title: Effects of Cd and Al stress on secondary metabolites, antioxidant and antibacterial activity of Hypoxis hemerocallidea Fisch. & C.A. Mey.
abstract: This study investigated the effects of cadmium (Cd) and aluminium (Al) on the accumulation of phenolics, flavonoids and the bioactive compound hypoxoside in Hypoxis hemerocallidea. In addition, antioxidant scavenging and antibacterial activity were assessed to evaluate if Cd and Al stress affect the accumulation of bioactive compounds in H. hemerocallidea. In vitro grown plantlets of H. hemerocallidea were acclimatized for seven months in a greenhouse. Thereafter plants were exposed to various concentrations of Cd and Al both singularly and in combination in the form of Cd(NO3)2 (2, 5, 10 mg Cd/L); Al3(NO3)3 (500, 1000, 1500 mg Al/L) and combinations of Cd and Al (Cd 2:Al 500, Cd 5:Al 1000 and Cd 10:Al 1500 mg/L) for a further six weeks. The highest amounts of Cd and Al translocated to the shoot were 34 and 1608 mg/L respectively. Phytochemical screening showed significantly high amounts of total phenolics and flavonoids at the moderate Cd treatment (5 mg/L) compared to the controls. Exposure to Cd and Al significantly decreased the accumulation of hypoxoside. There was a significant increase in diphenylpicrylhydrazyl (DPPH) antioxidant scavenging activity in most of the metal-treated plants compared to the positive control ascorbic acid. Extracts from Cd 2 mg/L treatment exhibited moderate antibacterial activity against Staphylococcus aureus compared to the control. The results of the present study revealed that cultivating H. hemerocallidea on metal contaminated soils affects the accumulation of the bioactive compound, hypoxoside.
authors.affiliation: Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville, 3209, South Africa.
authors.forename: Ambrose
authors.initials: A
authors.lastname: Okem
authors.affiliation: Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville, 3209, South Africa.
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Stirk
authors.affiliation: South African Medical Research Council, HIV Prevention Research Unit, 123 Jan Hofmeyer Road, Westville, 3630, South Africa.
authors.forename: Renée A
authors.initials: RA
authors.lastname: Street
authors.affiliation: School of Chemistry and Physics, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville, 3209, South Africa.
authors.forename: Colin
authors.initials: C
authors.lastname: Southway
authors.affiliation: Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville, 3209, South Africa.
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Finnie
authors.affiliation: Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal Pietermaritzburg, Private Bag X01, Scottsville, 3209, South Africa. Electronic address: rcpgd@ukzn.ac.za.
authors.forename: Johannes
authors.initials: J
authors.lastname: Van Staden
mesh_terms: D000480:Alkynes / Q000378:metabolism; D000535:Aluminum / Q000633:toxicity*; D000900:Anti-Bacterial Agents / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism*; D002104:Cadmium / Q000633:toxicity*; D005419:Flavonoids / Q000378:metabolism; D005960:Glucosides / Q000378:metabolism; D027802:Hypoxis / Q000187:drug effects* / Q000378:metabolism; D010636:Phenols / Q000378:metabolism; D064210:Secondary Metabolism / Q000187:drug effects*; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000480:Alkynes; D000900:Anti-Bacterial Agents; D000975:Antioxidants; D005419:Flavonoids; D005960:Glucosides; D010636:Phenols; D002104:Cadmium; C087941:hypoxoside; D000535:Aluminum
keywords: Antibacterial activity; Antioxidant activity; Flavonoids; Heavy metals; Hypoxoside; Phenolics