When tested against B16 murine melanoma it was found to be active in the low micromolar range. It also proved to be an effective antimicrobial agent against the Gram-positive bacteria ("Bacillus megaterium") and the Gram-negative bacteria ("Escherichia coli") and was found to be antifungal against ("Microbotryum violaceum") and antialgal against ("Chlorella fusca"). Secalonic acid D (SAD) is a toxic and teratogenic metabolite. Teratogenic effects were observed in the development of rats that were exposed to SAD injected during fetal development. SAD exhibited potent cytotoxicity on multidrug resistance (MDR) cells and their parental cells. Investigation of the antitumor activity of SAD showed that it exerted potent cytotoxic activity on SP cells, due to induction of ABCG2 degradation by calpain-1 activation. Ergoflavin showed good anti-inflammatory activity and good anticancer activities including significant inhibition of proliferation particularly in pancreatic, renal, and lung cancer cells, and may be exerting its effects via mechanisms similar to those of secalonic acid D.  Ergoflavin was first isolated in pure form from "Claviceps purpurea" (ergot) in 1958. It was shown to be a 2,2’- biaryl linked dimer in 1963 and the structure confirmed that year by single-crystal X-ray analysis. During the following decade the structures of secalonic acids A, B, C, D and ergochrysin A were similarly firmly established, and although there was some early contention whether they were 2,2’-, 4,4’- or even 2,4’-linked it was confirmed that they too were all 2,2’- linked between the biphenyl residues. In all known secalonic acids, the methyl and methoxycarbonyl substituents are found to be "trans" to each other, and X-ray analysis of the crystal structure of secalonic acid A showed that the 2,2’-biaryl linkage was nonplanar and the angle between the two biphenyl planes was 36.5°. The tetrahydroxanthone-containing secalonic acids have been demonstrated to be unstable under basic conditions, and they can easily undergo isomerizations arising from ether linkage replacement. The 2-2’linked secalonic acid A isomerizes in DMSO at room temperature to the 2-4’linked secalonic acid A and 4-4’linked secalonic acid A during 13hr, to reach an equilibrium of 3.2 : 2 : 1.