title: Cyclic Tetrapyrrolic Photosensitisers from the leaves of Phaeanthus ophthalmicus.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Cancer Research Initiatives Foundation (CARIF), Sime Darby Medical Centre,1, Jalan SS12/1A, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia. hongboon.lee@carif.com.my.
authors.forename: Pei Jean
authors.initials: PJ
authors.lastname: Tan
authors.forename: Cheng Yi
authors.initials: CY
authors.lastname: Ong
authors.forename: Asma
authors.initials: A
authors.lastname: Danial
authors.forename: Hirzun Mohd
authors.initials: HM
authors.lastname: Yusof
authors.forename: Bee Keat
authors.initials: BK
authors.lastname: Neoh
authors.forename: Hong Boon
authors.initials: HB
authors.lastname: Lee