Alkaloids sulfur-containing

New Nuphar alkaloids isolated since 1974 are listed in Table I. Table 1 includes monomeric CIS alkaloids and dimeric sulfur-containing alkaloids. 

The sulfur-containing alkaloid zapotidine has been found to have the structure (545) (61JA2022). A synthesis of (545) has been achieved from (544b) by lithium aluminum hydride reduction to iV -methylhistamine followed by ring closure to (545) with thiocarbonyl-diimidazole (67T239). 

These novel sulfur alkaloids and their properties are given in Table II. Structural studies have demonstrated for all the known Nuphar alkaloids shown in Tables I and II either the sesquiterpenoid or the triterpenoid structure incorporating the quinolizidine and furan systems, with the tetrahydrothiophcne system in the sulfur-containing alkaloids. 

From one 100-kg. lot of seeds, Bellet and Muller (300) isolated 1.7 g. of a basic, sulfur-containing alkaloid, CgjHjsNOgSg, m.p. 265-267° (dec,), [a] —366° (chloroform), which contains three methoxyl groups. It gives no ferric chloride test and is unaffected by concentrated hydrochloric acid or acetylation conditions. 

The new alkaloid, 3-epinuphamine from var. variegatwn, was given the structure shown (158). More recently another pair of sulfur-containing alkaloids have been isolated. They are glasslike solids— 6,6 -dihydroxythionuphlutine-A (C30H42N2O4S) and -B—whose structures are closely related to neothiobinupharidine 182, 183). 

Analogously, lissoclinotoxin A (42) [Fig. (12)], a sulfur-containing alkaloid isolated from the tunicate Lissoclinum perforatum [60], showed high activity against P. falciparum but was later found to be a DNA-damaging agent [61] at very low concentrations and, thus, its use as an antimalarial agent cannot be proposed. 

Cheng J, Ohizumi Y, Walchli MR, Nakamura H, Hirata Y, Sasaki T, Kobayashi J (1988) Prianosins B, C, and D, novel sulfur-containing alkaloids with potent antineoplastic activity from the Okinawan marine sponge Prianos melanos. J Org Chem 53 4621 624... 

Nishiyama S, Cheng JF, Tao XL, Yamamura S (1991) Synthetic studies on novel sulfur-containing alkaloids, prianosins and discorhahdins total synthesis of discorhabdin C. Tetrahedron Lett 32 4151-4154... 

In general sulfur containing alkaloids are resistant to heating and some oxidation agents, do not undergo quaternization and desulfuration in respect to exclusive removal of sulfur atom. 

Radchenko, O.S., Novikov, V.L., Wdbs, R.H., Murphy, P.T., and Elyakov, G.B. (1997) Synthesis of polycarpine, a cytotoxic sulfur-containing alkaloid from the asddian Polycarpa aurata, and related compounds. Tetrahedron Lett., 38, 3581-3584. 

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