Plant and family Plant part used Bioactive principles Mechanism of action References
Allium cepa (Onion); Alliaceae Onion bulbs. • S-methyl cysteine sulphoxide.
• S-allylcysteinesulphoxide.  
• Stimulate insulin secretion.
• Compete with insulin for insulin inactivating sites in the liver.
Allium sativum (Garlic); Alliaceae. Garlic gloves • S-methyl cysteine sulphoxide. Precursor of allicin and garlic oil.  • Stimulate insulin secretion.
• Inhibit glucose production by the liver
Aloe vera (Aloe barbedensis);
Leaf, pulp and gel. • Phytosterols. • Stimulate synthesis and/or release of insulin
• Alter the activity of carbohydrate metabolizing enzymes.
Catharanthusroseus; Apocynaceae Fresh leaf juice. • Alkaloids: catharanthine, leurosine and vindolinine.
• Taninins.
• Increase hepatic utilization of glucose.
• Suppress activities of gluconeogenic enzymes.
Cinnamomumcassie (Chinese cinnamon); Lauraceae Bark. • Cinnamaldehyde.
• Cinnamic alcohol.
• Methyl hydroxyl chaconne polymer.
• Enhance insulin action.
• Increase glucose uptake and glycogen synthesis.
Leaves. • Beta sitosterol.
• Pectin
• Suppress glucose-6-phosphatase.
• Stimulate glycogen synthase activity and reduction of phosphorylase activity.
Fiscusbengalensis; Moraceae Leaves and bark. • Lecoperlargonin derivative. • Increase insulin secretion.
• Inhibit insulinase activity.
Gymmemaslyvestre (Gurnar);
Leaves. • Gymnenosides and gymnemic acid (from saponin fraction).
• Trilepene glycosides.
• Stimulate insulin secretion from rat Islets.
• Decrease the activity of gluconeogenic enzymes.
• Induce β-cell regeneration.
Ginseng (Panax ginseng);
Fenugreek (Trigonellafoenumgraecum L.)
Roots and leaves. • Polysaccharides.
• Ginsenosides (steroidal saponins).
• Slow absorption and digestion of carbohydrates.
• Affect NO mediated glucose transport.
Momordicacymbalaria (Bitter Melon); Cucurbiteae Fruit pulp, seeds, leaves and whole plant. • Charantin (a peptide).
• Insulin-like polypeptide P (vegetable insulin).
• Stimulate insulin secretion.
• Suppress the activity of gluconeogenic enzymes.
• Increase β-cells in diabetic rats.
Muurrayikomingii(Cury leaf); Rutaceae.
Aeglemarmelos Corr. (Rutaceae)
Leaves. • Carbazole alkaloids.
• Copolin-α-glucose.
• Stimulate insulin secretion.
• Increase glycogenesis and decrease glycogenolysis and gluconeogenesis.
Ocimum sanctum (Holy basil); Lamiaceae Leaves. • Pectins. • Stimulate insulin secretion. [45]
cepa,Allium sativum,Aloe vera, Cajanuscajan, Cocciniaindica, Caesalpiniabonducella, Ficus
bengalenesis, Gymnemasylvestre, Momordicacharantia, Ocimum sanctum, Pterocarpusmarsupium,
Swertiachirayita, Syzigiumcumini, Tinosporacordifolia and Trigonellafoenumgraecum
Whole plant • Saponins and glycosides • Hypoglycemic and anti-hyperglycemic activity.
• Stimulate insulin release from isolated pancreatic Islets.
Polygala senega; Polygalaceae Rhizomes • Triterpenoid glycoside-Senegin-II
• saponins
• Decrease hepatic glucose output.
• Increase insulin sensitivity.
Pterocarpusmarsupium; Falcaceae Bark. • Epicatechin and catechin (tannins).
• Pterostibene (flavonoid),
• Prevent beta cell damage in rats.
• Regenerate functional pancreatic β-cells.
• Enhance insulin secretion.
Syzigiumcumini (Eugenia janbolaria); Mytaceae Seeds, leaves and fruit pulp. • Mycaminose. • Stimulate kinases involved in peripheral utilization of glucose. [46]
Trigonella foemum-graecum (Fenugreek); Falcaceae Seeds. • Alkaloids- trigoneline; nicotinic acid and coumarins.
• 4-hydroxy isoleucine.
• Galaclomannan.
• Slow digestion and absorption of carbohydrates.
• Increase glucose-induced insulin secretion.
• Enhancement of peripheral insulin action.
Table 1: Some common anti-diabetic bioactive principles of medicinal plants.