Antiviral Activities of Hibiscus sabdariffa L. Tea Extract Against Human Influenza A Virus Rely Largely on Acidic pH but Partially on a Low-pH-Independent Mechanism.

Influenza A virus (IAV) infection is perennially one of the leading causes of death worldwide. Effective therapy and vaccination are needed to control viral expansion. However, current anti-IAV drugs risk inducing drug-resistant virus emergence. Although intranasal administration of whole inactivated virus vaccine can induce efficient protective immunity, formalin and ß-propiolactone are the currently used and harmful inactivating agents. Here, we analyzed the antiviral activity of hibiscus (Hibiscus sabdariffa L.) tea extract against human IAV and evaluated its potential as a novel anti-IAV drug and a safe inactivating agent for whole inactivated vaccine. The in vitro study revealed that the pH of hibiscus tea extract is acidic, and its rapid and potent antiviral activity relied largely on the acidic pH. Furthermore, the mouse study showed that the acidic extract was not effective for either therapeutic or vaccination purposes. However, hibiscus tea extract and protocatechuic acid, one of the major components of the extract, showed not only potent acid-dependent antiviral activity but also weak low-pH-independent activity. The low-pH-independent activity did not affect the conformation of immunodominant hemagglutinin protein. Although this low-pH-independent activity is very limited, it may be suitable for the application to medication and vaccination because this activity is not affected by the neutral blood environment and does not lose antigenicity of hemagglutinin. Further study of the low-pH-independent antiviral mechanism and attempts to enhance the antiviral activity may establish a novel anti-IAV therapy and vaccination strategy.

Structure Revision of (22E)-Ergosta-7,22-diene-3ß,5α,6ß,9α,14α- pentol from the Spores of the Medicinal Mushroom Ganoderma lucidum.

Careful reexamination of the published ¹H and ¹³C NMR spectral data of (22E)-ergosta-7,22-diene-3ß,5α,6ß,9α,14α-pentol (1), isolated from the spores of the medicinal mushroom Ganoderma lucidum, indicates that, in reality, the compound is (22E)-ergosta-7,22-diene-3ß,5α,6ß,9α,14ß-pentol (5).

Structure Revision of (22E)-24-Methylcholesta-8(14),22-diene- 3ß,5α,6ß,7α-tetraol from the Marine-Derived Fungus Penicillium sp.

Careful reexamination of the published ¹H- and ¹³C-NMR spectral data of (22E)-24-methylcholesta-8(14),22-diene-3ß,5α,6ß,7α-tetraol (1), isolated from the marine-derived fungus Penicillium sp., indicates that, in reality, the compound is 5α,6α-epoxy-(22E,24R)-24-methylcholesta-8(14),22-diene-3ß,7α-diol (5).

Structure Revision of Two Polyoxygenated Sterols from the Marine Sponge Neofibularia nolitangere.

Careful reexamination of the published 1H- and 13C-NMR spectral data of (24S)-24-ethylcholest-8-ene-3ß,5α,6ß,7α-tetraol (1) and (24S)-24-ethylcholest-8(14)-ene-3ß,5α,6ß,7α-tetraol (2), isolated from the marine sponge Neofibularia nolitangere, indicates that, in reality, compounds 1 and 2 are (24S)-5α,6α- epoxy-24-ethylcholest-8-ene-3ß,7α-diol (9) and (24S)-5α,6α-epoxy-24-ethylcholest-(14)-ene-3ß,7α-dio (10), respectively.

Terpenoids and sterols from some Japanese mushrooms.

Over the past twenty years, our research group has been studying the chemical constituents of mushrooms. From nineteen species, namely, Amanita virgineoides Bas (Amanitaceae), Daedaleopsis tricolor (Bull.: Fr.) Bond. et Sing. (Polyporaceae), Grifolafrondosa (Fr.) S. F. Gray (Polyporaceae), Hericium erinaceum (Bull.: Fr.) Pers. (Hericiaceae), Hypsizigus marmoreus (Peck) Bigelow (Tricholomataceae), Lactarius piperatus (Scop.: Fr.) S. F. Gray (Russulaceae), Lentinula edodes (Berk.) Sing. (Pleurotaceae), Lyophyllyum connatum (Schum.: Fr.) Sing. (Tricholomataceae), Naematoloma sublateritium (Fr.) Karst. (Strophariaceae), Ompharia lapidescens Schroeter (Polyporaceae), Panellus serotinus (Pers.: Fr.) Kuhn. (Tricholomataceae), Pholiota nameko (T. Ito) S. Ito et Imai in Imai (Strophariaceae), Pleurotus eringii (DC.: Fr.) Quel. (Pleurotaceae), Polyporus umbellatus Fries (Polyporaceae), Russula delica Fr. (Russulaceae), Russula sanguinea (Bull.) Fr. (Russulaceae), Sarcodon aspratus (Berk.) S. Ito (Thelephoraceae), Tricholoma matsutake (S. Ito et Imai) Sing. (Tricholomataceae), and Tricholomaportentosum (Fr.) Quel. (Tricholomataceae), we isolated eight new sesquiterpenoids, six new meroterpenoids, three new triterpenoids, and twenty eight new sterols. In this review, structural features of these new compounds are discussed.

