Evaluation of grapefruit extract for the prevention of paracetamol-induced hepatotoxicity after overdose in rats
| dc.contributor.advisor | Walubo, A. | |
| dc.contributor.author | Baleni, Refuoe | |
| dc.date.accessioned | 2015-09-04T07:38:51Z | |
| dc.date.available | 2015-09-04T07:38:51Z | |
| dc.date.issued | 2015-05 | |
| dc.description.abstract | English: Paracetamol is a widely used analgesic and antipyretic agent. While it is generally safe for use at recommended doses, acute overdose of paracetamol can cause potentially fatal liver damage. Despite the understanding that some cytochrome P450 isoforms are responsible for activation of paracetamol to the hepatotoxic metabolite, N-acetyl-p-benzoquinine-imine (NAPQI), the use of enzyme inhibitors for prevention and/or treatment of paracetamol hepatotoxicity is still not well researched. Therefore grapefruit juice was evaluated for prevention of paracetamol-induced hepatotoxicity. A high performance liquid chromatography (HPLC) method for the determination of paracetamol in plasma was developed. It involved protein precipitation of 50 μl of paracetamol spiked plasma with zinc sulphate followed by centrifugation. The supernatant was directly injected into the HPLC. The sample was eluted with a mobile phase of 0.01% trifluoroacetic acid in distilled water: acetonitrile (75: 25, v/v) over a Phenomenex C18 (4.60 x 250 mm) 5 μ analytical column at 1 ml/min. 4’Aminoacetophenone was used as the internal standard. Under these conditions paracetamol and 4’aminoacetophenone eluted at retention times of 4.2 minutes and 6.2 minutes, respectively. The average calibration curve (0 - 20 μg/ml) was linear with a regression equation of y = 0.0603x + 0.089, and regression coefficient of r2 = 0.9957. The method was used to measure paracetamol concentrations in rat plasma. Evaluation of grapefruit juice for the prevention of paracetamol-induced hepatotoxicity was performed with Sprague Dawley rats. The rats were treated with one-off oral dose of saline, paracetamol only, paracetamol + grapefruit juice low dose and paracetamol + grapefruit juice high dose. A commercially available grapefruit derivative, bergamottin, was also evaluated. Thereafter, 5 rats from each group were sacrificed after 24, 48 and 72 hours. After the treatment period the blood samples were collected for liver function tests, full blood count and paracetamol concentration. A piece of liver was sent for histopathology. Administration of a toxic dose of paracetamol (1725 mg/kg) elevated the liver enzymes (ALT and AST) significantly when compared to the control group. Upon physical observation of the liver during surgery, the livers of the rats at 48 hours exhibited moderate to severe hepatic injury. The haematology results, especially platelet count, revealed a very low amount of platelets at 48 hours, which is indicative of thrombocytopenia. Paracetamol plasma concentrations of rats treated with paracetamol only were higher than at 24 hours and there was a slight decrease at 48 and 72 hours due to the drug metabolism. However, the hepatic injuries of the rats treated with paracetamol only were antagonised by co-administration of paracetamol with grapefruit juice and also co-administration with bergamottin. The significant decrease in liver enzymes (ALT and AST) and the slight increase in platelet count at 72 hours revealed that grapefruit juice and bergamottin may have hepatoprotective effects against paracetamol-induced hepatotoxicity. Similarly, the concentration of paracetamol in the plasma of rats treated with paracetamol + grapefruit juice/bergamottin were lowered even further as opposed to when paracetamol was administered alone. The results of this study imply that both grapefruit juice and bergamottin have enzyme inhibition ability and hence were able to play a role in inhibiting the enzymes which are involved in the production of a toxic metabolite known as NAPQI, which is produced in high quantity during overdose of paracetamol and is a major cause of liver injury. | en_ZA |
