A Review of the Efficacy and Safety of Banaba (Lagerstroemia speciosa L.) and Corosolic Acid

Creighton University, Medical Center, Omaha, NE 68178, USA.
Phytotherapy Research (Impact Factor: 2.4). 11/2011; 26(3):317-24. DOI: 10.1002/ptr.3664
Source: PubMed

ABSTRACT Banaba (Lagerstroemia speciosa L.) extracts have been used for many years in folk medicine to treat diabetes, with the first published research study being reported in 1940. This review summarizes the current literature regarding banaba and its constituents. The hypoglycemic effects of banaba have been attributed to both corosolic acid as well as ellagitannins. Studies have been conducted in various animal models, human subjects and in vitro systems using water soluble banaba leaf extracts, corosolic acid-standardized extracts, and purified corosolic acid and ellagitannins. Pure corosolic acid has been reported to decrease blood sugar levels within 60 min in human subjects. Corosolic acid also exhibits antihyperlipidemic, antioxidant, antiinflammatory, antifungal, antiviral, antineoplastic and osteoblastic activities. The beneficial effects of banaba and corosolic acid with respect to various aspects of glucose and lipid metabolism appear to involve multiple mechanisms, including enhanced cellular uptake of glucose, impaired hydrolysis of sucrose and starches, decreased gluconeogenesis and the regulation of lipid metabolism. These effects may be mediated by PPAR, MAP K, NF-κB and other signal transduction factors. No adverse effects have been observed or reported in animal studies or controlled human clinical trials. Banaba extract, corosolic acid and other constituents may be beneficial in addressing the symptoms associated with metabolic syndrome, as well as offering other health benefits.

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    ABSTRACT: The present study investigated the effects of soybean leaf extracts (SLEs) on blood glucose, insulin resistance, body fat and dyslipidemia in prediabetes subjects, and compared them with the effects of banaba extracts (BE) which is known to ameliorate diabetes in several animals and clinical studies. Overweight subjects with mild hyperglycemia (fasting blood glucose level of 100-125 mg dL(-1)) were randomly assigned to three groups and administered four capsules containing starch (2 g per day, Placebo), BE (300 mg per day, 0.3% corosolic acid) or SLE (2 g per day) during regular meals for 12 weeks. The SLE as well as BE significantly decreased the baseline-adjusted final blood glucose, HbA1c, HOMA-IR and transaminase levels compared to the placebo group. The body weight, BMI and WHR were not different between the groups, but the baseline-adjusted final body fat content and waist circumference were lower in the BE and SLE groups than in the placebo group. Furthermore, the baseline-adjusted final plasma triglyceride concentration was lower in the BE and SLE groups compared to the placebo group. There were no significant differences in plasma total cholesterol and LDL-cholesterol concentrations between the groups. However, the SLE, but not the BE, significantly increased the plasma HDL-cholesterol concentration and the ratio of HDL-cholesterol to total cholesterol after 12 weeks of supplementation compared to the placebo group, while the atherogenic index was decreased. Taken together, these data suggest that SLE may play an important role in improving blood glucose, insulin resistance, adiposity, and dyslipidemia in prediabetes subjects consuming their habitual diet, similar to or better than BE.
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May 16, 2014