Abstract

Consumption of cruciferous vegetables has continue to gain more acceptance particularly now in Africa, for reasons including wide range of health benefits; reducing the risks of developing cancer, bone health, fighting heart disease and as a good source of vitamins and minerals. The presence of glucosinolates, a class of Organic Anionic Sulfur rich secondary metabolites confers the heath servicing capacities on crucifers. This study is aimed at evaluating total and individual glucosinolates levels in cultivars widely consumed in Nigeria using High Performance Liquid Chromatography (HPLC), through both Cold methanol and Boiling water extraction treatments. A reverse phase High Performance Liquid Chromatography (HPLC) C18 column (Spherisorb 5µ ODS (2), 100 mm × 4.6 mm) was employed to evaluate the concentration of three intact glucosinolates: Progoitrin (2R)-2-Hydroxybut-3-enyl), Sinigrin (2-Propenyl) and Sulforaphane in four (4) different types of cruciferous vegetables: Broccoli (Brassica oleracea L. italica), Kale (Brassica, oleracea L. acephala group), Cauli flower (Brassica oleracea L. botrytis ) and Green cabbage (Brassica oleracea L. capitata). Glucosinolates (as desulfoglucosinolates) were quantified at 229 nm wavelength within the UV spectrum. The results show concentration of Progoitrin, Sinigrin and Sulforaphane range 0.133- 0.154, 0.590 – 0.640, and 0.820 -0.980 respectively for boiling water method while the range 0.00- 0.056, 0.108 -0.302 and 0.364- 0.398 for Cold Methanol treatment. The level of glucosinolates investigated was observed higher in stems than in the levels of vegetables studied. ANOVA at P < 0.05 revealed varying degree of significant and non- significant difference between the two extraction methods. Boiling water extraction was observed to give a higher yield than cold methanol extraction treatment.

Keywords: Progoitrin, Crucifereae, Sinigrin, and Sulforaphane