Ginkgo Biloba Extract . Supports Mental Acuity. Ginkgo-24™ is a standardized concentration of prime quality Ginkgo biloba leaves. The extraction yields 24% ginkgo flavoneglycosides (the key nutrients) from a 50 to 1 concentration. The Ginkgo biloba tree has survived for over 200 million years virtually unchanged -- the Earth's oldest living species of tree. Ginkgo biloba is the subject of extensive scientific research and is used worldwide as a nutritional supplement.