| dc.description.abstract | Afrikaans: Parasetamol word algemeen gebruik vir die behandeling van pyn en koors. Alhoewel dit veilig is om te gebruik teen die aanbevole dosis, kan `n akuute parasetamol-oordosering lei tot potensiële dodelike lewerskade. Ten spyte van die kennis dat die hepatotoksiese metaboliet van parasetamol, N-acetyl-p-benzoquinine-imine (NAPQI), gevorm word deur sitochroom P450 ensieme, is die kennis van ensieminhibeerders vir die voorkoming of behandeling van parasetamol hepatotoksisiteit baie beperk. Dus is pomelosap ondersoek vir die voorkoming van parasetamol-geïnduseerde hepatotoksiteit. ‘n Hoëdrukvloeistof-chromatografie (HPLC) metode vir die bepaling van parasetamol in plasma is ontwikkel. Dit behels proteïenpresipitasie van 50 μl plasma, wat parasetamol bevat, met sinksulfaat, gevolg deur sentrifugering. Die boonste laag is direk in die HPLC ingespuit. Die monster is geëlueer met `n mobiele fase van 0.01% trifluoroasetaatsuur: gedistilleerde water (75: 25, v/v) deur ‘n Phenomenex C18 (4.60 x 250 mm) 5 μ analitiese kolom teen 1 ml/min. 4’Aminoasetofenoon is as interne standaard gebruik. Onder die toestande het parasetamol en 4’aminoasetofenoon onderskeidelik teen 4.2 en 6.2 minute gëelueer. Die gemiddelde 5 dag kalibrasiekromme (0 – 20 μg/ml) was liniêr met ‘n regressievergelyking van y = 0.0603x + 0.089, en korrelasiekoëffisiënt (r2) van 0.9957. Die metode is suksesvol gebruik om parasetamolkonsentrasies in rotplasma te bepaal. Die ondersoek van pomelosap vir die voorkoming van parasetamolgeïnduseerde hepatotoksiteit was in Sprague-Dawley rotte uitgevoer. Die rotte is behandel met `n eenmalige orale dosis soutoplossing, parasetamol-alleen, parasetamol + pomelosap lae dosis, en parasetamol + pomelosap hoë dosis. `n Kommersiële pomelokomponent, bergamottin, is ook getoets. Daarna is 5 rotte uit elke groep geslag na 24, 48 and 72 uur. Na die behandelingsperiode is bloedmonsters geneem vir lewerfunksietoetse, volbloedtelling en parasetamolkonsentrasies. `n Lewersnit was gestuur vir histopatologiese ondersoek. Die toediening van `n toksiese dosis parasetamol (1725 mg/kg) het lewerensieme (ALT en AST) merkwaardig verhoog in vergelyking met die kontrolegroep. Na 48 uur en tydens fisiese ondersoek van die lewers gedurende chirurgie, is gesien dat daar matige tot ernstige lewerskade was. Die hematologie-uitslae en veral die plaatjietelling het teen 48 uur verlaag, wat aanduidend is van tromobositopenie. Parasetamol-plasmakonsentrasies van die rotte wat met parasetamol-alleen behandel is, was die hoogste teen 24 uur vanwaar dit effens verlaag het teen 48 en 72 uur as gevolg van metabolisme. Aldus is die lewerskade van die rotte wat met parasetamol-alleen behandel is teengewerk deur die gelyktydige toediening van pomelosap, so wel as bergamottin. Die merkwaardige verlaging van lewerensieme (ALT en AST) en die effense verhoging van die plaatjietelling teen 72 uur beteken dat pomelosap en bergamottin `n beskermende effek teen parasetamolgeïnduseerde hepatotoksiteit mag hê. In ooreenstemming is die konsentrasie van parasetamol in die plasma van rotte wat met parasetamol + pomelosap/bergamottin behandel is, selfs verder verlaag in teenstelling met die toediening van parasetamol-alleen. Die uitslae van die studie dui daarop dat beide pomelosap en bergamottin oor ensiem-inhiberende eienskappe beskik, en dus `n rol gespeel het in die inhibisie van die ensieme wat betrokke is by die vorming van die toksiese metaboliet, NAPQI, wat in groot hoeveelhede geproduseer word tydens parasetamol- oordosering en hoofsaaklik lei tot lewerskade. | af |
| dc.identifier.uri | http://hdl.handle.net/11660/1156 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Paracetamol | en_ZA |
| dc.subject | Grapefruit juice | en_ZA |
| dc.subject | High performance liquid chromatography | en_ZA |
| dc.subject | Dissertation (M.Med.Sc. (Medical Science in Pharmacology))--University of the Free State, 2015 | en_ZA |
| dc.subject | Acetaminophen | en_ZA |
| dc.subject | Hepatic encephalopathy | en_ZA |
| dc.subject | High performance liquid chromatography | en_ZA |
| dc.subject | N-acetyl-p-benzoquinone-imine | en_ZA |
| dc.subject | Liver damage | en_ZA |
| dc.subject | Bergamottin, | en_ZA |
| dc.title | Evaluation of grapefruit extract for the prevention of paracetamol-induced hepatotoxicity after overdose in rats | en_ZA |
| dc.type | Dissertation | en_ZA |