Effects of Cd and Al stress on secondary metabolites, antioxidant and antibacterial activity of Hypoxis hemerocallidea Fisch. & C.A. Mey.

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.

Plant growth regulators enhance gold uptake in Brassica juncea.

The use of plant growth regulators is well established and they are used in many fields of plant science for enhancing growth. Brassica juncea plants were treated with 2.5, 5.0 and 7.5 microM auxin indole-3-butyric acid (IBA), which promotes rooting. The IBA-treated plants were also sprayed with 100 microM gibberellic acid (GA3) and kinetin (Kin) to increase leaf-foliage. Gold (I) chloride (AuCl) was added to the growth medium of plants to achieve required gold concentration. The solubilizing agent ammonium thiocyanate (1 g kg(-1)) (commonly used in mining industries to solubilize gold) was added to the nutrient solution after six weeks of growth and, two weeks later, plants were harvested. Plant growth regulators improved shoot and root dry biomass of B. juncea plants. Inductively Coupled Plasma Optical Emission Spectrometry analysis showed the highest Au uptake for plants treated with 5.0 microM IBA. The average recovery of Au with this treatment was significantly greater than the control treatment by 45.8 mg kg(-1) (155.7%). The other IBA concentrations (2.5 and 7.5 microM) also showed a significant increase in Au uptake compared to the control plants by 14.7 mg kg(-1) (50%) and 42.5 mg kg(-1) (144.5%) respectively. A similar trend of Au accumulation was recorded in the roots of B. juncea plants. This study conducted in solution culture suggests that plant growth regulators can play a significant role in improving phytoextraction of Au.

An investigation of the antimicrobial and anti-inflammatory activities of crocodile oil.

ETHNOPHARMACOLOGICAL RELEVANCE: Crocodile oil has been used by traditional practitioners world-wide to treat microbial infections and inflammatory conditions. However, the scientific rationale behind its use is not completely understood. This study provides an updated fatty acid profile and novel scientific evidence of the antimicrobial and anti-inflammatory properties of crocodile oil, obtained from the Nile crocodile (Crocodylus niloticus), justifying its use by traditional healers. MATERIALS AND METHODS: The fatty acid content of the oil was determined by gas chromatography and the major fatty acids were identified. A microplate method was used to assess activity of the oil against Staphylococcus aureus, Klebsiella pneumoniae and Candida albicans. The anti-inflammatory activity of the oil was assessed by oral administration and topical application, utilising a mouse model of acute croton oil-induced contact dermatitis. RESULTS: Sixteen fatty acids were identified with oleic, palmitic and linoleic acid being the major components of the oil. The optimal activity of the oil against the bacteria and fungus was obtained with 15% and 6% (w/v) oil respectively. No significant selectivity was observed against the bacterial species, but Candida albicans was more susceptible. The anti-inflammatory assays showed optimal activity at 3h after the oral administration of oil (60.8±5.5%) and at 12h after topical application (57.5±5.9%). This suggested a short duration of action when the oil was orally administered, and a longer duration of action when it was topically applied. CONCLUSIONS: Subsequent studies may be directed towards the investigation of the mechanisms of action of the antimicrobial and anti-inflammatory activities of crocodile oil and its fatty acids.

Effect of cadmium accumulation on anti-inflammatory activity in two Eucomis species.

Eucomis species (Hyacinthaceae) are widely used in South Africa as traditional medicine. The bulbs are used to alleviate a variety of symptoms including pain and inflammation. High levels of cyclooxygenase-1 and -2 (COX-1 and COX-2) inhibitory activity have been associated with certain Eucomis species. The aim of this study was to quantify cadmium(Cd) accumulation and examine its effect on COX-1 and COX-2 anti-inflammatory activity in Eucomis autumnalis and Eucomis humilis. Cadmium application at 2 mg L(-1) over a 6 week period revealed a substantial difference in total Cd accumulation in E. autumnalis and E. humilis (40.2 and 15.3 mg Cd kg-1, respectively). When supplied with Cd at 2 mg L(-1), E. humilis bulbous extracts showed lower inhibitory activity than the control for both COX-1 and COX-2. E. autumnalis bulbous extracts had greater COX-1 activity compared to the control. While COX-2 activity was suppressed. Researchers should be aware of the effect of environmental contaminants when reporting on biological activity of crude plant extracts.