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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.

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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.

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The composition and content of the active constituents and their biological activity vary according to diverse factors including their maturation stages. A previous study showed that the fruits of Cudrania tricuspidata inhibited pancreatic lipase activity, a key enzyme in fat absorption. In this study, we investigated the chemical composition and pancreatic lipase inhibitory activity of unripe and ripe fruits of C. tricuspidata. Unripe fruits of C. tricuspidata have a higher content of total phenolic and flavonoids and exhibited stronger pancreatic lipase inhibition compared to ripe fruits. HPLC analysis revealed the different chemical compositions of the unripe and ripe fruits. Further fractionation resulted in the isolation of 30 compounds including two new isoflavonoids. Analysis of the chemical constituents of the unripe and ripe fruits revealed that a 2,2-dimethylpyran ring, a cyclized prenyl, was the predominant side chain in the unripe fruits, whereas it was a linear prenyl group in the ripe fruits. In addition, a new isoflavonoid (19) from the unripe fruits showed the most potent inhibition on pancreatic lipase. Taken together, the maturation stage is an important factor for maximum efficacy and that unripe fruits of C. tricuspidata are a good source of new bioactive constituents for the regulation of obesity

Rhus verniciflua is commonly known as a lacquer tree in Korea. The bark of R. verniciflua has been used as an immunostimulator in traditional medicine, but also causes allergic dermatitis due to urushiol derivatives. For the development of active natural resources with less toxicity, the antibacterial activity of various parts of R. verniciflua such as bark, lignum, leaves and fruit, together with chemical composition, were investigated. Among the various parts of R. verniciflua, lignum showed the most potent antibacterial activity against fish pathogenic bacteria such as Edwardsiella tarda, Vibrio anguillarum and Streptococcus iniae. Measurement of total phenolic content and flavonoid content clearly showed a high content of phenolic and flavonoids in lignum among the various parts of R. verniciflua. Further analysis showed a close correlation between antibacterial activity and phenolic content. In addition, methyl gallate and fustin, the major constituents of bark and lignum, showed antibacterial activity, which suggested phenolic constituents as active constituents. The content of urushiols, however, was highest in bark, but there was a trace amount in lignum. LC-MS-MS and PCA analysis showed good discrimination with the difference of phenolic composition in various parts of R. verniciflua. Taken together, phenolic compounds are responsible for the antibacterial activity of R. verniciflua. The lignum of R. verniciflua contains high content of phenolic compounds with less urushiols, which suggests efficient antibacterial activity with less toxicity. Therefore, the lignum of R. verniciflua is suggested as a good source for antibacterial material to use against fish bacterial diseases.

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