Evaluation of the wound healing properties of South African medicinal plants using zebrafish and in vitro bioassays.

ETHNOPHARMACOLOGICAL RELEVANCE: In South Africa, medicinal plants have a history of traditional use, with many species used for treating wounds. The scientific basis of such uses remains largely unexplored. AIM OF THE STUDY: To screen South African plants used ethnomedicinally for wound healing based on their pro-angiogenic and wound healing activity, using transgenic zebrafish larvae and cell culture assays. MATERIALS AND METHODS: South African medicinal plants used for wound healing were chosen according to literature. Dried plant material was extracted using six solvents of varying polarities. Pro-angiogenesis was assessed in vivo by observing morphological changes in sub-intestinal vessels after crude extract treatment of transgenic zebrafish larvae with vasculature-specific expression of a green fluorescent protein. Subsequently, the in vitro anti-inflammatory, fibroblast proliferation and collagen production effects of the plant extracts that were active in the zebrafish angiogenesis assay were investigated using murine macrophage (RAW 264.7) and human fibroblast (MRHF) cell lines. RESULTS: Fourteen plants were extracted using six different solvents to yield 84 extracts and the non-toxic (n=72) were initially screened for pro-angiogenic activity in the zebrafish assay. Of these plant species, extracts of Lobostemon fruticosus, Scabiosa columbaria and Cotyledon orbiculata exhibited good activity in a concentration-dependent manner. All active extracts showed negligible in vitro toxicity using the MTT assay. Lobostemon fruticosus and Scabiosa columbaria extracts showed noteworthy anti-inflammatory activity in RAW 264.7 macrophages. The acetone extract of Lobostemon fruticosus stimulated the most collagen production at 122% above control values using the MRHF cell line, while all four of the selected extracts significantly stimulated cellular proliferation in vitro in the MRHF cell line. CONCLUSIONS: The screening of the selected plant species provided valuable preliminary information validating the use of some of the plants in traditional medicine used for wound healing in South Africa. This study is the first to discover through an evidence-based pharmacology approach the wound healing properties of such plant species using the zebrafish as an in vivo model.

The mutagenic and antimutagenic activity of Sutherlandia frutescens extracts and marker compounds.

BACKGROUND: Sutherlandia frutescens (L.) R. Br is endemic to Southern Africa where it has been traditionally used for cancer and diabetes. In recent times it has been marketed for its reputed (but not proven) anticancer, antidiabetic and anti-HIV properties. Little is known about the mutagenic and antimutagenic potential of extracts and common marker compounds of Sutherlandia frutescens. Therefore this study aimed to investigate the putative efficacy and possible long-term adverse effects of using this herb. METHODS: Ethylacetate (EA) and 50% Methanol (MeOH) extracts were screened for mutagenic and antimutagenic activity using the Ames assay utilising TA97a, TA98, TA100 and TA102 in the presence and absence of metabolic activation. Four compounds, L-arginine, L-canavanine, GABA and D-pinitol known to occur in sutherlandia were also included. The total polyphenolic content of the both extracts was determined using the Folin-Ciocalteau method and FRAP and ABTS were used to determine the anti-oxidant potential of the extracts. RESULTS: The extracts and the standards did not show any cytotoxicity except in TA97a. The EA extract exhibited antimutagenicity against all the bacterial strains at all concentrations tested. The MeOH extract showed both pro-mutagenic and antimutagenic activities with 2-acetamidofluorene and aflatoxin B1 in the presence of metabolic activation of TA98 and TA100, respectively. All compounds, except L-canavanine exhibited antimutagenic activity against all strains. L-canavanine, on the other hand showed co-mutagenicity with 9-aminoacridine on TA97a, at all test concentrations. The extracts and pure compounds exhibited their antimutagenic activity in a dose response manner. L-arginine and GABA showed an some antimutagenic response. EA extract had three times the total phenolic content (12.56 µg GE / mg) observed in the MeOH extract. There was correlation between total phenolic content, antioxidant potential and antimutagenicity. CONCLUSION: Both extracts exhibited a protective effect, with the EA extract exhibiting greater potency. L-canavanine acted as a co-mutagen in a dose response manner without metabolic activation. It is suggested that the EA extract be priotized for future development work as it showed a better risk profile and activity.

