β2-Adrenergic receptor (β2AR) agonists are employed as bronchodilators to treat pulmonary disorders, but are attracting attention for their modulation of glucose handling and energy expenditure. Higenamine is a tetrahydroisoquinoline present in several plant species and has β2AR agonist activity, but the involvement of each functional groups in β2AR agonist activity and its effectiveness compared with endogenous catecholamines (dopamine, epinephrine, and norepinephrine) has rarely been studied. Glucose uptake of muscle cells are known to be induced through β2AR activation. Here, the ability to enhance glucose uptake of higenamine was compared with that of several methylated derivatives of higenamine or endogenous catecholamines. We found that: (i) the functional groups of higenamine except for the 4′-hydroxy group are required to enhance glucose uptake; (ii) higenamine shows a comparable ability to enhance glucose uptake with that of epinephrine and norepinephrine; (iii) the S-isomer shows a greater ability to enhance glucose uptake compared with that of the R-isomer.Download high-res image (67KB)Download full-size image

•Eurycomanone (1) and 13β,21-epoxyeurycomanone (2), isolated from Eurycoma longifolia, exert lipolytic activity.•EC50 values for compound 1 and 2 are 14.6 μM and 8.6 μM, respectively.•PKA inhibitor totally diminished the lipolytic activity of 1 and 2.•Immunoblotting analysis confirmed the activation of phosphorylated PKA by 1 and 2.•Eurycomanone and its epoxy derivate can be used as promising lead compounds to target lipid catabolism.Eurycomanone (1) and 13β,21-epoxyeurycomanone (2) were isolated from Eurycoma longifolia for studies of lipolytic activity. Compound 1 enhanced lipolysis in adipocytes with an EC50 of 14.6 μM, while its epoxy derivate, compound 2, had a stronger activity with an EC50 of 8.6 μM. Based on molecular mechanistic study using several specific inhibitors to lipolytic signaling pathways, it was found that PKA inhibitor totally diminished the lipolytic activity of 1 and 2. Further immunoblotting analysis confirmed the activation of phosphorylated PKA by both 1 and 2. With the growing need to develop new anti-obesity agents, eurycomanone and its epoxy derivate can be used as promising lead compounds to target lipid catabolism.Download high-res image (217KB)Download full-size image

Pancreatic α-amylase is a target for type 2 diabetes mellitus treatment. However, small molecule inhibitors of α-amylase are currently scarce. In the course of developing small molecule α-amylase inhibitors, we designed and synthesized conjugates of glucose and acarviosin. The synthetic compounds showed mild α-amylase inhibitory activity with higher activity compared with non-glucose conjugated compounds, but lower activity compared to acarviosin. Comparison of these activities revealed transglycosylation of acarviosin during the enzyme reaction. Additionally, the α-amylase inhibitory activity of acarviosin is expressed through these transglycosylation products.

Affinity chromatography of specific enzymes is limited by the presence of related enzymes and the limited selectivity of the affinity ligand. We synthesized and investigated the use of an uncompetitive inhibitor as an affinity ligand, to leverage its three-component interactions. Use of the potent α-glucosidase uncompetitive inhibitor 2-aminoresorcinol as the ligand of the affinity gel offered selective purification of maltase-glucoamylase complex from the crude mixture of intestinal α-glucosidases.

Diabetes mellitus is increasing in prevalence with patient numbers rising throughout the world. Current treatments for diabetes mellitus focus on control of blood glucose levels. Certain kinds of flavonoids or their glycosides stimulate cells to improve glucose uptake and lower blood glucose levels. We synthesized kaempferol 3-O-neohesperidoside (1), a naturally occurring substance present in Cyathea phalerata Mart., reported to mimic the action of insulin. Synthetic 1 promoted glucose uptake in the cultured cell line, L6. Further studies to determine the core structure responsible for this activity using synthetic compounds revealed neohesperidose to be the primary pharmacophore. These findings support the use of certain saccharides as a potential novel treatment for diabetes mellitus by replacing or supporting insulin.Keywords (keywords): Diabetes mellitus; flavonoid glycoside; glucose uptake; insulin

Chemical treatment of diabetes mellitus is widely studied and controlling of blood glucose level is the main course of therapy. In type 2 diabetes mellitus, insulin resistance is the major problem. An isoflavone C-glucoside, puerarin (1), is known to enhance glucose uptake into the insulin sensitive cell and is thought to be a candidate for treatment of diabetes mellitus. We synthesized 1 and several derivatives to apply for the structure–activity relationship study. The result against 3T3-L1 adipocyte indicated that the C-glucoside part of 1 is unconcerned in its activity when tested in vitro and the main structure responsible for its activity was the isoflavone moiety.