Perspectives of Secondary Metabolites in Reference to Vegetable Crops: A review

Vegetables are known as protective food as they are a rich source of biologically active substances like vitamins, fibers, antioxidants, cholesterol-lowering compounds, etc. The discovery of many health-promoting compounds or nutrients was made possible through various experiments or some by chance in the past. During the time course, some novel technologies like chromatography, mass spectrometry, infrared spectrometry, and nuclear magnetic resonance came into known which enabled quantitative, and qualitative measurements of a wide range of plant metabolites. Flavonoids, phenolics, and glucosinolates are the secondary metabolites that are required in plant growth & development, and stress or defence mechanism. Aside from providing strength to a plant's immune system, such metabolites influence the nutritional quality, colour, taste, and smell of the food, as well as medicinal properties. This review intends to gather the scattered information available on the SMs which included their classification, structural differentiation, their potential roles in defence mechanisms, ecological adaptation, and available extraction techniques in reference to vegetable crops.