Phytochemicals analysis and medicinal potentials of hydroalcoholic extract from Curtisia dentata (Burm.f) C.A. Sm Stem Bark.

Curtisia dentata (CD) is a vulnerable medicinal plant used for the treatment of stomach ailments in South Africa. However, there is a lack of sufficient data on its phytochemical components and medicinal properties. The phytochemical analysis of the extract was estimated using standard assay methods while its antibacterial activity was determined by the agar dilution method against selected bacteria. The antioxidant activity of the extract was done using ferric reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic-acid (ABTS), nitric oxide (NO), hydrogen peroxide (H(2)O(2)) and lipid peroxidation (LPO). The cytotoxicity assay of the extract was assessed using the brine shrimp lethality test with LC(50) value of 0.302 mg/mL. The antibacterial activity of the extract demonstrated an appreciable broad spectrum activity against the tested bacteria with minimum inhibitory concentration (MIC) ranges between 5000 and 0.5 mg/L. Both phenol and flavonoid concentrations were 14.86 mg tannic acid equivalent/g and 13.64 mg quercetin equivalent/g, respectively. The percentage composition of saponins (13.26) was highest, followed by steroids (1.42), while alkaloids and tannins had the same value of 0.51. Similarly, IC(50) values of the extract against DPPH, ABTS, H(2)O(2), LPO and NO were 0.017, 0.018, 0.159, 0.06 and 0.052 mg/mL, respectively. The reducing power of the extract was found to be concentration dependent. Our data suggest that the 70% ethanol extract from the CD extract has antibacterial and antioxidant properties due to the presence of bio-active compounds and thus support its folkloric use in the treatment of diseases.

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.

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.