Toxicological investigations of Aloe ferox Mill. extracts using Brine shrimp [Artemia salina L.] assay

Cytotoxicity of the extracts of Aloe ferox using brine shrimp was evaluated. Effects of the extracts on hatchability and lethality of brine shrimps were reported in terms of minimum inhibitory concentration and LD[50] respectively. The hatching success was in the order: aqueous root extract [39.8%] >aqueous leaf [26.5%] >acetone leaf [13.7%] > ethanol leaf extracts [2.5%]. Hatchability in incubations of ethanol and acetone extracts was found to be dose - dependent, with hatching success decreasing as the concentration of the extracts increased. The lethality of extracts was in the order: aqueous leaf extract [4.7%] >aqueous root extract [4.2%] >acetone leaf extract [3.5%] >ethanol root extract [2.6%] > ethanol leaf extract [1.8%] >acetone root extract [0.7%]. Mean mortality of nauplii in the control was higher [6.7%] than that of all the extracts. Based on Meyer's index of toxicity, the acetone leaf extract with LD[50] >1.0mg/mL could be considered as non toxic, while the ethanol root extract [LD[50] <1.0mg/mL was significantly toxic to the brine shrimp. Since the extracts of A. ferox have consistently exhibited significant pharmaceutical properties in-vitro, the nontoxic extracts could further be exploited for the development of plant-based pharmaceuticals

Assessment of allelopathic properties of Aloe ferox Mill. on turnip, beetroot and carrot

Turnip (Brassica rapa var. rapa L.), beetroot (Beta vulgaris L.) and carrot (Daucus carota L.) are common vegetables in South Africa. The allelopathic potential of aqueous leaf and root extracts of Aloe ferox Mill.- a highly valued medicinal plant- was evaluated against seed germination and seedling growth of the three vegetables in Petri dish experiments. The extracts were tested at concentrations of 2, 4, 6, 8, and 10 mg/mL. Leaf extract concentrations above 4 mg/mL inhibited the germination of all the crops, while the root extract had no significant effect on germination irrespective of concentration. Interestingly, the lowest concentration of leaf extract stimulated root length elongation of beetroot by 31.71%. Other concentrations significantly inhibited both root and shoot growth of the vegetable crops except the turnip shoot. The most sensitive crop was carrot, with percentage inhibition ranging from 29.15 to 100% for root and shoot lengths. Lower percentage inhibition was observed for the root extract than the leaf extract against shoot growth of beetroot and carrot. The results from this study suggested the presence of allelochemicals mostly in the leaves of A. ferox that could inhibit the growth of the turnip, beetroot and carrot.