Comparative Hypoglycemic effects of aqueous leaf extracts of Vernonia amygdalina, Ocimum gratissimum, Phyllanthus amarus, Gongronema latifolum, Piper nigrum and Solanum melongena on Blood Glucose Level of Alloxan-Induced Diabetic Guinea Pigs

 

Akunneh -Wariso C¹*, Aduema W²

¹Department of Human Physiology, Abia State University, Uturu, Abia State, Nigeria.

²Department of Medical Physiology, PAMO, University, of Medical Sciences, Port Harcourt, Rivers State, Nigeria.

 

ABSTRACT:

This research work was meant to explore the hypoglycemic potencies of different tropical herbal aqueous leaf extract of Vernonia amygdalina (Bitter lea), Phyllanthus amarus (Stone breaker), Ocimum gratissimum (Sent leaf), Gongronema latifolium (Utazi), Piper nigrum (Uziza) and Solanum melongena (Gardern egg) on blood sugar level of alloxan induced diabetic guinea pigs.Seventy guinea pigs of both male and female were randomly selected and grouped accordingly using Glibenclamide solution (a known oral hypoglycemic drug) as a positive control and physiological solution (0.9% Normal Saline) as a negative control. The average weight of the guinea pigs was 250g. each guinea pig was made diabetic by induction with a single dose of 5% alloxan monohydrate dissolved in 0.9% normal saline at 200mg/kg body weight intraperitoneally. This concentration of alloxan used for diabetic induction in these guinea pigs was determined during the preliminary test. Six different groups had oral administration of the aqueous leaf extract via Canula at 300mg/kg body weight per day for two weeks after alloxan induction. The positive and negative control groups had oral administration of glibenclamide solution (a know oral hypoglycemic agent) at 0.25mg/day and 0.9% NS (a physiological solution) at 15ml/day via canula for two weeks respectively.On the average, the results of this study revealed appreciable percentage reduction of fasting blood sugar level of the diabetic guinea pigs that had oral administration of aqueous leaf extracts of Phyllanthus amarus, Vernonia amygdalina, Gongronema latifolium and Ocimum gratissimum which was comparable to the fasting blood sugar level of positive control group (Glibernclamide solution), thereby showing an appreciable hypoglycemic effects.The group of diabetic guinea pigs that had aqueous leaf extracts of Solanum melongena had a low percentage reduction which depicts mild hypoglycemic effects, while the group that had Piper nigrum showed a very insignificant percentage of reduction of mean fasting blood sugar.The effect seen in this group that had aqueous leaf extract of piper nigrum was comparable to the effect seen in negative control group.Z-test as a statistical test revealed a significant difference between the post induction fasting blood sugar level and post aqueous leaf extract administration (p< 0.05).

 

 

INTRODUCTION:

Diabetes mellitus is one of the commonest tropical endocrine or metabolic diseases (Adetuyibi 1980). The incidence of diabetes mellitus is growing rapidly worldwide. For example, it is estimated that 135 million people worldwide are afflicted with the most common form of type II (Harvey and Champe 2006). It is also estimated that about 10 million Nigerians are diabetic (This Day Newspaper, February 4, 2009, Vol. 14 No 5036 Pages 33 and 34). An estimated 20 million people in the United States o America or 6.3 percent of the  population have diabetes, a serious life threatening condition. Diabetes mellitus is a syndrome characterized by hyperglycaemia caused by relative or absolute deficiency of insulin or peripheral resistance to insulin. It involves disturbance of carbohydrate, fat and protein metabolism, resulting from defects in insulin secretion or insulin action (Falase and Akinkugbe 2000).

