Experimental Study of Extracts from Dioscorea bulbifera on Anti-Inflammatory Action Mechanism

Jeung Hoan Kim

Department of Cosmetic Science The Graduate School
Hoseo University
Asan, Korea

( Supervised by professor Jin-Young Lee )

Dioscorea bulbifera has been cultivated in Korea, China and Japan as a food, and also widely used as a traditional medicine for a long time. Several biological activities, including anti-cancer, anti-thrombotic, anti-viral, hemolytic, hypercholesterolemic and hypoglycemic, have been reported.
This study aimed to investigate the enhancement of cosmeceutical activities of Dioscorea bulbifera by different extraction processes. The extracts were classified as follows: WE (water extract at 100℃,control), USEE (70% ethanol extract process for 24 hours after ultrasonification for 6 hours at 60℃), HPEE (high pressure for 12 hours at 60℃ whith 70% ethanol). Compared to the WE, total phenolic compounds contents in the EE, UEE and HPEE were increased to 134.2%, 139.5 % and 162.9% respectively. The HPEE showed the highest activity in 1,1-diphenyl- 2-picryl-hydrazyl (DPPH) radical scavenging, 2, 2'' - azinobis (3 ?ethylbenzothiazoline?6-sulfonic acid; ABTS) radical cation decolorization, inhibition activity of xanthine oxidase and superoxide dismutase (SOD)-like test, respectively. Allantoin concentrations of WE, EE, USEE and HPEE was measured as 6.28 mg/g, 13.54 mg/g, 15.75 mg/g and 17.17 mg/g, respectively. The HPEE showed the highest concentration diosgenin. It has been reported that diosgenin has anti-inflammatory effect through inhibition of macrophage-derived inflammatory mediators. Therefore, we evaluated the inhibitory effect of HPEE on production or expression of inflammatory mediators in various cells. The inhibitory effects of HPEE on LPS-induced production of IL-4 and IFN-γ, and expression of COX-II and IL-12 were investigated in the activated Jurkat cells. And the production of β-hexosaminidase was investigated in RBL-2H3 cells. Also, the effect of HPEE on LPS-induced production of TNF-α and PGE2, and expression of COX-II, iNOS and TNF-α were investigated in the activated RAW264.7 cells. HPEE significantly inhibited the production and suppressed the expression of pro-inflammatory mediators. Finally, we evaluated the inhibitory effect of HPEE on an atopic dermatitis-like mouse model. An atopic dermatitis-like skin lesion was induced by repeated treatment of 2,4-dinitrochlorobenzene (DNCB) on the ear skin of ICR mice. The efficacy of HPEE was tested by histopathologic analysis. Histopathologic analysis revealed a reduction in the ear thickness in the HPEE group. These results show that extract of Dioscorea bulbifera may explain some known biological activities including anti-inflammatory effect, and is of considerable benefit in the treatment for pro-inflammatory cytokine overproduction related immunological diseases.