Identification, Purification and Mass Spectrometric Characterization of Two Novel Cyclic Peptides from Clitoria ternatea

Kerala has a rich heritage of plant diversity and health traditions. The history of drug discovery reveals that the ethno-botanical approach is one of the most productive methods to screen bioactive compounds. Many drugs currently in use were developed after scientists began to analyze the chemical constituents of plants. Exploration of the medicinal uses of plants from traditional knowledge coupled to scientific research methodologies may be able to determine whether such plants provide therapeutically relevant drug candidates or not. Clitoria ternatea, a plant from the family Fabaceae is a slender, perennial climber used as an anti-inflammatory agent in folklore medicine. In an effort to identify biologically active molecules from Clitoria ternatea, we have isolated two novel, disulfide rich cyclic peptides using reversed phase high performance liquid chromatography (RP HPLC). Masses of these peptides were measured as 3058.8 Da and 3074.4 Da by an electrospray ionization mass spectrometer (ESI MS). Partial sequences of the peptides were assigned through manual de novo sequencing approach using tandem mass spectrometric data obtained from a matrix assisted laser desorption ionization time of flight mass spectrometer (MALDI-TOF MS).

Keywords: Clitoria ternatea, Cyclic Peptide, de novo sequencing, Electrospray, MALDI, Carboxamidomethylation.