Tan Pei Jean, Ong Cheng Yi, Danial Asma, Yusof Hirzun Mohd, Neoh Bee Keat, Lee Hong Boon
Cancer Research Initiatives Foundation (CARIF), Sime Darby Medical Centre,1, Jalan SS12/1A, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia.
Chem Cent J. 2011 Jun 20;5:32. doi: 10.1186/1752-153X-5-32.
Twenty-seven extracts from 26 plants were identified as photo-cytotoxic in the course of our bioassay guided screening program for photosensitisers from 128 extracts prepared from 64 terrestrial plants in two different collection sites in Malaysia - Royal Belum Forest Reserve in the State of Perak and Gunung Nuang in the State of Selangor. One of the photo-cytotoxic extracts from the leaves of Phaeanthus ophtalmicus was further investigated.
The ethanolic extract of the leaves from Phaeanthus ophtalmicus was able to reduce the in vitro viability of leukaemic HL60 cells to < 50% when exposed to 9.6 J/cm2 of a broad spectrum light at a concentration of 20 μg/mL. Dereplication of the photo-cytotoxic fractions from P. ophthalmicus extracts based on TLC Rf values and HPLC co-injection of reference tetrapyrrolic compounds enabled quick identification of known photosensitisers, pheophorbide-a, pheophorbide-a methyl ester, 132-hydroxypheophorbide-a methyl ester, pheophytin-a and 151-hydroxypurpurin 7-lactone dimethyl ester. In addition, compound 1 which was not previously isolated as a natural product was also identified as 7-formyl-151-hydroxypurpurin-7-lactone methyl ester using standard spectroscopic techniques.
Our results suggest that the main photosensitisers in plants are based on the cyclic tetrapyrrole structure and photosensitisers with other structures, if present, are present in very minor amounts or are not as active as those with the cyclic tetrapyrrole structure.
在我们针对来自马来西亚两个不同采集地点（霹雳州皇家贝尔姆森林保护区和雪兰莪州努昂山）64种陆生植物制备的128种提取物进行的生物测定导向的光敏剂筛选计划过程中，鉴定出了26种植物的27种提取物具有光细胞毒性。对来自多花山椒叶的一种光细胞毒性提取物进行了进一步研究。
当多花山椒叶的乙醇提取物在浓度为20μg/mL时暴露于9.6 J/cm²的广谱光下，能够将白血病HL60细胞的体外活力降低至<50%。基于薄层色谱比移值和高效液相色谱共注入参考四吡咯化合物对多花山椒提取物的光细胞毒性部分进行去重复，能够快速鉴定出已知的光敏剂，脱镁叶绿酸-a、脱镁叶绿酸-a甲酯、132-羟基脱镁叶绿酸-a甲酯、脱镁叶绿素-a和151-羟基紫红素7-内酯二甲酯。此外，使用标准光谱技术还鉴定出化合物1，它以前未作为天然产物分离出来，也被鉴定为7-甲酰基-151-羟基紫红素-7-内酯甲酯。
我们的结果表明，植物中的主要光敏剂基于环状四吡咯结构，而具有其他结构的光敏剂（如果存在）含量非常少或活性不如具有环状四吡咯结构的光敏剂。
