Banaba

Scientific Name(s): Lagerstroemia speciosa (L.) Pers.
Common Name(s): Banaba, Crepe myrtle, Pride of India, Queen's crepe myrtle, Queen's flower

Medically reviewed by Drugs.com. Last updated on Jul 22, 2024.

Clinical Overview

Use

Banaba leaf preparations have been used in Philippine folk medicine for treatment of diabetes; however, reviews of medical literature on the effects of banaba in diabetes have identified few quality clinical trials and some open-label or small studies. Clinical trial data are lacking to recommend banaba for any indication.

Dosing

Limited clinical trial data exist to provide dosing recommendations.

Contraindications

Contraindications have not been identified.

Pregnancy/Lactation

Avoid use. Information regarding safety and efficacy in pregnancy and lactation is lacking.

Interactions

None well documented.

Adverse Reactions

None well documented.

Toxicology

No toxicity has been reported.

Scientific Family

• Lythraceae (loosestrife)

Botany

Banaba is a semideciduous, tropical, flowering tree that grows in India, Southeast Asia, and the Philippines. L. speciosa, commonly planted as an ornamental along roadsides and in gardens and parks, can grow up to 20 m in height. The leaves are obovate, simple, and opposite. The flowers are pink to purple when in bloom and give way to oval, nut-like fruits. The bark of the tree peels off in flakes.(Chan 2014, Klein 2007, USDA 2016)

History

Banaba has been used in folk medicine to treat diabetes in various parts of the world, especially in the Philippines and Southeast Asia. Folkloric use of banaba leaf decoctions for diuretic and purgative purposes and of the bark and root parts for stomach ailments has also been recorded. The first research study evaluating the insulin-like activity of an aqueous extract of dried leaves was conducted in rabbits and published in 1940.(Chan 2014, Stohs 2012)

Chemistry

L. speciosa consists of several phytoconstituents such as glycosides, flavones, corosolic acid, ellagic acids, triterpenes, and tannins, which are reported to be present in the leaves, stem, flowers, fruit, bark, and roots.(Raju 2021) Corosolic acid, also known as "plant insulin," is a pentacyclic triterpenoid extracted from plants such as L. speciosa that has antidiabetic, anti-inflammatory, and antitumor effects.(Qian 2021) Reports have confirmed the presence of ellagitannins, lagerstroemin, flosin B, and reginin A, all of which are possible glucose transport enhancers.(Hayashi 2002) Lagertannins, beta-sitosterol, stigmasterol, campesterol, and some of the olefins have also been found in banaba leaves and extracts.(Hayashi 2002, Takahashi 1976, Tanaka 1992) Lageracetal (1,1-dibutoxybutane), 1-pentanol, ellagic acid, and corosolic acid (a triterpene) have also been isolated from the leaves,(Egawa 2001, Takahashi 1973) and one study reports that 16 amino acids, pyrogallol tannins, and lipids are also present.(Manalo 1993) Nonacosane, hentriacontane, tritriacontane, olefins, and esters of palmitic, daturic, stearic, arachinic, and behenic acids were identified from the neutral fraction of hot ethanol extracts of banaba leaves.(Takahashi 1979)

L. speciosa seed is a rich combination of organic compounds ranging from long-chain fatty acids, alcohols, esters, hydrocarbons, and phytosterols.(Raju 2021) L. speciosa seed oil contains caprylic, lauric, myristic, palmitic, stearic, arachidic, behenic, lignoceric, oleic, and linoleic acids(Badami 1970); 9-keotoctadec-cis-11-enoic acid has been isolated from seed oil as well.(Jehan 1990) Chemical investigation of amino acid components in banaba seed oil has been performed.(Laskarz 1998) The components nonanedioic acid, 12-acetyloxy-9-octadecenoic acid, and 16-methyl-heptadecandic acids, present in the seed extracts, have been identified as having antibacterial activity.(Sinhababu 1999)

Uses and Pharmacology

Antibacterial/Antifungal effects

In vitro data

Banaba preparations have shown antibacterial and antifungal activities in various studies.(Singh 2012, Sinhababu 1994, Sinhababu 1999, Stohs 2012) In one study, L. speciosa fruit extract modulated quorum sensing–controlled virulence factor production and biofilm formation in P. aeruginosa.(Singh 2012)

Anti-inflammatory activity

Animal and in vitro data

Anti-inflammatory activity of corosolic acid in rats has been reported.(Yamaguchi 2006) Insight into the anti-inflammatory mechanism of action of banaba may be gained from results of an in vitro experiment in a cardiomyocyte cell line in which an aqueous extract blocked activation of nuclear factor kappa B by tumor necrosis factor in a time-dependent manner.(Stohs 2012) Corosolic acid demonstrated effective anti-inflammatory activity against arachidonic acid and 12-O-tetradecanoylphorbol-13 acetate, as assessed in vivo using a mouse ear assay.(Murakami 1993, Stohs 2012)

Protective effects of banaba leaf methanolic extracts were observed in C57BL/6 mice with dextran sulfate sodium (DSS)–induced ulcerative colitis. Banaba extracts significantly prevented DSS-induced inflammatory and ulcerative damage of the colon, reduced lipid peroxidation, and restored levels of innate antioxidants in colon tissue.(Chaudhary 2017)

