Bacopa monniera - Monograph

Alternative Medicine Review, March, 2004

Introduction

Bacopa monniera, also referred to as Bacopa monnieri, Herpestis monniera, water hyssop, and "Brahmi," has been used in the Ayurvedic system of medicine for centuries. Traditionally, it was used as a brain tonic to enhance memory development, learning, and concentration, (1) and to provide relief to patients with anxiety or epileptic disorders. (2) The plant has also been used in India and Pakistan as a cardiac tonic. digestive aid, and to improve respiratory function in cases of bronchoconstriction. (3) Recent research has focused primarily on Bacopa's cognitive-enhancing effects, specifically memory, learning, and concentration, and results support the traditional Ayurvedic claims. Research on anxiety, epilepsy, bronchitis and asthma, irritable bowel syndrome, and gastric ulcers also supports the Ayurvedic uses of Bacopa. Bacopa's antioxidant properties may offer protection from tree radical damage in cardiovascular disease and certain types of cancer.

Description

Bacopa monniera, a member of the Scrophulariaceae family, is a small, creeping herb with numerous branches, small oblong leaves, and light purple flowers. In India and the tropics it grows naturally in wet soil, shallow water, and marshes. The herb can be found at elevations from sea level to altitudes of 4,400 feet, and is easily cultivated if adequate water is available. Flowers and fruit appear in summer and the entire plant is used medicinally. (2,4)

Active Constituents and Pharmacokinetics

Compounds responsible for the pharmacological effects of Bacopa include alkaloids, saponins, and sterols. Many active constituents--the alkaloids Brahmine and herpestine, saponins d-mannitol and hersaponin, acid A, and monnierin--were isolated in India over 40 years ago. Other active constituents have since been identified, including betulic acid, stigmastarol, beta-sitosterol, as well as numerous bacosides and bacopasaponins. The constituents responsible for Bacopa's cognitive effects are bacosides A and B.5. (5-9)

Mechanisms of Action

Since Bacopa's primary therapeutic use is to enhance cognitive function, most research has focused on the mechanism behind these properties. The triterpenoid saponins and their bacosides are responsible for Bacopa's ability to enhance nerve impulse transmission. The bacosides aid in repair of damaged neurons by enhancing kinase activity, neuronal synthesis, and restoration of synaptic activity, and ultimately nerve impulse transmission. (10)

Loss of cholinergic neuronal activity in the hippocampus is the primary feature of Alzheimer's disease. (11) Based on animal study results, bacosides appear to have antioxidant activity in the hippocampus, frontal cortex, and striatum. (12) Animal research has shown Bacopa extracts modulate the expression of certain enzymes involved in generation and scavenging of reactive oxygen species in the brain. (13) In vitro research has shown Bacopa exerts a protective effect against DNA damage in astrocytes (14) and human fibroblasts. (15)

In animals Bacopa has a relaxant effect on pulmonary arteries, aorta, trachea, and ileal and bronchial tissue, possibly mediated by inhibition of calcium-ion influx into cell membranes. (16) Bacopa appears to stabilize mast cells in vitro, (17) and possesses anti-inflammatory activity via inhibition of prostaglandin synthesis and lysosomal membrane stabilization. (18) In vitro research suggests an anticancer effect for Bacopa extracts, possibly due to inhibition of DNA replication in cancer cell lines. (19)

Clinical Indications

Cognitive Effects

Adults

Bacopa monniera has been studied clinically for its acute and chronic effects on cognitive function. In adults, it appears only chronic administration is associated with cognitive-enhancing effects. In a double-blind, placebo-controlled trial of 38 healthy volunteers (ages 18-60), subjects were given a single dose of 300 mg Bacopa monniera extract (standardized to 55-percent combined bacosides A and B) or placebo. Subjects were tested two hours after drug administration. coinciding with maximum pharmacodynamic effect. Acute administration of this dose of Bacopa extract resulted in no significant changes in cognitive function when compared to baseline values. Parameters assessed included attention, working and short-term memory, verbal learning, decision making, memory consolidation, executive processes, planning and problem solving, speed of information processing, and motor responsiveness. (20)

On the other hand, significant cognitive-enhancing benefits have been demonstrated with more chronic administration of Bacopa extracts. Australian researchers conducted a double-blind, placebo-controlled, 12-week trial utilizing the same patient selection criteria and same dose of Bacopa extract (300 mg daily) containing 55-percent combined bacosides. Forty-six healthy volunteers (ages 18-60) were randomly and evenly divided into treatment and placebo groups. The same series of tests administered in the acute dosage trial were administered at baseline, five, and 12 weeks after treatment began. At the end of the 12-week study, results indicated a significant improvement in verbal learning, memory consolidation, and speed of early information processing in the treatment group compared to placebo. These effects were not observed at baseline or at five weeks. These results may be attributed to Bacopa's antioxidant properties and/or its effect on the cholinergic system. (21)