Proximate and Mineral Composition of Bitter Leaf (Veronia Amygdalina L) and Scent Leaf (Ocimium Grastissimum)
Chapter One
The Objective of the Study
The aim and objectives of this study are to determine the proximate and mineral composition of bitter leaf and scent leaf.
CHAPTER TWO
LITERATURE REVIEW
The Genus Vernonia
Vernoniaamygdalina it is known as bitter leaf, due to its characteristic bitter taste and flavour, and may be used as an active anticancer (Izevbigie, 2003), antibacterial, anti-malaria and anti-parasitic agent (Tadesse et al.,2003). This plant contains complex active components that are pharmacologically useful. The roots and the leaves are used in ethno-medicine to treat fever, hiccups, kidney problems and stomach discomfort. The stem and root divested of the bark are used as chew-sticks in many West African countries like Cameroon, Ghana and Nigeria (Burkill, 2005; Hamowia, 2004). It is also documented that V. amygdalina has been used traditionally in blood clotting and has elicited a significant reduction in blood glucose levels at post-prandial time point (Uchenna et al.,2008). Fasola et al.,(2010) reported that V. amygdalina has hypoglycemic activity. They observed a dose-dependent reduction in fasting blood sugar level in alloxan-induced diabetic rats after treatment with different concentrations of the aqueous leaf extracts. Yedjou et al.,(2008) also demonstrated V. amygdalina leaf extracts as a DNA – damaging, anticancer agent in the management of breast cancer. However, much work has not been documented on the antimicrobial effectiveness of the stem extracts of this plant. This research is designed to screen the anti-microbial effectiveness of V. amygdalina leaf and stem extracts on selected urinary tract pathogens, compared to ciprofloxacin antibiotics.
Nutritional Composition of Bitter Leaf
Quite a number of researches have established the nutritional content of Vernoniaamygdalina. Proximate composition of Vernoniaamygdalina reveals the presence of protein, carbohydrate, moisture, ash, fibre and fat as reported by Argheore et al. (1998). The analysed moisture content (%) as reported by Argheore et al.,(1998) was 10.55% which was higher than that reported (10.02%) by Asaolu et al.,(2012). Variation was suggested to be due to soil nutrients and environmental factors which have effects on the nutrients availabilities for plants. The crude fibre content of Vernoniaamygdalina is 8.78% which is within the ranged for some Nigerian vegetables. Also, ash content indicates 4.28% which is lower than values reported by Asaolu et al.,(2012) for bitter leaf (9.56%) and scent leaf (13.01%). The presence of ash in bitter leaf is a confirmation of the presence of mineral elements. The crude protein (18.75%) was higher than the protein contents of some leafy vegetables such as Momordica balsamina (11.29%). This result affirms reports of Ezekiel et al.,(2015), Kokwaro et al.,(2009) and Sodimic et al.,(2006).
Ezekiel et al.,(2009) observes minerals contents in Vernoniaamygdalina in the trend; K > Na > Ca > Mg > Fe >Zn > Cu > Mn. Potassium was the predominant mineral element detected while manganese was the least detected minerals element. Inorganic mineral elements such as potassium and calcium are known to play important roles in the maintenance of normal glucose-tolerance and in the release of insulin from beta cells of islets of Langerhans which help to control the glucose level of the human body (Kadiri, 2015).
Antioxidant Properties
There has been increase scientific interest in antioxidants from plant sources in recent times. Antioxidants inhibit deleterious effects of free radicals in human body and deterioration of fats without corresponding side effects when compared with synthetic antioxidants. They are compounds that inhibits or stop the actions of these radicals and its reactive oxygen species (ROS) known for the development of disease originating from oxidative stress. Quite a number of researchers in the field of medical sciences have observed free radical scavenging ability and antioxidant property in Vernoniaamygdalina. Vernoniaamygdalina have been established to possess antioxidant properties which correlate to its medicinal properties. They are plants known to play dietary as well functional roles in disease prevention. Antioxidant activities of bioactive compounds isolated from Vernoniaamygdalina leaves have been established from various studies (Igile et al.,1994; Farombi and Owoeye, 2011; Ho et al.,2012; Udochukwu et al.,2015).
Comparative studies between the methanolic and aqueous extracts of Vernoniaamygdalina and Talinum triangulare leaves reveals Vernoniaamygdalina to possess higher antioxidant properties, phyto-nutrients and longer shelf life hence it’s common use and acceptability in folkloric and trado-medicine (God’s will et al.,2010). Methanolic extracts of Vernoniaamygdalina shows potent antioxidant properties in a study by Adesanoye and Farombi (2014). Correlation coefficients was observed between total phenolic/flavonoid content and the antioxidant and free radical scavenging activities of the plants which implies that these properties are dependent on the flavonoid and phenolic contents of the plant.
