Banaba is a deciduous tropical flowering tree, 5
to 10 meters high, sometimes growing to a height of 20 meters. Bark is smooth, grey to cream-colored, and peels off in irregular flakes. Leaves are smooth, large,
spatulate, oblong to elliptic-ovate, 4 to 8 centimeters in width, 12 to 25 centimeters
in length, shedding its leaves the
first months of the year. Flowers are 6-parted, purplish lilac or mauve-pink, rarely pink, 5 to 7.5 centimeters across, and borne in large, terminal panicles up to 40 centimeters in length. Petals are oblong-obovate or obovate, shortly clawed, and 3 to 3.5 centimeters long; the margins are undulate and hardly fimbriate. Fruit is a large nutlike capsule, obovoid or ellipsoid, and 2 to 3.5 centimeters long. Seed is pale brown, with a wing 12 to 18 millimeters long.
- In most or all islands and provinces, chiefly in secondary forests at low and medium altitudes.
- Found in the Batan Islands and northern Luzon to Palawan, Mindanao and the Sulu Archipelago.
- Cultivated in Manila for its beautiful flowers.
- Makes an excellent avenue tree.
- Also reported in India to southern China and southward through Malaya to tropical Australia.
- Phytochemical screening yielded phenolic compounds, flavonoids, and saponins.
Rich in tannin: fruit, 14 to 17 %; leaves
13 %; bark, 10%.
- Studies have isolated: (1) corosolic acid (2) ellagitannin Lagerstroemin (3) gallotannins.
- Penta-O-galloyl-glucopyranose (PPG) – identified as the most potent of the gallotannins, with a higher glucose transport stimulatory activity than Lagerstroemin. In addition to stimulating glucose uptake in fat cells, it also has anti-adipogenic properties.
- Before shedding, the leaves are bright orange
or red during which time it is thought to contain higher levels of corosolic
- Old leaves and ripe fruit are considered to yield the greatest amount of an insulin-like principle. Twenty grams of old leaves or fruit, dried from one to two weeks, in the form of 100 cc of 20% decoction was found to have activity equivalent to 6 to 7.7 units of insulin.
- Mature leaves, young leaves and flowers have an activity that ranged from 4.4 to 5.4 units of insulin per 100 cc of 20% decoction, or equivalent to around 70% of the activity of the leaves or fruit.
- Study of the wood yielded no insulin-like principle; the bark and roots yielded a very small amount.
- Leaves are considered purgative, deobstructive, diuretic.
- Roots are considered astringent, stimulant, febrifuge.
- Bark considered stimulant and febrifuge.
Leaves, fruits, flowers and bark.
- Decoction of leaves of all ages used for diabetes mellitus. Some physicians believe the dried fruit decoction to be better.
Roots have been
used for a variety of stomach ailments. Leaf decoction for diabetes;
also use as a diuretic and purgative.
- Decoction of old leaves and dried fruit (dried from one to two weeks),
50 gms to a pint of boiling water, 4 to 6 cups daily has been used for
diabetes. Old leaves and ripe fruit are preferred, believed to have
greater glucose lowering effect. Young leaves and flowers have a similar
effect, though only 70% that of matures leaves and fruits. The wood
has no known glucose lowering effect; the bark, a very small amount.
A decoction of 20 gms of old leaves or dried fruit in 100 cc of water
was found to have the equivalent effect to that of 6 to 7.7 units of
- In Pahang decoction of bark has been used for the treatment of diarrhea.
- Infusion of bark used for diarrhea.
- The bark, flowers and leaves used to facilitate bowel movements.
- Decoction of fruits or roots gargled for aphthous stomatitis.
- Decoction of leaves and flowers used for fevers and as diuretic.
- Leaf decoction or infusion used for bladder and kidney inflammation,
dysuria, and other urinary dysfunctions.
- Seeds considered to have narcotic properties; also employed against aphthae.
- Banaba makes a useful timber tree.
• Corosolic Acid / Lagerstroemin / Gallotannins: Studies have identified several compounds as responsible for its anti-diabetic activity. (1) corosolic acid (2) Lagerstroemin, an ellagitannin (3) gallotannins, of which PPG – penta-O-galloyl-glucopyranose–was identified as the most potent, with a higher glucose transport stimulatory activity than Lagerstroemin. In addition to stimulating glucose uptake in fat cells, it also has anti-adipogenic properties.
• Inhibition of TNF-induced Activation: Diabetes leads to cardiomyocyte hypertrophy in association with upregulation of vasoactive factors and activation of nuclear factor (NF)-kappaB and activating protein-1. Study results indicate L speciosa can inhibit DNA-binding of NF-kappaB which may explain its possible inhibition of diabetes-induced cardiomyocyte hypertrophy. (8)
• Ellagitannins / Insulin-like Glucose Uptake Stimulatory/ Inhibitory Activities / Adipocyte Differentiation-Inhibitory Activity: Study yielded seven ellagitannins, including lagerstroemin from the leaves of L speciosa. The ellagitannins exhibited strong activities in both stimulating insulin-like glucose uptake and inhibiting adipocyte differentiation . Also, ellagic acid derivatives showed inhibitory effect on glucose transport. (5)
• Glucose Transport Activators: Screening has identified lagerstroemin, flosin, and reginin A as activators of glucose transport in rat fat cells.
