Dae Sik Jang

Skin aging is a complex biological process influenced by a variety of factors, including UV radiation. UV radiation accelerates collagen degradation via the production of reactive oxygen species (ROS) and cytokines, including TNF-α. In a prior investigation, the inhibitory properties of flavonol and flavone glucuronides derived from Potentilla chinensis on TNF-α-induced ROS and MMP-1 production were explored. Consequently, we verified the skin-protective effects of these flavonol and flavone glucuronides, including potentilloside A, from P. chinensis, and conducted a structure–activity relationship analysis as part of our ongoing research. We investigated the protective effects of the extract and its 11 isolates on TNF-α-stimulated normal human dermal fibroblasts (NHDFs). Ten flavonol and flavone glucuronides significantly inhibited ROS generation (except for 7) and suppressed MMP-1 secretion, except for 2. In contrast, six isolates (1, 5, 6, 11, 9, 10, and 11) showed a significant reverse effect on COLIA1 secretion. Comparing the three experimental results of each isolate, potentilloside A (1) showed the most potent skin cell-protective effect among the isolates. Evaluation of the signaling pathway of potentilloside A in TNF-α-stimulated NHDF revealed that potentilloside A inhibits the phosphorylation of ERK, JNK, and c-Jun. Taken together, these results suggest that compounds isolated from P. chinensis, especially potentilloside A, can be used to inhibit skin damage, including aging.

Huntington’s disease (HD) is a neurodegenerative disease that affects the motor control system of the brain. Its pathological mechanism and therapeutic strategies have not been fully elucidated yet. The neuroprotective value of micrandilactone C (MC), a new schiartane nortriterpenoid isolated from the roots of Schisandra chinensis, is not well-known either. Here, the neuroprotective effects of MC were demonstrated in 3-nitropropionic acid (3-NPA)-treated animal and cell culture models of HD. MC mitigated neurological scores and lethality following 3-NPA treatment, which is associated with decreases in the formation of a lesion area, neuronal death/apoptosis, microglial migration/activation, and mRNA or protein expression of inflammatory mediators in the striatum. MC also inhibited the activation of the signal transducer and activator of transcription 3 (STAT3) in the striatum and microglia after 3-NPA treatment. As expected, decreases in inflammation and STAT3-activation were reproduced in a conditioned medium of lipopolysaccharide-stimulated BV2 cells pretreated with MC. The conditioned medium blocked the reduction in NeuN expression and the enhancement of mutant huntingtin expression in STHdhQ111/Q111 cells. Taken together, MC might alleviate behavioral dysfunction, striatal degeneration, and immune response by inhibiting microglial STAT3 signaling in animal and cell culture models for HD. Thus, MC may be a potential therapeutic strategy for HD.

Alpinia galanga have been widely used as spice or traditional medicine in East Asia, commonly known as Thai ginger. In the present study, seven major phenylpropanoids, (±)-1′-hydoxychavicol acetate (1; HCA), (1′S)-1′-acetoxychavicol acetate (2; ACA), (1′S)-1′-acetoxyeugenol acetate (3; AEA), eugenyl acetate (4), trans-p-coumaraldehyde (5), trans-p-acetoxycinnamyl alcohol (6), and trans-p-coumaryl diacetate (7), were isolated from the 95% EtOH and hot water extracts of the rhizomes of A. galanga by chromatographic method. Phenylpropanoids 1–7 were evaluated for glucose-stimulated insulin secretion (GSIS) effect and α-glucosidase inhibitory activity. Phenylpropanoids 1–4 increase GSIS effect without cytotoxicity in rat INS-1 pancreatic β-cells. In addition, INS-1 cells were treated with AEA (3) to determine a plausible mechanism of β-cell function and insulin secretion through determining the activation of insulin receptor substrate-2 (IRS-2), phosphatidylinositol 3-kinase (PI3K), Akt, and pancreatic and duodenal homeobox-1 (PDX-1). Upon treatment with AEA (3), INS-1 cells showed an increase in these protein expressions. Meanwhile, AEA (3) exhibited α-glucosidase inhibitory activity. On the basis of the above findings, we suggest AEA (3) as a potential antidiabetic agent.