Ginkgolide diterpene

Ginkgolide A (ginkgolide diterpene) Nagilactone C (totarane-like diterpene)... 

Overall, however, the immensity of temperate land corresponds to a most various secondary metabolic production, different from that of tropical land. The most renowned alkaloids belong to the morphine class (Chart 6.2.A1), and, in combination with isoprenoids, to the ergot and triterpene classes (Chart 6.2. A2). Prominent in the peptides are the cyclosporins (the first of which was isolated from a fiingus collected in Norway), streptogramins, and P-lactams (Chart 6.2.P). The isoprenoids are represented by pyrethrin monoterpenes, cedrane sesquiterpenes, ginkgolide and taxane diterpenes, ophiobolane sesterterpenes, and arborane and amyrin-like triterpenes (Chart 6.2.1). In the polyketides, epothilones, recently discovered from Myxobacteria, and the long known rapamycin, are two prominent classes of macrolides (Chart 6.2.FA/PO/C). 

Recently, a key player in the ginkgolide biosynthesis has been isolated and characterized A cDNA that encodes G. biloba levopimaradiene synthase, a diterpene synthase involved in ginkgolide biosynthesis, was isolated and characterized. Similarly, a new geranylgeranyl diphosphate synthase gene from G. biloba, was characterized. ... 

The effects of GB are attributed to several chemical constituents of the whole plant rather than to any one individual component. These chemicals include many flavonoids (also called flavonol, flavone, or flavonoid glycosides, ginkgo flavone glycosides, dimeric bioflavones), and the terpene lactones (also called terpenoids, diterpenes, terpenes), including the ginkgolides and bilobalide (2,5-7). 

A series of jeco-diterpenes, the ginkgolides (55), are only known to occur in the leaves and root bark of Ginkgo biloba (Fig. 22.19) (Nakanishi et al., 1974). 

Chen et al. [365] analyzed Ginkgo biloba extracts for diterpenes (ginkgolides A, B, and C) and the sesquiterpene (bilobalide) content using a C g column (RI detector) and a 23/77 methanol/water mobile phase. Peaks were somewhat broad (perhaps due to the RI), but good resolution was achieved and elution was complete in 24min. A plot of k vs. percent methanol is,shown. A linear range of 4-60 pg... 

Of considerable interest is the New York Times report on March 1, 1988, of E.J. Corey s group s synthesis of the diterpene, ginkgolide B. Ginkgo extracts have a long history of use in Oriental medicine and have found therapeutic use in treating circulatory problems, asthma, toxic shock, and Alzheimer s disease, and as a possible replacement for cyclosporin used to prevent rejection of organ transplants. 

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