 

Diabetes mellitus is classified mainly into type I Diabetes Mellitus, Type II Diabetes Mellitus and Maturity-Onset Diabetes in Youth (MODY) or gestational diabetes.Type I diabetes mellitus formally called insulin dependent diabetes mellitus (IDDM) or juvenile diabetes is associated with profound insulin deficiency and accounts for only about 5-10% of those with diabetes mellitus.Type II diabetes mellitus formerly known as Non-insulin dependent diabetes mellitus (NIDDM) accounts for about 90-95% of those with diabetes. It is associated with insulin resistance. Management of this disease is basically lifestyle modification, diet, oral hypoglycaemic agents and insulin therapy. These selected tropical herbs used in this study are extensively applied by herbalists and taxonomists or several medical conditions such as diabetes mellitus. The major emphasis is on their aqueous leaf extracts. Vernonia Amygdalina (bitter leaf) is a tropical shrub in the plant family of compositae. The leaves are widely used as vegetables probably because of its therapeutic properties. Those who consumes, bitter leaf regularly stand a better chance of being prevented from developing diabetic and hypertensive complications (Bunkhil 2000). This herb which grows to about 5 meters high especially around forest margins or along the edge of agricultural fields is widely distributed throughout tropical African (Muanya 2005).  The leaves of vernonia amygdalina are given with a characteristic odour and bitter taste attributed to anti-nutritional factors including alkaloids, saponins, tannins, glycosides, sesquiterpenes flavinods as seen in phytochemical screening (Butler and Berlly 1973).

 

Strong anti-oxidant activities have been reported for flavionoids from vernonia amygdalina and its saponins have been reported to elicit anti-tumoral activities in leukaemic cells (Jisaka etal, 1993). Ocimum gratissimum: Ocimum gratissimum commonly called Scent leaf is a herbaceous perennial herb and wood at its base. It is commonly used in preparing foods owing to its spicy nature apart from its therapeutic importance. This herb is in the family of Labitae, and it is widely seen in Africa, east India and Brazil. It comprises of green leaves, stem and roots. The aqueous extract of ocimum gratissium has a hypoglycemic effect which is due to methanolic extract of the leaves which enhance its hypoglycemic activity. The extracts contain essential oil. The essential oil is anti-protozoan. It inhibits the growth of protozoan (Holetz 2003). Antibiotic effects have been associated with the extract of ocimum gratissimum leaves. This is basically due to its essential oil. The essential oil in ocimum gratissimum has been found to inhibit staphylococcus. Aside the essential oil, the methanol extract has antibiotic properties and also facilitates wound healing (Internet: http:www. google.com.ng). Phyllanthus amarus commonly called stone-breaker is a perennial herb grown in the tropical forest such as Africa. It is also seen in china and Asia. This herb has tiny green leaves and soft stems. It is in the family of Euphorbiaceae. The extract of phyllanthus amarus has been widely found and used in diabetic management by some herbalists probably due to its hypoglycemic effects. Aside its application in diabetic management, it has also been found useful in viral hepatitis including chronic hepatitis. Its extracts is said to be hepato-protective and it’s used in the herbal treatment o primary hepatocellular carcinoma (Boender 2000). Gongronema latifolium is a rainforest tropical plant in the family of Asclepiadaceae. It is a herb with a climbing stem. It is called “Utazi” in Igbo or Ibibio, while in Yoruba it is called “Arokeke or Madumaru”. It is used in food preparation as vegetable or as a herbal remedy in herbal practice. The aqueous or ethanolic extract of those leaves are used in herbal practice for management of diabetes because of its hypoglycemic (antiperglycemic) effects. The extracts of those leaves have anti-inflammatory and anti-oxidant effect. Owing to the above effects, they can be used to abort inflammation as anti-inflammatory extracts to reduce serum, cholesterol in cases of hyperlipidaemia and as anti-oxidant as to remove free radical or toxin in the body (Ugochukwu 2002 and 2003). Piper nigrum is a herb in the family of piperaceae. It is also called black pepper or “Uziza” in Igbo. It is a monoecious or dioecious climbing vine. The stout climbing stems are flexibleThis herb is widely used as a homeopathis remedy, so its therapeutic values are more appreciated in the homeopathic or herbal practice (Wikimedia.org/wikipipermigrum). It is also used as spice in food preparation especially, in tropics. Solanum melongena. These are the tropical economic flowering plants belonging to the family of solanaceace. Solanum species are popularly known as Garden egg plants.  They are widely grown in farms of tropical and temperate region. In Igbo, it is called “Anara” or “Afufa”; “guata” in Hausa, “Igbaaja”, in Yoruba, “Nya”, in Ibibio “Anyara”, in Efik. It is also called bitter tomatoes.  The leaves and fruits of this tropical plant are consumable. The leaves are used for preparing soups as vegetables aside its therapeutic value. There are two major botanical species namely, Solanum aergiopicum and solanum melongena. In this study, solanum melangena leaf extract was used. In herbal practice, the aqueous leaf extracts are used for treatment of diabetes mellitus due to its mild hypoglucemic effects. The aqueous leaf extracts of this herb is popularly used by many herbalist in the management of chronic anaemia. Solanum melongena may be used by patients suffering rom raised intraocular pressure (Glaucoma) and convergence insufficiency (Igwe etal 2002). The aqueous leaf extracts of these tropical herbs may be obtained by squeezing the green leaves with a given quantity of water. The aqueous leaf extract should be taken when fresh; otherwise storage of the extract in the refrigerators or deep freezer reduces the potency to nil (Arazu and Okafor 2005).

