Synergism of Azadirachta indica Seed and Nigella sativa on Plasmodium falciparum: Study on Wistar Rats

Abstract

Aim: This study was carried out to determine the Phytochemical contents of Azadirachta indica seed and Nigella. sativa and their synergistic therapeutic effect on indices of clinical importance in malaria-induced male wistar rats.
 Study Design: The animals that were used for this study where divided into 4 groups of 6 rats each. All rats in the 3 test groups were inoculated with 0.2 ml blood parasitized with Plasmodium falciparum and observed for 3 days for manifestation of signs of malaria. Treatment with Azadirachta indica seed extract only, Nigella sativa extract only and a combination of Azadirachta indica seed and Nigella sativa extracts was conducted for a period of 14 days. Changes in weight of the rats and hematological parameters RBC, WBC,PCV and Hemoglobin were assessed before commencement of treatment and through the 14 day period.
 Place and Duration of Study: This study was conducted at the National Veterinary Research Institute (NVRI), Vom in collaboration with the Department of Biological Sciences Abubakar Tafawa Balewa University, Bauchi, Nigeria between March 2022 and May 2022. 
 Methodology:  Azadirachta indica seed and Nigella sativa seeds were extracted with distilled water and the lethal doses (LD₅₀) were determined on the rats. Qualitative phytochemical screening of Azadirachta indica seed and Nigella sativa extracts was performed. Plasmodium infected rats were divided into 3 groups of 6 rats each and a normal control group which was left uninfected. Symptoms of malaria infection were observed three days after infection. The treatment was commenced on day 4 post-infection and was continued for a period of 14 days. Each plant extract and the mixture of both extracts were administered at 100, 200, and 300mg/kg body weight of the rats. After first 4 days, 7 days, and at 14 days of treatment each rat’s blood sample was taken for hematological analysis.
 Results: The plant extracts lethal dose (LD₅₀) was considered safe for Azadirachta indica seed at 5000mg/kg and 2000mg/kg for Nigella sativa respectively. Qualitative phytochemical screening revealed the presence of saponins, alkaloids, flavonoids, resins, glycosides, steroids in both  Azadirachta indica seed extract and  Nigella. sativa extract. Treatment with a mixture of both extracts showed a high restoration of red blood cell count with a significant (p>0.05) increase in RBC with a non-significant decrease in PCV and WBC. There was no significant decrease in hemoglobin concentration observed across all treatment groups at the end of the 14 day study.
 Conclusion; The combination of both Azadirachta indica seed and  Nigella sativa  is well tolerated and safe for Plasmodium parasites effects on wistar rats at concentration of 400mg/kg of body weight which showed highest values of restoration of RBC count as compared to the normal control group. Group A treated with only Nigella sativa also showed RBC count higher than that obtained in group B treated with only Azadirachta indica seed. PCV values compared with the normal control group showed an 8% increase at concentration of 400mg/kg at the end of the experiment in group C treated with the mixture of Azadirachta indica seed and Nigella sativa. At 200mg/kg concentration, the mixture of Azadirachta indica seed and  Nigella. sativa gave a 25% increase in PCV values. This shows that the synergistic effect of Azadirachta  indica seed and Nigella sativa has better therapeutic effects against Plasmodium parasites than either Nigella sativa or Azadirachta indica seed as a single therapy. This study provides a basis for the development of a cheaper plant-based antimalarial combination therapy.