| Platanus acerifolia, is an interspecific hybrid of P. occidentalis and P. orientalis. In 1640, it was bred in London by manual means. With the unremitting efforts of several generations, Platanus acerifolia is widespread across temperate regions as afforestation tree. Because of the tall trunks and thick leaves, and its tenacious vitality, Platanus acerifolia is known as "the king of street trees". However, every year in early summer, during the new leaf growth, its ripe fruits creating lots of fur while fruits drop from the tree. The fur pollutes the environment, and causes a lot of respiratory diseases and skin diseases like asthma, skin allergies, which directly affect the quality of people’s lives. Nowadays, there is no report about the uses of the fur. Tones of fur are disposed as rubbish, which is a waste of manpower and natural resource. To utilize resources rationally and find the chemical compounds of fur, the ethanolic extract of the fur of Platanus acerifolia was investigated. In the meantime, related pharmacological experiments on some compounds have been done.The subject mainly used repeated chromatography on silica gel colum and combined separation materials like Sephadex LH-20, MCI to get compounds from the ethanolic extract of the fur. As a result,20 compounds were obtained from the extraction of petroleum ether and ethyl acetate. The structures of 19 compounds including 3 new compounds were identified according to physical and chemical properties, and mainly identified by techniques of NMR and single-crystal X-ray diffraction analysis. The compounds were identified as kaempferol (Ql), luteolin (Q2), galangin (Q3),8-methoxy-5,7-dihydroxyflavonol (Q4), 6-methoxy-8-methyl-5,7-dihydroxyflavonol (Q5*), (2S)-6-methyl-8-prenylpinocembrin (Q6),4’-methyl-dihydroxyflavanone (Q7), pityrogrammin (Q8),8-(1, 1-dimethyl-2-propen-1-yl)-galangin (Q9),3’-methoxy-8-C-(1, 1-dimethyl-2-propen-1-yl)-kaempferol (Q10*),3’-methoxy-6’-C-(3, 3-dimethyl-2-propen-l-yl)-kaempferol (Q11*), xanthyletin (Q12),2a, 3a-dihydroxytaraxer-14-en-28-oic acid (Q13), aleuritolic acid (Q14), betulinic acid (Q15), /?-sitosterol (Q16), daucosterol (Q17), eicosyl ferulate (Q18), tiliroside (Q19). Among them, compounds Q5*, Q6 and Q7, Q8, Q10* and Q11*, Q13 were found from Platanus acerifolia for the first time, and Q5*, Q10* and Q11* were 3 new compounds.The research showed that the fur was rich in flavonoids, and contained small amount of triterpenoids, steroids and so on. The new compound Q5* was a member of the family of flavonol, and the next two compounds Q10*, Q11* were the novel kaempferol derivatives which both have a isopentene group in their structures. The paper mainly focused on the cytotoxic activities of compounds Q5*, Q10*, Q11*, Q4 against MGC-803, T24, HepG-2, SKOV-3, NCI-H460 and HL-7702 cell lines by MTT assay. And the result showed the new compound Q5* had strong effect on MGC-803 cell lines with the IC50 values of 17.3μM which was 2.5 times as positive control (5-Flurouracil). In cell apoptosis assay, the apototic cells was detected by Annexin V/PI, the resulted showed that the apoptotic cell proportion (Q2+Q3) were 5.15%,54.1%,98.8% respectively when at the concentration of 20 μM,40 μM,60 μM. The experiment confirmed the Q5* can induce MGC-803 cell line apoptosis.The paper enriched the chemical study on Platanus acerifolia and provided a new plant resource which can obtain kaempferol derivatives with isopentene group in their structures. |
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