Cephalotaxus harringtonia

An isomeric alkaloid (alkaloid E) was isolated from S. pedunculata and found to be the major alkaloid in S. multiflora R.Br. (55). Values of 4.0 and 11 Hz for J3A suggested that it was the C-3 epimer 81b of schelhammericine. Structure 81b was proved by identification of 3-epischelham-mericine with 2,7-dihydro-3-epischelhammeridine (see Scheme 23) 84). Later on, another group reported the isolation of 81b from P. comosa, and was able to convert 3-epischelhammerine (80b) to 81b by chlorination and reduction, as shown in Scheme 23 (57). Cephalotaxus harringtonia var. harringtonia has also yielded 3-epischelhammericine 91). 

Other alkaloids in the Al(6)-alkene series have been reported. Two isomeric alkaloids (C20H27NO3) were obtained from Cephalotaxus harringtonia K. Koch var. harringtonia. Their spectroscopic properties closely resembled those of schelhammericine except that their NMR spectra revealed the presence of two aromatic methoxyl groups in place of the methylenedioxy group of schelhammericine. The alkaloids were therefore 3-epihomo-2,7-... 

Powell RG, Madrigal RV, Smith CR, Mikolajczak KL. Alkaloids of Cephalotaxus harringtonia var. drupacea. 11-Hydroxycepha-lotaxine and drupacine. J. Org. Chem. 1974 39 676-680. 

Powell RG, Weisleder D, Smith CR. Antitumor alkaloids for Cephalotaxus harringtonia structure and activity. J. Pharm. Sci. 1972 61 1227-1230. 

Cephalotaxus harringtonia (32) gave two alkaloids, 3-epi-2,7-dihydrohomoerysotrine (53) and 2,7-dihydrohomoerysotrine (54), whereas Cephalotaxus wilsoniana (34) afforded wilsonine (60) and epiwilsonine (61). Alkaloids 57, 58, and 59 were isolated from Phelline comosa Labiil. (33), and holidinine (52) and comosidine (57) were isolated from Phelline sp. aff. (25). 

Cephalotaxus harringtonia K. Koch var. fastigiata Rehder (leaves) I-6-Methyl-I-2,3-dihydroginkgetin (36) I-6-methyl-I-2,3-dihydrobilobetin (35) I-6-methyl-I-2,3-dihydrosequoiaflavone (33). Sasaki et al., 2008[224]. 

Incidentally, a yew-related species from China named Cephalotaxus fortunei yields a toxic anticancer substance known as harringtonine (Griggs, 1991, p. 318). A similar species in the United States is known as Cephalotaxus harringtonia, from which is derived the bioactive substance homoharringtonine. 

New homoerythrina alkaloids, alkaloid II (246), III (247), and VI (248), were more recently isolated from Cephalotaxus harringtonia (71). 

Intense structural-elucidation and synthetic activity has continued, no doubt as a consequence of the significant antitumour activity of this class of alkaloids. A pilot-plant extraction of harringtonine (13a), isoharringtonine (13b), and homoharringtonine (13c) from Cephalotaxus harringtonia using counter-current distribution has been described.This method provides 36 g of the three alkaloids in pure form from 455 kg of plant material. 

Five Homoerythrina alkaloids (3 R = Me, = H), (3 R + R = OCH2O), (3 R - R = Me), (4 R R = H, Me), and (4 R = R = Me) have been shown to co-occur with cephalotaxine (5 R = H) and its ester derivatives in Cephalotaxus harringtonia var. harringtoniaf The structures of the minor Homoerythrina alkaloids were established by spectroscopic studies and comparison with the known alkaloids (3 R = Me, R — H) and (3 R + R = OCHjO) which had been previously isolated from Schelhammera pedunculata and whose structures and absolute chemistry had been established. The co-occurrence of Homoerythrina and Cephalotaxus alkaloids makes it most attractive to propose that both types are derived from a common dienone (Scheme 1). An alternative biogenetic scheme for the formation of cephalotaxine (5 R = H) from an Erythrina precursor has been previously offered as speculation. Deoxyharringtonine (6), a new alkaloid with antileukemic activity of the same order of magnitude as the other known cephalotaxine alkaloids, has been... 

Takano, 1. Yasuda, M. Nishijima, Y. Hitotsuyanagi, K. Takeya, and H. Itokawa, New Oxygenated Cephalotaxus alkaloids from Cephalotaxus harringtonia var. drupaced, J. Nat. Prod., 1996, 59, 1192 - 1195. 

The slowly growing tree Cephalotaxus harringtonia is the source of cephalotaxine (12) and its esters harringtonine (13), deoxyharringtonine, isoharringtonine, and homoharringtonine. These compounds have shown significant antitumor activity. Production of these alkaloids by means of cell and tissue cultures has been patented (see Table XXI). 

U.S. SEC of Agriculture. US 4152-214. 07-10-1977-US-840423 (01-05-1979). Preparation of cephalotaxine and related antitumor alkaloid(s) by cultivation of Cephalotaxus harringtonia tissue in nutrient medium. 

Rohr, R., Piola, F. Pasquier P. (1997). Somatic embryogenesis in Cephalotaxus harringtonia embryo-megagametophyte co-culture. Journal of Forest Research, Vol. 2, No. 2 (May 1997), pp. 69-73, ISSN 1341-6979... 

Delfel, N. E. and J. A. Rothfus, Antitumor alkaloids in callus cultures of Cephalotaxus harringtonia. Phytochemistry, 16, 1595-1598 (1977). 

The diterpenoid tropone, harringtonolide, first isolated in North America from seeds of Cephalotaxus harringtonia (Taxaceae) and independently... 

Delfel N E 1980 Alkaloid distribution and catabolism in Cephalotaxus harringtonia. Phytochemistry 19 403-408... 

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