Gerda Fouche

Cytotoxicity and acetylcholinesterase inhibitory activity of an isolated crinine alkaloid from Boophane disticha (Amaryllidaceae)

ETHNOPHARMACOLOGICAL RELEVANCE Boophane disticha of the family Amaryllidaceae is used traditionally in southern Africa in the treatment of several neurological disorders. AIM OF THE STUDY Although acetylcholinesterase (AChE) inhibitory activity has been reported for this plant, the aim of the study was to identify and characterise the compound responsible for this activity using bioassay guided fractionation. Toxicity of the isolated compound was also assessed. MATERIALS AND METHODS Bioassay guided isolation of the active compound from the methanol extract was carried out using column chromatography, TLC and preparative thin layer chromatography. Structural elucidation was carried out using high field 1D and 2D NMR and mass spectroscopy. AChE inhibitory activity was determined using the Ellmans colorimetric method. Cytotoxicity assessment was determined in human neuroblastoma (SH-SY5Y) cells using the MTT and neutral red uptake assays. RESULTS The data obtained from the integration of the (1)H spectra confirmed the compound to be a 3:1 mixture of two epimers, with epimer A, 6α-hydroxycrinamine as the major epimer. The IC(50) value for AChE inhibitory activity of the compound was 445 μM. The compound was observed to be cytotoxic in both the MTT and neutral red assays with IC(50) values of 54.5 and 61.7 μM, respectively. CONCLUSION The present study describes for the first time, the isolation of 6-hydroxycrinamine, a crinine alkaloid, from the methanol extract of the bulbs of B. disticha. Although this compound possessed AChE inhibitory activity, it was found to be toxic to the neuroblastoma cells. Quantitative structure-activity relationship studies could be carried out to modify the structure in order to make it less toxic and improve its activity.

Investigation of in vitro and in vivo anti-asthmatic properties of Siphonochilus aethiopicus

AIM OF THE STUDY Asthma is a chronic inflammatory disease of the lungs, characterized by increased sensitivity to bronchoconstriction associated with infiltration of immune cells, mucus hypersecretion and structural remodelling of the airways. In South Africa, the indigenous plant Siphonochilus aethiopicus, is used by traditional health practitioners to treat colds, wheezing of the chest, coughs, influenza, sinus problems and mild asthma. In this study we aimed to investigate the potential anti-inflammatory and anti-allergic properties of S. aethiopicus in vitro and its efficacy in a mouse model of allergic asthma. MATERIALS AND METHODS The dried and powdered S. aethiopicus plant material was extracted separately with organic solvents (diethyl ether, ethanol) and water. Dried extracts as well as a purified furanoterpenoid compound present in the extracts were screened in vitro in a glucocorticoid and histamine H(1) receptor binding assay and a phosphodiesterase IV enzyme inhibition assay. Extracts were also evaluated for efficacy against ovalbumin (OVA)-induced allergic airway disease in mice. RESULTS Biological assaying of extracts of the plant and the isolated furanoterpenoid showed significant in vitro inhibition of glucocorticoid and histamine H(1) receptor binding and phosphodiesterase IV activity, supporting a possible anti-inflammatory, anti-allergic and bronchodilatory effect. Administration of S. aethiopicus extracts to OVA-sensitized and challenged mice significantly reduced lung inflammation and the percentage of eosinophils in bronchoalveolar lavage fluid but did not influence airway hyperreactivity. CONCLUSION This study provides evidence that S. aethiopicus has anti-inflammatory and anti-allergic properties in vitro and in vivo. These findings may support anecdotal accounts of its effectiveness against asthma, sinusitis, colds and flu.

Antifungal and antibacterial activity and chemical composition of polar and non-polar extracts of Athrixia phylicoides determined using bioautography and HPLC

BackgroundAthrixia phylicoides DC. (Asteraceae) is used medicinally in South Africa to treat a plethora of ailments, including heart problems, diabetes, diarrhoea, sores and infected wounds. It is also prepared in the form of a tea (hot decoction) taken as a refreshing, pleasant-tasting beverage with commercialization potential.MethodsExtracts of the dried ground aerial parts were prepared using organic solvents (diethyl ether, dichloromethane/methanol, ethyl acetate and ethanol) and water. These extracts were subjected to HPLC, TLC and bioautography analysis with the aim of linking a range of peaks visualized in HPLC chromatography profiles to antibacterial and antifungal activity of the same extracts.ResultsHPLC revealed a group of compounds extracted by more than one solvent. Compounds identified include inositol, caffeic acid, quercetin, kaempferol, apigenin, hymenoxin and oleanolic acid. The organic extracts displayed similar TLC profiles, and bioautography indicated approximately five antibacterial compounds, but only two antifungal compounds in these extracts. Bioautography indicated that cold water extracted the least antimicrobial compounds.ConclusionsSeveral previously unknown compounds were identified in Athrixia phylicoides extracts, and bioautography indicated a number of antibacterial and antifungal compounds. There were notable differences in chemical composition and bioactivity between the organic and aqueous extracts. Further research is necessary to fully characterize the active components of the extracts.

