MOLECULAR EFFECTS OF RAW GARLIC JUICE ON DIESEL EXHAUST PARTICLES INDUCED CARDIOHEPATIC DYSFUNCTIONS IN WISTAR RATS

Abstract

Air pollution has been reported to account for most deaths worldwide and is due to particulate matter (PM). Diesel exhaust particles (DEP), an example of PM have been reported to induce oxidative stress and inflammation. Garlic (Allium sativum) is one of the oldest medicinal plant that has been shown in several studies to have high antioxidant and anti-inflammatory properties. This study was designed to evaluate the protective effects of raw garlic juice (RGJ) extract on the oxidative and proinflammatory effects of DEP in hepatic and cardiovascular systems of exposed rats. Diesel exhaust particles was collected from Akure, Nigeria and standard reference material (SRM 2975) DEP was obtained from NIST, USA. Both DEP were extracted in n-hexane to obtain the n-hexane extracts of DEP (HDEP) and SRM 2975 (HSRM). The polycyclic aromatic hydrocarbons (PAHs) content was determined by GC-MS, while redox potential of the extracts were evaluated using in vitro. Garlic was soaked in aqueous solution for 4 hours and blended, followed by sieving to obtain RGJ. The molecular docking to check for the possible molecular interactions between the watersoluble organosulphur compounds in RGJ and DEP-targeted proteins was evaluated using in-silico method. Forty male albino rats were divided into 8 experimental groups of 5 rats/group: control group was given saline orally for 3 weeks and DMSO orally twice in the final week of treatment; groups 2 and 3 received 0.064-, 0.64-, 0.064- mg/kg of HDEP orally respectively twice in the final week of treatment; group 4 received 0.064- mg/kg of HSRM orally twice in the final week of treatment; groups 5 and 6 received 500-mg/kg RGJ for 3 weeks and 0.064- mg/kg of HDEP and HSRM orally respectively twice in the final week of treatment; group 7 received 500-mg/kg RGJ for 3 weeks and 0.064- mg/kg of HSRM orally respectively twice in the final week of treatment; group 8 received 500 mg/kg RGJ alone orally for 3 weeks. The rats were sacrificed 24 hrs after the last treatment and tissues (liver, heart and aorta) biopsies were collected and stored at -800C. Serum was prepared from blood and stored at -200C. Alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), cholesterol, triglyceride, high density lipoprotein (HDL)-Cholesterol, low density lipoprotein (LDL)-Cholesterol were all assessed in the serum. Makers of oxidative stress (lipid peroxidation (LPO), conjugated dienes (CD) and reduced glutathione (GSH)) were assessed in the tissues (heart, aorta and liver). Nuclear factor erythroid 2 (Nrf2) and HO-1 gene expression were quantified by reverse transcriptase polymerase chain reaction (RT-PCR) in the tissues (heart and liver). The level of inflammatory cytokines (IL-1β, TNF-α and IL-10) and also IkKB, IkB, NF-kB were assessed by RT-PCR in the tissues (heart, aorta and liver). Proprotein convertase subtilin kexin type 9 (PCSK-9) and LDL-receptor mRNA were quantified in the liver by RT-PCR. The results showed that HDEP caused 0.43673 μM/min reductions in DTT concentration. The GC-MS results also detected majorly the non-polar PAH of HDEP collected in Akure. The molecular docking result of Sallylcysteine, S-allylmercaptocysteine, S-methylcysteine with NF-kB gave a binding energy of -3.9, -3.6, -4.0 respectively and also with PCSK-9 gave a binding energy of - 4.8, -4.8, -4.4 respectively. The results showed that HDEP and HSRM caused significant (p<0.001) increase in ALT, ALP and AST activity and also cholesterol, triglycerides and LDL-cholesterol levels in the serum of the rats but this increase was significantly (p<0.001) attenuated by RGJ. Diesel exhaust particles caused significant (p<0.001) increase in LPO and CD levels in the tissues but this increase was significantly (p<0.001) attenuated by RGJ. Diesel exhaust particles induced TNFα, IL- 1β, NF-kB, IkB and IkKB genes and decreased IL-10 gene expressions, all of which were reversed in the presence of RGJ. The pre-treatment with RGJ attenuated the decreased Nrf2 and HO-1 mRNA levels caused by DEP. This indicates the potential of RGJ extract to protect against DEP-induced cardio-hepato toxicity.