 

MATERIALS AND METHODS:

Seventy guinea pigs of different sexes were randomly selected for this study, and weighted with a weighing scale before administration of any substance or induction with alloxan. The average weight of the guinea pigs was 250grams body weight. These guinea pigs were grouped into eleven groups with five guinea pigs in each group. The first three groups were for the substances or extract used for the study. In these eight groups, groups one and two were negative and positive control groups with oral administration of 0.9% N/S (Physiological solution) and solution of Glibenclamide (Oral hypoglycemic) respectively. All the grouped guinea pigs were intraperitoneally induced with a single dose of 5% alloxan monohydrate dissolved in 0.9% Normal saline after determining their fasting blood sugar with a glucometer (Pre-induction fasting blood sugar). Those for the preliminary test were induced with a single dose of alloxan intraperitoneally at concentration of 100ml/dl, 150ml/dl and 200mg/dl for the respective groups as to determine the optimal concentration of alloxan that will bring about a significant increase in fasting blood sugar three days post alloxan induction in three consecutive readings.The eight main groups of guinea pigs were induced with a single dose of alloxan intraperitoneally with  200mg/kg body weight with a 2ml syringe to make them diabetic after blood sugar level pre-alloxan induction had been taken by the glucometer.These guinea pigs were fed with elephant grasses and fasted for 9 hours in each reading.Aqueous leaf extract of the fresh leaves of these tropical herbs were obtained by squeezing one kg each bunch of fresh leaves in 280 mls of water in different washing basin and thereafter received in different labeled bottles after sieving. Prior to extraction, the leaves were bought from the local market aside the phyllanthus amarus which was gotten from the bush. These leaves were identified by staff of department of Plant Science University of Port Harcourt.The aqueous leaf extracts were given per oral with a canula at 300mg/kg body weight to the grouped alloxan induced diabetic guinea pigs. Solution of glibenclamide at 0.25mg/day orally was given via canula to the positive control group post alloxan induction. In the same manner, 0.9% normal saline was also administered  orally via canula to the diabetic induced negative control group. The fasting blood sugar level was determined after three consecutive days for two weeks and then the mean values determined. The aqueous leaf extracts were taken for phytochemical analysis at the department of Biochemistry, Macdonald University Elele, Rivers State.

 

Phytochemical screening:

The phytochemical screening (test) was done in the department of Biochemistry Macdonald University Elele, Rivers State. Phytochemical screening of the six aqueous leaf extracts under study was carried out on the crude menthanolic extract and the weakly acidic fraction using standard procedure and reagent outlined by Harbourine (1984). In general, test for the presence or absence of phytochemical compounds using the above method involving the addition of an appropriate chemical reagent to the tests sample in a test tube. The presence or absence of the phytochemical compounds in each extract was established. These phytochemical compounds are saponnins, flavinoids, alkaloids, tannins, carbohydrates such as glucosides (reducing sugars), proteins, resins, oil, steroids and terpenes. All the extracts were tested for these above phytochemical compounds.

