Preparation and evaluation of ecofriendly nanocreams containing some plant essential oils and monoterpenes against adults of Culex pipiens L. with some biochemical and histological studies on albino rat

Abstract

AbstractPlant essential oils (EOs) are considered a vital tool of novel natural mosquito repellents and botanical adulticides. Five plant EOs (cinnamon, cypress, lavender, lemon eucalyptus and tea tree) and their major constituents (cinnamaldehyde, citronellal, β-cymene, (R)-linalool, and α-terpinyl acetate) were investigated against adults of Culex pipiens. The efficacy of the tested compounds was manipulated as mortality and knockdown using a fumigation technique. After that, the most active compounds against adults (lemon eucalyptus oil and linalool) were investigated once more as repellents after incorporating them on a cream base against C. pipiens adults compared to their nano-cream using arm-in-cage technique. In addition, the biochemical and histological effects of dermal treatment of linalool, lemon eucalyptus,, and their nanoemulsions (NEs) were studied on male albino rats. Total protein assay, acetylcholinesterase (AChE), adenosine triphosphatase (ATPase), and liver and kidney functions were determined in blood serum. Complete blood count (CBC) was determined in whole blood. The results showed that lemon eucalyptus oil and (R)-linalool caused the highest knockdown activity against C. pipiens adults with Kt50 40.29 s and 12.73 s, respectively. The repellent effect (RC50) of nanocream formulations of lemon eucalyptus oil (10.03 mg/L) and (R)-linalool (68.11 mg/L) were higher than the original effects of these compounds with RC50 values = 100.82 mg/L and 998.54 mg/L, respectively. There are no obvious harmful side effects of the dermal topical treatments of (R)-linalool and lemon eucalyptus oil on the tested biochemical parameters of treated albino rats compared with the control. Furthermore, there are no obvious effects of the dermal topical treatments of (R)-linalool and lemon eucalyptus oil on the histological status of the treated skin of albino rats compared with untreated treatment. The tested oils and monoterpenes could be considered promising candidates for botanical adulticides against C. pipiens. Also, nano-cream of lemon eucalyptus oil and (R)-linalool could be considered promising ecofriendly repellents for C. pipiens adults.