Seon Beom Kim

Macrophage activating activity of pyrrole alkaloids from Morus alba fruits.

ETHNOPHARMACOLOGICAL RELEVANCE The fruits of Morus alba have been traditionally used as a tonic to enhance immune responses. MATERIALS AND METHODS The macrophage activating constituents of Morus alba fruits were purified using various column chromatography techniques. The structures of isolated compounds were determined on the basis of spectroscopic data interpretation such as 1D and 2D NMR analysis. The macrophage activating activities of isolated compounds were evaluated by measuring the production of nitric oxide, TNF-α and IL-12 in RAW 264.7 cells. The phagocytic activity was also evaluated. RESULTS Five pyrrole alkaloids, 5-(hydroxymethyl)-1H-pyrrole-2-carboxaldehyde (1), 2-formyl-1H-pyrrole-1-butanoic acid (2), 2-formyl-5-(hydroxymethyl)-1H-pyrrole-1-butanoic acid (3), 2-formyl-5-(methoxymethyl)-1H-pyrrole-1-butanoic acid (4) and Morrole A (5) were isolated from the fruits of Morus alba. Morrole A (5) is first reported in nature and other pyrrole alkaloids (1-4) are first reported from Morus species. Among the isolated compounds, compounds 3 and 4 significantly activated macrophage activity by the enhancement of nitric oxide, TNF-α and IL-12 production, and the stimulation of phagocytic activity in RAW 264.7 cells. CONCLUSION Pyrrole alkaloids, including a new compound, were isolated from Morus alba fruits. These compounds activated macrophage activity in RAW 264.7 cells.

Pyrrole alkaloids from the fruits of Morus alba

Phytochemical investigation of the fruits of Morus alba afforded seventeen pyrrole alkaloids including five new compounds. The structures of five new pyrrole alkaloids, named morroles B-F (4, 5, 7, 16 and 17), were determined on the basis of spectroscopic interpretations. 4-[Formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl]butanoate (2) was synthesized by chemical reaction but first isolated from nature. Among isolated compounds, compounds 6 and 14 significantly inhibited pancreatic lipase activity.

Synthesis and Biological Evaluation of Resveratrol Derivatives as Melanogenesis Inhibitors

Resveratrol (1), a naturally occurring stilbene compound, has been suggested as a potential whitening agent with strong inhibitory activity on melanin synthesis. However, the use of resveratrol in cosmetics has been limited due to its chemical instability and poor bioavailability. Therefore, resveratrol derivatives were prepared to improve bioavailability and anti-melanogenesis activity. Nine resveratrol derivatives including five alkyl ether derivatives with C2H5, C4H9, C5H11, C6H13, and C8H17 (2a–2e) and four ester derivatives with CH3, CH=C(CH3)2, CH(C2H5)C4H9, C7H15 (3a–3d) were newly synthesized and their effect on melanin synthesis were assessed. All the synthetic derivatives efficiently reduced the melanin content in α-MSH stimulated B16F10 melanoma cells. Further investigation showed that the inhibitory effect of 2a on melanin synthesis was achieved not by the inhibition of tyrosinase activity but by the inhibition of melanogenic enzyme expressions such as tyrosinase and tyrosinase-related protein (TRP)-1. Our synthetic resveratrol derivatives have more lipophilic properties than resveratrol by the addition of alkyl or acyl chains to free hydroxyl moiety of resveratrol; thus, they are expected to show better bioavailability in skin application. Therefore, we suggest that our synthetic resveratrol derivatives might be promising candidates for better practical application to skin-whitening cosmetics.

Pancreatic lipase inhibitory constituents from Morus alba leaves and optimization for extraction conditions.

