Nostoc cryptophycins

Twenty-five cryptophycins, e.g. cryptophycin 1 (162), have been isolated from a Nostoc sp. strain. They exhibit various degrees of cytotoxicity against three tumor cell lines, namely KB (human nasopharyngeal), LoVo (human colorectal adenocarcenoma), and SKOV3 (human ovarian carcinoma). Removal of the chlorine atom leads to a 10-fold reduction in cytotoxicity [124]. The antitumor activity of a number of cryptophycins from Nostoc sp. has been evaluated [125]. 

Golakoti T, Ogino J, Heltzel CE, Husebo TL, Jensen CM, Larsen LK, Patterson GML, Moore RE, Mooberry SL, Corbett TH, Valeriote FA (1995) Structure Determination, Conformational Analysis, Chemical Stability Studies, and Antitumor Evaluation of the Cryptophycins. Isolation of 18 New Analogs from Nostoc sp. Strain GSV 224. J Am Chem Soc 117 12030... 

Chaganty S, Golakoti T, Heltzel C, Moore RE, Yoshida WY (2004) Isolation and Structure Determination of Cryptophycins 38, 326, and 327 from the Terrestrial Cyanobacterium Nostoc sp. GSV 224. J Nat Prod 67 1403... 

The cryptophycins (e.g. 16) form a group of depsipeptide antibiotics with a (R)-/7-AiB (R)-2 or / -Ala 1 substructure. They have already been isolated from cyanobacteria (Nostoc sp., see below) [47] arenastatin A 17 has been isolated from a marine sponge [42]. The cryptophycins are new lead structures within cancer drug research for their potent tumor-selective cytotoxicity [92]. The synthetic analog cryptophycin-52 (= 6-methylcryptophycin-l, LY-355703, 18) has reached clinical phase II trials [93]. 

Cyanobacteria are also sources of substances of pharmaceutical interest, for example, antibiotics [54]. Moore et al. isolated structurally unique cytotoxins from a lipophilic extract of Nostoc spp. GV 224. These cyclic depsipeptides called cryptophycins showed both solid tumor and tumor-selective cytotoxicity in the Corbett assay and in vivo studies revealed them to be very active against a number of tumors implanted in mice [55]. These studies may lead to the discoveries of new antitumor drags [56]. 

Nostopeptolides Al, A2, and A3 were isolated in 2000 from the terrestrial cryptophycin-producing cyanobacterium Nostoc sp. GSV224 (Figure 5.22) [83]. 

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