Three new lactarane sesquiterpenoids from the mushroom Russula sanguinea.

The family Russulaceae is one of the largest in the subdivision Basidiomycotina in Whittaker's Kingdom of Fungi [1] and comprises hundreds of species, worldwide distributed, belonging to the genera Lactarius and Russula. While secondary metabolites occurring in the fruiting bodies of Lactarius species have been well investigated [2], the Russula mushrooms have received less attention, notwithstanding the larger number of existing species [3]. In a previous paper, we reported the isolation and structural elucidation of sterols from the fruiting bodies of Russula sanguinea (Bull.) Fr. [4]. In the course of further studies on the constituents of the above mushroom, three new lactarane sesquiterpenoids, sangusulactones A-C (1-3), along with two known compounds have been isolated (Figure 1). This paper deals with the structural elucidation of the new compounds. The known compounds 4 and 5 were identified as blennin A (4) [5] and 15-hydroxyblennin A (5) [6], respectively, by comparison of their spectral data with those reported in the literature.

[New sesquiterpenoids from the rhizomes of Petasites japonicus MAXIM. and the roots of Ligularia dentata HARA].

Over the past twenty years, our research group has been involved in the phytochemical study of terpenoids from Compositae plants. From seven species, namely, Erigeron annuus (L.) PERS., Erigeron philadelphicus L., Erigeron sumatrensis RETZ., Ligularia dentata HARA, Ligularia stenocephala MATSUM. et KOIDZ., Petasites japonicus MAXIM., and Tussilago farfara L., we isolated 83 new compounds. In this review, structural features of 19 eremophilane-type sesquiterpenoids from rhizomes of P. japonicus and 9 bisabolane-type sesquiterpenoids from roots of L. dentata are discussed.

A new geranylated aromatic compound from the mushroom Hericium erinaceum.

A new geranylated aromatic compound, 5-[(2'E)-3',7'-dimethyl-2',6'-octadienyl]-4-hydroxy-6-methoxy-1-isoindolinone (1), was isolated from the fruiting bodies of the mushroom Hericium erinaceum (Bull.: Fr.) Pers. (Hericiaceae) together with three known sterols, 5alpha,6alpha-epoxy-(22E)-ergosta-8(14),22-diene-3beta,7alpha-diol (2), (22E)-ergosta-7,9(11),22-triene-3beta,5alpha,6beta-triol (3) and (22E)-ergosta-7,22-diene-3beta,5alpha,6alpha,9alpha-tetrol (4). The structure of the new compound was elucidated on the basis of spectral data.

Terpenoids and related compounds from plants of the family Compositae (Asteraceae).

This review will summarize the authors' studies on the structures of terpenoids and related compounds from plants of the family Compositae (Asteraceae). Eighty three new compounds have been obtained and characterized from seven species of the plants, namely, Erigeron annuus (L.) Pers., Erigeron philadelphicus L., Erigeron sumatrensis Retz, Ligularia dentata Hara, Ligularia stenocephala Matsum. et Koidz., Petasites japonicus Maxim. and Tussilago farfara L.

Six new secoiridoids from the dried fruits of Ligustrum lucidum.

Six new secoiridoid constituents, named isoligustrosidic acid (1), 6'-O-trans-cinnamoyl 8-epikingisidic acid (2), 6'-O-cis-cinnamoyl 8-epikingisidic acid (3), oleopolynuzhenide A (4), nuzhenals A (5) and B (6) were isolated from the dried fruits of Ligustrum lucidum AIT. Their structures were established on the basis of spectral and chemical data.

Structure and cytotoxic activity of enzymatic hydrolysis products of secoiridoid glucosides, isoligustroside and isooleuropein.