 

RESULTS AND DISCUSSION:

Table1: The preliminary tests showing differential increase in mean fasting blood sugar level after alloxan induction at concentration of 100mg/kg and 200ml/kg.

Sub groups	Mean fasting blood sugar level before alloxan induction (mmol/L)	Mean fasting blood sugar level after alloxan induction (mmol/L)
		100 mg/kg	150 mg/kg	200 mg/kg
1 (n=5)	5.0	5.4	-	-
2 (n=5)	5.0	-	5.8	-
3 (n=5)	5.1	-	-	6.7
Differential increase in mean fasting blood sugar level after alloxan induction		0.4	0.8	1.6

 

In this preliminary test, single dose alloxan induction of the guinea pigs given intraperitoneally at different concentrations of 100mg/kg, 150mg/kg and 200mg/kg body weight was seen in the table above. This table shows the mean fasting blood sugar level after a single dose alloxan induction of the five guinea pigs in three different subgroups. Induction with 200mg/kg body weight revealed an appreciable increase in the mean fasting blood sugar level of 1.6mmol/L which was greater than the readings obtained using the other two concerntrations. Alloxan induction with 100mg/kg and 150mg/kg revealed an increase in the mean fasting blood sugar of 0.4mmol/L and 0.8mmol/L respectively. These mean values were less than 1.0mmol/L.

 

Table 2: The percentage reduction of mean fasting blood sugar level readings obtained from induced groups of guinea pigs with alloxan (200mg/kg) after administration of aqueous leaf extracts using 0.9% normal saline and Globenclamide solution as negative and positive control groups respectively.

Substances Administered	Mean weight of 70 Guinea pigs(g) (250g)	Mean fasting blood sugar level before alloxan induction (mmol/L)	Mean fasting blood sugar level after alloxan induction (mmol/L)	Mean fasting blood sugar level after substance administration (mmol/L)	Actual rate of reduction	Percentage reduction of mean fasting blood sugar level of alloxan induced diabetic guinea pigs after substance administration (%)
0.9% Normal Saline (n=5)		4.98	6.97	7.05	1.98	-
Glibenclamide (n=5)		5.02	7.0	5.02	1.83	20
Phyllanthus amarus (Stone breaker) (n=5)		4.98	6.95	5.02	1.93	20
Vernonia amygdalina (Bitter leaf) (n=5)		5.02	7.0	5.07	1.9	19
Gongronema latifolium (Utazi leaf) (n=5)		4.94	6.95	5.23	1.8	18
Ocimum gratissimum (Scent leaf) (n=5)		5.07	6.67	5.42	1.3	13
Solanum melongena (Garden egg)		4.97	7.04	6.02	1.0	10
Piper nigrum (Uziza) (n=5)		5.03	6.96	6.85	0.1	1

 

This table shows the percentage reduction of the mean fasting blood sugar using aqueous leaf extracts of the six tropical herbs on alloxan induced diabetic guinea pigs when administered singly with the glibenclamide solution (oral hypoglycemic drug) as positive control and 0.9% Normal saline as a negative control.In this table, the percentage reduction of blood sugar level in different alloxan induced diabetic guinea pig groups were compared with that of the control groups.The percentage reduction of blood sugar level of these diabetic guinea pigs was seen to be highest for the groups of guinea pigs that had oral administration of aqueous leaf extract of Phyllanthus amarus, Vernonia amygdalina and Gongronema latifolium which were comparable with the positive control groups that had oral administration of glibenclamide solution.This indicates an appreciable hypoglycemic effect. Ocimum gratissimum and Solanum melongena aqueous leaf extracts also showed moderate percentage reduction of 13% and 10% respectively which were less than the readings from positive control group of 20% reduction in mean fasting blood sugar level after those extracts. The aqueous leaf extracts of Piper nigrum showed a minimal percentage reduction of 1% which was as good as no reduction of the mean fasting blood sugar level of the diabetic guinea pigs in this group. The negative control group of diabetic guinea pigs that had 0.9% Normal saline which is a physiological solution revealed no percentage reduction of blood sugar level.

