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The dried leaves and rhizomes of Alpinia zerumbet have been traditionally used as food and medicine. Anti-inflammatory activity-guided phytochemical investigation into the rhizomes of A. zerumbet led to the isolation of 17 compounds including 10 neolignans (1-10, 1a, 1b, 2a, 2b, 3a, 3b, 4, and 5 are new compounds) and seven diarylheptanoids (11-17) in which 1-3 were three pairs of enantiomers. 4 was only one enantiomer and 5 was a racemic mixture. Compounds 1a, 1b, 2a, and 2b incorporated an 8',9'-dinorneolignan skeleton, which was rare in the lignan family. The planar structures of these compounds were elucidated by extensive analyses of spectroscopic data. The relative and absolute configurations were determined by the time-dependent density functional theory (TDDFT)-based electronic circular dichroism (ECD) calculation method. The 95% ethanol extract and ethyl acetate extract of A. zerumbet were found to show anti-inflammatory activity against croton oil-induced ear edema in mice with inhibition rates of 20.0 and 47.6% at a dose of 80 mg/kg, respectively. Bioassays showed that compounds 1a, 1b, 2a, 2b, and 12 moderately inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 cells with IC50 values of 3.62, 7.63, 6.51, 5.60, and 8.33 μM, respectively.

In folkloric plant medicines, Alpinia zerumbet (AZ) has been popularly recognized as an exellent hepatoprotector. To search for a good high-density lipoprotein cholesterol (HDL-C) elevating herbal preparation, we examined AZ for its antioxidant and hypolipidaemic bioactivities, especially its HDL-C elevating activity. AZ seeds contain 0.51% essential oils (SO), which are comprised of monoterpenoids, oxygenated monoterpenoids, sesquiterpenoids, oxygenated sesquiterpenoids, aldehydes, acid, and esters. Gas chromatography/mass spectrometry analysis indicated that most of the monoterpenes and sesquiterpenes were recoverable in pentane eluent, whilst the oxygenated monoterpenoids and sesquiterpenoids remained in ether eluent. The high contents of rutin, quercetin, and polyphenolics in ethanolic extract of AZ seeds exhibit moderate antilipoperoxidative but potent DPPH free radical scavenging bioactivities. Conclusively, both seed powder (SP) and SO are effective hypolipidaemics with amazingly potent HDL-C elevating capabilities. On the basis of hepatoprotectivity, SP is a more feasible hypolipidemic agent as well as a promising HDL-C elevating plant medicine.

AIDS and influenza are viral pandemics and remain one of the leading causes of human deaths worldwide. The increasing resistance of these diseases to synthetic drugs demands the search for novel compounds from plant-based sources. In this regard, the leaves and rhizomes of Alpinia zerumbet, a traditionally important economic plant in Okinawa, were investigated for activity against HIV-1 integrase (IN) and neuraminidase (NA). The aqueous extracts of leaves and rhizomes had IN inhibitory activity with IC(50) values of 30 and 188 μg/mL, whereas against NA they showed 50% inhibition at concentrations of 43 and 57 μg/mL, respectively. 5,6-Dehydrokawain (DK), dihydro-5,6-dehydrokawain (DDK), and 8(17),12-labdadiene-15,16-dial (labdadiene) were isolated from the rhizomes and were tested for enzyme inhibitions. DK and DDK strongly inhibited IN with IC(50) of 4.4 and 3.6 μg/mL, respectively. Against NA, DK, DDK, and labdadiene exhibited mixed type of inhibition with respective IC(50) values of 25.5, 24.6, and 36.6 μM and K(i) values ranging from 0.3 to 2.8 μM. It was found that DDK is a slow and time-dependent reversible inhibitor of NA, probably with a methoxy group as its functionally active site. These results suggest that alpinia could be used as a source of bioactive compounds against IN and NA and that DK and DDK may have possibilities in the design of drugs against these viral diseases.