Toyoshige Endo

Evolutional study on acetylcholine expression.

Acetylcholine (ACh) is a well-known neurotransmitter in the cholinergic nervous systems of vertebrates and insects; however, there is only indirect evidence for its presence in lower invertebrates, such as plants and fungi. We therefore investigated the expression of ACh in invertebrates (sea squirt, sea urchin, trepang, squid, abalone, nereis, sea anemone, coral and sponge), plants (arabidopsis, eggplant, bamboo shoot, cedar, hinoki, pine, podcarp, fern, horsetail and moss), fungi (yeast and mushroom) and bacteria by assaying ACh content and synthesis, focusing on the presence of two synthetic enzymes, choline acetyltransferase (ChAT) and carnitine acetyltransferase (CarAT). Using a specific radioimmunoassay, ACh was detected in all samples tested. The levels varied considerably, however, with the upper portion of bamboo shoots having the highest content (2.9 micromol/g). ACh synthesis was also detected in all samples tested; moreover, the activity in most samples from the animal kingdom, as well as bamboo shoots and the stem of the shiitake mushroom, were sensitive to both ChAT and CarAT inhibitors. Levels of ACh synthesis were lower in samples from other plants, fungi and bacteria and were insensitive to ChAT and CarAT inhibitors. These findings demonstrate the presence of ACh and ACh-synthesizing activity in evolutionally primitive life as well as in more complex multicellular organisms. In the context of the recent discovery of non-neuronal ACh in various mammalian species, these findings suggest that ACh been expressed in organisms from the beginning of life, functioning as a local mediator as well as a neurotransmitter.

Biosynthetic studies of versipelostatin, a novel 17-membered α-tetronic acid involved macrocyclic compound isolated from Streptomyces versipellis

Versipelostatin, a novel microbial metabolite consisting of a 17-membered macrocyclic aglycone with an α-acyltetronic acid functional group and sugar moieties was shown to be biosynthesized through a polyketide intermediate and the involvement of glyceric acid.

Inhibitory effect of Lysichiton camtschatcense extracts on Fe2+/ascorbate-induced lipid peroxidation in rat kidney and brain homogenates

Lysichiton camtschatcense is a well-known plant in Japan where it has been used as a traditional medicine by the “Ainu” people for the treatment of acute nephritis. It is presumed that L. camtschatcense has an inhibitory effect against nephritis caused by reactive oxygen species (ROS) owing to its antioxidant activities. Consequently, the antioxidant effect of L. camtschatcense extracts was assessed against Fe2+/ascorbic acid (AsA)-induced lipid peroxidation in rat kidney and brain homogenates. The antioxidant effect of the chloroform extract (CE) was more potent than that of the methanol extract (ME) for both homogenates. The antioxidant effect of both extracts was similar to those of α-tocopherol, a lipid-soluble antioxidant, and glutathione (GSH), a water-soluble antioxidant, which were used as reference compounds. Although CE showed a low radical-scavenging effect for superoxide anion radicals (O2·−) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, assessed by using an electron spin resonance (ESR) method, hydroxyl radicals (·OH) were markedly scavenged by more than 80%. On the other hand, ME showed more significant scavenging effect for DPPH radicals and O2·− than CE. These results suggest that the inhibitory effects of the L. camtschatcense extract on lipid peroxidation in rat kidney and brain are based on its high radical-scavenging effect against ·OH, O2·−, and lipid-derived radicals generated from the cell membrane.