Disaccharide Esters Screened for Inhibition of Tumor Necrosis Factor‐α Release Are New Anti‐cancer Agents

Tumor necrosis factor‐α (TNF‐α) is a proinflammatory cytokine playing a part in various pathological states. Non‐toxic inhibitors of TNF‐α release are thought to be promising agents for cancer prevention. We found that the acetone fraction of the tobacco leaf surface lipid containing glucose esters and sucrose esters inhibited both TNF‐α release from BALB/3T3 and KATO III cells induced by okadaic acid and tumor promotion by okadaic acid on mouse skin initiated with 7,12‐dimethylbenz(a)anthracene (DMBA). Next, we investigated the inhibition of TNF‐α release with synthetic disaccharide esters, such as 6,6′‐di‐0‐alkanoyl‐α,α‐trehaloses (6,6′‐diester‐trehaloses), 4,4′‐di‐0‐alkanoyl‐α,α‐trehaloses (4,4′‐diester‐trehaloses) and 6,6′‐diamino‐6,6′‐dideoxy‐N, N′‐dial‐kanoyl‐α,α‐trehaloses (6,6′‐diamide‐trehaloses) bearing fatty acids of various chain lengths, and n‐ dodecyl‐β‐D‐maltoside as a disaccharide monoester. 6,6′‐Diester‐trehaloses and 4,4′‐diester‐treha‐loses of C(8) to C(14) fatty acids, 6,6′‐diamide‐trehaloses of C(8) to C(14) fatty acids, and n‐dodecyl‐β‐D‐maltoside all inhibited TNF‐α release in a dose‐dependent manner. The IC(50) values are 7.4‐14.8 μM for 6,6′‐diester‐trehaloses (C(8) to C(12)), 14.6‐21.6 μM 4,4′‐diester‐trehaloses (C(8) to C(12)), 2.9‐15.0 μM for 6,6′‐diamide‐trehaloses (C(8) to C(14)) and 23 μM for dodecyl‐β‐D‐maltoside. Both 6,6′‐di‐O‐octanoyl‐α,α‐trehalose (C(8), designated as SS555) and n‐dodecyl‐β‐D‐maltoside (C(12)) inhibited tumor promotion by okadaic acid on mouse skin initiated with DMBA. Percentages of tumor‐bearing mice in week 15 of tumor promotion were reduced from 60.0 to 13.3 with SS555, and to 46.7 with n‐dodecyl‐β‐D‐maltoside. Moreover, SS555 inhibited TNF‐α gene expression mediated through inhibition of AP‐1 activation, but not NF‐αB activation. This paper reports that diester‐trehaloses of C(8) to C(12) fatty acids and mimics of disaccharide monoesters such as n‐dodecyl‐β‐D‐maltoside appear to be potential cancer‐preventive agents of a new type.