Paliasanines A-E, 3,4-Methylenedioxyquinoline Alkaloids Fused with a Phenyl-14-oxabicyclo[3.2.1]octane Unit from Melochia umbellata var. deglabrata
- J Nat Prod. 2020 Oct 23;83(10):2931-2939. doi: 10.1021/acs.jnatprod.0c00454.
- 1. School of Pharmaceutical Sciences, College of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, 920-1192, Japan.
- 2. Department of Pharmacognosy-Phytochemistry, Faculty of Pharmacy, Hasanuddin University, Makassar, 90245, Indonesia.
- 3. School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan.
- 4. Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599-7568, United States.
- 5. Duke University Medical Center, Durham, North Carolina 27710, United States.
- 6. Chinese Medicine Research and Development Center, China Medical University and Hospital, Taichung 401, Taiwan.
Five new Quinoline Alkaloids, paliasanines A-E (1-5), and 17 known compounds (6-22) were isolated from a methanol extract of Melochia umbellata var. deglabrata leaves. Their chemical structures were elucidated by analysis of HRMS and 1D and 2D NMR spectroscopic data. Compounds 1-5 are the first naturally occurring 3,4-methylenedioxyquinolines incorporating an oxabicyclo[3.2.1]octane unit. Compounds 6 and 7 displayed selective cytotoxicity (IC50 5.9-8.4 μM) against A549 and MCF-7 cell lines, while compounds 1-5 were not active. Compounds 1-3 did not exhibit an anti-HIV effect in MT4 cells, although the related Quinolone derivative waltherione A exhibited significant activity. These preliminary results indicate that the 3-methoxy-4-quinolone skeleton might be preferred for both antiproliferative and anti-HIV activities.