No abstract

Five antioxidative caffeoylquinic acid derivatives were isolated from the roots of burdock (Arctium lappa L.), an edible plant in Japan. Their structures were established as 1-0-,5-O-dicaffeoylquinic acid (1), l-0-,5-0-dicaffeoyl-3-0-succinylquinic acid (2), l-0-,5-0-dicaffeoyl-4-0-succinylquinic acid (3), l-0-,5-0-dicaffeoyl-3-0-,4-0-disuccinylquinic acid (4), and 1-0-,3-0-,5-0-tricaffeoyl-4-0-succinylquinic acid (5) on the basis of chemical and spectral (NMR, MS) evidence. The antioxidant activities were measured in a hexane/2-propanol solution of methyl linoleate in the presence of a radical initiator. The antioxidant efficiency increased in the order of -tocopherol < chlorogenic acid < caffeic acid < (1) = (2) = (3) = (4) < (5).

An aqueous methanol extract from green tea showed potent acetyl-CoA carboxylase inhibitory activity. An active compound was isolated from the extract and identified as (-)-epigallocatechin gallate by instrumental analyses. The IC50 value of (-)-epigallocatechin gallate was 3.1 x 10(-4) M. Among tea catechins and related compounds, nearly equal activity was found in (-)-epigallocatechin gallate and (-)-epicatechin gallate, whereas (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, gallic acid and methyl gallate each had no inhibitory activity. These results indicate that the 3-O-gallate group of the catechin structure was necessary for this activity. (-)-Epigallocatechin gallate inhibited triglyceride accumulation in 3T3-L1 cells at a concentration of 1.0 x 10(-7) M or higher.

Casein is the main protein component of milk and is of remarkable colloidal stability. Under the influence of milk clotting enzymes casein shows the striking behaviour of coagulation. This clotting process has already been studied by other groups, neglecting the fact that casein is not a homogeneous protein. The purpose of the present study is focused, in this first stage, on the determination of the structure of the various casein components. In cooperation with other laboratories we have been able to obtain the well separated individual proteins. Studies have been performed so far with/~-and x-casein. For detailed structural information we carried out small angle neutron scattering and combined static and dynamic light scattering measurements and determined the molecular weight, Mw, the radius of gyration, ($2), the hydrodynamic radius, Ru, the 0-value and the particle scattering factor, Pz(q). The two caseins show a strikingly different behaviour. For the/~-casein we found a star-like structure, i. e. an aggregation pattern that is expected for a common micelle. The micelle consists of about 38 monomer chains. The aggregates of x-casein appear to be composed of star-like submicelles, where each submicelle contains nine ~e-casein chains and the total degree of aggregation is about 140.