EFFECTS OF GNETUM AFRICANUM WELW. AND OCIMUM GRATISSIMUM LINN. AQUEOUS LEAF EXTRACTS ON THE HAEMATOLOGICAL AND BIOCHEMICAL CHANGES IN CYANIDE-TREATED RATTUS RATTUS

ABSTRACT

Cyanide toxicity is of public health concern. Cyanide is among the most potent and deadly poisons and sources of potential human exposure to it are numerous, arising through its release into the environment from both natural and anthropogenic sources. Gnetum Africanum (GA) and Ocimum Gratissimum (OG) which contain essential amino acids required to abate cyanide toxicity effects, are widely used local plants for both nutritional and therapeutic purposes in Nigeria. There is dearth of information about ameliorating effects of these plants on cyanide toxicity. The study was aimed at determining the effects of these plants on some indices of cyanide toxicity in Rattus rattus.
Thirty 7-week old albino rats of same breed and similar exposure were randomly allocated to five treatment and one control groups of five rats each. Lyophilised aqueous extracts of GA and OG leaves were reconstituted in water to give a concentration of 3mg/L respectively while potassium cyanide (KCN) was prepared at 3mg/L concentration. After acclimatisation period of three weeks, the rats were randomly distributed as follow: group 1(control); group 2 (3mg/kg body weight KCN only); group 3 (3mg/kg body weight each of aqueous GA extract and KCN; group 4 (3mg/kg body weight each of aqueous OG extract and KCN); group 5 (3mg/kg aqueous GA extract only); group 6 (3mg/kg aqueous OG extract only). Treatments were administered by gavage while maintaining the rats on commercial rat pellets and water ad libitum for 14 days during which their body weights were noted daily. After exposure to the various treatments, biochemical analysis and haematological examination were done using the International Council for Standardisation in Haematology (ICSH) standard procedures. The results were analysed using descriptive statistics and Kruskal-Wallis at p=0.05.   
The mean rat weights (g) were significantly increased in group 3 (95.5+17.3) and group 5 (98.9+11.7) in comparison with the control (88.9+17.9). Slimy nasal discharge was found in 18.6% of rats in group 2 and 10.0% of rats in group 4. No discharge was found in control, group 3, group 5 and group 6. In group 2, 17.1% of the rats had ocular lesion while other groups had no ocular lesion. Mean haemoglobin values (g/dL) were significantly lowered in group 2 (12.9+0.7), group 3 (13.0+0.5), group 4 (13.1+0.5), group 5 (12.6+0.8) and group 6 (13.2+1.5) than the control (14.4+0.7) while mean white blood cell counts (cell/lmm3) were elevated with no significant difference with regards to the control. Total protein (g/dL) were significantly lowered except in group 2 than the control. Globulin production (g/dL) was suppressed significantly in groups 2 to 4 when compared with the control. Mean creatinine values (mg/dL) were increased in groups 2 to 6 than the control. Mean Aspartate aminotransferase values (unit/l) were significantly reduced in group 3 (9.6+2.5) than the control (21.6+5.5).
Gnetum africanum and Ocimum gratissimum suppressed the haemopoietic system. Gnetum africanum had more deleterious effects and did not alleviate the haematologic and the biochemical effects of cyanide toxicity. The consumption of these plants with cyanoglycoside-containing food is not recommended.
Key words:  Cyanide poisoning, Ocimum gratissimum, Gnetum africanum,
      Ameliorating effects.

TABLE OF CONTENTS

Title..................................................................................................................    i
Certification....................................................................................................    ii
Dedication.......................................................................................................    iii
Ackowledgement.............................................................................................    iv
Abstract..........................................................................................................    v
Table of contents.............................................................................................    vii
List of Tables...................................................................................................    xii
List of Plates………………………………………………………………    xiii
List of Figures..................................................................................................    xiv

CHAPTER ONE……………………………………………………….…    1
1.0 Introduction................................................................................................    1
1.1 Problem Statement.....................................................................................    3
1.2 Rationale of the Study...............................................................................    6
1.3 Public health significance of the study......................................................    6
1.4 Broad objective of the study......................................................................    7
1.5 Specific objectives.....................................................................................    7
1.6 Limitation of the study...............................................................................    7

