Development and validation of a set of laboratory activities in natural products based on isolation, structure elucidation and biossay of secondary metabolites from Malachra Fasciata, Jacq. and cosmos caudatus, HBK

• Main Author: Penalosa, Beatriz Agustin
• Format: text
• Language: English
• Published: Animo Repository 1998
• Subjects: Extracts; Chemistry, Organic; Chemistry > Experiments; Organic compounds; Plants, Useful; Organic Chemistry
• Online Access: https://animorepository.dlsu.edu.ph/etd_doctoral/806
• Institution: De La Salle University

The main objective of this study is to isolate, elucidate and evaluate the bioactivity potential of the isolates from the chloroform extracts of Malachra fasciata and Cosmos caudatus. Also, it aims to develop and validate laboratory activities in natural products for introductory organic chemistry.Isolation was carried out by gravity column chromatography and the isolates were purified by recrystallization or rechromatography. The isolates were bioassayed for antimicrobial and antimutagenic activity using the agar cup/paper disc diffusion method and the micronucleus test, respectively. Malachra fasciata afforded MF4, commonly known as aurantiamide acetate. Its structure was established to be N-bensoyl-L-phenylalanyl-Lphenylalaninol acetate based on extensive 1-D and 2-D NMR spectroscopic analyses. From Cosmos caudatus, three known compounds, C-1 (costunolide), C-2 (stigmasterol) and C-3 (lutein), were isolated. The identities of these compounds were confirmed by comparison of their 1H NMR and 13C NMR spectral data with literature values.The results of the bioactivity tests revealed that all isolates were antimutagens. MF4 and C-1 were found to be antifungal and antibacterial, while C-2 was antifungal only. Eight activities in natural products were developed based on the procedures used, the principles learned, and the laboratory techniques developed from the experimental phase of the study. These were content validated by experts and their readability levels were determined using the JB formula. The activities were tried out and evaluated by B.S. Biology students of Leyte Normal University. The activities were found to be valid as to content and to have an average reading level suited for third and fourth year high school students. The students found the activities to be informative, interesting, enjoyable, relevant to their lives and useful in developing manipulative skills and laboratory techniques.From the findings of the study, the following conclusions were drawn: 1) The choloform extracts of the two plant samples yielded four bioactive metabolites: aurantiamide acetate, costunolide, stigmasterol and lutein, and 2) the laboratory activities developed were found to be valid as to content, to have reading levels appropriate for the intended users and acceptable as perceived by the users.