Nanotechnology can be defined as the field of science and technology that studies material at nanoscale (1–100 nm). These nanomaterials, especially carbon nanostructure-based composites and biopolymer-based nanocomposites, exhibit excellent chemical, physical, mechanical, electrical, and many other properties beneficial for their application in many consumer products (e.g., industrial, food, pharmaceutical, and medical). The current literature reports that the increased exposure of humans to nanomaterials could toxicologically affect their environment. Hence, this paper aims to present a review on the possible nanotoxicology assays that can be used to evaluate the toxicity of engineered nanomaterials. The different ways humans are exposed to nanomaterials are discussed, and the recent toxicity evaluation approaches of these nanomaterials are critically assessed.

Senecio serratuloides DC is used in folk medicine for treating hypertension, skin disorders, internal and external sores, rashes, burns and wounds. This study aimed at investigating the antihypertensive effects of the hydroethanol extract of S. serratuloides (HESS) in N-Nitro-L-arginine methyl ester (L-NAME) induced hypertension in rats. Methods: Acute toxicity of HESS was first determined to provide guidance on doses to be used in this study. Lorke’s method was used to determine safety of the extract in mice. Female Wistar rats were treated orally once daily with L-NAME (40 mg/kg) for 4 weeks and then concomitantly with L-NAME (20 mg/kg) and plant extract (150 and 300 mg/kg), captopril (20 mg/kg) or saline as per assigned group for 2 weeks followed by a 2-week period of assigned treatments only. Blood pressure was monitored weekly. Lipid profile, nitric oxide, renin and angiotensin II concentrations were determined in serum while mineralocorticoid receptor concentration was quantified in the kidney homogenate. Nitric oxide (NO) concentration was determined in serum and cardiac histology performed. HESS was found to be non-toxic, having a LD50 greater than 5000 mg/kg. Blood pressure increased progressively in all animals from the second week of L-NAME treatment. HESS treatment significantly and dose-dependently lowered systolic blood pressure (p < 0.001), diastolic blood pressure (p < 0.01), low density lipoprotein cholesterol (p < 0.01) and triglycerides (p < 0.01). It significantly prevented L-NAME induced decrease in serum angiotensin II (p < 0.01), high density lipoprotein cholesterol (p < 0.001) and serum nitric oxide concentrations (p < 0.001). HESS also significantly (p < 0.01) prevented collagen deposition in cardiac tissue. The hydro-ethanol extract of Senecio serratuloides showed antihypertensive, antihyperlipidemic and cardioprotective effects in rats thus confirming its usefulness in traditional antihypertensive therapy and potential for antihypertensive drug development.

Background: Hypertension is a silent killer with no obvious signs and symptoms; thus, it is crucial to prevent its development. Oxidative stress and hyperlipidemia are associated risk factors for developing hypertension. This study aimed at investigating the role of a crude extract of Senecio serratuloides in preventing the development of hypertension, oxidative stress and hyperlipidemia in a rat model of nitric oxide deficiency. Methods: Female Wistar rats were co-treated with Nω-Nitro L-arginine methyl ester (L-NAME) (40 mg/kg) and the hydroethanolic extract of S. Serratuloides (HESS150 or HESS300 mg/kg) for 4 weeks. Twenty-hour urine samples were collected weekly during the study. At the end of the study serum, heart and kidneys were harvested for biochemical and histopathological analysis. Results: The higher dose (300 mg/kg) of the extract was more effective in preventing increase in systolic (p<0.001) and diastolic (p<0.05) blood pressure. At the end of the treatment period HESS300 treated rats had significantly (p<0.01) higher concentration of creatinine (91.24 ± 6 mg/dL) in urine and significantly (6.36 ± 0.4 mg/24 h; 0.001) lower proteinuria compared to L-NAME control rats (55.75 ± 8 mg/dL and 18.92 ± 2 mg/24 h, respectively). Creatinine clearance and glomerular filtration rate were lower in the L-NAME control group compared to all treatment groups. HESS300 prevented L-NAME-induced decrease in serum angiotensin II concentration, significantly decreased malondialdehyde concentration in serum (p<0.05) and kidneys (p<0.001). It also significantly (p<0.001) decreased low-density lipoprotein concentration while increasing the concentration of high-density lipoprotein cholesterol. It showed cardio- and reno-protective effects and significantly (p<0.01) prevented collagen deposition in these target organs. Conclusion: These findings demonstrate the potential of S. Serratuloides in protecting rats from developing hypertension, hyperlipidemia and oxidative stress.