Page 27 - Drug Discovery and Development: Prospects and Challenges

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Figure 14: Mature adipocyte stained with oil red O

The effects of several phytochemical compounds have been
studied on 3T3-L1 adipocytes, such as cinnamtannin B1, which is
a type of proanthocyanidin from Cinnamomum zeylanicum (Figure
15). Cinnamtannin B1 showed an improved glucose uptake in 3T3-L1
preadipocytes. In our study, we have concluded that the sweet agent
cinnamtannin B1 in cinnamon mimics insulin by attaching to the β-subunit
of the receptor in the cell membrane, followed by autophosphorylating
the tyrosine residues of the b-subunit. Subsequently, the phosphoinositide
3-kinases (PI3K), glucose transporter 4 (GLUT4) translocation, and
glucose absorption were activated. Based on the response of the
cinnamtannin B1, it was concluded that the phosphorylation of the
insulin receptor (IR ) b-subunit is an important molecular target for the
treatment of diabetes (Taher et al., 2004, 2006, 2007).
Fascinatingly, our finding had attracted the attention of the national
newspaper at that time with an article “Sweet hope for diabetics”
(Abdullah, 2006). The study was supported by a clinical trial on aqueous
cinnamon extract in which 120 mg (low dose) and 360 mg (high dose)
mg was given to patients with type 2 diabetes daily for three months.
The results showed that the HbA1c and fasting plasma glucose levels
significantly decreased (reduction of 1.62 mmol/L vs. 0.22 mmol/L in
the placebo group) (Lu et al., 2012). Based on a systematic review and
meta-analysis studies involving 1025 participants, the supplementation
of cinnamon was found to decrease serum triglycerides, total cholesterol,
and low-density lipoprotein cholesterol (Jamali et al., 2020).