Natural products that come from plants have long been regarded as a useful source of potential drug-active ingredients. A paradigm change in the study of natural products as drugs has been brought about by the development of metabolomics as an essential tool for the analysis of thousands of metabolites from crude natural extracts. In order to thoroughly annotate the contents of plant natural products for screening, analytical techniques including mass spectrometry (MS) and nuclear magnetic resonance (NMR) are applied. The extraction of bioactive metabolites from biomass using various extraction methods, such as supercritical fluid extraction, microwave- and ultrasonic-assisted extraction, molecular distillation techniques, and membrane separation technology, is the first step in the discovery of lead compounds from natural sources. The thorough characterization of these agents and, ultimately, their structural elucidation has been made possible by new technologies including nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), and ultraviolet-visible spectroscopy (UV-Vis).