A flavanone derivative from the Asian medicinal herb (Perilla frutescens) potently suppresses IgE-mediated immediate hypersensitivity reactions.

Perilla frutescens is a dietary leafy herb consumed as a traditional Japanese condiment as well as used for Chinese medicine with anti-inflammatory activity. Here we report a hitherto-unrecognized P. frutescens phytochemical that potently suppresses IgE-mediated type I hypersensitivity reactions. Structural analysis reveals that the purified anti-allergic compound (Perilla-derived methoxyflavanone, PDMF) is identified as 8-hydroxy-5,7-dimethoxyflavanone. PDMF significantly inhibits IgE-mediated histamine release from RBL-2H3 rat basophilic leukemia cells as compared with those seen in known P. frutescens-derived anti-inflammatory polyphenols. We also show that oral administration of PDMF not only suppresses passive cutaneous anaphylaxis, but also prevents allergic rhinitis-like nasal symptoms in a murine model of Japanese cedar pollinosis. Mechanistically, PDMF negatively regulates Akt phosphorylation and intracellular Ca2+ influx, both of which are essential for mast cell secretory granule translocation and its exocytosis upon high-affinity IgE receptor (FcεRI) cross-linking. These results represent PDMF as a new potent anti-allergic phytochemical useful for prevention of IgE-driven hypersensitivity reactions.

Synergistic tumor suppression by a Perilla frutescens-derived methoxyflavanone and anti-cancer tyrosine kinase inhibitors in A549 human lung adenocarcinoma.

Anti-cancer tyrosine kinase inhibitors (TKIs) are effective in many types of cancers including non-small cell lung cancer, while appearance of TKI-resistant tumors suggests a need for the development of their potentiation strategies. We have previously shown that a methoxyflavanone derivative from the Asian medicinal herb Perilla frutescens (Perilla-derived methoxyflavanone; PDMF) shows a prominent anti-tumor activity against A549 human lung adenocarcinoma. Here we show that PDMF and anti-cancer TKIs (nilotinib, bosutinib, dasatinib, and ponatinib) synergistically suppress proliferation of A549 cells. Flow cytometric analysis indicated that co-stimulation with nilotinib (4 µM) and PDMF induced G2/M cell cycle arrest in low PDMF doses (10-50 µM), whereas this combination triggered de novo G1 arrest in higher PDMF dosages (50-125 µM). We also found that co-administration with nilotinib and PDMF significantly suppressed in vivo tumorigenicity of A549 cells in athymic nude mice.

A methoxyflavanone derivative from the Asian medicinal herb (Perilla frutescens) induces p53-mediated G2/M cell cycle arrest and apoptosis in A549 human lung adenocarcinoma.

Perilla frutescens is an Asian dietary herb consumed as an essential seasoning in Japanese cuisine as well as used for a Chinese medicine. Here, we report that a newly found methoxyflavanone derivative from P. frutescens (Perilla-derived methoxyflavanone, PDMF; 8-hydroxy-5,7-dimethoxyflavanone) shows carcinostatic activity on human lung adenocarcinoma, A549. We found that treatment with PDMF significantly inhibited cell proliferation and decreased viability through induction of G2/M cell cycle arrest and apoptosis. The PDMF stimulation induces phosphorylation of tumor suppressor p53 on Ser15, and increases its protein amount in conjunction with up-regulation of downstream cyclin-dependent kinase inhibitor p21Cip1/Waf1 and proapoptotic caspases, caspase-9 and caspase-3. We also found that small interfering RNA knockdown of p53 completely abolished the PDMF-induced G2/M cell cycle arrest, and substantially abrogated its proapoptotic potency. These results suggest that PDMF represents a useful tumor-preventive phytochemical that triggers p53-driven G2/M cell cycle arrest and apoptosis.

Impact of Histone H1 on the Progression of Allergic Rhinitis and Its Suppression by Neutralizing Antibody in Mice.

Nuclear antigens are known to trigger off innate and adaptive immune responses. Recent studies have found that the complex of nucleic acids and core histones that are derived from damaged cells may regulate allergic responses. However, no fundamental study has been performed concerning the role of linker histone H1 in mast cell-mediated type I hyperreactivity. In this study, we explored the impact of histone H1 on mast cell-mediated allergic responses both in vitro and in vivo. In the course of a bona-fide experimental allergen sensitization model upon co-injection with alum adjuvant, ovalbumin (OVA), but not PBS, induced elevated levels of circulating histone H1. Intranasal challenge with histone H1 to OVA/alum- (but not PBS/alum)-sensitized mice induced significantly severer symptoms of allergic rhinitis than those in mice sensitized and challenged with OVA. A monoclonal antibody against histone H1 not only suppressed mast cell degranulation, but also ameliorated OVA-induced nasal hyperreactivity and IgE-mediated passive cutaneous anaphylaxis. Our present data suggest that nuclear histone H1 represents an alarmin-like endogenous mediator acting on mast cells, and that its blockage has a therapeutic potential for mast cell-mediated type I hyperreactivity.