The leaves of Morus alba (Moraceae) have been traditionally used for the treatment of metabolic diseases including diabetes and hyperlipidemia. Thus, inhibitory effect of M. alba leaves on pancreatic lipase and their active constituents were investigated in this study. Twenty phenolic compounds including ten flavonoids, eight benzofurans, one stilbene and one chalcones were isolated from the leaves of M. alba. Among the isolated compounds, morachalcone A (20) exerted strong pancreatic lipase inhibition with IC50 value of 6.2 μM. Other phenolic compounds containing a prenyl group showed moderate pancreatic lipase inhibition with IC50 value of <50 μM. Next, extraction conditions with maximum pancreatic lipase inhibition and phenolic content were optimized using response surface methodology with three-level-three-factor Box-Behnken design. Our results suggested the optimized extraction condition for maximum pancreatic lipase inhibition and phenolic content as ethanol concentration of 74.9%; temperature 57.4 °C and sample/solvent ratio, 1/10. The pancreatic lipase inhibition and total phenolic content under optimized condition were found to be 58.5% and 26.2 μg GAE (gallic acid equivalent)/mg extract, respectively, which were well matched with the predicted value.

Anthraquinones from Morinda officinalis roots enhance adipocyte differentiation in 3T3-L1 cells.

To search for anti-diabetic and insulin-sensitising natural products, the effect on adipocyte differentiation was investigated by assessing fat accumulation in 3T3-L1 preadipocytes using Oil Red O staining. Fractionation and separation of n-hexane and CHCl3 fractions of Morinda officinalis (Rubiaceae) using several chromatographic methods led to the isolation of three anthraquinones, 1,2-dimethoxyanthraquinone (1), alizarin-2-methyl ether (2) and rubiadin-1-methyl ether (3). Among them, alizarin-2-methyl ether (2) showed the strongest enhancing activity, followed by rubiadin-1-methyl ether (3) and 1,2-dimethoxyanthraquinone (1). At a concentration of 100 µM, alizarin-2-methyl ether (2) enhanced adipocyte differentiation by up to 131% (compared to insulin-treated cells). Thus, these compounds could be beneficial in the treatment of diabetes.

Optimization of Extraction Condition of Bee Pollen Using Response Surface Methodology: Correlation between Anti-Melanogenesis, Antioxidant Activity, and Phenolic Content

Bee pollen is flower pollen with nectar and salivary substances of bees and rich in essential components. Bee pollen showed antioxidant and tyrosinase inhibitory activity in our assay system. To maximize the antioxidant and tyrosinase inhibitory activity of bee pollen, extraction conditions, such as extraction solvent, extraction time, and extraction temperature, were optimized using response surface methodology. Regression analysis showed a good fit of this model and yielded the second-order polynomial regression for tyrosinase inhibition and antioxidant activity. Among the extraction variables, extraction solvent greatly affected the activity. The optimal condition was determined as EtOAc concentration in MeOH, 69.6%; temperature, 10.0 °C; and extraction time, 24.2 h, and the tyrosinase inhibitory and antioxidant activity under optimal condition were found to be 57.9% and 49.3%, respectively. Further analysis showed the close correlation between activities and phenolic content, which suggested phenolic compounds are active constituents of bee pollen for tyrosinase inhibition and antioxidant activity. Taken together, these results provide useful information about bee pollen as cosmetic therapeutics to reduce oxidative stress and hyperpigmentation.

Sesquiterpene lactones from the roots of Lindera strychnifolia

Phytochemical investigation of the roots of Lindera strychnifolia resulted in the isolation of seven sesquiterpene lactones named linderolide G-M (1-7), together with twelve known sesquiterpenes. The structures and relative configurations of 1-7 were determined through spectroscopic observations, and the absolute configurations were defined by CD analysis. Linderolide G (1) and lindestrene (16) showed cytotoxicity against HSC-T6 hepatic stellate cells.

