Comparative Analysis of the Phytochemicals, Proximate and Mineral Compositions of Scent Leaf (Ocimum gratissimum) and Bitter Leaf (Vernonia amygdalina) Leaves

Abstract

Ocimum gratissimum (fam.Lamiaceae) ‘Scent leaf’ and Vernonia amygdalina (fam.Asteraceae) ‘Bitter leaf’ are commonly consumed vegetables in Southern Nigeria. O. gratissimum is used by the ‘Igbos’ of South East Nigeria to flavor soups and stews while it is popular with the ‘Yorubas’ of South West Nigeria for treatment of stomach disorders. V. amygdalina is a well known vegetable in West Africa used as both food and for its pharmaceutical properties. The enormous use of these vegetables in the diet motivated the present study whereby the food compositions, mineral constituents and the phytochemicals of the two vegetables were determined. Qualitative analysis, of the aqueous extracts, revealed the presence of saponins, terpenoids, tannins, flavonoids, steroids, alkaloids, phenolics and anthraquinones in both vegetables. Generally V. amygdalina contained higher quantities of secondary metabolites, saponin which was reported as the highest amount was 5.71±0.12 mg/g and 3.52±0.01 mg/g followed by terpenoids 5.64±0.11 mg/g and 3.40±0.11 mg/g in V. amygdalina and O. gratissimum respectively. There is however a minute amount of anthraquinone in the two vegetables. Proximate analysis and macro elements were determined using their various standard methods. The results of proximate analysis revealed the presence of moisture (12.28 ± 0.02% and 10.01± 0.01%) protein (35.37±0.11% and 22.20±0.02%) and total ash (6.00±0.20% and 5.75±0.10%) each in V. amygdalina and O. gratisimum respectively. The following minerals were present calcium, magnesium, potassium, sodium, iron, copper and zinc, with zinc being in the highest concentration (46.80± 0.03 mg/kg and 58.00±0.12 mg/kg) followed by copper (9.45±0.11 mg/kg and 16.60 ± 0.03 mg/kg) each in V. amygdalina and O. gratissimum respectively. There are higher values of phytochemicals and food components in V. amygdalina while O. gratissimum had higher mineral contents. These two vegetables are potential source of components for complementary medicine.