Antioxidant activity

Animal and in vitro data

Banaba aqueous extract showed potent radical scavenging activity (in a concentration-dependent manner) on 1,1-diphenyl-2-picrylhydrazyl radical and superoxide radicals generated by a hypoxanthine-xanthine oxidase system. Additionally, lipid peroxidation was inhibited in a rat liver homogenate system.(Unno 2000, Unno 1997) Further antioxidant activity has also been reported.(Guo 2016, Sahu 2015, Sinhababu 1994, Stohs 2012)

Antiviral activity

In vitro data

A study evaluated antiviral properties and the mechanism of action of ellagic acid from L. speciosa leaves.(Park 2014) Protection of HIV-infected cells by ellagic acid constituents, possibly via inhibition of reverse transcriptase and HIV protease, has been reported.(Nutan 2013) One study suggested quercetin 7-glucoside from L. speciosa had antiviral activity against human rhinovirus 2.(Song 2013)

Cancer

Animal and in vitro data

Various in vitro studies report effects of corosolic acid on a variety of human tumor cells.(Stohs 2012, Sung 2014) L. speciosa leaf extracts have attenuated lung tumorigenesis by alleviating oxidative stress, inflammation, and apoptosis during in vivo mouse studies.(Mousa 2019) The molecular docking binding interaction of phytosterol derivatives identified from ethanolic extracts of L. speciosaseeds against breast cancer target proteins suggests that phytosterols could act as promising candidates against breast cancer.(Raju 2021) Quercetin isolated from a methanolic extract of L. speciosashowed significant in vitro cytotoxic activity against MCF-7 cell lines.(Sai Saraswathi 2017)

Cardioprotective effects

Animal data

An ethanol extract of L. speciosa reduced myocardial ischemic/reperfusion injury in rats.(Dhote 2020)

Diabetes and metabolic syndrome

Animal and in vitro data

In various reports, the constituent corosolic acid was shown to be a glucose transport activator, suggesting antidiabetic activity. Further investigations have revealed valoneaic acid dilactone as an amylase inhibitor. The ellagitannins lagerstroemin, flosin B, and reginin A increased glucose uptake by rat adipocytes.(Egawa 2001, Hayashi 2002, Murakami 1993)

Another report noted inhibitory effects of banaba on postprandial hyperglycemia via inhibition of alpha-amylase and alpha-glucosidases.(Suzuki 2001, Trinh 2016)

Banaba extracts have been examined in several rodent studies, with reported beneficial effects on both blood glucose levels and obesity.(Kakuda 1996, Suzuki 1999, Suzuki 2001)

Clinical data

Reviews of medical literature on the effects of banaba in diabetes have identified few quality clinical trials and a number of open-label or small clinical studies.(Miura 2012, Stohs 2012)

In one small clinical trial of patients with type 2 diabetes (N=10), administration of 32 mg or 48 mg of the standardized extract from L. speciosa leaves (Glucosol) (standardized to corosolic acid 1%) for 10 days reduced blood glucose levels.(Judy 2003) In a small, open-label study in individuals with blood glucose levels higher than 110 mg/dL (N=15), 100 mg of a water-soluble banaba extract administered for 1 year produced a significant decrease (16.6%) in fasting blood glucose. Improvements in both glucose tolerance and glycated albumin were observed after 6 months, as well as after 1 year of treatment.(Stohs 2012) A double-blind, randomized, placebo-controlled trial conducted in 24 patients with metabolic syndrome reported statistically significant differences from baseline in fasting glucose and insulin area under the curve (AUC) with 12-week administration of banaba extract 500 mg (standardized to 1.13% corosolic acid) twice daily before meals. Statistical data for comparisons to placebo were not reported, presumedly because no statistically significant difference was observed. However, absolute mean changes from baseline in fasting glucose were −0.2 and −0.1 mmol/L for banaba and placebo, respectively, and for insulin AUC, they were −12,692 and −4,343 pmol/L/min. Remission of metabolic syndrome was reported in 67% of patients (8 of 12) on banaba extract; however, no data were provided for placebo patients. Loose stools were reported by 75% of patients (9 of 12) on banaba extract, which was reported to be significantly different than placebo (P<0.001). Because loose stools was not listed among the adverse events for placebo patients, it is presumed that the incidence was zero.(Lopez-Murillo 2022)

Data from other unpublished studies and reports are generally supportive of a role for banaba in treating diabetes; however, additional quality clinical trials are required.(Stohs 2012)

Hepatic effects

Animal and in vitro data

In vitro experiments have reported that a bioactive fraction of L. speciosa may assist with the prevention of hepatic steatosis through antilipogenesis, anticholesterologenesis, and prolipolysis activity in HepG2 cells.(Tandrasasmita 2021) One animal study suggested developing a hepatoprotective health drink enriched with antioxidants from L. speciosa.(Tiwary 2017)

Obesity

In vitro data

In vitro experiments suggest that bioactive fractions from L. speciosa leaves (DLBS3733) reduce fat droplets by inhibiting adipogenesis and lipogenesis, which may provide an effective and potential benefit in the prevention of obesity.(Karsono 2019)