Alzheimer's disease, the nematode Caenorhabditis elegans, and ginkgo biloba leaf extract.

Alzheimer's disease (AD) is affecting larger and larger proportions of our population as lifespan increases. Thus, the means to prevent or reduce the rate of this disorder is a high priority for medical research. A standardized extract of Ginkgo biloba leaves EGb 761 is a popular dietary supplement taken by the general public to enhance mental focus and by the elderly to delay onset of age-related loss of cognitive function. EGb 761 has been used for treatment of certain cerebral dysfunctions and dementias associated with aging and AD. Substantial evidence indicates that EGb 761 has neuroprotective effects. But, mechanisms of action of the components of the extract are, unfortunately, poorly understood. Research in my laboratory focuses on understanding mechanisms of action of the components of the herbal extract EGb 761 in protection against Alzheimer's disease. We have demonstrated that EGb 761 inhibited amyloid beta aggregation in vitro and attenuates reactive oxidative species (ROS) in a model organism - the round worm Caenorhabditis elegans. Furthermore, EGb 761 eased its toxicity in the transgenic C. elegans. We also found that only a certain size of the amyloid beta aggregates is toxic to the worms. These findings suggest that EGb 761 has a clear therapeutic potential for prevention and/or treatment of AD. A better understanding of the mechanisms of neuroprotection by EGb 761 will be important for designing therapeutic strategies, for basic understanding of the underlying neurodegenerative processes, and for a better understanding of the effectiveness and complexity of this herbal medicine.