INTRODUCTION
One of the medicinal
plants with the potential to be used as a novel medication source or as an
alternative therapy for the treatment of a number of illnesses is Ocimum gratissimum
L., also known as scent leaf. It is a common perennial herbaceous plant with a
potent aroma that is also commercially viable. It can be found in Africa, Asia,
and South America and is a member of the Lamiaceae
family (Akara et al., 2021). Ocimum the plant has
been reported to have numerous health benefits, including antimicrobial,
anti-inflammatory, antioxidant, and anticancer properties. The leaves, stems,
and essential oils of the plant are used in the treatment of various ailments
including colds, headaches, stomach disorders, and infections (Okigbo & Mmeka, 2006).
Figure 1: Ocimum gratissimum plant
PHYTOCHEMICAL PROPERTIES
Ocimum Gratissimum
is known to contain various bioactive compounds. These include:
Essential
Oils:
The plant is known for its strong aromatic properties, which are largely due to
its essential oil content. The composition of the essential oil can vary
depending on the plant's geographical location and other factors. However,
common components of the essential oil include eugenol,
thymol, and various terpenoids.
Eugenol gives the plant its characteristic clove-like aroma (Santana et al.,
2013). The essential oil of Ocimum gratissimum is rich in eugenol, a compound that gives
the plant its characteristic clove-like aroma and contributes to its
antimicrobial properties (Santana et al., 2013).
Flavonoids: Flavonoids are a
group of plant metabolites thought to provide health benefits through cell
signaling pathways and antioxidant effects. These molecules are found in
various fruits and vegetables, and Ocimum gratissimum is no exception (Oboh
et al., 2016).
Phenols: These are another
group of chemical compounds that often have antioxidant properties. The total
phenolic content in Ocimum gratissimum
leaves has been associated with its antioxidant activity (Oboh
et al., 2016).
Tannins: Tannins are a class
of astringent, polyphenolic biomolecules that bind to and precipitate proteins
and various other organic compounds. They are found in many species of plants,
including Ocimum gratissimum.
Saponins: These are
phytochemicals that can produce a soap-like foaming when shaken in aqueous
solutions. Saponins have been found in various parts
of the Ocimum gratissimum
plant (Okoli et al., 2007).
The presence and
concentration of these components can however vary based on several factors,
including the plant's growing conditions, harvest time, and the part of the
plant used (leaf, stem, flower, etc.).
DIABETES
MELLITUS
Diabetes mellitus,
commonly known as diabetes, is a chronic metabolic disease characterized by
high levels of glucose in the blood (hyperglycemia). This results from defects
in insulin production, insulin action, or both. Insulin is a hormone produced
by the pancreas that regulates the amount of glucose in the blood. Diabetes can
lead to serious health complications if not managed properly, including heart
disease, stroke, kidney disease, and nerve damage (Silva, 2018).
There are primarily
two types of diabetes:
Type 1
Diabetes:
Also known as insulin-dependent diabetes, this type typically develops in
childhood or adolescence but can also occur in adulthood. In type 1 diabetes,
the body's immune system destroys the insulin-producing cells in the pancreas,
leading to insulin deficiency. People with type 1 diabetes need to take insulin
daily to survive (Atkinson et al., 2014).
Type 2
Diabetes:
This is the most common form of diabetes, accounting for about 90% of all
cases. It mainly occurs in adults, but it's increasingly being diagnosed in children
and adolescents. Type 2 diabetes is characterized by insulin resistance, where
the body's cells become less responsive to insulin. Over time, the pancreas may
also produce less insulin. Type 2 diabetes is strongly associated with obesity,
physical inactivity, poor diet, and a family history of diabetes (Chatterjee et
al., 2017).
A third
type, gestational diabetes, occurs in some pregnant women and typically resolves
after childbirth. However, women with gestational diabetes have an increased
risk of developing type 2 diabetes later in life.
PREVALENCE
OF DIABETES
Diabetes mellitus is
a significant global health concern, with the prevalence of the disease
increasing dramatically in recent decades. The International Diabetes
Federation (2021) estimated that approximately 463 million adults (20-79 years)
were living with diabetes worldwide in 2019. This number is projected to rise
to 700 million by 2045.
The prevalence of
diabetes varies widely across different regions and populations. Factors
contributing to these differences include age, genetic susceptibility,
lifestyle, diet, and socio-economic factors.
Regional variations: The Western Pacific
region, which includes countries like China and Japan, had the highest number
of people with diabetes in 2019, according to the IDF. However, the prevalence
of diabetes was highest in the North America and Caribbean region.
Age: The IDF reports that the global
prevalence of diabetes is higher in adults over 65 years, affecting over 136
million people in this age group in 2019.