Antitrypanosomal isoflavan quinones from Abrus precatorius

Human African trypanosomiasis is a neglected tropical disease in sub Saharan Africa that is fatal if left untreated. In a search for new natural products with antitrypanosomal activity, we recently identified abruquinones B and I from Abrus precatorius as potent in vitro trypanocidal compounds with high selectivity indices. To obtain sufficient compound for in vivo efficacy tests in mice, a second batch of plant material was re-collected and extracted. However, the chemical profiles of the two batches differed, and additional abruquinones were isolated and identified by HR-ESI-MS, and 1D and 2D NMR ((1)H, (13)C, COSY, HMBC, HSQC, and NOESY) spectroscopy. Abruquinones J (1), K (2), and L (3) were new, while abruquinones A (4) and D (5) were known from the first batch of plant material. The absolute configuration of compounds 1 to 3 was determined by comparison of electronic circular dichroism (ECD) spectra with calculated ECD data. Compounds 2 to 5 showed high in vitro activity against T. b. rhodesiense (IC50 of 0.01, 0.02, 0.02 and 0.01 μM, respectively), and remarkable SIs of 508, 374, 1379, and 668, respectively.

Acaricidal activity of the organic extracts of thirteen South African plants against Rhipicephalus (Boophilus) decoloratus (Acari: Ixodidae).

The African blue tick, Rhipicephalus (Boophilus) decoloratus, is a common tick species found in South Africa and affects cattle production as well as vectoring pathogens in regions of Africa and Asia. In an attempt to develop a non-toxic, lower cost and environmentally friendly tick control method, twenty-six plant extracts were prepared from thirteen plant species using 99.5% acetone and 99% ethanol. The adapted Shaw Larval Immersion Test (SLIT) was used to test the efficacy of the extracts. A 1% solution of each of the plant extracts was prepared for efficacy testing and the ethanol extracts were found to have better acaricidal activity than the acetone extracts. The ethanol extract from the leaves and flowers of Calpurnia aurea had the best activity [corrected mortality (CM)=82.9%] which was followed by the stem extract of Cissus quadrangularis (CM=80.4%). The plant species were screened against Vero cells and were found to have low toxicity. From this study it is apparent that there is potential for the development of botanicals as natural acaricides against R. (B.) decoloratus.

Further studies on South African plants: Acaricidal activity of organic plant extracts against Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

The goal of our research is to develop a lower cost eco-friendly tick control method because acaricides that are commonly used to control ticks are often toxic, harmful to the environment or too expensive for resource-limited farmers. Acetone and ethanol extracts were prepared and their acaricidal activities determined against the southern cattle tick, Rhipicephalus (Boophilus) microplus. A 1% solution of each of the plant extracts was prepared for efficacy testing using the adapted Shaw Larval Immersion Test (SLIT). The acetone stem extract from Cissus quadrangularis (Vitaceae) and the ethanol leaf and flower extract from Calpurnia aurea (Fabaceae) had potent activity like that of the commercial acaricide, chlorfenvinphos [corrected mortality (CM)=100.0%]. The ethanol extracts of the stem of C. quadrangularis (CM=98.9%) and that of the roots, leaves and fruit of Senna italica subsp arachoides (CM=96.7%) also had good acaricidal activity. There is potential for the development of botanicals as natural acaricides against R. (B.) microplus that can be used commercially to protect animals against tick infestation. Further studies to isolate the acaricidal active compounds and to determine the environmental fate, species toxicity and skin toxicity of these plants species are, however, required before they can be considered as a treatment against ticks.

Anthelmintic activity of acetone extracts from South African plants used on egg hatching of Haemonchus contortus

The nematode, Haemonchus contortus, is responsible for major economic losses in the livestock industry. The management of parasites such as H. contortus has been through the use of synthetic parasiticides. This has resulted in the presence of residues in meat and milk, which affects food safety. The development of resistance to available anthelmintics coupled with their high cost has further complicated matters. This has led to the investigation of alternative methods to manage nematodes, including the use of plants and plant extracts as a potential source of novel anthelmintics. Acetone extracts were prepared from 15 South African plant species and their anthelmintic activity determined using the egg hatch assay (EHA). The leaf extract of Cleome gynandra had the best inhibitory activity (68% ± 3%) at a concentration of 2.5 mg/mL, followed by the stem extract of Maerua angolensis (65% ± 5%). The extracts had a relatively low toxicity on Vero cells determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cellular assay.