CHAPTER TWO……………………………………….…………………    8
2.0 Literature review........................................................................................    8
2.1 Brief description of cyanide.......................................................................    8
2.2 Historical use of cyanide ..........................................................................    8
2.3 Properties of cyanide..................................................................................    12
2.3.1. Identity and physical properties.............................................................    12
2.3.2 Chemical properties................................................................................    13
2.4 Sources of human and environmental exposure of cyanide.......................    15
2.4.1 Natural occurrence..................................................................................    15
2.4.2 Anthropogenic sources............................................................................    18
2.4.2.1 Production............................................................................................    18
2.4.2.2 Use.......................................................................................................    18
2.4.2.3 Release to the environment..................................................................    20
2.5 Environmental levels and human exposure to cyanide..............................    22
2.5.1 Environmental levels...............................................................................    22
2.5.1.1 Air .......................................................................................................    22
2.5.1.2 Water....................................................................................................    22
2.5.1.3 Soil.......................................................................................................    23
2.5.1.4 Food.....................................................................................................    23
2.5.1.5 Other....................................................................................................    26
2.6 Human exposure........................................................................................    26
2.6.1 General population..................................................................................    26
2.6.2 Occupational exposure............................................................................    27
2.7    Comparative kinetics and metabolism of cyanide in laboratory
        animals and humans................................................................................    28
2.7.1 Absorption..............................................................................................    28
2.7.2 Distribution.............................................................................................    29
2.7.3 Kinetics of cyanide and health effects in human....................................    30
2.7.4 Metabolism and excretion.......................................................................    32
2.8 Toxicity......................................................................................................    35
2.8.1 Mechanism of cyanide toxicity..............................................................    35
2.8.2 Potential health effects in humans..........................................................    37
2.8.2.1 Effects of short-term (acute) exposure.................................................    37
2.8.2.2 Effects of long-term (chronic) exposure..............................................    40
2.8.2.3 Long-term studies and cyanide diseases..............................................    45
2.9 Treatments of poisoning and antidotes......................................................    46
2.9.1 Scavengers..............................................................................................    47
2.9.2 Detoxification..........................................................................................    50
2.9.3 Physiological...........................................................................................    51
2.9.4 Biochemical............................................................................................    51
2.9.5 Problems associated existing antidotes...................................................    53
2.10 Leafy vegetables .....................................................................................    53
2.10.1 Cultural aspects in the consumption of forest foods............................    54
2.10.1.1 Gnetum africanum..............................................................................    56
2.10.1.2 Ocimum gratissimum.........................................................................    66
2.10.2 Lyophylization .....................................................................................    70
2.11 Haematological indices of tissue damage and toxicity............................    72
2.11.1 Complete blood count...........................................................................    72
2.11.1.1 Red blood cell tests............................................................................    72
2.11.1.2 White blood cell tests........................................................................    75
2.11.2 Blood protein........................................................................................    79

CHAPTER THREE…………………………………………………......…    85
3.0  Materials and methods.............................................................................    85    86
3.1 Purchase of vegetables...............................................................................    85
3.2 Procedures for aqueous extraction of the two vegetables
      (Gnetum africanum and Ocimum gratissimum) .......................................    85
3.3 Lyophilization (freeze drying) of vegetables.............................................    85
3.4 Preparation of the stock and working concentration stock........................    85
3.5 Experimental animals.................................................................................    88
3.5.1 Identification operation strategy.............................................................    88
3.5.2 Observations...........................................................................................    89
3.6 Experimental procedure.............................................................................    91
3.6.1 Procedure for administering KCN and the vegetable extracts................    91
3.6.2 Collection of blood samples ...................................................................    93
3.6.2.1 Determination of heamatological parameters......................................    93
3.6.2.2 Determination of biochemical parameters...........................................    93
3.3.7 Data and statistical analysis....................................................................    93

CHAPTER FOUR………...............………………………………………    94
4.0 Results........................................................................................................    94
4.1 Effects of treatment exposure on average body weight, feed and water    
     consumption...............................................................................................    95
4.2.Trend in weight changes between each treatment group and the
     control within the last five days of drug administration............................    96
4.3.Physical changes during experimental period...........................................    103
4.4 Predominant signs of cyanide poisoning in treatment groups ..................    106
4.5 Effects of various treatments on haematological and biochemical   
      indicators...................................................................................................    109


CHAPTER FIVE...………………………………………………………    113
5.0 Discussion..................................................................................................    113

CHAPTER SIX……………………...............……………………………    124
6.0  Conclusion and recommendation..............................................................    124
References .......................................................................................................    125