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The aim of this study has been to analyse the value chain of African leafy vegetables in the Limpopo Province of South Africa. This was done by identifying the prominent value chain actors, institutions governing the chain, the infrastructural endowments, key factors and challenges affecting the success or failure of the value chains for African leafy vegetables. Relationships among the value chain actors were weak, with transactions based mostly on spot markets. While smallholder farmers attain high gross margins, their intention to take part in the mainstream markets are prevented by lack of technical advice on production, lack of packaging and processing services, poor infrastructure, deficiency of contractual agreements between actors, and lack of access to finance. Although producers currently attain relatively higher gross margins, more benefits might be realized if government services (such as training, seed production and distribution) could either be decentralized or privatized. Future policy interventions should focus on promoting value addition along the African leafy vegetable chain, provision of cold storage facilities by municipalities closer to smallholder farmers in the rural areas and this will stabilize farm gate prices to encourage continuation of production. [ABSTRACT FROM AUTHOR]

Background: Ethiopian kale (Brassica carinata) is a horticulturally important crop used as leafy vegetable in large parts of East and Southern Africa. The leaves are reported to contain high concentrations of health-promoting secondary plant metabolites. However, scientific knowledge on their health benefits is scarce. Objective: This study aimed to determine the cancer preventive potential of B. carinata using a human liver in vitro model focusing on processing effects on the pattern of secondary plant metabolites and bioactivity. Design: B. carinata was cultivated under controlled conditions and differentially processed (raw, fermented, or cooked) after harvesting. Human liver cancer cells (HepG2) were treated with ethanolic extracts of raw or processed B. carinata leaves and analyzed for their anti-genotoxic, anti-oxidant, and cytostatic potential. Chemical analyses were carried out on glucosinolates including breakdown products, phenolic compounds, carotenoids, and chlorophyll content. Results: Pre-treatment with B. carinata extracts concentration dependently reduced aflatoxin-induced DNA damage in the Comet assay, reduced the production of reactive oxygen species as determined by electron paramagnetic resonance spectroscopy, and induced Nrf2-mediated gene expression. Increasing extract concentrations also promoted cytostasis. Processing had a significant effect on the content of secondary plant metabolites. However, different processing methodologies did not dramatically decrease bioactivity, but enhanced the protective effect in some of the endpoints studied. Conclusion: Our findings highlight the cancer preventive potential of B. carinata as indicated by the protection of human liver cells against aflatoxin in vitro. In general, consumption of B. carinata should be encouraged as part of chemopreventive measures to combat prevalence of aflatoxin-induced diseases. [ABSTRACT FROM AUTHOR]