A Systematic Review of Different Analytical Methods for the Quantification of Natural Bioactives

Natural bioactive compounds have significant potential for the development of therapeutic interventions, but the success of their discovery and use is greatly influenced by the development of efficient methods for their extraction, structural determination, quantification, and validation. Existing reviews have failed to adequately address the analytical approaches for the efficient determination of bioactive compounds, which is the main purpose of this systematic review: to comprehensively evaluate the current methods used in the extraction, determination of the structure, quantification, validation, and dose-response relationship in the assessment of natural bioactive compounds, which may be derived from plant and marine sources, with the aim of determining their structures for the development of new drugs, as well as validating the results obtained from the use of these compounds.

An extensive simulated search was carried out on prominent scientific information sources, such as PubMed, Scopus, and Google Scholar, to gather literature published from 2000 to 2024. The literature selected for the study was based on the information provided on the extraction methods, structural elucidation mechanisms, analytical validation, and pharmacological investigation of bioactive compounds derived from plants. The information on 40 bioactive compounds and the analytical mechanisms was gathered and synthesized.

Extraction is normally carried out using techniques such as Soxhlet extraction, MicrowaveAssisted Extraction (MAE), and maceration. For structural analysis, the most preferred methods include Nuclear Magnetic Resonance (NMR), Mass Spectrometry (MS), Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet-Visible Spectroscopy (UV-Vis), and X-ray crystallography. Validation indicates excellent linearity (R² > 0.99), specificity, and accuracy with %RSD < 2. Dose-response curves for compounds such as curcumin, quercetin, and silymarin indicate excellent potency, as indicated by IC50 values < 50 µM. However, drawbacks include issues such as interference in the matrix, the high cost of equipment, and the lack of universal standardization methods.

The evidence is sound: modern spectroscopy and chromatography techniques provide impressive accuracy. However, disparities in standardization practices and expenses make it difficult to fully embrace the approach. This review highlights the importance of blending eco-friendly solvents and cost-effective approaches to fill the gap.

For the purpose of precise characterization of bioactive compounds, it is necessary to integrate extraction techniques with analytical validation and spectroscopy. This review offers a useful guide to help researchers in selecting the best possible strategies depending on the nature of the compound and the objectives of the research. It also emphasizes the need to standardize analytical techniques and the feasibility of using green solvents.