Acute and Subacute Toxicological Evaluation of the Aerial Extract of Monsonia angustifolia E. Mey. ex. A. Rich in Wistar Rats

The acute and subacute toxicity profile of the aerial extract of Monsonia angustifolia in Wistar rats was evaluated. The Organization for Economic Cooperation and Development (OECD) 420 guideline was adopted in the acute toxicity testing with a single oral dose of 5000 mg/kg (b.w.). For the 28-day daily oral dosing, the extract was administered at 75, 150, and 300 mg/kg b.w.; 1% ethanol in sterile distilled water was used as control. Clinical toxicity signs were subsequently evaluated. At a single dose of 5000 mg/kg b.w. the extract elicited no treatment-related signs of toxicity in the animals during the 14 days of experimental period. In the subacute toxicity, there was no significant difference in hematological, renal, and liver function indices. However, dose-dependent significant increases were observed on the plasma concentrations of white blood cell and platelet counts of the treated animals compared to the control group. While cage observations revealed no treatment-facilitated signs of toxicity, histopathological examinations of the kidneys and liver also showed no obvious lesions and morphological changes. These results suggest that the extract may be labelled and classified as safe and practically nontoxic within the doses and period of investigation in this study.

Ent-abietane diterpenoids from Suregada zanzibariensis Baill. (Euphorbiaceae), their cytotoxic and anticancer properties

Abstract The stem bark extract of Suregada zanzibariensis afforded a previously undescribed ent-abietane diterpenoid trivially named mangiolide (1) and a known jolkinolide B (2) via anticancer bioassay-guided fractionation. The CH2Cl2:MeOH extract of S. zanzibariensis was initially analysed for its anticancer properties against three cancer cell lines, renal (TK10), melanoma (UACC62), and breast (MCF7) and was found to be potent at low μg/mL ranges. Compound 1, 6α-acetoxy-14-keto-ent-abieta-7(8),13(15)-diene-16,12-olide (mangiolide) inhibited the growth of renal (TK10) with a GI50 of 0.02 μg/mL; a GI50 of 0.03 μg/mL for melanoma (UACC62) and a GI50 of 0.05 μg/mL for breast (MCF7) cancer cell lines. Compound 2, 8,13-diepoxy-13,15-ent-abietene-16,12-olide (jolkinolide B) inhibited the growth (GI50) of the cell lines at 3.31 μg/mL for renal (TK10), 0.94 μg/mL for melanoma (UACC62) and 2.99 μg/mL for the breast (MCF7). The structures were established on the basis of their spectroscopic analysis and the absolute stereostructures assigned using electronic circular dichroism (ECD).

Investigation of the acaricidal activity of the acetone and ethanol extracts of 12 South African plants against the adult ticks of Rhipicephalus turanicus

The acaricidal activity of acetone and ethanol extracts of 12 plant species was evaluated using the contact method on Rhipicephalus turanicus (Acari: Ixodidae) ticks at an initial concentration of 20% (200 mg/mL). Eight of the 12 plants had mortality greater than 50% and the acetone extracts had better acaricidal activity than the ethanol extracts. The acetone extract of Calpurnia aurea (leaves and flowers) had the highest corrected mortality (CM) of 92.2% followed by Schkuhria pinnata (whole plant) with a CM of 88.9%, Ficus sycomorus (bark and stems) 86.7% and Senna italica subsp. arachoides (roots, leaves and fruits) 83.3%. Selected extracts were tested at five different concentrations using the adult immersion test. From dose–response assays, EC50 values of 61.82 mg/mL, 115.21 mg/mL and 161.02 mg/mL were obtained for the acetone extracts of S. pinnata (whole plant), S. italica subsp. arachoides (roots, leaves and fruits) and C. aurea (leaves and flowers) respectively. The ethanol extract of Monsonia angustifolia (whole plant) had the highest CM of 97.8% followed by S. pinnata (whole plant) with a CM of 86.7%, C. aurea (leaves and flowers) 81.1% and Cleome gynandra (leaves) 77.8%. There is potential for the development of environmentally benign botanicals as natural acaricides against R. turanicus.