Diffractaic acid

Diffractaic acid (CAS No.436-32-8 ), a secondary metabolite derived from the lichen Pseudocyphellaria magellanica, demonstrates notable biological activities, including cytotoxic effects against various human cancer cell lines (HCT116, HeLa, and MCF-7) with IC₅₀ values ranging from 42.2 to 93.4 μM, and inhibitory activity against Mycobacterium tuberculosis (MIC of 41.7 μM). In vivo studies in rats show that diffractaic acid (25–200 mg/kg) can attenuate indomethacin-induced gastric mucosal injury by reducing neutrophil infiltration, lipid peroxidation, myeloperoxidase activity, and gastric lesions, while restoring antioxidant enzyme activities (SOD and GPx). Additionally, diffractaic acid exhibits analgesic effects by decreasing acetic acid-induced writhing and increasing the pressure pain threshold in animal models.

References：

[1] Brisdelli F, Perilli M, Sellitri D, Piovano M, Garbarino JA, Nicoletti M, Bozzi A, Amicosante G, Celenza G. Cytotoxic activity and antioxidant capacity of purified lichen metabolites: an in vitro study. Phytother Res. 2013 Mar;27(3):431-7. doi: 10.1002/ptr.4739. Epub 2012 May 25. PMID: 22628260.

[2] Honda NK, Pavan FR, Coelho RG, de Andrade Leite SR, Micheletti AC, Lopes TI, Misutsu MY, Beatriz A, Brum RL, Leite CQ. Antimycobacterial activity of lichen substances. Phytomedicine. 2010 Apr;17(5):328-32. doi: 10.1016/j.phymed.2009.07.018. Epub 2009 Aug 14. PMID: 19683421.

[3] Bayir Y, Odabasoglu F, Cakir A, Aslan A, Suleyman H, Halici M, Kazaz C. The inhibition of gastric mucosal lesion, oxidative stress, and neutrophil-infiltration in rats by the lichen constituent diffractaic acid. Phytomedicine. 2006 Sep;13(8):584-90. doi: 10.1016/j.phymed.2005.07.002. Epub 2005 Oct 28. PMID: 16920514.

[4] Okuyama E, Umeyama K, Yamazaki M, Kinoshita Y, Yamamoto Y. Usnic acid and diffractaic acid as analgesic and antipyretic components of Usnea diffracta. Planta Med. 1995 Apr;61(2):113-5. doi: 10.1055/s-2006-958027. PMID: 7753915.