Epimeric Aspidosperma-Type Monoterpene Indole Alkaloids from Kopsia fruticosa Leaves Shabrina Hikmatul Aliya Rohmadi (a), Edwin Riski Sukandar (a), Dikhi Firmansyah (a), Yusuf Eka maulana (a), Dyah Ayu Rachmadhaningtiyas (a), Hendra Helmanto (b), and Lia Dewi Juliawaty (a*)
a) Organic Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesha no. 10 Bandung 40132, Indonesia
*liadewi[at]itb.ac.id
b) Research Center for Biota System, National Research and Innovation Agency, Kawasan Sains Teknologi Dr. (H.C.) Ir. H. Soekarno, Jl. Raya Jakarta-Bogor Km.46, Cibinong, Kab. Bogor, Jawa Barat 16911, Indonesia
Abstract
Kopsia fruticosa, localy named in Indonesia as pronojiwo, is one species belong to the family Apocynaceae known to be rich sources of bioactive alkaloids, particularly monoterpene indole alkaloids (MIAs), with diverse structural frameworks and pharmacological potential. However, phytochemical investigations of this species growing in Indonesia are limited. In this study, two aspidosperma-type MIAs, fruticosamine and fruticosine, were isolated and characterized from the leaves of K. fruticosa growing in the Bogor Botanical Garden, West Java. Both compounds were identified as C-16 epimers sharing the same molecular framework. Their structures were established through 1D and 2D NMR spectroscopic analyses, supported by specific optical rotation measurements, and compared with data in the literature. Further structural investigations were conducted to gain deeper insights into their stereochemical features, including electronic circular dichroism (ECD) spectroscopy and X-ray diffraction (XRD) analysis. These complementary approaches provide additional evidence for distinguishing the subtle configurational differences between the two epimeric alkaloids. The ECD and X-ray diffraction (XRD) analysis of both compounds are reported for the first time. This study highlights the importance of comprehensive structural characterization in elucidating closely related MIAs and contributes to a more complete understanding of alkaloids from K. fruticosa.
