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Pausinystalia yohmibe is a member of the family Rubiaceae. It is a valuable medicinal tree, distributed in evergreen closed canopy forests in West Africa.  It is traditionally used for treatment mostly on erectile dysfunction. This research was carried out to evaluate the immunomodulatory effect of (Pausinystalia yohmibe) stem bark methanolic extract. The yohimbe extract has been reported for its medicinal use for the treatment of impotence in men and for its anti-oxidants effects but have not be reported for any sign of immunomodulation or suppressive activity, which Is the basic aim for this research. This was achieved by assessments of the extract in the following parameters, using albino mice the phytochemical analysis which received the presence of alkaloids, flavonoids, tannnis . The acute toxicity effect of the extract which showed LD50 above 1000mg/kg and other signs of toxicity like dizziness and depression at dose 800mg/kg on a prolong administration . The animals were divided into four groups which received 100, 300 and 600 mg/kg , respectively while group four served as the control which revived a standard drug (levmisole) for the Delayed-type hypersensitivity response analysis while group four in the determination of humoral  received   distilled water .The extract significantly (p < 0.05) showed dose related stimulation of humoral immunity at 600mg/kg dose compared to the standard and also a significantly (p>0.05) anti-inflammatory activity at 300mg/kg compared with the control group. This result showed potential immunomodulatory effect because the immunomodulatory suppressed the antigenic response in system.


Title Page                                                                                                                                pages

Certification                                                                                                                              i

Dedication                                                                                                                                ii

Acknowledgement                                                                                                                   iii

Abstract                                                                                                                                    iv

Table Contents                                                                                                                          vi

List of Tables                                                                                                                            vii

List of Figures

CHAPTER ONE: INTRODUCTION                                                                                                         

  • Background of study                                                                                                        1
  • Pausinystalia yohmibe                                                                                                     2
  • Botancial information                                                                                                      2
  • Traditional uses                                                                                                               3
  • State of the problem                                        3
  • Aim and objectives 3




2.1 pausinystalia yohmibe                                                                                                      4

2.2 General description of the plant                                                                                       4

2.3   Botanical description                                                                                                      5

2.4Botanicalclassification                                                                                                       5

2.5 chemical formular                                                                                                             7

2.6 chemical composition                                                                                                       7

2.7 phytochemical constituens                                                                                                8

2.7.1 Alkaloid                                                                                                                        8

2 .7.2 Terpenoids                                                                                                                                9

2.7.3 flavonids                                                                                                                        9

2.7.4 saponins                                                                                                                        10

2.8 Medicinal use                                                                                                                    11

2.8.1 Pharmcology and toxicology                                                                                         11

2.8.2 In virto data                                                                                                                    11

2.9 Mechanism of immunomodulation                                                                                   12

2.9.1 Benfits of immunomodulation                                                                                       13

2.9.2 Drug used for immunomodulation                                                                                 14

2.9.3 Immunosuppressants                                                                                                     15

2.9.4immunosutimulnts                                                                                                         15 Baciillus calmette – Guren (BCG)                                                                             15 Levamisole                                                                                                                  16 Thalidomide                                                                                                                16 Recombinant Cytokines                                                                                              16 Interfons                                                                                                                      16 Interleukins                                                                                                                16 Isoprinosins                                                                                                                17 immunocynin                                                                                                              17




3.1 Materials                                                                                                                           18

3.1.1 Chemcials                                                                                                                      18

3.1.2 Reagents                                                                                                                        19

3.1.3 Preparation of reagents                                                                                                  19

3.1.4 Equipments                                                                                                                   19

3.1.5 Biological materials                                                                                                       20

3.2 collection and identification of sample                                                                            20

3.2.1 Collection plants materials                                                                                           20

3.2.2 collection of animals                                                                                                     20

3.2.3 Animal grouping                                                                                                            20

3.2.4 Preparation of extracts                                                                                                  21

3.2.5 Antigen                                                                                                                         21

3.2.6 Preparation of sheep blood cell                                                                                    22

3.2.7 Micro- organism                                                                                                           22

3.2.8. Handling of animals                                                                                                     22 Acute toxicity study                                                                                                    22 type hypersensivitity response (DTHR)                                                          22 Determination of humoral immune response (DIHR)                                                23 In vivo analysis                                                                                                           23

3.3 Preparation candida albicans                                                                                            24

3.3.1 Evaluation of phagocytosis                                                                                            24

3.4 Preparation of reagents                                                                                                     25

3.4.1 Preparation of drangedoff                                                                                              25

3.4.2 Preparation of phosphate buffer saline                                                                          25

3.4.3 Preparation of normal saline                                                                                          25


3.4.4 Preparation of Mc-Farland standard                                                                              25

3.4.5 Preparation of diluted sodium hydroxide                                                                      25

3.4.6 Preparation of 1% lead acetate                                                                                      25

3.5 Qualitative phytochemical analysis                                                                                  25

3.5.1 Test for Alkaloids                                                                                                          25

3.5.2 Test for Flavonoids                                                                                                        26

3.5.3 Test for saponins                                                                                                            26

3.5.4 Test for Tanins                                                                                                               26

3.6 Statistical analysis                                                                                                            26




4.1 Acute toxicity LD50                                                                                                         27

4.2 phytochemicals                                                                                                                 28

4.3 Delay-type hypersensivity response (DTHR)                                                                  29

4.4 Determination of humoral immune response (DHIR)                                                      32

4.5 Evaluation of Phagocytosis                                                                                              35



