International Journal of Advanced Research in Chemical Science Volume 7, Issue 5, 2020, PP 30-36 ISSN No.: 2349-0403 DOI: https:// doi.org/10.20431/2349-0403.0705004 www.arcjournals.org International Journal of Advanced Research in Chemical Science Page | 30 Potentials of Ocimum Gratissimum Extracts as Mosquito Repellents and Mosquitocidal Candles Okorie Angela Nkeiruka 1 , Verla Andrew Wirnkor 1* , Enyoh Christian Ebere 1 , Verla Evelyn Ngozi 2 and Amaobi Collins Emeka 1 1 Group Research in Analytical Chemistry, Environment and Climate Change (GRACE&CC), Department of Chemistry, Imo State University, Owerri, Imo State, Nigeria. 2 Department of Environmental Technology, Federal University of Technology, Owerri, Imo State, Nigeria 1. INTRODUCTION The leading cause of morbidity in Nigeria and in Africa as a whole is vector borne diseases transmitted by mosquitoes. The diseases transmitted include malaria, filariasis, yellow fever, Japanese encephalitis and dengue fever while seeking for a human blood meal. Malaria, in particular causes about 1.2 million deaths annually [1.2]. In south eastern Nigeria, Anopheles gambiae is the major vector transmitting malaria [3]. There has been exploration of various methods over the centuries to combat threats from mosquito borne diseases such discovery of insecticidal properties of DDT in 1939. However its deleterious impact on non-target population and the development of resistance prompted for the search of alternative, simple and sustainable methods of mosquito control [4]. In recent transmitting times, the use of environment friendly and biodegradable natural insecticides of plant origin to control insect vectors of diseases is gaining ground [5]. These botanical insecticides have been found to be effective, user-friendly and inexpensive [6]. Ocimum gratissimum commonly called “nchuanwu” in South-Eastern Nigeria, meaning mosquito repellent is cultivated around houses. It is an herb, which grows up to six feet high with an erect stem. Ethnomedicinally, it is used as remedy for cold and catarrh, stomach pain, diarrhoea and piles [7-9]. The plant has numerous uses both medicinal and non-medicinal in the modern scientific world same of these uses include insecticidal, pharmacological, flavoring agent, raw materials and also serve as vetegetables. Other documented ethnopharmacological activities of the herb include; antipyretic [10], divietic, laxative and hepatoprotective [11] and treatment for mental illness [12]. It is also used as food spices by the people [13]. There are various research reported on the insect repellent and insecticidal activities of ocimum gratissimum in the field and laboratory. [14], [15] and [16] have tried the activity on mosquitoes and *Corresponding Author: Verla Andrew Wirnkor, Group Research in Analytical Chemistry, Environment and Climate Change (GRACE&CC), Department of Chemistry, Imo State University, Owerri, Imo State, Nigeria. Abstract: Ethanol and distilled water extracts of the Ocimum gratissimum leaves were obtained using standard methods. The preliminary phytochemical analysis carried out showed the presence of alkaloids, tannins, glycosides, saponins, flavonoids and absence of steroids in both extracts. Three extractives were used in compounding candle samples. The produced candle samples were tested for their mosquitos’ repellent ability by knockdown effect. The knockdown effect result showed that the number of mosquitoes still flying for hot water extract after 5 minutes was 8(20%), then at 10 minutes was 6(20%). However, the highest mosq uito’s knockdown effect was at 15 minutes which had 3 mosquitos knockdown. Cold water extract result showed the lowest knockdown effect at 10 minutes 9(10%) while for ethanol extract, there was highest knockdown effect at 10 minutes which have 4(40%). Studies revealed that occimum gratissimum has the tendency and ability of eliminating mosquitoes in less than 10 minutes of application with ethanolic extracts being the most efficient. However, the health implication of this research was not studied to ascertain possible implication on the person inhaling the product. Keywords: Candles, Knockdown, Malaria, Mosquito, Phytochemical, Repellants