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Atherosclerosis is a chronic inflammatory disease initiated by vascular inflammation and monocyte recruitment in part. Diosgenin, a precursor of steroid hormones, has been shown to have a variety of biological activities including anti‐inflammatory activity. Resent findings that diosgenin inhibits VCAM‐1 expression on vascular smooth muscle cells and leukocyte adhesion led us to evaluate its ability to inhibit the development of atherosclerosis in experimental mice. 34 male ApoE −/− mice and 17 control (C57BL/6J) mice were fed a high‐fat/high‐cholesterol diet for 21 weeks. To examine the effect of dietary diosgenin on atherosclerosis, 17 of the ApoE −/− mice were also given diosgenin (oral administration of 50 mg/kg body weight, 3 times per week for the duration of the study). Diosgenin had slight but insignificant suppressive effects on the lipid deposition and the local infiltration of monocytes/macrophages in aorta. However, diosgenin significantly decreased serum levels of CRP, MCP‐1 and total cholesterol while it slightly increased the level of HDL. In addition, diosgenin attenuated the level of oxLDL in serum. The present study demonstrates that diosgenin might have a protective effect against atherosclerosis by regulating proinflammatory mediators in serum.

Allergies are immediate hypersensitive responses to antigens and IL‐4 is involved in the initiation and development of allergic responses. Lichen‐derived compounds have been known to have a variety of biological activities including anti‐inflammatory activity, but the effect of polar lichen extract (PLE) on allergic responses is not known yet. The present study was undertaken to examine whether PLE has an inhibitory effect on allergic response in mouse splenocytes and mouse model. Our results showed that PLE suppressed both T and B cells proliferation induced by mitogens. RT‐PCR analysis also revealed that mRNA levels of IL‐4 were in vitro suppressed in the presence of diosgenin. In allergic mouse model, application of PLE on atopic dermatitis like skin lesions improved skin condition and inhibited starching behaviors. In addition, PLE application suppressed IL‐4 mRNA levels and its secretion. Moreover, PLE suppressed foot swelling in rats. Taken together, these results suggest that PLE has a potent inhibitory role in T cell activation and may be a candidate for therapeutic agent in allergy.