American Journal of Plant Sciences, 2013, 4, 221-229 http://dx.doi.org/10.4236/ajps.2013.42029 Published Online February 2013 (http://www.scirp.org/journal/ajps) Evaluation of Antioxidant Capacity of Two Ocimum Species Consumed Locally as Spices in Nigeria as a Justification for Increased Domestication Edak A. Uyoh * , Peter N. Chukwurah, Imabasi A. David, Anna C. Bassey Department of Genetics and Biotechnology, University of Calabar, Calabar, Nigeria. Email: * gen_uyoh @yahoo.com Received December 19 th , 2012; revised January 21 st , 2013; accepted January 28 th , 2013 ABSTRACT The antioxidant activities of Ocimum basilicum and Ocimum gratissimum consumed as spices in Nigeria were evaluated in a bid to provide better scientific basis for increased domestication efforts on them. Total phenol and flavonoid con- tents of the spice extracts ranged from 9.09 - 27.41 μg GAE/mg and 5.38 - 22.88 μg RE/mg respectively. The DPPH and hydroxyl radical scavenging activities of the spice extracts ranged from 58.43% - 92.37% and 6.27% - 16.67% re- spectively. The total antioxidant capacities and reducing powers of the extracts (measured as absorbance values) ranged from 0.137 - 0.160 and 0.130 - 0.158 respectively. Generally, Ocimum basilicum maintained superior antioxidant ac- tivities to O. gratissimum in all the test assays, and all the extracts showed dose-dependent antioxidant activities. Ascorbic acid, Gallic acid and Rutin used as reference compounds generally showed higher antioxidant activities to the spice extracts except in the hydroxyl radical scavenging assay. Put together, these results confirm that Ocimum basili- cum and O. gratissimum extracts possess appreciable natural antioxidant potentials, thereby providing good justification for their increased domestication and consumption. Keywords: Antioxidant Activity; Scavenging Activity; Reducing Power; Ocimum spp.; Spices; Domestication 1. Introduction Spice plants have important uses in food and medicine and interestingly, the Nigerian ecology has been ad- judged as favourable for the production of a wide range of these spices [1]. Many of them, however, are in the wild where a lot of factors including forest fires, over exploitation, lack of conservation programmes, land clearing for roads and development, none-recognition of valuable species by incidental farmers and uncontrolled deforestation threaten their production. Significant among the factors limiting optimal production and domestication of some of these spices is general lack of knowledge on the full range of benefits, especially medicinal, that these plants possess. Ocimum basilicum L. and Ocimum gratissimum L. are two popular spices used widely in many Nigerian cui- sines. Commonly known as scent leaf in Nigeria, Oci- mum gratissimum L. is also used in traditional medicine for treatment of several ailments such as urinary tract and gastro intestinal infections [2]. The leaves are used as a general tonic and possess anti-diarrhoeal [3] and anti- diabetic properties [4]. Essential oils of O. gratissimum contain eugenol and show some evidence of anti-bacte- rial activity [5]. Ocimum basilicum is used in folk medi- cine due to its stimulant, carminative and anti-spasmodic properties. It has important uses in pharmaceutical and cosmetic industries [6]. Its green aromatic leaves are used fresh or dried as flavourings or spices while the essential oil is an important part of toiletry products like mouth washes and dental creams. Among the medicinal benefits of plants, antioxidant properties have received increasing attention due to their role in preventing or down regulating myriads of oxida- tive damages caused by free radicals in the body [7]. Oxidative stress is initiated by free radicals, which seek stability through electron pairing with biological macro- molecules such as proteins, lipids and DNA in healthy human cells and cause protein and DNA damage along with lipid peroxidation. These changes contribute to can- cer, atherosclerosis, cardiovascular diseases, ageing and inflammatory diseases [8,9]. Spices are harmless sources for natural antioxidants [10], which are generally preferred to synthetic counter- parts in combating free radical damage due to the in- creased risk of carcinogenesis associated with the use of * Corresponding author. Copyright © 2013 SciRes. AJPS