Biological safety of leech salivary extract-mediated silver nanoparticles in wistar rats

Abstract

Leeches are annelid worms that feed on blood and dwell in freshwater environments. Both leech saliva and silver nanoparticles have been shown to possess remarkable antibacterial properties against microorganisms. Although the worms are considered dangerous, their saliva may not be harmful. Silver nanoparticles mediated by leech salivary extract (LSE-Ag) were biologically synthesized and studied using UV spectroscopy and a nanosizer. Using standard method, the acute (LD50) and sub-acute toxicity of LSE-Ag were evaluated. The LSEAg had a wavelength of 456 nm and a size of 98.04 nm. The LSE-Ag LD50 in rats was above 5000 mg/kgbw. Oral delivery of LSE-Ag to rats (25, 50 and 100 mg/kgbw) for 21 days showed no significant (P > 0.05) change in body weight, differential blood count (lymphocytes, monocytes, neutrophils, eosinophils, and basophils), red blood cell indices (Platelets, HB, WBC, RBC, PCV, MCV, MCH and MCHC), renal function indices (urea, sodium, creatinine and potassium) and liver biomarkers (protein, albumin, alkaline phosphatise, alanine amino transferase, and aspartate amino transferase). When compared to the control, LSE-Ag at 100 mg/kgbw increased absolute spleen weight and decreased feed consumption in treated rats. The findings show that LSE-Ag is relatively safe and could be a rich source of antimicrobial agent but caution should be taken at higher doses