Modern Screening Techniques for Plant Extracts

Abstract

In order to discover new bioactive compounds from plant sources which could become new leads or new drugs, extracts should be simultaneously evaluated by chemical screening and by various biological or pharmacological targets. Chemical screening using hyphenated techniques such as LC/UV and LC/MS, and more recently LC/NMR, quickly provides ample structural information, leading in many cases to the identification of compounds. This allows researchers to distinguish between known compounds (dereplication) and new molecules directly from crude plant extracts. Thus, the tedious isolation of known compounds can be avoided, and a targeted isolation of constituents presenting novel or unusual spectroscopic features can be undertaken. In parallel, extracts are also subjected to various bioassays that should be simple, reproducible, and rapid. This approach will be illustrated by the search for new molluscicidal, antioxidant, and antifungal compounds from tropical plants.

Detection of antimicrobial compounds by bioautography of different extracts of leaves of selected South African tree species

“…Over the last decade, there has been a renewed interest in plants; and the pharmaceutical industry considers plants as a viable option for the discovery of new leads (Soejarto, 1996). In fact, it is also estimated that natural products are implicated in the development of 44% of all new drugs, generally as leads for the preparation of semi-synthetic derivatives (Hostettmann et al, 2001).…”

“…Over the last decade, there has been a renewed interest in plants; and the pharmaceutical industry considers plants as a viable option for the discovery of new leads (Soejarto, 1996). In fact, it is also estimated that natural products are implicated in the development of 44% of all new drugs, generally as leads for the preparation of semi-synthetic derivatives (Hostettmann et al, 2001).In an effort to discover new lead compounds, many research groups screen plant extracts to detect secondary metabolites with relevant biological activities. In this regard, several bioassays were developed for screening purposes (Hostettmann, 1991).…”

Antibacterial activity of the alkaloid extract and isolated compounds from Croton bonplandianum Baill. (Euphorbiaceae)

“…In fact, it is estimated that natural products are involved in the development of the 44% of all new drug molecules, mainly as a basis for obtaining semisynthetic derivatives (Hostettmann et al, 2001;Lahlou, 2013).…”

Dereplication Study on Glaucium Aleppicum Boiss. in Jordan

“…It is of great importance to discriminate between previously isolated, known compounds and new compounds, at the level of the crude extract 6,7,811,12 . Dereplication is an essential component of natural products studies, It is used to make sure that resources are expended on only the most promising samples and avoid the tedious isolation of known constituents, which are those most likely to yield bioactive and structurally unique compounds [13][14][15][16][17] . As a result, some molecular masses and the corresponding fragmentations do not correlate with any known compounds, thus revealing potentially novel natural products that could be investigated on a larger scale and could completely find application as new drugs 6 .…”