426
20.5.4 Anti-diabetic Activity
Recently, it was reported that carotenoids may be more effective in the management
of diabetes mellitus (Sathasivam and Ki 2018) and most of these bioactive compounds are derived from diet and high concentration of β-carotene in plasma is
inversely related to insulin resistance and the level of fasting blood glucose (Ylonen
et al. 2003). The incidence of type-2 diabetes (T2D) has been reported to be greatly
reduced in women and men by dietary carotenoids by many studies (Ylonen et al.
2003; Sluijs et al. 2015). Some studies have indicated that lutein, zeaxanthin and
lycopene are examples of carotenoids that inhibit the development of diabetic retinopathy (Brazionis et al. 2009). Also, intake of dietary carotenoids is inversely associated with the level of HbA1c in plasma of humans (Suzuki et al. 2002).
Astaxanthin, one of the well-studied carotenoid, shows higher antioxidant properties than other carotenoids like the lutein, zeaxanthin and β-carotene and it has
been reported to be effective in the prevention and management of diabetes (Yeh
et al. 2016; Sathasivam and Ki 2018). The treatment of diabetes in db/db mice
resulted to a reduced glucose tolerance, ameliorates level of blood glucose and stimulates the level of insulin in serum. Thus, the data shows that the antioxidant effect
of astaxanthin can be effective in the preservation of β-cell function and morphology (Uchiyama et al. 2002). In another study, it was reported that in older Japanese
and middle aged patients, the level of β-cryptoxanthin and α-carotene are related to
lower T2D incidence (Sugiura et al. 2015). This studies indicated the relationship
between the level of carotenoids in serum and smoking with 15 years of incidence
of diabetes (Hozawa et al. 2006). Also, the concentration of zeaxanthin, α-carotene,
lycopene, β-carotene and lutein were remarkably decreased in diabetic individuals
(Ylonen et al. 2003). In mice feed on high fat and fructose, astaxanthin elevates the
concentration of adiponectin and HDLc as well as decrease in the level of TAG and
blood glucose (Hussein et al. 2007). Another important carotenoid is β-carotene,
which its concentration in serum is inversely association with the concentration of
HbA1c in serum as well as impaired insulin sensitivity (Hozumi et al. 1998; Arnlov
et al. 2009). Lutein, a carotenoids, significantly reduces hyperglycaemia induced by
streptozotocin and revealed a remarkable antioxidant action in the renal organs of
diabetic animals (Katyal et al. 2013). Another vital carotenoids with anti-diabetic
action is fucoxantin. In obese mice treated with carotenoid, the level of serum insulin and blood glucose was restored to normal. In this work, the genetic expression
and level of mRNA of glucose transporter-4 (GLUT-4) was up-regulated in the cells
of skeletal muscle (Maeda et al. 2009). In a similar work, fucoxanthin enhances the
expression of GLUT-4 gene in skeletal muscles and it was stated that stimulation of
PPARγ co-stimulator 1α regulates this process, which is associated with an upregulation in the level of insulin receptor mRNA, with a corresponding high level of
phosphorylation of Akt/PKB. All this play a vital role in the modulation of GLUT-4
translocation to the plasma membrane (Nishikawa et al. 2012). In addition to the
studies carried out on fucoxanthin, it was reported that this carotenoid stimulates the
gene expresstion of GLUT-4 and PPARγ (Maeda et al. 2006). Thus, it was indicated
A. Olatunde et al.
20.5.4 Anti-diabetic Activity
Recently, it was reported that carotenoids may be more effective in the management
of diabetes mellitus (Sathasivam and Ki 2018) and most of these bioactive compounds are derived from diet and high concentration of β-carotene in plasma is
inversely related to insulin resistance and the level of fasting blood glucose (Ylonen
et al. 2003). The incidence of type-2 diabetes (T2D) has been reported to be greatly
reduced in women and men by dietary carotenoids by many studies (Ylonen et al.
2003; Sluijs et al. 2015). Some studies have indicated that lutein, zeaxanthin and
lycopene are examples of carotenoids that inhibit the development of diabetic retinopathy (Brazionis et al. 2009). Also, intake of dietary carotenoids is inversely associated with the level of HbA1c in plasma of humans (Suzuki et al. 2002).
Astaxanthin, one of the well-studied carotenoid, shows higher antioxidant properties than other carotenoids like the lutein, zeaxanthin and β-carotene and it has
been reported to be effective in the prevention and management of diabetes (Yeh
et al. 2016; Sathasivam and Ki 2018). The treatment of diabetes in db/db mice
resulted to a reduced glucose tolerance, ameliorates level of blood glucose and stimulates the level of insulin in serum. Thus, the data shows that the antioxidant effect
of astaxanthin can be effective in the preservation of β-cell function and morphology (Uchiyama et al. 2002). In another study, it was reported that in older Japanese
and middle aged patients, the level of β-cryptoxanthin and α-carotene are related to
lower T2D incidence (Sugiura et al. 2015). This studies indicated the relationship
between the level of carotenoids in serum and smoking with 15 years of incidence
of diabetes (Hozawa et al. 2006). Also, the concentration of zeaxanthin, α-carotene,
lycopene, β-carotene and lutein were remarkably decreased in diabetic individuals
(Ylonen et al. 2003). In mice feed on high fat and fructose, astaxanthin elevates the
concentration of adiponectin and HDLc as well as decrease in the level of TAG and
blood glucose (Hussein et al. 2007). Another important carotenoid is β-carotene,
which its concentration in serum is inversely association with the concentration of
HbA1c in serum as well as impaired insulin sensitivity (Hozumi et al. 1998; Arnlov
et al. 2009). Lutein, a carotenoids, significantly reduces hyperglycaemia induced by
streptozotocin and revealed a remarkable antioxidant action in the renal organs of
diabetic animals (Katyal et al. 2013). Another vital carotenoids with anti-diabetic
action is fucoxantin. In obese mice treated with carotenoid, the level of serum insulin and blood glucose was restored to normal. In this work, the genetic expression
and level of mRNA of glucose transporter-4 (GLUT-4) was up-regulated in the cells
of skeletal muscle (Maeda et al. 2009). In a similar work, fucoxanthin enhances the
expression of GLUT-4 gene in skeletal muscles and it was stated that stimulation of
PPARγ co-stimulator 1α regulates this process, which is associated with an upregulation in the level of insulin receptor mRNA, with a corresponding high level of
phosphorylation of Akt/PKB. All this play a vital role in the modulation of GLUT-4
translocation to the plasma membrane (Nishikawa et al. 2012). In addition to the
studies carried out on fucoxanthin, it was reported that this carotenoid stimulates the
gene expresstion of GLUT-4 and PPARγ (Maeda et al. 2006). Thus, it was indicated
A. Olatunde et al.