Some Aspects of Guanidine Secondary Metabolites

The isolation of water-soluble natural products – challenges, strategies and perspectives

“…The early days of microbial natural product discovery revealed very polar metabolites such as streptomycin and related aminoglycosides, streptothricins, polar peptides, modified nucleosides and macrocyclic lactones, which were isolated using ion-exchange, cellulose and gel-permeation chromatography. 28–30 For example, Ōmura's method for the discovery of bacterial alkaloids started by looking at water-soluble fractions first, and then at organic solvent fractions. 31,32 Also, the National Cancer Institute biodiscovery program has included screenings of water-soluble fractions for decades.…”

“…Few examples reported in the literature for the isolation of secondary metabolites using HILIC include the separation of saxitoxin, tetrodotoxin and related guanidine derivatives, such as 11β-hydroxysaxitoxin ( 99 ), 11β-hydroxy- N -sulfocarbamoylsaxitoxin ( 100 ), 11,11-dihydroxy- N -sulfocarbamoylsaxitoxin ( 101 ) and 11,11-dihydroxysaxitoxin ( 102 ) from a mixture of the mussels Mytilus edulis and M. trossulus , 385 isolation of rebaudioside A ( 103 ) from the aqueous extract of Lycopus lucidus , 386 and several tetrodotoxin (TTX) derivatives and analogues such as 104 and 105 and other TTX-derived guanidines isolated from pufferfish and newts. 30,387–390…”

“…As mentioned above, normal-phase chromatography on silica-gel with aqueous mixtures for the isolation of highly polar metabolites is in use for at least 50 years. 365 Examples include the isolation of highly polar polyketides, such as the first macrocyclic lactone antibiotics bearing an alkyl guanidine chain isolated from different bacteria culture media 30,391 and fumonisin mycotoxins ( e.g. , fumonisin C 1 , 90 ) from corn cultures of Fusarium moniliforme 392 and several alkaloids including nagelamide A ( 106 ) from the sponge Agelas sp., 393 β-carboline alkaloids such as dichotomine A ( 107 ) from the roots of Stellaria dichotoma , 394 farinosone B ( 108 ) from culture media of the entomogenous deuteromycete Paecilomyces farinosus 395 and pyraxinine ( 109 ) from the marine sponge Cymbastela cantharella .…”

Batzella, Crambe and Monanchora: Highly Prolific Marine Sponge Genera Yielding Compounds with Potential Applications for Cancer and Other Therapeutic Areas

“…Marine sponges (phylum Porifera), even though they are the most primitive class within the animal kingdom, are considered renewable powerful suppliers for bioactives. The marine genera belonging to the order Poecilosclerida, Batzella (family Chondropsidae), Crambe and Monanchora (family Crambeidae), are rich in the production of highly physiologically active pyrroloquinoline and guanidine-derived alkaloids [ 4 , 5 , 6 ], with a vast scope of biological potentialities including cytotoxic and antiviral [ 7 , 8 , 9 , 10 , 11 , 12 ], HIV-1 inhibitors [ 13 , 14 ], enzyme inhibitors [ 15 ], receptor antagonist [ 16 ], Ca 2+ channel blocker [ 17 ], antifungal [ 18 ] and antimicrobial [ 19 , 20 , 21 ]. These interesting compounds are considered taxonomic markers in particular for some Poecilosclerida and Axinellida marine sponge genera [ 5 ].…”

A Synthetic Method to Access Symmetric and Non-Symmetric 2-(N,N'-disubstituted)guanidinebenzothiazoles

“…The guanidine group has attracted considerable attention since it is found in a wide array of natural and synthetic biologically active compounds [ 1 , 2 , 3 ]. The guanidine groups are categorized as organosuperbases whose basicity is magnified because of the resonance stabilization of the corresponding conjugated acids.…”