Food Science and Technology Project Topics

Antibacterial and Physicochemical Properties of Scent Leaf and Bitter Leaf

Antibacterial and Physicochemical Properties of Scent Leaf and Bitter Leaf

Antibacterial and Physicochemical Properties of Scent Leaf and Bitter Leaf

Chapter One

Objectives of the study

The objectives of this study are to:

  1. Determine antibacterial properties of Bitter leaf and Scent leaf
  2. Determine the physicochemical properties of bitter leaf and scent leaf.



Botanical Overview of Bitter leaf

  1. amygdalina Del, commonly called bitter leaf, is a perennial shrub of 2-5m in height that grows throughout tropical Africa. It belongs to the family Asteraceae, has a rough bark with dense black straits, and elliptic leaves that are about 6 mm in length. The leaves are green and have a characteristic odor and bitter taste (Singha, 2006). In many parts of West Africa, the plant has been domesticated (Igile et al., 2004). It is known as ‘Grawa’ in Amharic, ‘Ewuro’ in Yoruba, ‘Etidot’ in Ibibio, ‘Onugbu’ in Igbo, ‘Ityuna’ in Tiv, ‘Oriwo’ in Edo and ‘Chusar-doki’ in Hausa (Egedigwe, 2010). Vernonia amygdalina is drought tolerant (though it grows better in a humid environment). It thrives on a range of ecological zones and is used as a hedge plant in some communities (Bonsi et al., 1995).

Nutritional Composition/Nutritional Uses

An estimated 815 million people in developing countries suffer from malnutrition, and infants and children are the worst hit (FAO, 2004). Unfortunately, efforts at improving food production and accessibility in these regions have been directed lope-sidedly to roots/tubers, cereals, and animal production. The largely ignored dark green leafy vegetables can however augment the nutrients derivable from other sources, thereby reducing malnutrition tremendously. Leaves are easy to prepare, and contain appreciable quantities of nutrients (Devadas and Saroja, 2000; Oshodi, 2002).

  1. amygdalina Del. has been shown to contain significant quantities of lipids (Ejoh et al., 2007; Eleyinmi et al., 2008), proteins with high essential amino acid score (Igile et al., 2004; Udensi et al., 2002; Ejoh et al., 2007; Eleyinmi et al., 2008) that compare favorably with values reported for Telfairia occidentalis and Talinum triangulare (Ijeh et al., 2006), carbohydrates (Ejoh et al., 2007) and fiber (Udensi et al., 2002; Ejoh et al., 2007; Eleyinmi et al., 2008). The plant has also been shown to contain appreciable quantities of ascorbic acid and caroteinoids (Udensi et al., 2002; Ejoh et al., 2007). Calcium, iron, potassium, phosphorous, manganese, copper and cobalt have also been found in significant quantities in Vernonia amygdalina (Bonsi et al., 1995; Ejoh et al., 2007; Eleyinmi et al., 2008).

Unfortunately, the dietary use of the leaves of Vernonia amygdalina has remained limited only to the cultures that use it as vegetable (after maceration to remove the bitter principles) in soup and porridge preparation, suggesting an under-utilization of the plant’s leaves.

 Medicinal Uses

  1. amygdalina Del. is probably the most used medicinal plant in the genus Vernonia (Erasto et al., 2006). The observation that an apparently sick wild chimpanzee chewed V. amygdalina Del. and seemed to return to normal activity after a while, by Huffman and Seifu (2009) and Ohigashi et al. (2001) elicited the attention of the phytomedicine community such that dozens of studies have been done since then to test the efficacy of different extracts of the plant in managing a wide array of medical ailments. Igile et al. (2004) reported that in traditional medicine, practitioners use the plant as an anti-helminth, anti-malarial, and as a laxative. Others use it as a digestive tonic, appetizer, and febrifuge and for the topical treatment of wounds (Iwu, 2006).

Dalziel (2007) was about the first to report that the root and twig of the plant are used for the treatment of stomach and gastrointestinal problems by the Hausas of Northern Nigeria, while the decoction from the leaves is used in treating malaria fever in Guinea and cough in Ghana. In some parts of Nigeria, the stems are used as chew sticks for oral hygiene, and for the management of some dental problems. In Malawi and Uganda, VA is used by traditional birth attendants to aid the expulsion of the placenta, after birth, aid post-partum uterine contraction, induce lactation and control post-partum hemorrhage (Bullough and Leary, 2002; Kamatenesi-Mugisha, 2004). Many of these traditional uses of the plant have been scrutinized scientifically.

  Antibiotic/Antimicrobial/Antimalarial Properties of V. amygdalina Del

The sap of the leaves of VA was found to show inhibitory capacities against Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeroginosa (Ijeh et al., 2006). A 60% methanolic extract of the leaves gave antimicrobial activity against Bacillus subtilis, Klebsiella pneumonia, P. aeruginosa, Proteus vulgaris, Shigella dysenteriae and S. aureus (Akinpelu, 1999).  Both vernolide and vernodalol isolated from VA showed activity against the Gram positive Bacillus cereus, S. epidermidis, S. aureus, Micrococcus kristinae and Streptococcus pyrogens and the Gram negative Salmonella pooni, but neither of the two had any activity against the Gram negative E. coli, Serratia marcescens, P. aeruginosa and K. pneumonae (Erasto et al., 2006). This implies that the activity reported for the extracts of VA against E. coli and P. aeruginosa by Ijeh et al. (2006) and P. aeruginosa and K. pneumonae by Akinpelu (1999) may be mediated by other phytochemicals other than the Sesquiterpene lactones vernolide and vernodalol. Reports from Huffman et al. (2006) and Moundipa et al. (2005) show that the plant extracts possess potent amoebicidal activity. This implies that it may be useful in the management of amoebic dysentery – a fairly common ailment in poor settings where environmental sanitation and personal hygiene are often neglected. These results justify the use of VA in the treatment of wounds and some gastrointestinal problems in traditional medicine.





Fresh leaves of Vernonia amygdalina (bitter leaf) and Ocimum gratissimum (scent leaf) were collected from Oja Oba, Owo, Ondo State, Nigeria. The plants were identified and authenticated. The fresh leaves were washed with distilled water, sun dried for fifteen days and then milled into powder.




Table 4.1: Physico-chemical Properties of Bitter leaf and Scent leaf





            In conclusion, bitter leaf and scent leaf are apparently plants with diverse potentials as shown table 4.1 and 4.2 above, its chemical constituent makes it ideal for nutritional and medicinal uses. According to the results on the ash content of both samples which shows that both samples are rich in minerals which is essential for human health, the results on the tested microorganisms shows that both samples can be used effectively in controlling bacterial such as E.coli, Staphylococcus aureus, Streptococcus spp, Klebsiella pneumonia and Pseudomina gemymosa      


            Based on this research study above it is therefore recommended that more research has to be done, to transform the large volume of research already done on these plants into practical, readymade nutraceuticals phytotherapeutics so that mankind may begin to effectively utilize these plants (Bitter leaf and Scent leaf) for maximal benefit.


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