New Indole Glycosides from Aesculus chinensis var. chekiangensis and Their Neuroprotective Activities

The dried seeds of Aesculus chinensis Bge. var. chekiangensis (Hu et Fang) Fang, called &ldquo
Suo Luo Zi&rdquo
have been used in traditional Chinese medicine. Nevertheless, most studies have been focused on components of less polarity fractions. In this research, twelve indoles, including six new indole glycosides (1&ndash
6) as well as six known analogs were isolated from the polar portion which has been seldom studied. This is the first description of N-glucosylated indoles obtained from the genus of Aesculus. Structures of the new compounds (1&ndash
6) were elucidated based on comprehensive interpretation of HRESIMS, 1D and 2D NMR. Additionally, the neuroprotective activities of the N-glucosylated indoles were evaluated for the first time indicating that compounds 1&ndash
5 and 9&ndash
10 exhibited moderate neuroprotective activities. Further cytotoxicity tests of isolates 1&ndash
10 on three human tumor cell lines suggested that none of these compounds were cytotoxic (IC50 &gt
50 &mu
M).