Phytochemical Screening v1

Phytochemical screening is a foundational approach in natural product research, enabling the detection of bioactive compounds in medicinal plants. This protocol outlines a systematic qualitative analysis conducted by the Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila. Tests were performed to identify both primary and secondary metabolites, using classical and modified methods based on color reactions and precipitate formation. Primary metabolite detection included assays for proteins (Ninhydrin, Biuret, and Xanthoproteic tests) and carbohydrates (Benedict’s, Fehling’s, Molisch’s, and Seliwanoff’s tests), confirming presence through colorimetric changes. Secondary metabolites were examined through multiple biosynthetic pathways. The acetate pathway was assessed for anthraquinone glycosides via Bornträger and Shouteten reactions. Shikimate pathway-derived compounds such as phenols, tannins, flavonoids, and coumarins were confirmed using ferric chloride, lead acetate, gelatin precipitation, and Shinoda tests. Terpenes and steroids were detected through Salkowski and Liebermann-Burchard tests, aligned with the mevalonate pathway. Alkaloids were identified using five classical reagents (Mayer’s, Wagner’s, Dragendorff’s, etc.), while cyanogenic glycosides were confirmed through sodium picrate assays. Saponins and cardiac glycosides were verified using frothing and Keller-Killiani tests, respectively. Results were interpreted based on color development or precipitate formation, confirming the presence of targeted phytochemical classes. This protocol provides a robust, reproducible framework for plant extract analysis, supporting future pharmacognostic, pharmacologic, or phytopharmaceutical research in natural medicine discovery.