DPPH (2, 2-diphenyl 1-picrylhydrazyl) assay of the methanolic extract of Vernoniaamygdalina leaves reveals significant antioxidant properties (Ezekiel et al.,2015). The antioxidant properties exhibited by the leaves may explain the antioxidant benefits which explains it usefulness in the prevention of diseases caused by free radicals and reactive oxygen species (ROS). Also, comparative study of the ethanolic extracts of Vernoniaamygdalina and Ocimum gratissimumleaves showed significant antioxidant activity (P<0.05) when compared with antioxidant standards like ascorbic acid in a study by Udochukwu et al.,(2015). Significant content of phenol and flavonoid were also estimated even though detected values for Ocimum gratissimumleaves showed significant higher amount than Vernoniaamygdalina leaves. These results substantiate the medicinal value of these vegetables. Vernoniaamygdalina leaf extracts was also shown to increase in vivo antioxidants activities of test rats in an in vivo antioxidants assay (Argheore et al.,1998).
Antioxidant and anti-diabetic properties of sequential petroleum ether, chloroform, methanol and water extracts of Vernoniaamygdalina based on the chemical composition of the most effective anti-diabetic extract was reported using DPPH and ABTS radical scavenging as well as FRAP assays by Akpaso et al.,(2011). Extracts of the various solvent extractions were observed to show a consistent dose-dependent trend of potent antioxidant activity in the following solvents: water extract > methanol extract > chloroform extract > and petroleum ether extracts. The extracts were also observed to inhibit DPPH activity in a dose-dependent manner with significantly higher potencies in the polar extracts compared to the non-polar extracts. Omoregie and Osagie (2012) reported the in vitro and in vivo antioxidant effects of methanolic extracts of six locally consumed Nigeria plants on nutritionally-stressed rats. These plants include; Vernoniaamygdalina, Crassocephalum rubens, Jatropha tanjorensis, Amaranthus hybridus, Talinum triangulare and Gnetum africana. Laboratory test rats were exposed to nutritional oxidative stress using a low protein diet and In vivo antioxidant activities assay was carried out on the test animals and the control animals.
Plant extracts were observed to exhibit comparable DPPH free radical scavenging ability in a dose-dependent manner. Extracts treated rats showed normal levels of antioxidant enzymes (superoxide dismutase, catalase, vitamins E and C) as well as high level of malonaldehyde probably due to the bioactive principles inherent in them. The overall antioxidant capacity of the extracts suggested a positive correlation as well as synergistic effects with respect to the DPPH scavenging activity, total phenol, flavonoid and proanthocyanindin components of the extracts. This they observes might indicate that the components are more likely to contribute to the antioxidant potential of the extracts and confirms local claims on the efficacy of the plants leaves (Omoregie and Osagie, 2012). More recent studies by Ekaluo et al.,2015, Udochukwu et al.,2015 and Ezekiel et al.,2015 affirms previous studies on the antioxidant properties of Vernoniaamygdalina leaves extracts.
CHAPTER THREE
MATERIALS AND METHOD
The experimental work was carried out in processing laboratory department of Food Scienceand Technology, Rufus Giwa Polytechnic Owo, Ondo State.Fresh bitter leaf and scent leaf was purchased local market in Owo, Ondo state, Nigeria.
Sample Preparation
The leafy vegetables (bitterleaf and scent leaf) were thoroughly washed differently with distilled water and sundried. The dried leaves were ground into powder using pestle and mortar. The ground portion was kept in a plastic bottle in a freezer prior analysis.
Proximate Analysis
The proximate analysis of the food samples was carried out according to AOAC procedure (2000) for moisture, fat, ash, Protein, crude fibre and carbohydrate.
CHAPTER FOUR
RESULTS AND DISCUSSION
Results
Table 4.1: Proximate Composition of Scent leaf and Bitter leaf
CHAPTER FIVE
CONCLUSION AND RECOMMENDATION
Conclusion
The above study shows that both samples (bitter leaf and scent leaf) are medicinal plants as well as antimicrobial plants due to their constituent which help a long way in health complications. The result on proximate composition of both samples shows that scent leaf has higher moisture, ash, and protein contents compared to bitter leaf, though they both shares the same value in fat content with a value of 7.50% with a little difference of 0.20% in crude fiber. The energy given level i.e. carbohydrate content of bitter leaf is higher than that of scent leaf which is shows that bitter is a good source of carbohydrates. The study also helps in concluding that scent leaf is rich in mineral composition that bitter leaf.
Recommendation
Based on the above finding it is therefore recommended that both bitter leaf and scent leaf should be cultivated as well consumed not because of their delicious which can be prepared using these two plants but because of their health benefits and their nutritive value.
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