Loganin is one of the best-known of the iridoid glycosides.It is named for the Loganiaceae,having first been isolated from the seeds of a member of that plant family,namely those of Strychnos nux-vomica the strychnine tree.It also occurs in Alstonia boonei (Apocynaceae), a medicinal tree of West Africa and in the medicinal/entheogenic shrub Desfontainia spinosa (Columelliaceae) native to Central America and South America. Loganin exhibits CNS-exciting and analgesic activity and holds a key position in the biogenesis of certain indole alkaloids of the type occurring in Yohimbe : Pausinystalia johimbe (formerly known as Corynanthe yohimbe) (Rubiaceae),a medicinal tree found in tropical West Africa noted for its aphrodisiac properties.