 Sherifat Aboaba (Correspondence)  saboaba@gmail.com  + This article is published under the terms of the Creative Commons Attribution License 4.0 Author(s) retain the copyright of this article. Publication rights with Alkhaer Publications. Published at: http://www.ijsciences.com/pub/issue/2018-02/ DOI: 10.18483/ijSci.1529; Online ISSN: 2305-3925; Print ISSN: 2410-4477 Volatile Constituents and Toxicity Profile of the Leaves, Stem Bark and Root Bark Essential Oils of Holarrhena Floribunda and Crescentia Cujete Sherifat A. Aboaba 1 , Gbenro F. Fasimoye 1 1 Department of Chemistry, University of Ibadan, Ibadan, Nigeria Abstract: Essential oils are highly concentrated substances extracted from flowers, leaves, stems, roots, seeds, barks, resins, or fruit rinds. The increased interest in creating a compendium of plant essential oils for the purpose of discovering drugs from natural source led to the characterization of the leaves, stem bark and root bark of Holarrhena floribunda and Crescentia cujete. The essential oils from the plants parts were extracted by means of hydrodistillation using an all glass Clevenger apparatus while the chemical constituents were determined by Gas Chromatography-Mass Spectroscopy technique. The toxicity of the essential oils was tested using Brine shrimps (Artemia salina). The GC-MS results identified 5, 8, and 7 components in H. floribunda (leaves, stem bark and stem bark respectively) while leaves, stem bark and root bark of C. cujete had 15, 11 and 10 constituents respectively. The compounds found in high quantity in the essential oils of H. floribunda are friedelan-3-one (22.85%), sesquirosefuran (31.93%), octadec-9-enoic acid (46.28%), and longifolene (59.77%) while the major components in the oils of C. cujete are cyclotetradecane (13.75%), diisooctylphthalate (33.96%), and phytol (46.33%). The LC 50 value ranged from 10.85 to 288.76 (μg/mL) which was a pre-test for toxicity potential. The essential oils of C. cujete stem bark, C. cujete root bark and H. floribunda root bark were the most toxic with LC 50 10.85, 16.54 and 36.33 μg/mL respectively. The level of toxicity of these essential oils is an indication of the pharmacological properties the plants may possess. Keywords: Essential oil, Crescentia cujete, Holarrhena floribunda, Longifolene, Toxicity INTRODUCTION Holarrhena floribunda, also known in English as False rubber tree, belongs to the family Apocynaceae (Letouzy, 1972). It is known as ire-oju-ona in Yoruba, gaman sauwa in Hausa and mba in Igbo (Nigeria). It is a tree or shrub about 17 m high. It is widely distributed in the centre and west regions of Cameroon. The stem bark is used in Cameroon to treat various ailments such as abdominal pains, nausea, indigestion and diarrhea (Berhaut 1971). The stem bark of H. floribunda is febrifuge and could be a quinine substitute, since it showed remarkable inhibitory activity against drug-resistant strains of Plasmodium falciparum (Fortie et al., 2006). This plant has been found to display a wide spectrum of biological and pharmacological activities such as antibacterial (Bogue et al., 2007), analgesic (Udobre et al., 2014), hypoglycemic (Gnangoran (2012) and antiamiboedal (Goutarel (2012). The common calabash tree (Crescentia cujete) is of the Curcubitaceae family and has been cultivated widely throughout the new world tropics since prehistoric times; its exact native range is uncertain. It is a small tree with light green bell-shaped flowers (5 to 6.5 cm long) that are borne singly on stout stalks on the trunk and branches. The flowers are bat- pollinated and are produced irregularly throughout the year. The large fruit has a thin hard shell and whitish pulp and does not split open. The many seeds are dark brown, thin, and flat. Like some other fruits of species in the family Bignoniaceae, the fruits of this species possess nectar-producing nectaries. In some other species in this family, these nectaries have been shown to attract ants that drive away animals that feed on the plants (Elias, 1978). Ejelonu et al. 2011 investigated the proximate composition of C. cujete and found out that the value of the fat, protein, nitrogen, crude fibre, moisture content, sucrose, fructose, galactose and energy content were quite high. Nandita et al. 2014 also investigated the antioxidant properties of the ethanol extracts and fractions of leaves and stem bark and reported the stem bark as having the highest antioxidant activity.