Abstract:
Prevention of insect bites
is the first line of defense against Insect borne
diseases such as malaria, de ngue, and filariasis and u se of insect repellents
is the most common approach among them. Eucalyptus citriodora is an
effective plant based insect repellent that is proven to exert minimal risk to
environment, wildlife and humans. The oil contains a mixtur e of
monoterpenes out of which citronellal is the major component (84%).
Moreover, it has been reported that nerol, limonene and para menthane 3,8
diol in oil of eucalyptus exhibit mosquito repellent activity. A ttempts were
made to convert citronellal in t he oil into components showing repellent
activity via a simple citric acid catalyzed reaction. The acid treated oil
samples were tested for their mosquito repellent ability using a static air
repellency apparatus. The reaction was carried out by varying th e volume of
the acid catalyst (7% acid), temperature and reaction time in order to
investigate the optimum reaction conditions. The acid treated oil s displayed
a significantly high mosquito repellent activity against Aedes aegypti
mosquitoes compared to th e untreated oil The highest mosquito repellency
within a period of 3 hours was observed, when 3.7 g of the oil was reacted
with 20 mL of 7% citric acid solution at 50 C for 15 hours. The percentage
repellency of 2% of this sample in a neutral lotion was 72 % whereas the
untreated oil had the repellency of 27% at the 0 th hour. The results of this
study indicated the success of this simple synthetic approach towards
enhancing the mosquito repellency of Eucalyptus citriodora oil in an
economical and efficient m anner
