Kuniyoshi Shimizu

In the present study, we isolated seven compounds from olive mill wastes (OMW), one of them being novel, and investigated their antidiabetic potential through inhibition of α-glucosidase and α-amylase enzymes. To assist the possible characterization of the mechanisms involved, we analyzed the inhibitory kinetics of the active compounds. Oleanolic acid <b>1</b>, maslinic acid <b>2</b>, 1-acetoxypinoresinol <b>3</b>, and luteolin-7-<i>O-</i>β-d-glucoside <b>6</b> exhibited stronger inhibitory acti

A novel vitamin E derivative, (6"-hydroxy-2",5",7",8"-tetramethylchroman-2"-yl)methyl 3-(2',4'-dihydroxyphenyl)propionate (TM4R), which has a chromanoxyl ring and 4-substituted resorcinol moieties, was synthesized; and its inhibitory effects on tyrosinase, antioxidant ability, and lightening effect of ultraviolet B (UVB)-induced hyperpigmentation were estimated. TM4R showed potent inhibitory activity on tyrosinase, which is the rate-limiting enzyme in melanogenesis. The scavenging activities of

Besides being a useful building material, bamboo also is a potential source of bioactive substances. Although some studies have been performed to examine its use in terms of the biological activity, only certain parts of bamboo, especially the leaves or shoots, have been studied. Comprehensive and comparative studies among different parts of bamboo would contribute to a better understanding and application of this knowledge. In this study, the biological activities of ethanol and water extracts

The methanol extract of heartwood of Artocarpus incisus showed potent 5 alpha-reductase inhibitory activity. We investigated the 5 alpha-reductase inhibitory effects of nine compounds isolated from A. incisus. Chlorophorin (IC50 = 37 microM) and artocarpin (IC50 = 85 microM) showed more potent inhibitory effects than did alpha-linolenic acid, which is known as a naturally occurring potent inhibitor. Structure-activity investigations suggested that the presence of an isoprene substituent (prenyl

Our effort to find new material for anti cancer from natural resources leads us to focus on stingless bee products such as honey, bee pollen, and propolis. The products were from seven stingless bees named <i>Homotrigona fimbriata, Heterotrigona itama, Heterotrigona bakeri, Tetragonula sarawakensis, Tetragonula testaceitarsis, Tetragonula fuscobalteata, Tetragonula laeviceps.</i> The stingless bee products were evaluated for their cytotoxicity effect on MCF-7, HeLa and Caco-2 cancer cell lines.

As olive oil production increases, so does the amount of olive oil by-products, which can cause environmental problems. Thus, new ways to utilize the by-products are needed. In the present study, five bioactive characteristics of olive oil by-products were assessed, namely their antioxidant, anti-bacterial, anti-melanogenesis, anti-allergic, and collagen-production-promoting activities. First, the extracts of leaves (May and October), stems (May and October), flowers, olive milled waste, fruit p

Abstract. Syafrizal, Ramadhan R, Kusuma IW, Egra S, Shimizu K, Kanzaki M, Arung ET. 2020. Diversity and honey properties of stingless bees from meliponiculture in East and North Kalimantan, Indonesia. Biodiversitas 21: 4623-4630. Kalimantan Island in Indonesia is covered by tropical rain forests that are rich in biodiversity. Species, include a stingless bee (Trigona spp.). Recently, stingless bee beekeeping (Meliponiculture) in this region has become popular because the honey has a unique taste

One of the conventional strategies for treating osteoporosis is to eliminate the multinucleated osteoclasts that are responsible for bone resorption. Our previous study revealed that ursolic acid, isolated from leaves of loquat that is used as tasty tea in Japan, suppressed osteoclastogenesis. We confirmed that ursolic acid exhibited osteoclast differentiation inhibitory activity with an 50% inhibitory concentration (IC₅₀) value of 5.4 ± 0.96 μM. To disclose its mechanism of action, t

Phytochemical examination of corncob extracts led to the isolation of a new lignan identified as 7,7'-dihydroxy-3'-O-demethyl-4-methoxymatairesinol, together with seven known compounds, identified as β-sitosterol, β-sitosteryl-β-D-glucoside, 6β-hydroxy-campest-4-en-3-one, 5α,8α-epidioxyergosta-6,22-dien-3β-ol, tricin, kaempferol and p-coumaric acid. The isolated compounds were identified by one and two-dimensional NMR spectroscopies and mass spectrometry.