The Phytochemical Analysis and Amino Acid Profile of Allium CEPA(Onions) Extracts
Abstract
It has been established that plants which naturally synthesize and accumulate some secondary metabolites such as alkaloids, glycosides, tannins, volatile oil, minerals and vitamins have medicinal properties. Then phytochemical and amino acid profile of allium cepa extracts was carried out.
The proximate values of the nutrients in 100g of raw onion were analyzed using qualitative and quantitative method. Amino acid profile of the onion extracts was done by extraction, digestion, distillation, hydrolysis, titration, and evaporation techniques and finally analysed using Technicon Seqential Multisample analyser (DNA model). The standard quantitative method of analysis was used to determine the phytochemicals (toxicants) in the onion extracts while qualitative method was used for the screening.. The result of proximate compositions proved that onions contain Water (86.5%), carbohydrate (11.1%), Protein (1.3%), Fats and oil (0.2%) and Ash (0.5%). The Amino acid profile revealed that Arginine (3.74g/100g) and Histidine (1.21g/100g) were present in the extracts. Others include; Isoleucine (2.22g/100g), Leucine (4.11g/100g), Lysine (3.60g/100g) Methionine (0.86g/100g), Phenylalanine (2.29g/100g), Threonine (1.25g/100g) and valine (2.01g/100g), in 100g of protein. There was a change in the values of amino acid profiles of the aqueous extract when compared with that of solvent extracts. The results of the phytochemical screening showed that; flavonoid, terpernoids, carbohydrate, cardiac glycosides, saponins, anthraquinone, phlobatannins, alkaloid and polyphenol were present. The amounts of toxicants in 100g raw onion were: Alkaloid (13.0%), Tannic acid (0.03g), Oxalate (1.15g), Cyanogenic glycosides (2.91mg) and phytic acid (6.05mg). likewise the solvent extracts. But at alpha – level (p ≥ 0.05), there was no significant difference (p = 0.222) between the effects of aqueous and solvent extracts. The research has shown that; onions widely used as food, could serve as natural medicine, flavour enhancer and antimicrobial agent in food and pharmaceutical industries to improve Nigeria’s ailing economy.
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Introduction
The history of herbal medicine dated back to 2800BC (Gerber, 2010). Medicinal herbs contain substances that can be used for therapeutic purposes and synthesis of useful drugs. Meanwhile, plants that possess therapeutic properties or exert beneficial pharmacological effects on the body of animals are generally termed “Medicinal plants” (Tapsell et al., 2006; Giovannimi et al., 2016). They have no specific morphological characteristic but possess some special qualities that make them medically important. It has been established that plants which naturally synthesize and accumulate some secondary metabolites such as alkaloids, glycosides, tannins, volatile oil, minerals and vitamins have medicinal properties (Edeoga and Erratodo, 2000; Benkeblia, 2004).
Allium cepa (Onions) is one of the edible species of a large genus (Allium) consisting of more than 700 species (Burnie et al., 1999). Among the edible Allium, the onion (Allium cepa) ranks first in the warm-temperate hills of eastern Nepal, followed by garlic (Allium sativum) and shallot (Allium cepa Aggregatum group) (Gautam et al., 1997). Allium cepa belongs to the family of Liliaceae.
Conclusion
This study has shown that the efficacy of the extracts might be due to presence of bioactive constituents in Onion. These bioactive molecules are potential sources of antimicrobial drugs that could tackle the problem of drugs resistance that is currently a challenge to our country‟s Food and Medical industries.