Isolation and identification of the bioactive metabolites of Eupatorium toppingianum and mimosa invisa: Proposed investigatory activities for chemistry teachers

• Main Author: Largo, Guillermo O.
• Format: text
• Language: English
• Published: Animo Repository 1995
• Subjects: Plant metabolites; Chemistry > Study and teaching; Chemistry teachers; Mimosa; Chemistry > Experiments; Leaves > Microbiology; Microbial sensitivity tests; Alkaloids > Spectra; Chemistry; Teacher Education and Professional Development
• Online Access: https://animorepository.dlsu.edu.ph/etd_doctoral/728
• Institution: De La Salle University

This study is a two-phased investigation. The first phase is confined to the isolation and identification of the bioactive metabolites of Eupatorium toppingianum and Mimosa invisa. The second phase develops investigatory activities for Chemistry teachers in the regions of Visayas.The proposed investigatory activities were based on the results obtained in the first phase of this study. Along the course of isolation of the metabolites from the chloroform leaf extract of E. toppingianum and M. invisa, the former afforded 3 isolates (A,B, and C) while the latter yielded 4 isolates (D,E, F, and G). Of the 3 isolates of E. toppingianum, only isolate B (RT, 0.62, in EtOAc) showed bioactivity with Brine Shrimp Bioassay (LC50 7.7 ug.mL). Likewise, with M. invisa, only isolate F (Rf 0.62, in 80 percent EtOAc) showed significant bioactivity potential (LC50 24.2 ug/mL) among 4 isolates. Isolate B showed antimicrobial potential against the common pathogens: S. typhi, B. subtilis, S. aureus, E. coli, V. cholera, S. dysenteriae and A. niger. Similarly, isolate F showed a complete inhibition against B. subtilis, S. aureus, E. coli, S. aeruginosa and C. albicans at a concentration of 2.0 ug/mL. When these 2 bioactive isolates were subjected to micronucleus test, isolate B (LD50 31 mg/kg mouse) showed 93 percent reduction of Micronucleated Polychromatic Erythrocytes (MPCE), induced by Mitomycin C. Isolate F, on the other hand, showed only 81 percent reduction at 200 ug/kg mouse. Of these 2 antimutagens, only isolate B was fully elucidated when used with chemical spectroscopic methods: 1HNMR, 13C COSY, 1H-1H COSY. Based on the extensive computer search of the proposed structure of isolate B, it was confirmed as a novel chromene. However, isolate F was not elucidated due to time constraint and scarcity of sample. But it was inferred as a carotenoid based on its physical properties, chromatogram, [cx]D1 melting point, IR and UV spectra. Enrichment program in Natural Products Research was proposed. For the self-survey questionnaires, 10 stress factors experienced by the teacher-participants surfaced. Along the course of the enrichment program, 13 plant species in the campus of the University of San Carlos were screened for alkaloids and terpenes, antimicrobial and cytotoxic plant extracts. Eight plant species were found to contain anticancer metabolites.After the 18-hour lecture in Chemical Spectroscopy, the teacher-participants showed significant improvement in their interpretative skills of spectral data at 0.01 level of significance.It is recommended that a continued enrichment program in natural products be provided to improve and upgrade the Natural Products Research in the Visayan region.