Gymnema montanum (G. montanum, GM) is a plant belonging to Apocynaceae family, an endemic, woody climbing shrub found mainly in Africa and India. Momordica charantia (M. charantia, MC), a plant belonging to the Cucurbitaceae family, is commonly known as a bitter gourd, balsam pear, bitter melon, or Karela and could be found in India, Japan, Singapore, Vietnam, Cuba, Ghana, Haiti, the Middle East, Central and South America and many other regions. Moringa oleifera (M. oleifera, MO) Lam is a plant that belongs to the Moringaceae family and naturally occurs widely in many tropical and subtropical areas. The extracts of Gymnema montanum, Momordica charantia and Moringa oleifera represent a promising and attractive source of phytochemicals with proven antidiabetic and antioxidant activity in rat models of diabetes. They increase pancreatic insulin and insulin sensitivity in peripheral tissues, reduce insulin resistance and hepatic gluconeogenesis, and have a modulatory effect on glycolysis, gluconeogenesis and antihyperlipidemic properties. All three extracts reduced oxidative stress and revealed antiperoxidative features to protect β-cells against ROS. They are, therefore, good candidates for the management and treatment of diabetes in mammals, especially humans. Moreover, all three plants have been widely used in traditional medicine.
In vitro and animal model studies are of great interest for selecting new phytochemicals, including polyphenols with antioxidative properties, as candidates for antidiabetic drugs.
This review provides evidence from a critical literature data analysis on the effects of plant extract supplementation in diabetes mellitus management. Authors considered and meta-analyzed the efficacy of oral supplementation of plant extracts in animal model studies and examined physiological and oxidative stress parameters.
The extracts of Gymnema montanum, Momordica charantia and Moringa oleifera represent a promising and attractive source of phytochemicals with proven antidiabetic and antioxidant activity in rat models of diabetes. They increase pancreatic insulin and insulin sensitivity in peripheral tissues, reduce insulin resistance and hepatic gluconeogenesis, and have a modulatory effect on glycolysis, gluconeogenesis and antihyperlipidemic properties. All three extracts reduced oxidative stress and revealed antiperoxidative features to protect β-cells against ROS.
They are, therefore, good candidates for the management and treatment of diabetes in mammals, especially humans. Moreover, all three plants have been widely used in traditional medicine.
The following analysis was aimed to systematically evaluate the literature and indicate potent plant candidates for a restricted meta-analysis. Authors applied Cochrane guidelines to investigate the efficacy of oral supplementation of subjected plant origin extracts in diabetes mellitus management in animal model studies.
The initial literature search revealed about 300 original papers indicating three potent plant extracts for further analysis, of which only 23 articles were finally included in the restricted meta-analysis, revealing the experimentally confirmed in vivo and in vitro antidiabetic properties of Gymnema montanum (9 articles),
Momordica charantia (7 articles) and Moringa oleifera (7 articles).
In the meta-analysis protocol, data on physiological and oxidative stress parameters extracted from the original papers were examined and statistically analyzed. The categories of the analyzed parameters and observed tendencies of changes are presented in Table 1Table 2 [1].
Table 12. Distribution and changes of analyzed parameters in meta-analysis.
Distribution and changes of analyzed parameters in meta-analysis.
SOD↓ | |
CAT↑ | |
Plant |
Physiological Efficacy Parameters |
Oxidative Stress Parameters | ||
Momordica charantia |
vs control |
no data analyzed Ø | ||
Glycemia↓ Insulinemia↑ body weight ↔ | ||||
Gymnema montanum |
vs control |
vs drug |
vs control |
vs drug |
Glycemia↓ Insulinemia↑ body weight ↑ food intake↓ |
Glycemia↓ Insulinemia↓ body weight ↔ food intake ↓ |
TBARS ↓ Hydroperoxides↓ |
TBARS ↓ Hydroperoxides↓ | |
Moringa oleifera |
vs control |
vs control | ||
Glycemia↓ Insulinemia↔ |
SOD↓ CAT↑ |
Plant |
Physiological Efficacy Parameters |
Oxidative Stress Parameters | ||
Momordica charantia |
vs control |
no data analyzed Ø | ||
Glycemia↓ Insulinemia↑ body weight ↔ | ||||
Gymnema montanum |
vs control |
vs drug |
vs control |
vs drug |
Glycemia↓ Insulinemia↑ body weight ↑ food intake↓ |
Glycemia↓ Insulinemia↓ body weight ↔ food intake ↓ |
TBARS ↓ Hydroperoxides↓ |
TBARS ↓ Hydroperoxides↓ | |
Moringa oleifera |
vs control |
vs control | ||
Glycemia↓ Insulinemia↔ |
Changes of parameters in experimental group: ↓—decrease, ↑—increase, ↔—unchanged, Ø—not analyzed.
Gymnema montanumFinally, Momordica charantia23 articles were indcluded in Moringa oleiferathe metare-analysis, revealing three plants with experimentally confirmed in vivo and in vitro antidiabetic properties: Gymnema montanum, Momordica charantia and Moringa oleifera.
The following parameter changes resulted from an investigation of the supplementation: reduced oxidative stress, decreased insulin resistance, increased insulin release, reduced adiposity, and a modulatory effect on glycolysis and gluconeogenesis, as well as attenuation of diabetes-associated weight loss, reduced fasting blood glucose and lowered oxidative status.
A comparison of Gymnema Gymnema montanummontanum versus Glybenclamide revealed the superiority of extracts over drug administration in some aspects.
EThe presented meta-analysis confirmed that extracts of Gymnema montanum, Momordica charantia and Moringa oleifera represent a promising and attractive source of phytochemicals with proven antidiabetic and antioxidant activity in rat models of diabetes. They increase pancreatic insulin and insulin sensitivity in peripheral tissues, reduce insulin resistance and hepatic gluconeogenesis, and have a modulatory effect on glycolysis, gluconeogenesis and antihyperlipidemic properties. All three extracts reduced oxidative stress and revealed antiperoxidative features to protect β-cells against ROS.
They are, therefore, good candidates for the management and treatment of diabetes in mammals, especially humans. Moreover, all three plants have been widely used in traditional medicine.
Despite the limitations, the results of this meta-analysis strongly encourage further studies to evaluate the impact of plant-derived extracts on diabetic patients’ physiological and oxidative status parameters. Further study to investigate the activity of these analyzed extracts in humans is strongly recommended since there is no direct way to extrapolate results obtained from animals to humans due to their complexity. There is always a risk of severe adverse events and toxicity from such supplementation in humans. It is crucial to indicate the differences between the animal model of diabetes and the physiology of human patients with this disease, and this constitutes a critical limitation at the entry point of study design and on further data analysis. The abovementioned results are promising and may trigger the further development of experimental and clinical approaches to investigate the application of these plant extracts in more advanced and detailed studies. Considering all the strengths and limitations, this meta-analysis is a reliable source of data and might constitute an inducement for further physiological and mechanistic studies.
This review would shed light on how plant-based drugs could potentially be a beneficial agents in treating of aging, oxidative stress and hyperglycemia-associated abnormalities.