Background: Diabetes is a chronic disease affecting a large population worldwide and stands as one
of the major global health challenges to be tackled. According to World Health Organization, about 400 million
are having diabetes worldwide and it is the seventh leading cause of deaths in 2016. Plant-based natural products
have been in use from ancient times as ethnomedicine for the treatment of several diseases, including diabetes.
As a result of that, there are several reports on plant-based natural products displaying antidiabetic activity.
In the current review, such antidiabetic potential compounds reported from all plant sources along with their
chemical structures are collected, presented and discussed. These kinds of reports are essential to pool the
available information to one source, followed by statistical analysis and screening to check the efficacy of all
known compounds in a comparative sense. This kind of analysis can give rise to a few potential compounds
from hundreds, which can further be screened through in vitro and in vivo studies, and human trails leading to
the drug development.
Methods: Phytochemicals, along with their potential antidiabetic property, were classified according to their
basic chemical skeleton. The chemical structures of all the compounds with antidiabetic activities were elucidated
in the present review. In addition to this, the distribution and their other remarkable pharmacological activities
of each species are also included.
Results: The scrutiny of literature led to the identification of 44 plants with antidiabetic compounds (70) and
other pharmacological activities. For the sake of information, the distribution of each species in the world is
given. Many plant derivatives may exert anti-diabetic properties by improving or mimicking insulin production
or action. Different classes of compounds including sulfur compounds (1-4), alkaloids (5-11), phenolic compounds
(12-17), tannins (18-23), phenylpropanoids (24-27), xanthanoids (28-31), amino acid (32), stilbenoid
(33), benzofuran (34), coumarin (35), flavonoids (36-49) and terpenoids (50-70) were found to be potential active
compounds for antidiabetic activity. Of the 70 listed compounds, majorly 17 compounds are obtained from
triterpenoids, 13 from flavonoids and 7 from alkaloids. Among all the 44 plant species, the maximum number
(7) of compounds were isolated from Lagerstroemia speciosa followed by Momordica charantia (6) and S. oblonga
with 5 compounds.
Conclusion: This is the first paper to summarize the established chemical structures of phytochemicals that
have been successfully screened for antidiabetic potential and their mechanisms of inhibition. The reported
compounds could be considered as potential lead molecules for the treatment of type-2 diabetes. Further, molecular
and clinical trials are required to select and establish therapeutic drug candidates.