CHAPTER
ONE
INTRODUCTION AND LITERATURE REVIEW
BACKGROUND OF STUDY
Plants are important in
our everyday existence. They provide our foods, produce the oxygen we breathe,
and serve as raw materials for many industrial products such as clothes, foot
wears and so many others. Plants also provide raw materials for our buildings
and in the manufacture of biofuels, dyes, perfumes, pesticides and drugs.
Historically, plants
have always provided a source of inspiration for novel drug compounds as plant
derived medicines have made large contributions to human health and well being.
Medicinal plants which produce and accumulate constituents have medical
properties (Adedeji et al., 2006). The
use of plants in traditional medical practice has a long drawn history, and
remains the mainstay of primary health care in most of the third world.
Traditional medicines are used by about 60% of the world population; in both
developing and developed countries where modern medicines are predominantly
used (Mythilypriya et al., 2007).
While an estimated 60-80% Africa’s population depends solely on herbal remedies
for its primary health care needs. In diversity, plants are thought to be
between 250,000 to 400,000 species spread across all continents from the
Antarctic to the Arctic. They thrive in all environments from the flooded
planes to the deserts, and from those who live on the seas and oceans to others
that thrive on fresh water and ponds.
For classification and
easy identifications, plants were divided into different taxonomical groups
known as kingdoms; these are further streamlined into phylum, class, order,
family genus and species. Within the family of the Clusiacea is found an amazing plant called the
bitter kola (Garcinia kola).
Garcinia
kola (Heckel) is an
angiospermae, belonging to the family Guttiferae and is known in commerce as
bitter cola. On chewing, G. kola seed
has a bitter astringent and resinous taste, somewhat resembling that of raw
coffee, followed by a slight sweetness. Bitter cola is a highly valued
ingredient in African ethno medicine because of its varied and numerous uses
which are social and medicinal; thus making the plant an essential ingredient
in folk medicine. Medicinal plants such as G.
kola are believed to be an important source of new chemical substances with
potential therapeutic benefits (Eisner, 1990).
Bitter Kola (Garcinia Kola) is popular in Southern
Nigeria. The plant is extensively used in herbal medicine and as food. It
prevails as a multipurpose tree crop in the home gardens of Southern Nigeria.
Traditionally, the
plant is used as a natural antimicrobial. Other medicinal properties of the
plant include its usage in the treatment of skin infections in Liberia and
Congo Democratic Republic. The powdered bark of the plant is applied to malignant
tumors, cancers etc. The plants latex is taken internally for gonorrhea and
externally to seal new wounds and prevent sepsis.
LITERATURE
REVIEW
World Health
Organization (1999) estimated that there were 135 million people in the world
with diabetes and that this would rise to 380 million by 2025, this report also
highlighted the fact that low and middle income countries will bear the brunt
of the increase with Africa contributing significantly to this rise (King et al., 1998). In Nigeria, World Health
Organization has disclosed that more than 1.71 million citizens above 15 years
are diabetic, 70, 000 children under 15 years develop insulin dependent
diabetes each year, if nothing is done, diabetes sufferers will grow to about
484 million by 2030 (Winifred, 2008).
Diabetes mellitus and other numerous pathological events such as
atherosclerosis and inflammatory processes are associated with the generation
of Reactive Oxygen Species (ROS) and consequently the induction of several
chain reactions among them, lipid peroxidation (Grober, 2010). Evidence
suggests that oxidative cellular injury caused by free radicals contributes to
the complications of diabetes mellitus (Baimbolkar and Sainani, 1995). Some of
these radicals are extremely reactive and therefore interact with some vital
macromolecules including lipids, nucleic acids and protein (Nia et al., 2003).
Before the introduction
of insulin in 1922, the treatment of diabetes mellitus relied heavily on the
use of traditional plant therapies (Gray and Flatt, 1999). In Africa and
beyond, application of traditional medical practices to the treatment of
diabetes is quite popular; several plant species have been used for this
purpose (Nwaegerue et al., 2007).
Active components of these plants are now being investigated and their extract
are developed into drugs and little or no negative effects as
contraindications, one of such plants is Garcinia
kola (Adedeji et al., 2006).