Sex: The
prevalence of type 2 diabetes mellitus is increasing in both sexes, but men are
usually diagnosed at a younger age (Kautzky-Willer et al., 2023).
Education: In both genders,
there is a clear educational gradient in the diabetes prevalence with the lower
educated bearing the greater burden of disease. Therefore, the lower the
education level, the greater the diabetes prevalence (Bartolini
et al., 2020).
Type of diabetes: The vast majority of
people with diabetes have type 2 diabetes, which is closely
linked to obesity and physical inactivity. Type 1
diabetes, which is generally diagnosed in children and young adults and is not
linked to lifestyle factors, is much less common.
It's important to
note that a significant number of people with diabetes are undiagnosed. The IDF
estimated that around 232 million people, or half of all people living with
diabetes in 2019, were unaware of their condition.
TREATMENT
OF DIABETES MELLITUS
Treatment for
diabetes involves lifestyle modifications (healthy diet, regular exercise,
weight management) and medication (Marín-Peñalver et
al., 2016). People with type 1 diabetes require insulin therapy, while those
with type 2 diabetes may be treated with oral
medications, insulin, or other injectable medications. Blood glucose monitoring
is crucial for managing diabetes. There is currently no cure for the condition.
STUDIES
ON THE ANTIHYPERGLYCEMIC ROLES OF OCIMUM GRATISSIMUM
Several studies have
shown that Ocimum gratissimum
possesses various pharmacological properties which includes anti-anaemic, hepatoprotective (Akara et al., 2021), anti-hypertensive (Shaw et al., 2017),
antifungal (Mohr et al., 2017), and anti-oxidative properties (Joshi, 2013),
etc. Regarding its role in diabetes, some studies have also shown the anti-hyperglycaemic (Casanova et al., 2014) effect of ocimum gratissimum; though
the majority of these studies have been conducted in animal models or in vitro,
not in human clinical trials.
A study conducted by Okoli et al. (2007) showed that aqueous extracts of Ocimum gratissimum
leaf reduced blood glucose levels in rats with induced diabetes. The study
suggested that the plant could be beneficial in managing diabetes and its
complications.
From a study by
Mohammed et al., (2007), the hypoglycemic effects of the aqueous leaves extract
of O. gratissimum were examined in streptozocin-induced diabetic rats,
A single dose of 250, 500, or 1000 mg/kg body weight of the extract was given.
After 24 hours of extract administration, the diabetic rats' blood glucose
levels were considerably (P 0.05) reduced by 81.3% by the aqueous extract at a
dose of 500 mg/kg. Reducing sugars, cardiac glycosides, resin, tannins, saponins, glycosides, flavonoids, glycerin, and steroids
were all found during the preliminary phytochemical screening. The computed
median lethal dose (LD50) for rats was 1264.9 mg/kg body weight. O. gratissimum leaf
extract was found to have antidiabetic action in streptozocin-induced diabetic rats.
Another study by Oyedemi et al. (2012) showed that the aqueous leaf extract
of Ocimum gratissimum
has a protective effect on the pancreas of diabetic rats. This study suggested
that the extract could be a potential source of natural antioxidants for the
management and/or prevention of diabetes. Likewise, Adisa
et al. (2013), found that Ocimum gratissimum leaf extracts exhibited anti-diabetic
activity in diabetic rats, potentially through the regeneration of pancreatic
beta cells (which produce insulin) and the inhibition of glucose absorption in
the intestines.
More recently, in a
study by Shimada et al., (2019), mice subjects were co-administered with O. gratissimum
leaf extract, and an oral starch and glucose treatment,
the result showed that there was a prevention of the rise in postprandial blood
glucose levels. This suggested that one of the potential mechanisms underlying
the anti-hyperglycemic effects of the leaf extract of O. gratissimum could be the inhibitory
action on sodium-dependent glucose transporter (SGLT1).
CONCLUSION
Several preclinical
studies have explored the antihyperglycemic effects
of Ocimum gratissimum.
These studies have demonstrated promising results, showcasing the potential of
the plant as a complementary therapy for diabetes management.
Despite these
promising findings, the evidence regarding the antihyperglycemic
effect of Ocimum gratissimum
remains limited. Currently, there is a lack of clinical studies evaluating its
efficacy and safety in humans. Therefore, further research is necessary to
validate the potential of Ocimum gratissimum as a therapeutic agent for diabetes
management. The future research should focus on conducting well-designed
clinical trials to evaluate the antihyperglycemic
efficacy, safety, and optimal dosage of Ocimum gratissimum in humans. These trials should include
diverse populations, considering factors such as age, gender, and diabetes
type.
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