivermectin. In all cases the method of evaluation shows ultrastructural changes, with albendazole inducing mitochondrial damage and ivermectin inducing muscle degeneration, both as previously described. Incubation with the plant extract and AG resulted in the formation of numerous non-membrane bound multi-vesicular like bodies and evenly spread disruptions/erosion in the epicuticle. Combining AG with ivermectin or albendazole resulted in an absence of effect of AG. Based on the structural changes induced by AG, together with the absence of an effect in combination with ivermectin and albendazole would suggest a disrupted microtubular network. The latter does however require biochemical confirmation.The National Research Foundation of South Africahttp://www.elsevier.com/locate/yexpr2020-12-01hj2020Paraclinical Science

Investigations of medicinal plants used traditionally in southern Africa to treat helminth infections in sheep

Haemonchus contortus is a major gastrointestinal helminth parasite causing haemonchiasis in production animals. Infections are characterized by fever, anaemia, weight loss and ultimately death. Haemonchiasis is a serious economic challenge globally resulting in poor reproductive efficiency, increased susceptibility to bacterial and fungal infections, as well as low production of wool, milk and meat. Treatments with synthetic drugs are currently the only effective way to control the infestation. Albendazole is a drug of choice against this parasite; it acts by binding to tubulins and causes depolymerisation of microtubules. No other anthelminthic compounds of comparable efficacy are available yet and there is a critical need to find alternative drugs. An alternative strategy is to investigate ethnoveterinary plants with putative anthelminthic properties. The aim of this study was to evaluate selected plant extracts for anthelmintic activity in vitro against Haemonchus contortus, as well as antifungal activity to determine correlations in these activities. Cytotoxicity of the plant extracts was also tested, and isolation of compounds was performed. The crude extracts of Diospyros whyteana and Peddiea africana showed low cytotoxicity with LC50 greater than 1 mg/ml. Good antifungal activity was observed in D. whyteana, Peddiea africana and Schotia brachypetala with MICs ranging from 40-160 mg/ml against Candida albicans and selectivity index (SI) values from 6.25-12.5. In the egg hatch inhibition assay, D. whyteana had good results with EC50=0.7377 mg/ml for acetone while water extracts were 1.508, thus the SI ranged from 0.66 to 1.35. Water extracts showed better anthelmintic activity compared to acetone extracts of D. whyteana, P. africana and Schotia brachypetala. The extracts had good activity in the egg hatch assay, good antifungal activity, and they were non-toxic to Vero cells. Four bioactive compounds have been isolated from Diospyros whyteana with excellent activity against Candida albicans and the structures of these are being determined.Poster presented at the University of Pretoria, Faculty of Veterinary Science Faculty Day, August 25, 2016, Pretoria, South Africa.ab201