Studies On The Alkaloids From Daphniphyllum Macropodum

Daphniphyllum macropodum is a kind of evergreen tree which distributed in thebroad-leaved forest in south of China such as Yunnan, Sichuan, Chongqing, Guizhou, et al.The seeds, stems, leaves and roots of the Daphniphyllum macropodum are used as folkmedicines to treat fester, asthma, cough, rheumatism and fever. It is one species of thegenus Daphniphyllum which are well known for producing highly polycyclic andstructurely diverse alkaloids. Some of the Daphniphyllum alkaloids exhibit significantcytotoxic activity against several human cancer cell lines. The stem bark and seeds containthe most of alkaloids in the tree of genus Daphniphyllum, and the first identifiedDaphniphyllum alkaloid was isolated from Daphniphyllum macropodum.With the purpose of searching for bioactive and structurally unique Daphniphyllumalkaloids, an investigation of the ethanol extracts from the stem bark of Daphniphyllummacropudum was conducted, and this resulted in the isolation of24compounds includingthree unidentified compounds; five new alkaloids they are calyciphylline R (5),daphnicyclidin M (6), daphnicyclidin N (7), calyciphylline Q (10) and calyciphylline S(11); twelve known alkaloids they are longistylumphylline A (8), paxiphylline E (9),daphniyunnine B (12), macropodumine C (13), daphnicyclidin H (14), daphnicyclidin D (15), daphnicyclidin C (16), paxiphylline B (17), daphmacrodin A (18), macropodumine B(19), daphnicyclidin L (20) and daphnicyclidin A (21); four phenol derivatives they are4-hydroxy ethyl benzoate (1),3-(4-hydroxy) phenyl ethyl acrylate (2),2,3-dyhydroxy-4-methyl ethyl benzoate (3) and2,4-dyhydroxy-3,6-dimethyl methylbenzoate (4). The compounds were isolated and purified by silica gel column, SephadexLH-20gel column, RP-C18column and HPLC, and their structures were elucidated on thebasis of spectroscopic methods. Among them, four known alkaloids8,9,12and17, andfour phenol derivatives (1-4) are isolated from Daphniphyllum macropodum for the firsttime. Except compounds14,15and21all the compounds are isolated from the stem barkof Daphniphyllum macropodum for the first time.The cytotoxic activity of the5new compounds and the known alkaloids (exceptcompounds18-20) against four tumor cell lines (P-388, A-549, SGC-7901and HL-60)were evaluated by MTT method and cisplatin was used as positive control. Compounds6,7,13,14,16,17and21exhibited cytotoxic activity against p-388cells. Except thatcompounds6and7showed a moderate cytotoxic activity against SGC-7901cells withIC5022.4and25.6mol/L, respectively, the rest compounds were inactive to the threetested tumor cell lines A-549, SGC-7901and HL-60(IC50>50mol/L). Becausecompounds6and7possessed a rare skeleton structure and a moderate cytotoxic activityagainst SGC-7901cells, they are worth of a further investigation.Innovations and significance:1. The investigation of the ethanol extracts from the stem bark of Daphniphyllummacropudum lead to the isolation and identification of21compoounds. Among them fourknown alkaloids8,9,12and17and four phenol derivatives (1-4) were isolated fromDaphniphyllum macropodum for the first time.2. There are five new compounds which are compounds5,6,7,10, and11.Compounds6and7possess a rare skeleton structure with a carbonyl at C-2and a16(17)double bond, and C-1connecting to C-3without through C-2. The analog which shares a similar gross structure with compounds6and7has been isolated for only once.Compound10is the first Daphniphyllum alkaloids which possess a double bond betweenC-18and C-19.4. Both compounds6and7exhibited cytotoxic activity against P-388and SGC-7901cells and possessed the potential for further investigation.5. This research provided a valuble reference for the structure classification, chemicaland biological synthesis, bioactive investigation and further studies of Daphniphyllumalkaloids and the genus of Daphniphyllum.