Chromatography: An important tool for drug discovery.

Despite substantial developments of extraction and separation techniques, isolation of natural products from natural sources is still a challenging task. Undoubtedly hybrid methods like liquid chromatography with NMR spectroscopy or liquid chromatography coupled with mass spectrometry made on-line structure elucidation possible and provided impressive examples of natural product identification without prior isolation, however, in many cases the necessity to get the purified compounds in hand is still a fact. The process begins with the collection of desired plant material which is subjected to the suitable extraction process. The complex crude extracts are then monitored by various chromatographic procedures to separate and quantify the desired compounds. The active plant extracts are then fractionated to isolate the bioactive compounds in their pure form. The fully identified compound is used as a lead for the production of related analogues to modulate the biological activity and to carry out structure-activity relationship. The major isolated bioactive compound is used for semi-synthetic modification or total synthesis should be carried out such that it is relatively easy to modify the structure of the lead compound. This is a simple and cost-effective way to increase the chance to discover lead compounds. The biological activity in vitro and in vivo has to be done after purification.

4-epi-Pimaric acid: a phytomolecule as a potent antibacterial and anti-biofilm agent for oral cavity pathogens.

The present study focused on the antibacterial and biofilm inhibitory potential of 4-epi-pimaric acid isolated from aerial parts (stem and leaves) of Aralia cachemirica L. (Araliaceae) against oral cavity pathogens. 4-epi-Pimaric acid exhibited minimum inhibitory concentration (MIC) in the range of 4-16 µg/ml and minimum bactericidal concentration (MBC) two- to four-folds higher than MIC. There was significant inhibition in the biofilm formation by Streptococcus mutans on the saliva coated surface (P < 0.05), and confocal microscopy revealed that 4-epi-pimaric acid inhibited the clumping and attachment of S. mutans. At 8 × MIC concentration, it significantly prevented the pH drop and reduced S. mutans biofilms (P < 0.05). Increased propidium iodide staining and leakage of 260- and 280-nm absorbing material by 4-epi-pimaric acid treated cells of S. mutans suggested that it probably causes disruption of the cytoplasmic membrane structure. It also exhibited significant suppression of TNF-α expression in human neutrophils, suggestive of its anti-inflammatory activity. Furthermore, the compound was found to be significantly safe (IC(50) >100 µg/ml) in the MTT assay on AML-12 cell lines. In conclusion, 4-epi-pimaric acid showed promising antibacterial, anti-biofilm and anti-inflammatory potency and this compound can be exploited for therapeutic application in oral microbial infections.

Sub-acute toxicity evaluation of an aqueous extract of Labisia pumila, a Malaysian herb.

Labisia pumila (Myrsinaceae), is a popular herb among the women in Malaysia known locally as "Kacip Fatimah". Recently many nutraceutical products containing the powdered or extracted parts of the plant have become available for women's health care. However no evaluation of the effect of the repeated dosing of any herbal product of this plant had been undertaken prior to a 28-day sub-acute study presented in this report. The results showed that a dose of 50mg/kg of an aqueous extract of L. pumila corresponded to no-adverse-effect-level (NOAEL), whereas higher doses were associated with some toxicity concerns.