(1990). The Shikimate Pathway — A Metabolic Tree with Many Branche. Critical Reviews in Biochemistry and Molecular Biology: Vol. 25, No. 5, pp. 307-384.

The shikimate pathway―a metabolic tree with many branches

Biochemistry and Molecular Biology The Shikimate Pathway - A Metabolic Tree with Many Branches

On the origins of triterpenoid skeletal diversity.

Prenylated indole derivatives from fungi: structure diversity, biological activities, biosynthesis and chemoenzymatic synthesis

Occurrence and distribution of free flavonoid aglycones in plants

Papaverine, m.p. 147 °C a benzylisoquinoline alkaloid, co-occurs with morphine and other related alkaloids in opium (Papaver somniferum, Fam. Papaveraceae) [1]. It is present in opium to the extent of 0.5–1 %, and its other companion alkaloids are codeine, thebaine, etc. (Chap. 23). It was first isolated from the mother liquor of morphine in 1848.

Papaverine (l-Tyrosine-Derived Alkaloid)

The dimeric indole alkaloid vinblastine (vincaleukoblastine) (VLB), serendipitously discovered from Madagascan periwinkle (Catharanthus roseus syn. Vinca rosea, Apocynaceae) [1], exhibits remarkable cancer-fighting activity and contributed immensely to dispel the sufferings of human beings caused by certain types of cancer (see Chap. 33). Subsequent discovery of a few more dimeric indole alkaloids leurocristine (LCR) (also known as vincristine), leurosine, and leurosidine (vinrosidine) from the same plant (Fig. 28.1) and the study of their anticancer activities add another name vincristine to the list of important cancer-fighting drugs. The molecular structures of vincristine and vinblastine with some stereochemical reservations have been proposed from the studies of their spectral properties, degradations, characterizations of their degradation products, and on biogenetic grounds [2–4].

Dimeric Indole Alkaloids. Vinblastine (Vincaleukoblastine), Vincristine (Leurocristine), and Their Derivatives

(−)-Ephedrine, m.p. 33–42 °C (depending on the water content) and its diastereomer (+)-pseudoephedrine (also written as (+)-ψ-ephedrine) occur in various Ephedra species [1] (Fam. Ephedraceae). (−)-Ephedrine was first isolated from the Chinese drug “Ma Huang” in 1885 and was purified in 1887 by Nagai who also obtained pseudoephedrine from the same source. The drug Ma Huang is reported to be Ephedra sinica as well as a mixture of E. equisetina, E. sinica, and E. distachya. Ephedra belongs to the order Ephedrales, of which it is a single genus [2]. In some literature, the genus Ephedra has been included in the family Gnetaceae [3]. The E. sinica plant extracts containing (−)-ephedrine have been used for nearly 5,000 years in Chinese folk medicine. The genus Ephedra is not confined to China and Japan but has a much wider geographical distribution [1, 3, 4]. Ephedrine and ψ-ephedrine are also obtained from other sources [1].

Ephedrine and Pseudoephedrine (C6–C1 Part Derived from l-Phenylalanine and Nitrogen Derived by Transamination)

(+)-Pilocarpine is the most important imidazole alkaloid because it exhibits extensive pharmacological properties. It co-occurs with its diastereomer (+)-isopilocarpine in the leaves of various South American Pilocarpus species (Fam. Rutaceae). The dried leaves of some Pilocarpus species, P. jaborandi, P. macrophyllus, and P. pennatifolium are commonly known as “jaborandi.” P. macrophyllus is the major source of pilocarpine in which it occurs to the extent of 0.5 % along with other congener alkaloids, raising the total alkaloid content to ~1 %. Pilocarpine and isopilocarpine are generally obtained as viscous liquids, but both can also be obtained as low melting hygroscopic crystals.

Pilocarpine and Isopilocarpine (l-Histidine-Derived Imidazole Alkaloids)

Whenever there is life there are diseases, decay, and death. Death is the most inevitable biological event of a living system. Since life is the most precious gift of Nature, people want to preserve it as along as possible. In an endeavor to arrest the approach of death, our ancestors had not only to withstand the fury of Nature but also had to fight against diseases and decay. People were thus in search of remedial measures since the dawn of human intellect. The relationship of man and Nature was symbiotic and the immediate source of such remedial measures had been the forests, the home of our ancestors. They used to roam in and around the forests, and through thousands of years of interactions with Nature by trial and error methods, and under the pressure of experience and need they could discover a large number of plants with varying healing properties. These plants are referred to as the medicinal plants, and the people having the knowledge of their curative applications were known as medicine men. Thus a wealth of information on the curative properties of plants resulted.

Sunil Kumar Talapatra

Papers

Papaverine (l-Tyrosine-Derived Alkaloid)

Dimeric Indole Alkaloids. Vinblastine (Vincaleukoblastine), Vincristine (Leurocristine), and Their Derivatives

Ephedrine and Pseudoephedrine (C6–C1 Part Derived from l-Phenylalanine and Nitrogen Derived by Transamination)

Pilocarpine and Isopilocarpine (l-Histidine-Derived Imidazole Alkaloids)

Natural Products in the Parlor of Pharmaceuticals