| Nerve growth factor (NGF) as one of neurotrophic factors is not only important for the survival and maintenance of central neurons, but also can repair the injured neurons. However, because of unable to cross the blood-brain barrier (BBB), its clinic application is limited. Therefore, it is significant to find natural compound with NGF mimic activity for curing AD patients, which can cross the BBB.We found that the crude sample of Desmodium sambuense significantly induced PC 12 cells to differentiate to neuron-like cells. Guided by bioassay, the active sample was purified by silica gel open column?ODS open column and HPLC, and finally we obtained Compounds 1-3. Their chemical structures were identified by analysis of spectral data and comparison with the references. Compounds 1 and 2 are 3?,23,28-trihydroxy-12-oleanene 3?-caffeate and 3?,23,28-trihydroxy-12-oleanene 23-caffeate, which are active. Compound 3 is 3?,23,28-triol olean-12-ene, which is inactive.We preliminarily studied their structure-activity relationships, and got 5 compounds by acetylation and methylation. The biological activities of them decreased, which suggested that the acetylation and methylation of hydroxyl groups did not benefit for improving the biological activity.In our studies, we found two active compounds with neuritogenic activity from the crude sample of Desmodium sambuense, which are triterpene phenolic acid esters. Whether their mother nucleus structure or acetyled and methylated products are less active than Compound 1 and 2. It is of great importance to find the lead compound from triterpene phenolic acid esters. |
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