Peanuts, Aflatoxins and Undernutrition in Children in Sub-Saharan Africa.

Peanuts (Arachis hypogaea) is an important and affordable source of protein in most of Sub-Saharan Africa (SSA) and a popular commodity and raw material for peanut butter, paste and cooking oil. It is a popular ingredient for foods used at the point of weaning infants from mother's milk. It is at this critical point that childhood undernutrition occurs and the condition manifests as stunting, wasting and growth restriction and accounts for nearly half of all deaths in children under five years of age in SSA. Undernutrition is multi-factorial but weaning foods contaminated with microbiological agents (bacteria and fungi) and natural toxins have been shown to play a big part. While peanuts may provide good nutrition, they are also highly prone to contamination with mycotoxigenic fungi. The high nutritive value of peanuts makes them a perfect substrate for fungal growth and potential aflatoxin contamination. Aflatoxins are highly carcinogenic and mutagenic mycotoxins. This article reviews the nutritional value and aflatoxin contamination of peanuts, the role they play in the development of childhood malnutrition (including the different theories of aetiology) and immunological problems in children. We also discuss the control strategies that have been explored and advocacy work currently taking shape in Africa to create more awareness of aflatoxins and thus combat their occurrence with the goal of reducing exposure and enhancing trade and food safety.

Aflatoxin biomarkers in hair may facilitate long-term exposure studies.

Aflatoxins are highly toxic fungal metabolites produced by some members of the Aspergillus species. They are low molecular weight lipophilic compounds that are easily absorbed from the gastrointestinal tract. They contaminate most staple foods, including maize, peanuts, peanut butter and sorghum mainly in the tropics where hot and humid conditions promote fungal growth. Absorbed aflatoxins are metabolized by the cytochrome P450 enzyme system in the liver into toxic metabolites. Aflatoxin B (AFB)1 is the most toxic, carcinogenic and mutagenic naturally occurring toxin. Aflatoxin exposure assessment has been traditionally achieved through food use frequency questionnaires and laboratory analysis of food samples. However, estimation of individual exposure to aflatoxins based on these methods may not be accurate. The use of aflatoxin biomarkers in urine and blood for use in exposure studies has emerged in more recent times. However, the current biomarkers (e.g., AFB-N7 -guanine and AFB1 -albumin adduct) in use have a short half-life and are only practically useful to indicate levels over 24 h-3 months post-exposure. There is therefore an immediate need to study and evaluate alternative biomarkers in non-conventional matrices such as hair and nails. Hair analysis revealed considerable interest in forensic analysis particularly in the detection of drugs of abuse where it has emerged as a sensitive and specific technique complementary to blood and urinalysis. This article provides an overview of aflatoxins, current aflatoxin biomarkers and proposes the use of hair as a potential matrix for biomarkers of long-term aflatoxin exposure. Copyright © 2016 John Wiley & Sons, Ltd.

Determination of aflatoxin in processed dried cassava root: validation of a new analytical method for cassava flour.

A new method that uses HPLC with a photochemical reactor for enhanced detection was developed and validated for the determination of aflatoxins in cassava flour. Samples were spiked with a mixture of four aflatoxins at 5, 10, and 20 microg/kg mixed with either 1 or 5 g NaCI and extracted with methanol-water (80 + 20, v/v) by shaking for 10 or 30 min. An immunoaffinity column was used for cleanup. HPLC with postcolumn derivatization, for enhancement of aflatoxin fluorescence, and fluorescence determination were used for quantitation of the toxin concentration. The method was validated for recovery, linearity, and precision at the three concentrations tested. Recovery ranges were 52-70, 69-85, and 80-89% for the spiking levels of 5.0, 10.0, and 20.0 microg/kg, respectively. It appears that the amount of salt (NaCl) and the shaking time are critical factors in this method; optimal performance was obtained when 1 g salt was used and the shaking time was 10 min. The good linearity and precision of the method allowed baseline separation from interferences, e.g., coumarins.