Hiroshi Kusuoku

Asymmetric hetero Diels-Alder reaction of homochiral thiabutadienes, 3-(arylmethylene)thiocamphors

Abstract The highly diastereoselective hetero Diels-Alder reactions of homochiral camphor-derived thiabutadienes to afford novel, optically active bornene ring-fused dihydrothiopyrans are described.

The N-terminal amino acid of apolipoprotein D is putatively covalently bound to 3-hydroxy-3-methyl hexanoic acid, a key odour compound in axillary sweat

Axillary sweat is odourless when freshly collected at the surface of human skin, but it contains non‐odoriferous precursors, which can be transformed into odorous substances by bacteria. E‐3‐methyl‐2‐hexanoic acid (3M2H) is one of the key odorous substances, but there are two contradictory reports about its precursor form. One report states that 3M2H linked non‐covalently to apolipoprotein D (apoD) is the precursor, while a second report states that 3M2H–Gln identified in human axillary sweat is the precursor. Recently, 3‐hydroxy‐3‐methyl hexanoic acid (HMHA) and 3‐methyl‐3‐sulfanylhexane‐1‐ol (3M3T) have also been identified and reported as characteristic components found in apocrine sweat. To better understand the formation of axillary odours and the structural relationships between these compounds and apoD, we characterized the linkage between odorous substances and apoD in human axillary secretions. ApoD was purified from human axillary secretions collected from 50 healthy female volunteers and was then digested by trypsin and analysed by MALDI‐TOF mass spectrometry. A Mascot search showed that 8 peaks identified in the trypsin‐digested samples correspond to the masses calculated for theoretically digested apoD sequences and the purified protein was assigned as a precursor of apoD [Homo sapiens]. One spectrum corresponded to the theoretical peak of HMHA linked covalently to the N‐terminal fragment of apoD. In contrast, no spectrum corresponded to the theoretical peak of a 3M2H adduct or to an unmodified N‐terminal fragment of apoD. These results indicate a possibility that HMHA binds covalently to the N‐terminal amino acid of apoD in human axillary secretions.

Isolation and structural determination of spilacleosides A and B having a novel 1,3-dioxolan-4-one ring

Abstract As the first natural product incorporating 1,3-dioxolan-4-one in spiro structure, spilacleosides A and B were isolated from Ruscus aculeatus , and the absolute structures determined.

Enhancement of lipolytic responsiveness of adipocytes by novel plant extract in rat.

Subcutaneous adipocytes accumulate excess energy as triglycerides, but lipolytic response is less sensitive to catecholamines than visceral adipocytes. Obesity also induces catecholamine resistance of adipocytes. We have searched for crude drugs that could enhance the lipolytic response to noradrenalin. In this study, the lipolysis-promoting activities and action mechanisms of a novel plant extract from Hemerocallis fulva (HE) were investigated in isolated adipocytes from rat subcutaneous fat. HE exhibited no lipolysis-promoting activity alone but markedly promoted lipolysis when combined with noradrenaline; however, this synergistic activity was accompanied by no increase of intracellular cAMP production. This activity of HE was also observed when combined with cAMP analogue and was further enhanced by phosphodiesterase inhibitor. PKA inhibitor could reduce these activities of HE. These results indicate that HE is a novel lipolysis-promoting material that can sensitize the lipolytic response of adipocytes to catecholamine and suggest that HE can amplify the intra-cellular signaling pathway related to PKA or modify the other mechanism-regulating lipase activity. This characteristic material could contribute to improvement of adipose mobility in obesity-related disorder or in subcutaneous adiposity and to suppression of body fat accumulation.