(+/-)-Sigmoidin A

Planta Medica, 2009, 76(6):589-594.

Comparative Antioxidant, Prooxidant and Cytotoxic Activity of Sigmoidin A and Eriodictyol.[Reference: WebLink]

Sigmoidin A (SGN) is a prenylated flavanone derivative of eriodictyol (ERD) with reported moderate antioxidant, antimicrobial and anti-inflammatory activity.
METHODS AND RESULTS:
Since ERD and other structurally similar antioxidant phenolic compounds have been shown to induce prooxidative macromolecular damage and cytotoxicity in cancer cells, the comparative IN VITRO effects of these structural analogues on cancer cell viability and Cu(II)-dependent DNA damage were studied. In the presence of Cu(II) ions, both SGN and ERD (7.4-236 microM) caused comparable concentration-dependent pBR322 plasmid DNA strand scission. The DNA damage induced by SGN and ERD could be abolished by ROS scavengers, glutathione (GSH) and catalase as well as EDTA and a specific Cu(I) chelator neocuproine. Both ERD and SGN readily reduce Cu(II) to Cu(I) suggesting a prooxidative mechanism of DNA damage.
CONCLUSIONS:
In a cell free system, ERD and SGN did also show comparable radical scavenging activity. SGN was, however, by an order of magnitude more cytotoxic to cancer cells than ERD and this effect was significantly attenuated by GSH suggesting a prooxidative mechanism of cell death. A depletion of intracellular GSH level by SGN in cancer cells is also demonstrated.

Planta Medica, 2004, 70(02):104-107.

Anti-Inflammatory Activities of Two Flavanones, Sigmoidin A and Sigmoidin B, from Erythrina sigmoidea[Reference: WebLink]

Two prenylated flavanones isolated from Erythrina sigmoidea Hua (sigmoidin A and sigmoidin B) were studied for their ability to inhibit the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and arachidonic acid metabolism. In addition, the compounds were studied in two experimental models of inflammation induced in mouse ears by 12- O-tetradecanoylphorbol 13-acetate (TPA) and the phospholipase A (2)-induced mouse paw oedema.
METHODS AND RESULTS:
Both sigmoidins A and B proved to be potent scavengers of the DPPH radical, while the study of the inhibition of arachidonic acid metabolism demonstrated that these same compounds were selective inhibitors of 5-lipoxygenase, with no effect on cyclooxygenase-1 activity. Dose-response inhibitor potency was established for sigmoidin A (IC (50) = 31 microM). In the assay of phospholipase A (2)-induced mouse paw oedema, only the sigmoidin B derivative inhibited oedema formation at 60 min, showing a percentage of inhibition below that obtained with cyproheptadine (59 % vs. 74 %). In the TPA test, sigmoidins A and B decreased the induced oedema by 89 % and 83 %, respectively.
CONCLUSIONS:
This is the first time that the anti-inflammatory activity and antioxidant properties of these prenylflavanones have been reported. The results indicate that the compounds have different mechanisms of action depending on whether one or two prenyl groups are present in ring B.