Monodemethylated polymethoxyflavones from sweet orange (Citrus sinensis) peel inhibit growth of human lung cancer cells by apoptosis

Hang Xiao, Chung S. Yang, Shiming Li, Huanyu Jin, Chi Tang Ho, Trusha Patel

Research output: Contribution to journalArticlepeer-review

120 Scopus citations

Abstract

Polymethoxyflavones (PMFs) are almost exclusively found in the Citrus genus, particularly in the peels of sweet orange (Citrus sinensis L. Osbeck) and mandarin (C. reticulate Blanco). We studied the effects of two major PMFs, namely, nobiletin and 3,5,6,7,8,3′,4′-heptamethoxyflavone (HMF), and two major monodemethylated PMFs, namely 5-hydroxy-3,7,8,3′,4′- pentamethoxyflavone (5HPMF), and 5-hydroxy-3,6,7,8,3′,4′- hexamethoxyflavone (5HHMF), on the growth of human lung cancer H1299, H441, and H460 cells. Monodemethylated PMFs were much more potent in growth inhibition of lung cancer cells than their permethoxylated counterpart PMFs. In H1299 cells, cell cycle analyses further revealed that monodemethylated PMFs caused significant increase in sub-G0/G1 phase, suggesting possible role of apoptosis in the growth inhibition observed, whereas the permethoxylated counterpart PMFs did not affect cell cycle distribution at same concentrations tested. These results strongly suggested that the phenolic group is essential for the growth inhibitory activity of monodemethylated PMFs. Further studies in H1299 cells demonstrated that monodemethylated PMFs downregulated oncogenic proteins, such as iNOS, COX-2, Mcl-1, and K-ras, as well as induced apoptosis evidenced by activation of caspase-3 and cleavage of PARP. Our results provide rationale to develop orange peel extract enriched with monodemethylated PMFs into value-added nutraceutical products for cancer prevention.

Original languageEnglish (US)
Pages (from-to)398-406
Number of pages9
JournalMolecular Nutrition and Food Research
Volume53
Issue number3
DOIs
StatePublished - Mar 2009

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Food Science

Keywords

  • Apoptosis
  • Lung cancer
  • Monodemethylated polymethoxyflavone

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