5.1 Discussion                                                                                                                         39

5.2 Conclusion                                                                                                                        40

References                                                                                                                             41




Many plants have been screened for their medicinal properties; this includes yohimbine, which is an alkaloid chemically similar to reserpine. It is gotten from the bark of the yohimbe tree, it posses alpha-adrenergic blocking properties and is used as hydrochloride sympatholytic, mydriatic and for the treatment of impotence (Dorland’s medical dictionary 2007). Sexual dysfunction is a serious medical and social problem that occurs 10%- 52% in men and 25%-63% in women numerous central and peripheral neural circuits control sexual activity impairment one or more of these functional circuits may have a significant impact on  personal , social and biological relationships. Although several aspects of sexual motivation and performance are known, complete picture of the various factors that control human sexual activity is still unknown and the available drugs and pleasant side effects and contraindications in certain disease conditions. A variety of botanical plants are known to have a potential effect on immunomodulatory (suppressive and stimulatory) functions thereby supporting older claims and offering newer hopes (Therakan and Manyam, 2005).

Presently, there is a growing interest in the use of various natural plants parts and plants products as medicines and these folk medicines are being marked in almost all parts of Nigeria and the world at large. They range from herbal toothpaste to various drug supplements. Some of these herbal preparations may have some properties, which have contributed to their persistent use over the years, under scoring the need for validation of most them. It is said that only about 2% of all the plants on the earth have been subjected to pharmacological investigation. The rational able for utilization of medical plants has rested largely on long term clinical experience with little or no scientific data on their effect and safety (Zhu M, et.al 2002), with the upsurge in the use of herbal medicines through scientific investigation of these plants is imperative, based on the need to validate their folk usage (Sofowora E.A,1989).

Yohimbe bark extracts   standardized to varying amounts of yohimbine are widely available in health food stores and through direct mail companies. Extracts are supplied as capsules tablets and liquids. Some of these yohimbe preparations are sold in combination formula’s with other herbs. Yohimbine hydrochloride is a Food and Drug Administration (FDA) approved prescription drug for the treatment of impotence (Bet J.M, et.al, 1995).

Bet J.M and Coworkers (1995) also investigated yohimbe in commercial yohimbe products. Gas chromatography determinations were done on liquids and powders (from capsules and caplets). Virtually all the products tested did not specify on their labels that the products contained yohimbe bark extract concentration of yohimbine in the commercial products ranged from > 0.1 to 489pppm , compared with 7089ppm in authentic bark material  of the 26 products examined , nine contained no quantifiable amount of yohimbe ; eight contained only trace amounts (0.1-1ppm). The authors suggest that the absence of alkaloids in the products indicated that the original extracts was aqueous (because the alkaloids are not particularly water soluble), the extract was extremely diluted in the final dosage form or no yohimbe bark was used to make the product.

Yohimbe is available in research quantities at 98% purity from Aldrich chemical company. Yohimbine hydrochloride from Aldrich and Sigma are available at 99 and 80% purity, respectively (Aldrich chemical co., 199; sigma, 1999).


Pausinystalia yohimbe is also known as corynanthe   yohimbe. Another   common name is Yocon, the Yorubas’ know it as Idagbon, while the Hausas’ call it Dankamaru.


It is an evergreen tree which grows to a height of 30m with a spread of 8m, the stem is erect and branching the less are oval, acuminate and about 10cm long. The seed are small winged silvers, almost paper thin.  Pausinystalia yohimbe is a native of the rain forest of Nigeria, Cameroon and the Congo. It prefers rich soils in a protected part sun to shady position, and is drought and frost tender. The propagation of pausinystalia yohimbe is by seed or cutting. Seeds are sown in a free draining seed micorshagnum moss and will need temperature above 250C to germinate quickly. Seeds have a very short viability, which declines rapidly in dry and warm conditions (Shaman Australia Botanicals 1998).



Yohmibe is the only natural medicinal aphrodisiac. It popularly used as an aphrodisiac in its native area and has been well documented and its unique effect was soon valued in many parts of the world, especially in Europe, Africa and Nigeria. Its modern times products have found a wide market ranging from medically treated impotence and self administered sexual enhancement “smart products” like “Cloud 9”™, “Viagra”, Barbecue for Suya and other herbal ecstasy formulations.


Although yohimbe has been found to reduce blood sugar level in induced diabetic mice and impotency, but its administration has be seen to be an unsafe herbal practice because the percentage yohimbine in yohimbe bark has not been documented, making it impossible to determine the exert percentage concentration presents in various yohimbe products used as folk medical and other health benefits of such as immunomodulatory potentials of this plant has not been fully investigated. Many countries especially in Nigerian, Yohimbe extract and its products are promoted and still been indiscriminately used.


The aim of this research work was to evaluate the immunomodulatory effects of Pausinystalia yohimbe methanolic extract in albino mice.

This aim was achieved through the following objectives;

  1. Quantitative and qualitative analyses of the phytochemical constituents of Pausinystalia yohimbe.
  2. Investigation of the toxicity effect (LD50) of the methanol extract.
  3. Investigation of the immunomodulatory potentials of Pausinystalia yohimbe methanol extract in mice via the following parameters;
  4. Evaluation of phagocytosis
  5. Determination of delayed-type hypersensivity response (DTHR).
  6. Determination of humoral immune response (IgG and IgM).
  7. In vivo leucocyte mobilization test.


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