 

Table 3. The mean fasting blood sugar level of the grouped guinea pigs before and after alloxan induction using ANOVA as the statistical analytic method as seen in the table above.

Substances	Fasting Blood Sugar before Alloxan induction (mmol/L)	Fasting Blood Sugar after Alloxan Induction (mmol/L)	Fasting Blood Sugar after substance administration (mmo/L)	ANOVA
0.9% N/S (n=5)	4.98±0.08	6.97±0.04	7.05±0.05	0.01
	4.88-5.10	(6.9-7.0)	(7.0-7.10)
Glibenclamide (n=5)	5.02±0.12	7.0±0.12	5.02±0.12	0.02
	4.90-5.13	(6.8-7.1)	(4.83-5.10)
Phyllanthus Amarus	4.98±0.07	6.95±0.42	5.02±0.02	0.01
	4.90-5.10	(6.9-7.0)	(5.0-5.04)
Vermonia Amygdalina (n=5)	5.02±0.03	7.0±0.10	5.07±0.04	0.01
	(4.98-5.05)	(6.6-6.9)	(5.03-5.10)
Gongronema Latifolium (n=5)	4.94±0.05	6.95±0.12	5.23±0.07	0.02
	4.88-5.0	(6.8-7.1)	(5.23-5.40)
Ocimum Gratissium	5.07±0.48	6.67±0.10	5.42±0.36	0.03
	5.0-5.10	(6.5-6.8)	(5.38-5.53)
Solanum Melongena (n=5)	4.97±0.57	7.04±0.05	6.02±0.25	0.01
	4.88-5.03	(7.0-7.1)	(5.73-6.40)
Piper Nigrum (n=5)	5.03±0.09	6.96±0.67	6.85±0.05	0.01
	4.90-5013	(6.9-7.0)	(6.80-6.90)

 

 

 

Using ANOVA as the statistical analytic methos, mean fasting blood sugar level of different gropus as shown in this table before alloxan induction could be compared with fasting blood sugar level after alloxan induction. This table indicates that there was a significant difference between the mean fasting blood level before and after alloxan induction in all the eight groups (p<0.05).

 

Table 4. Comparison between the mean fasting blood sugar level of the grouped guinea pigs after alloxan induction and after substance administration using Z-Test.

Substances	Mean Fasting Blood Sugar Level after Alloxan Induction (mmol/L)	Mean Fasting Blood Sugar after substance administration (mmol/L)	Z-Test
0.9% N/S (n=5)	6.97	7.05	0.08 (No)
Glibenclamide (n=5)	7	5.02	0.03 (yes)
Phyllanthus Amaraus (n=5)	6.95	5.02	0.01 (Yes)
Vernonia Amygdalina (n=5)	7	5.07	0.01 (Yes)
Gongronema Latifolium (n=5)	6.95	5.23	0.04 (Yes)
Ocimum Gratssimum (n=5)	6.67	5.42	0.01 (Yes)
Solanum Molengena (n=5)	7.04	6.02	0.02 (Yes)
Piper Nigrum (n=5)	6.96	6.85	0.279 (No)

 

Using Z-Test to compare the mean fasting blood sugar level of these guinea pigs after alloxan induction and mean fasting blood sugar after substance administration, a significant difference was seen in groups of guinea pigs that had glibenclamide solution and those that had aqueous leaf extracts of phyllanthus amarus, vernonia amygdalina, gongronema latifolium, ocimum gratissimum and solanum melongena (P<0.05). this indicates that the mean fasting blood sugar level of the groupd of guinea pigs that had these first five aqueous leaf extracts above is comparable to the mean fasting blood sugar level of the positive control group that had glibenclamide (oral hypoglycemic agent).Also using Z-Test, no significant difference was seen in the negative control group of guinea pigs that had oral administration of 0.9% Normal Saline (physiological solution) and the group that had piper nigrum (P>0.05).

