桑葉為桑科Moraceae植物桑Morus alba L.之乾燥葉，黃酮類化合物為主要成分，最近文獻報導，Moracinflavan E是由桑葉中分離與確認出來的新天然化合物，屬於黃烷類，具有抗氧化、抗發炎活性，根據文獻報導，天然或合成的黃酮類化合物顯示具有不同的生物活性如抗氧化、抗菌、抗發炎、抗癌等，因此被關注可以開發成為治療用藥的可能，在本研究中，針對Moracinflavan E的類似物18與32進行有效的合成方法探討。從2’,4’-dihydroxyacetophenone為起始物，經8個合成步驟成功的合成了類似物18與32，所有合成的化合物皆由核磁共振光譜分析確認其結構，結果顯示類似物18與天然物Moracinflavan E的文獻數據一致，天然物Moracinflavan E的正確結構有可能是類似物18的結構。
Mulberry leaf is the dry leaf of Morus alba L. (Fam. Moraceae). Flavonoids are the major components. Recently, moracinflavan E was isolated and characterized as a new flavan from the leaves of Morus alba and displayed antioxidant and anti-inflammatory activity. Naturally occurring flavonoids and synthesized analogues have been reported to have various bioactivities, such as antioxidant, antibacterial, anti-inflammatory, and anticancer activities. Due to the variety of their beneficial effects, compounds related to flavonoids have attracted attention as a novel potential therapeutic target. In this study, the total synthesis of analogues 18 and 32 of moracinflavan E has been accomplished in eight steps from 2’4’-dihydroxyacetophenone. The structures of synthesized compounds were confirmed on the basis of NMR spectroscopic analysis. The results showed that the NMR spectroscopic data of analogue 18 is consistent with those reported data of naturally occurring moracinflavan E. It suggested that the correct structure of naturally occurring moracinflavan E could be the structure of synthesized compound 18.
