Cephalotaxine extractabilities

Another example for SFE of alkaloids using basified modifiers was reported for cephalotaxine (7) from Cephalotaxus wilsoniana leaves [45]. In this report, basified methanol was found to greatly enhance the extraction efficiency relative to any other modifiers (Figure 13). 

Figure 13. Relative extraction yields (%) of cephalotaxine (7) from C. wilsoniana leaves by SC-C02 by added modifiers when compared with methanol extraction [45], Reproduced with permission from the Pharmaceutical Society of Korea 1999.

The alkaloids were best isolated from the ethanol extract of the plant material, partially fractionated by counter-current distribution, and subsequently purified by preparative chromatography. Of the 11 known Cephalotaxus alkaloids (105-115 in Figs. 8 and 9), cephalotaxine (105a) is ubiquitous and the most abundant (up to 64% of the total alkaloid extract) in all species examined. C. wilsoniana Hay., which yields only minor quantities of cephalotaxine, is the exception, however it is rich in Homoerythrina alkaloids,... 

When the alkaloidal extracts of C. harringtonia var. harringtonia were found to possess antileukemia properties, a search for the responsible alkaloids was initiated, since the major component, cephalotaxine, was inactive. Four alkaloids (the harringtonines) that exhibited anticancer properties were isolated. The structures of harringtonine, isoharringtonine, and homo-harringtonine were reported in 1970 (107), and that of deoxyharringtonine was reported in 1972 (108). 

Antitumor activity in P388 and L1210 experimental leukemia systems was detected in extracts from the seeds of C. harringtonia K. Koch var. harring-tonia (8, 95). It was soon discovered that the major component, cephalotaxine (105a), was inactive and that the activity resided in the esters 107-110 (the harringtonines) (184-187). 

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