 

Table 5. The quantitative analysis obtained from phytochemical screening of the aqueous leaf extracts

·          = absence of the phytochemical compound

·          = presence of the phytochemical compound.

Phytoconstituent	Piper nigrum	Vernonia amygdalina	Ocimum gratissimum	Solanum melongena	Gongronema latifolium	Phyllanthus amarus
Alkaloids	-	+++	-	++	++	+
Glycosides	-	++	++	++	-	++
Carbohydrates	+	-	++	+	+	-
Reducing sugar	-	-	++	+	-	+
Flavinoids	+++	+++	+++	+	+	-
Resins	+	+	-	+	+	+
Tannins	++	++	+	++	++	++
Steroids	-	++	+	-	+	-
Saponnins	+	+++	++	+	++	+
Terpenes	-	+	+	-	+	+
Proteins	-	+	+	-	++	-

 

This table 5 represented above showed the quantity of the phytochemical constituents in each aqueous leaf extract of these tropical herbs during the phytochemical analysis. The presence of these phytochemical constituents is related to the hypoglycemic potency.

 

Table 6. The percentage composition of the phytochemical constituents found in phytochemical screening of the aqueous leaf extracts of these six tropical herbs used for the study.

Phytoconstituent	Piper nigrum (%)	Vernonia amygdalina (%)	Ocimum gratissimum (%)	Solanum melongena (%)	Gongronema latifolium (%)	Phyllanthus amarus (%)
Alkaloids	0	100	0	66.6	66.6	0
Glycosides	0	66.6	66.6	66.6	0	66.6
Carbohydrates	33.3	0	66.6	33.3	33.3	0
Reducing sugar	0	0	66.6	33.3	0	33.3
Flavinoids	100	100	100	33.3	33.3	0
Resins	33.3	33.3	0	33.3	33.3	33.3
Tannins	66.6	66.6	33.3	0	66.6	66.6
Steroids	0	66.6	33.3	0	33.3	0
Saponnins	33.3	100	66.6	33.3	66.6	33.3
Terpenes	0	33.3	33.3	0	33.3	33.3
Proteins	0	33.3	33.3	0	66.6	0

% = percentage composition of Phytochmical constituents in extracts.

 