Anti-Obesity Effect of 6,8-Diprenylgenistein, an Isoflavonoid of Cudrania tricuspidata Fruits in High-Fat Diet-Induced Obese Mice

Obesity, which is characterized by excessive fat accumulation, is associated with several pathological disorders, including metabolic diseases. In this study, the anti-obesity effect of 6,8-diprenylgenistein (DPG), a major isoflavonoid of Cudrania tricuspidata fruits was investigated using high fat-diet (HFD)-induced obese mice at the doses of 10 and 30 mg/kg for six week. The body weight of the DPG-treated groups was significantly lower compared to the HFD-treated group. In addition, fat accumulation in epididymal adipose tissue and liver was dramatically decreased in the HFD + DPG groups. The food efficiency ratios of the HFD + DPG groups were also lower compared to the HFD group with the same food intake. Metabolic parameters that had increased in the HFD group were decreased in the HFD + DPG groups. Further studies demonstrate that DPG efficiently reduces lipogenic genes by regulation of transcription factors, such as peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα), and hormones, such as leptin and adiponection. DPG also regulates acetyl-CoA carboxylase (ACC) and hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) by AMP-activated protein kinase (AMPK) activation. Taken together, DPG is beneficial for the regulation of obesity, especially resulting from high fat intake.

Characterization of Melanogenesis Inhibitory Constituents of Morus alba Leaves and Optimization of Extraction Conditions Using Response Surface Methodology

Melanin is a natural pigment that plays an important role in the protection of skin, however, hyperpigmentation cause by excessive levels of melatonin is associated with several problems. Therefore, melanogenesis inhibitory natural products have been developed by the cosmetic industry as skin medications. The leaves of Morus alba (Moraceae) have been reported to inhibit melanogenesis, therefore, characterization of the melanogenesis inhibitory constituents of M. alba leaves was attempted in this study. Twenty compounds including eight benzofurans, 10 flavonoids, one stilbenoid and one chalcone were isolated from M. alba leaves and these phenolic constituents were shown to significantly inhibit tyrosinase activity and melanin content in B6F10 melanoma cells. To maximize the melanogenesis inhibitory activity and active phenolic contents, optimized M. alba leave extraction conditions were predicted using response surface methodology as a methanol concentration of 85.2%; an extraction temperature of 53.2 °C and an extraction time of 2 h. The tyrosinase inhibition and total phenolic content under optimal conditions were found to be 74.8% inhibition and 24.8 μg GAE/mg extract, which were well-matched with the predicted values of 75.0% inhibition and 23.8 μg GAE/mg extract. These results shall provide useful information about melanogenesis inhibitory constituents and optimized extracts from M. alba leaves as cosmetic therapeutics to reduce skin hyperpigmentation.

Luteolin downregulates IL-1β-induced MMP-9 and -13 expressions in osteoblasts via inhibition of ERK signalling pathway

The inhibitory effect of four structurally related flavonoids, apigenin, baicalein, luteolin and quercetin on the matrix metalloproteinase (MMP)-9 and -13 expressions in osteoblasts was investigated. Treatment with IL-1β induced both MMP-9 and -13 mRNA expressions as measured by quantitative real-time PCR. Luteolin and apigenin decreased IL-1β-induced MMP-9 and -13 mRNA expressions, whereas baicalein and quercetin showed little effects. Related to signalling, treatment with IL-1β induced ERK phosphorylation as measured by Western blotting. Further studies showed that transfection with a constitutively active form of the Ras protein (RasV12) induced stronger ERK phosphorylation and upregulated MMP-9 and -13 mRNA expressions. However, transfection with a dominant-negative form of the Ras protein (RasN17) inhibited the ERK activation and MMP-9 and -13 mRNA expressions induced by IL-1β, which supported the involvement of ERK signalling in IL-1β-induced MMP-9 and -13 expressions. Treatment with luteolin effectively inhibited the IL-1β-induced ERK activation in dose-dependent manner. Taken together, luteolin might inhibit IL-1β-induced MMP-9 and -13 expressions, in part, via inhibition of ERK signalling.