Potentiation Effects of Ficus sycomorus Active Fraction Against Permethrin-Resistant Field-Population of Anopheles coluzzii (Diptera: Culicidae)

Insecticide resistance in mosquitoes is increasing amidst growing cases of global malaria, leading to high fatality in mostly Africa. To overcome the resistance as well as environmental effects of the synthetic insecticides, preliminary insecticidal and botanical potentiating effects of sub-lethal concentration (LC₂₅) Ficus sycomorus active fraction (AFFS) and its synergistic potential with standard insecticide permethrin were evaluated against malarial vector Anopheles coluzzii (Coetzee & Wilkerson) populations. The glutathione-S-transferase (GST) inhibitory activity of the AFFS was also investigated compared to standard GST inhibitor, diethyl meleate (DEM). The WHO standard protocol for adult bioassay was used to expose the adult mosquitoes with sub-lethal concentration (LD₂₅=0.49 mg/ml) of the plants' active fraction and permethrin (0.75%). The permethrin susceptibility screening result showed high level of resistance to permethrin in the field populations of A. coluzzii from Kano with 50.29 ± 2.14% average mortality after exposure to WHO diagnostic dose 0.75% permethrin. Post hoc Fisher's exact test showed that combination of sub-lethal concentration of AFFS with permethrin (mortality=73.02±12.10%; p=0.00352; RR=0.6923 and 95% CI = 0.5358-0.8946) was statistically significant, while the combination of sub-lethal concentration of AFFS with DEM showed no statistical difference (mortality=63.22±5.03; p=1; RR=0.6667 and 95% CI=0.4470-0.8438). This potentiation effect was signified to be additive effects with co-toxicity factor (CTF) of - 12.66. There was significant reduction of GST activities in the AFFS- and permethrin -exposed groups compared to unexposed populations of A. coluzzii (p < 0.05). The AFFS additively potentiate the permethrin activities by inhibiting GSTs, bio-transformational enzymes implicated in pyrethroids resistance. This study finding generally signifies the potential for bio-rational insecticide approach for malarial vector control.

Alterations in the liver histology and markers of metabolic syndrome associated with inflammation and liver damage in L-arginine exposed female Wistar albino rats

Metabolic Syndrome (MES), a cluster of metabolic disorders, is pandemic and more prevalent in females. It was associated with inflammation, liver damage and reduced nitric oxide concentration. Since L-arginine (ARG) may enhance nitric oxide synthesis, this study investigated the effect of ARG on the liver histology and selected serum markers of MES related to inflammation and liver damage. Two groups (n = 8) of female Wistar albino rats were exposed to 60 mg kg(-1) b. wt. of ARG and 3 mL kg(-1) b.wt. of distilled water, respectively as treated and control groups. Per oral exposure to ARG for twenty eight days caused a non-significant increase (p > 0.05) in the neutrophils count (22.50 +/- 10.35%, representing 38.46%) but a decrease (p > 0.05) in the lymphocytes count (77.50 +/- 10.35%, representing 8.82%) and in the total bilirubin concentration (0.40 +/- 0.19 mg/100 mL, representing 52.38%) of the rats, suggesting non-treatment related influence on these parameters. However, the exposure elicited a significant decrease (p < 0.01) in the serum alanine aminotransferase (ALT) activity (66.47 +/- 0.37 IU L(-1), representing 18.55%) and in the total White Blood Cell (WBC) count (2.73 +/- 0.75 x 10(9) L(-1), representing 43.24%), suggesting absence of inflammation and liver damage. ALT had a significant positive correlation with WBC (r = 0.01), while the liver histology revealed possible benefit in the ARG-fed rats, seeminlgly confirming benefit on these markers of inflammation and liver damage that could improve related MES features in the rats. Further studies using ARG rich nuts are required to harness insight gained from this study.