In this table, the quantity of phytochemical constituents of these aqueous leaf extracts is expressed in percentages.The result obtained from the phytochemical screening of these aqueous leaf extracts as shown in table 5 and 6 indicated that Vernonia amygdalina contains moderate levels of Alkaloids, Saponnine, Flavinoids at 100% composition  and glycosides, tannins, Steroids at 66.6% composition with mild levels of Resins, terpenes and Proteins at 33.3% composition. In other words, there are more alkaloids, flavinoids, saponnins than other phytochemical compounds in vernonia amygdalina. This extract contains no carbohydrates or reducing sugars. The presence of many of these phytochemical constituents in appreciable quantities up to 100% and the absence of carbohydrate including reducing sugars may be responsible for its high hypoglycemic potency. Phyllanthus amarus was found to have moderate levels of glycosides and tannins at 66.6% each, with mild level of reducing sugars, resins, saponnins and terpenes at 33.3% composition. It was also found to contain no alkaloids, carbohydrates aside reducing sugars, flavinoids, steroids and proteins. The aqueous leaf extracts of this herb contains more of glycosides and tannins than any other phytochemical compounds. The saponnins in this extract is far less than that of vernonia amygdalina but contains the same quantity of tannins and resins. The absence for its hypoglycemic effect. It has been noted that steroids are diabatagenic. Ocimum gratissimum contained moderate levels of flavinoids, glycosides and carbohydrates, reducing sugars and saponnins at 66.6% each during phytochemical screening. The glycosides and terpenes were found to be of the same quantity as in the above two extracts. The saponnins in this leaf extracts is less than the quantity obtained from vernonia amygdalina but contained the same quantity of flavinoids at 100% composition. Gongronema latifolium aqueous leaf extracts showed moderate level of tannins at 66.6% composition as seen in all the aquoes leaf extracts used in the study. They alos contained moderate level of proteins at 66.6% composition which was mmore than the quantity seen in both vernonia amygdalina and ocimum gratissmum. Moderate level of saponnins which was less than the quantity seen in vernonia amygdalina was observed during the screening. It was found that these aqueous leaf extracts contained mild levels of alkaloids, carbohydrates, resins, flavinoids and terpenes at 33.3%. However, gongronema latifolium aqueous leaf extracts contained no glycosides and reducing sugars. The presence of carbohydrates in this extract may be responsible for the decreased hypoglycemic effect while the absence of reducing sugars may account for its hypoglycemic effect.The aqueous leaf extracts of solanum melongena was found to contain moderate level of alkaloids, glycosides and tannins at 66.6% composition with mild levels of carbohydrate, reducing sugars, flavinoids, resins and sapronnins at 33.3% quantity of saponnins seen in this extract was less than the quantity seen in vernonia amygdalina 100% ocimum gratissimum (66.6%) and in gongronema latifolium (66.6%).Nevertheless, there were no steroids, terpenes and proteins seen during phytochemical screening of this aqueous leaf extract. The presence of both carbohydrates and reducing sugars may be responsible for its decreased hypoglycemic effects. The aqueous leaf extracts of piper nigrum contained moderate levels of flavinoids (100%) and tannins (66.6%) with mild levels of carbohydrates, resins and saponnins at 33.3% each. There were no presence of alkaloids, glycosides, steroids, terpenes and proteins during the phytochemical screening of this aqueous leaf extracts. The absence of many of these phytochemical constituents such as terpenes, alkaloid, proteins etc may account for its lack of hypoglycemic effect. However, flavinoids as a phytochemical constituent has antioxidation effect while saponnins and peptides have antitumoral effects as stated in the early part of this work.

 

CONCLUSION:

The results obtained from this study have revealed that aqueous leaf extracte of phylianthus amarus, vernonia amygdalina, gongronema latifolium and ocimum gratissimum have appreciable hypoglycemic effect owing to the presence of mild level of terpenes and can be termed oral hypoglycemic agents. These agents are associated with significant reduction in blood sugar level which was comparable with the effect seen in glibenclamide (positive control) and hence showed no significant difference with the effects seen in glibenclamide (p>0.05). solanum melongena revealed mild hypoglycemic effects probably due to presence of carbohydrates and reducing sugars which are diabetogenic and hence it could be termed mild hypoglycemic agent. Therefore the above extracts may have similar mechanism of action as the other groups of oral hypoglycemic drugs. However, using a statistical test such as Z-Test, a significant difference was seen between the post-alloxan induction and post-extract administration of these above four tropical leaves (P<0.05).

 

RECOMMENDATION:

Having reviewed significant hypoglycemic effects of aqueous leaf extracts of phyllanthus amarus, vernonia amygdalina, Gongronema latifolium and Ocimum gratissimum in this study, formulation of these as suppliments may be useful for diabetic patients. Considering the fact that most of these leaves have nutritive values, they may be recommended in our daily food delicacies as useful nutritive ingredients. The aqueous extracts of these tropical herbs may be recommended to persons who are at risk of having type II diabetes mellitus such as those with family history of diabetes in the first degree relative older age (more than 45 years).

ACKNOWLEDGEMENT:

My gratitude goes to Mrs Ngozi Akunneh-Wariso Chris and Mrs Precious Wadioni for their support and encouragement.

 

CONFLICT OF INTEREST:

No conflict of interest.

 

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Received on 14.02.2019         Modified on 08.03.2019

Accepted on 18.03.2019       ©A&V Publications All right reserved