Effects of traditionally used anxiolytic botanicals on enzymes of the γ-aminobutyric acid (GABA) systemThis article is one of a selection of papers published in this special issue (part 1 of 2) on the Safety and Efficacy of Natural Health Products.

2007 ◽  
Vol 85 (9) ◽  
pp. 933-942 ◽  
Author(s):  
R. Awad ◽  
D. Levac ◽  
P. Cybulska ◽  
Z. Merali ◽  
V.L. Trudeau ◽  
...  
Keyword(s):  
Aminobutyric Acid ◽  
Natural Health Products ◽  
Special Issue ◽  
Natural Health ◽  
Safety And Efficacy ◽  
Health Products ◽  
Selection Of

Postmarket surveillance of natural health products in Canada: clinical and federal regulatory perspectivesThis article is one of a selection of papers published in this special issue (part 1 of 2) on the Safety and Efficacy of Natural Health Products.

2007 ◽  
Vol 85 (9) ◽  
pp. 952-955 ◽  
Author(s):  
Mano Murty
Keyword(s):  
Adverse Reactions ◽  
Safety Evaluation ◽  
Public Communication ◽  
Natural Health Products ◽  
Special Issue ◽  
Natural Health ◽  
Efficacy Data ◽  
Safety And Efficacy ◽  
Health Products ◽  
Selection Of

Postmarket surveillance, particularly adverse reactions (ARs), forms an integral part of the ongoing safety evaluation for natural health products (NHPs). ARs can be related to many factors, including inherent toxicity, misuse, hypersensitivity, NHP–drug interactions, or product quality. High consumer use and limited safety and efficacy data from human clinical trials for many NHPs present a challenge to consumers, healthcare practitioners, and federal regulators. Canada’s Natural Health Products Regulations mandate NHPs to be licensed. As the currently available unauthorized NHPs are being brought into compliance in Canada, the transition has produced some challenges, requiring ongoing public communication and education to promote the safe use of NHPs. This article will highlight Health Canada’s key postmarket initiatives in strengthening the regulation of NHPs.

In vitro activity of uva-ursi against cytochrome P450 isoenzymes and P-glycoproteinThis article is one of a selection of papers published in this special issue (part 2 of 2) on the Safety and Efficacy of Natural Health Products.

2007 ◽  
Vol 85 (11) ◽  
pp. 1099-1107 ◽  
Author(s):  
B. Chauhan ◽  
C. Yu ◽  
A. Krantis ◽  
I. Scott ◽  
J. T. Arnason ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Moderate Activity ◽  
Natural Health Products ◽  
Natural Health ◽  
Herbal Products ◽  
Safety And Efficacy ◽  
Methanol Extracts ◽  
Metabolism Enzymes ◽  
Health Products

Some natural health products (NHPs) affect drug metabolism enzymes and transport proteins, potentially affecting the safety and efficacy of the drug or other NHPs. This study was undertaken to characterize the effect of uva-ursi ( Arctostaphylos uva-ursi ) on cytochrome P450 isozyme (3A4, 3A5, 3A7, 2C19, and 19)-mediated metabolism and P-glycoprotein (P-gp) transport. Three bulk and 2 capsulated uva-ursi samples were obtained from commercial outlets. The capsules were batched, and herbal samples were ground to a common consistency. Aqueous and methanol extracts were freshly prepared. Cytochrome P450 isozyme-mediated metabolism was determined by using in vitro bioassays. P-gp transport function was determined by using a rhodamine 123 (Rh123) uptake test in human (THP-1) monocytes and human Caco-2 cells. All products were analyzed by HPLC for arbutin, gallic acid, myricitrin, and isoquercetin. A large variation was observed in the biomarkers found between the bulk and capsulated samples. Our data indicate that both the aqueous and methanol extracts of all 5 uva-ursi products showed high cytochrome P450 isozyme inhibition, with the exception of the methanol extracts against cytochromes P3A4 and P19, which had low to moderate activity. The aqueous extracts of uva-ursi showed an inhibitory effect on Rh123 efflux by P-gp at 1 h and an inductive effect at 18 h for both cell lines. Our results show that the uva-ursi herbal products tested here have pharmacological properties, including the potential capacity to affect drug safety and efficacy. Further studies are warranted against a wider range of cytochrome P450 isozymes and to determine whether these effects are clinically significant.

Senecio latifolius induces in vitro hepatocytotoxicity in a human cell lineThis article is one of a selection of papers published in this special issue (part 2 of 2) on the Safety and Efficacy of Natural Health Products.

2007 ◽  
Vol 85 (11) ◽  
pp. 1063-1075 ◽  
Author(s):  
Manuela G. Neuman ◽  
Angela Y. Jia ◽  
Vanessa Steenkamp
Keyword(s):  
Control Treatment ◽  
Natural Health Products ◽  
Dependent Manner ◽  
Aqueous Extracts ◽  
Natural Health ◽  
Transmission Electron ◽  
Health Products ◽  
Induced Apoptosis ◽  
Selection Of

The objectives of this study were twofold: (i) to determine the mechanism(s) of Senecio -induced toxicity in human hepatoblastoma cells (HepG2) in vitro and whether such toxicity could be prevented using N-acetyl-cysteine (NAC), and (ii) to evaluate whether caspases are involved in Senecio-induced apoptosis. Cells were treated with aqueous extracts of Senecio (10 mg·mL–1) with and without NAC. Cytotoxicity was determined by using the MTT assay. Total glutathione (GSH) was measured by using the Tietze assay. Cells were also treated with aqueous extracts of Senecio in the presence or absence of 50 μmol/L caspase-3 inhibitor (IDN) for 24 h. Apoptosis was determined by transmission electron microscopy, and DNA fragmentation was determined by ELISA and terminal dUTP nick-end labelling (TUNEL). Senecio produced cytotoxicity and depleted GSH in a concentration- and time-dependent manner. A significant depletion in GSH was observed after 15 min (p < 0.001 vs. control), whereas significant cytotoxicity was only observed after 3 h (p < 0.001 vs. control). Treatment with NAC prevented Senecio-induced GSH depletion and resulted in a significant decrease in Senecio-induced cytotoxicity (p < 0.001 vs. NAC-untreated cells). Treatment with Senecio for 24 h resulted in 22% ± 2.5% (p < 0.001) apoptosis (vs. control). Pretreatment with 50 μmol caspase inhibitor reduced Senecio-induced apoptosis significantly (vs. non-exposed to IDN) (12% ± 1.5%; p < 0.05). Our results suggest the mechanism of Senecio-induced cytotoxicity in HepG2 cells in vitro involves depletion of cellular GSH. Cytotoxicity is reduced by supplementation with NAC, which thus prevents GSH depletion. Caspase activation is involved in Senecio-induced apoptosis.

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