Plant-derived essential oils (EOs) are used in medicines, disinfectants, and aromatherapy products. Information on the antifungal activity of EO of Alpinia zerumbet var. exelsa (known as Daito-gettou) found in Kitadaito Island, Okinawa, is limited. Therefore, we aimed to evaluate the antifungal activity of EOs obtained via steam distillation of leaves of Daito-gettou, which is a hybrid of A. zerumbet and A. uraiensis. Daito-gettou EO showed antifungal activity (minimum inhibitory concentration = 0.4%) against Aspergillus brasiliensis NBRC 9455, which was comparable to that of A. zerumbet found in the Okinawa main island. Gas chromatography/mass spectrometry revealed that the main components of Daito-gettou EOs are γ-terpinene, terpinen-4-ol, 1,8-cineole, 3-carene, and p-cymene. Terpinen-4-ol content (MIC = 0.075%) was 17.24%, suggesting that the antifungal activity of Daito-gettou EO was mainly attributable to this component. Daito-gettou EO and terpinen-4-ol inhibited mycelial growth. Moreover, calorimetric observations of fungal growth in the presence of Daito-gettou EO showed a characteristic pattern with no change in the initial growth rate and only a delay in growth. As this pattern is similar to that of amphotericin B, it implies that the action mode of Daito-gettou EO and terpinen-4-ol may be fungicidal. Further studies on the molecular mechanisms of action are needed for validation.

The number of people with dementia is increasing annually worldwide. Alzheimer’s disease (AD), which accounts for the highest percentage of dementia-causing diseases, remains difficult to cure, and prevention of its onset is important. We aimed to discover new AD-preventive ingredients and investigate the inhibitory effects of ten different species of seafood digests prepared by protease treatment on β-secretase 1 (BACE1) activity. Substantial inhibition of BACE1 activity was observed in five species of seafood, and protease-digested whitebait (WPD) showed the highest inhibitory effect among the ten marine samples. We further examined the potential of WPD as an AD preventive component using a familial AD strain (5xFAD) murine model. The intraperitoneal administration of WPD for 28 days substantially decreased the insoluble amyloid β_1–42 content and the expression of glial fibrillary acidic protein, a marker of astrogliosis, in the cerebral cortex of the 5xFAD mice. These results strongly suggest that WPD is a novel functional food-derived ingredient with preventive effects against AD.

We have previously demonstrated the anti-influenza virus activity of a soybean extract, indicating the presence of compounds that prevent viral entry into cells. In this study, we sought to identify the compounds in hydrothermal extracts of soybean that blocked viral entrance and analyzed their mechanisms of action. Hot aqueous extracts of roasted soybeans were separated by reverse-phase chromatography on an octadecylsilyl C18 column, and the antiviral activity of individual fractions was measured during the viral entry and culture phases. Fractions 2-5 were found to have a significantly high antiviral activity during the culture phase, whereas during the entry phase, fractions 2-4 showed strong antiviral activity, with fraction 4 having notably potent inhibitory effects. We accordingly analyzed fractions 3 and 4 using liquid chromatography quadrupole time-of-flight mass spectrometry and identified potential anti-viral compounds, including acacetin, 9,10,13-trihydroxy-11-octadencenoic acid, and soy saponin IV. Furthermore, the analysis of these active components revealed that acacetin and soyasaponin were active during the entry phase, and subsequent assessments of their inhibitory effects on influenza virus entry into cells revealed that acacetin inhibits the endocytosis process during viral uptake, whereas soyasaponin inhibits virus binding to its receptor. These findings thus indicate a novel mechanism for the anti-influenza activity of acacetin.