• Diabetes: (1) Banaba has been extensively studied for its application
in the treatment of diabetes. Early on, Its ability to lower blood sugar was attributed
to corosolic acid, a triterpenoid glycoside, believed to facilitate
glucose-transport into cells. (2) Studied with abutra,
for antidiabetic activity through activation of glucose transporter activity.
One of the active principles from Banaba was the tripertene, corosolic
• Weight loss: Studies in mice suggest an antiobesity effect.
It is becoming a common ingredient in weight-loss supplements / products
as a metabolic enhancer.
• Hypertension: It is also being studied for its use in the
treatment of blood pressure, renal and immune system benefits.
Lipid-lowering: Studies in mice suggest
a lipid lowering effect - decreasing triglyceride and total cholesterol
levels. To date, no toxicity has been identified.
• Hypoglycemic Activity of Irradiated Banaba
Leaves: Study showed irradiated banaba leaf extract mixed with insulin was found to have a higher hypoglycemic activity compared with mixtures of nBLE and insulin. Results may suggest the potential of reducing the cost of insulin management by lessening the dependence on recombinant insulin. (3)
• Xanthine oxidase inhibitors from the leaves
of Lagerstroemia speciosa (L.) Pers: Xanthine oxidase is a key
enzyme involved with hyperuricemia, catalyzing the oxidation of hypoxanthine
to xanthine to uric acid. The study supports the dietary use of the
aqueous extracts from Banaba leaves for the prevention and treatment
of hyperuricemia. (4)
• Antidiabetic Activity: Study showed a significant reduction
of blood glucose levels with the soft gel formulation showing better
bioavailability than a dry-powder formulation. (7)
• Other studies report potential uses:
(1) antibacterial effects from seed extracts (2) significant protection
of HIV-infected cells by ellagic acid constituents (3) antioxidative
activity of a water extract (4) inhibition of xanthine oxidase by aqueous
extract, 31 and anti-inflammatory activity in mice.
• Anti-Inflammatory / Free Radical Scavenging: Study showed antioxidant and anti-inflammatory activities from the ethyl acetate and ethanol extracts of Lagerstroemia speciosa. (9)
• Antioxidant: A hydroalcoholic extract of leaves of L. speciosa demonstrated antioxidant activity in the nitric oxide model. (10)
• Hypoglycemic Activity / Mechanism of Action: Study of a hot water extract of leaves of L. speciosa showed hypoglycemic activity on experimental diabetic rats through suppression of gluconeogenesis and stimulation of glucose oxidation using the pentose phosphate pathway. (11)
• Hepatoprotective: L. speciosa pers roots showed hepatoprotective activity protecting hepatocytes from CCl4-induced liver damages due to antioxidant effect on hepatocytes. (12)
• Pharmacognostic Evaluation of Leaves: Study provided important information for the correct identification and herbal standardization of L. speciosa leaves. Phytochemical screening yielded alkaloids, tannins, flavonoids, triterpenoids, sterol, and saponins. Study suggests the season of collection and storage conditions may lead to fluctuations in the corosolic acid content. (13)
• Antimicrobial / Quorum Sensing Modulation: Study showed a fruit extract caused downregulation of the quorum sensing related genes and respective signaling molecules, without affecting P. aeruginosa growth. Results suggest a possible role for quorum sensing mechanisms and the potential source of QS-based antibacterial drugs. (15)
• Review / Antiobesity Therapeutics and Mechanisms: A review of natural products with anti-obesity activity included Lagerstroemia speciosa: (1) a crude aqueous extract promoting lipid metabolism; a 3% decrease in body weight, through PPARs (peroxisome-proliferator activated receptor) agonistic activity (2) Ellagitannins via inhibition of GPDH activity by 20%. (18)
• Antiobesity and Antiobesity Polyherbal Formulation: A polyherbal formulation for obesity containing G. sylvestre, G. cambogia, and Lagerstroemia speciosa was studied in normal and obese STZ-induced diabetic rats. Results showed an antidiabetic and antiobesity effect similar to that observed with glibenclamide and sibutramine. (19)
• Safety of Banaba and Corrosoli Acid: The hypoglycemic effect of banaba has been attributed to corrosolic acid and elligatannins. Corrosoli acid also exhibited antihyperlipidemic, antioxidant, anti-inflammatory, antifungal, antiviral, antineoplastic, and osteoblastic activities. Its antidiabetic and lipid effects involve multiple mechanisms, including enhanced cellular uptake of glucose, impaired hydrolysis of starches and sucrose, plus other signal transduction factors. No adverse effects were observed in animal studies or controlled human clinical trials. (20)
• Antibacterial / Phytochemicals: A methanolic extract of leaves yielded anthraquinones, flavonoids, saponins, and tannins. The extract exhibited high antibacterial activity against Salmonella typhimurium. (21)
Cultivated for flowers.
Commercial: Tablets, extracts, capsules, powder and tea.