Natural products and bacterial strains continue to provide a diverse and unique source of bioactive lead compounds for drug discovery.
Isolation and identification of biologically active compounds can be a serious challenge which may have much more in common with scientific research work rather than with routine analytical task. In order to solve it, in addition to high performance equipment capabilities one should possess both an expertise in analytical chemistry and an ability to perform the most sophisticated scientific experiments.
Since ‘discovery’ implies having very little initial information about a given specimen and its bioactive constituents, such experiments cannot be straightforward. Bioactive compounds may belong to different chemical classes; they may possess different molecular weight, spectral and adsorption properties; they may occur in higher or trace concentrations. There can be several active constituents in a sample, or even several different sub-classes of compounds that demonstrate bioactivity.
Therefore, discovery of bioactive compounds presents a systematic study that includes generating a number of initial hypotheses and their further prioritizing by carrying out appropriate scientific experiments. From the technical viewpoint, such experiments may include:
development of analytical, screening and preparative HPLC methods;
isolation of active fractions and their characterization by spectral methods;
isolation and purification of bioactive compounds;
elucidation the chemical structure of bioactive compounds.
As a rule, the research starts from carrying out a number of screening HPLC separations in different HPLC modes. This step is aimed in estimating the number of bioactive compounds within the sample, and also in elucidating their adsorption and, if possible, their spectral properties.
Next, a special high performance HPLC method (or methods) should be developed in order to separate constituents of fractions that include bioactive compounds with the highest resolving power possible. It is usually done using HPLC modes that are orthogonal to the one used for screening HPLC separations.
Appropriate detection technique is also selected at this step according to the principle that the HPLC method and the detection technique put together should be capable of indicating the specific signals that can be unequivocally attributed to compounds that demonstrate activity.
This is followed by development of preparative HPLC methods for isolating discovered bioactive compounds.
Next, in order to elucidate chemical structure of isolated compounds, they should be characterized by a number of spectral methods, such as:
mass-spectroscopy: high resolution MS in ESI (+, -) and APCI/APPI (+, -) modes; MSn experiments;
NMR: 1H, 13C, 1H/13C COSY, DEPT experiments;
molecular spectroscopy: FTIR, Raman;
elemental analysis: CHNS-O, ICP.
Identification of bioactive compounds is usually followed by large scale production of target compounds with a high-purity degree.
Our team of professional analytical chemists can provide you with all necessary solutions in the field of isolation, identification and large-scale production of bioactive compounds, regardless the complexity of organic matrices to be studied and the chemical nature of target molecules.