Hydrolysis of isoligustroside (1) and isooleuropein (2), secoiridoid glucosides, in the presence of ß-glucosidase provided 2-(4-hydroxyphenyl)methyl (2R,3S,4S)-3-formyl-3,4-dihydro-4-(2-methoxy-2-oxoethyl)-2-methyl-2H-pyran-5-carboxylate (3) and 2-(3,4-dihydroxyphenyl)methyl (2R,3S,4S)-3-formyl-3,4-dihydro-4-(2-methoxy-2-oxoethyl)-2-methyl-2H-pyran-5-carboxylate (4), respectively. The structures of 3 and 4 were elucidated on the basis of extensive spectral analyses, including 2D-NMR experiments. Compounds 3 and 4 were found to be new rearrangement products of the aglycones of 1 and 2. The cytotoxic activities of 3 and 4 were evaluated using a disease-oriented panel of 39 human cancer cell lines and showed moderate cytotoxic activity for 4, while 3 exhibited weaker activity compared to that of 4.

Two new glycosides from Viburnum plicatum Thunb. ex Murray var. plicatum f. plicatum.

Two new glycosides, named plicatumoside A (1) and (+)-neomedioresinol 4,4'-di-O-ß-D: -glucopyranoside (2), together with 13 known compounds, were isolated from the leaves of Viburnum plicatum Thunb. ex Murray var. plicatum f. plicatum. Their structures were established on the basis of NMR, MS, and chemical data.

Two new phenolic glycosides from Viburnum plicatum var. plicatum f. plicatum.

Two new glycosides, named dideoxyplicatumoside A (1) and erythro-syringylglycerol-beta-O-4'-(+)-isoeucommin A 4'''-O-beta-D-glucopyranoside (2), together with seven known compounds, were isolated from the leaves of Viburnum plicatum Thunb. ex Murray var. plicatum f. plicatum. Their structures were established on the basis of NMR, MS and chemical data.

Glycosides from whole plants of Glechoma hederacea L.

From dried whole plants of Glechoma hederacea L. (Labiatae), seven known glycosides were isolated and identified: (6R,7E,9R)-megastigma-4,7-dien-3-one 9-O-beta-D-glucopyranoside (1), apigenin 7-O-neohesperidoside (2), chrysoeriol 7-O-neohesperidoside (3), (+)-pinoresinol 4,4'-bis-O-beta-D-glucopyranoside (4), (+)-syringaresinol 4,4'-bis-O-beta-D-glucopyranoside (5), (+)-lariciresinol 4,4'-bis-O-beta-D-glucopyranoside (6), and (7R,8R)-threo-7,9,9'-trihydroxy-3,3'-dimethoxy-8-O-4'-neolignan 4-O-beta-D-glucopyranoside (7).

Three new glycosides from the leaves of Hydrangea macrophylla subsp. serrata (THUNB.) MAKINO.

Three new glycosides, 7-deoxyloganic acid beta-D-glucopyranosyl ester (1), (3R)-hydrangenol 8,4'-di-O-beta-D-glucopyranoside (2), and (6R,7E,9R)-megastigma-4,7-dien-3-one 9,13-di-O-beta-D-glucopyranoside (3), have been isolated from the leaves of Hydrangea macrophylla subsp. serrata (THUNB.) MAKINO (Saxifragaceae). The structures of 1-3 were elucidated on the basis of spectral data and chemical evidence.

Two new glycosides from the whole plants of Glechoma hederacea L.

Two new glycosides, 7S,7'S,8R,8'R-icariol A(2)-9-O-beta-D-glucopyranoside (1) and 4-allyl-2-hydroxyphenyl 1-O-beta-D-apiosyl-(1-->6)-beta-D-glucopyranoside (2), were isolated from the dried whole plants of Glechoma hederacea L. (Labiatae) together with four known compounds, cistanoside E (3), dihydrodehydrodiconiferyl alcohol 4-O-beta-D-glucopyranoside (4), apigenin 7-O-beta-D-glucuronopyranoside (5) and luteolin 7-O-beta-D-glucopyranoside (6). The structures of the new compounds were elucidated on the basis of chemical and spectral analysis.

Five new phenylethanoid glycosides from the whole plants of Lamium purpureum L.

Five new phenylethanoid glycosides, lamiusides A (1), B (2), C (3), D (4) and E (5), were isolated from the whole plants of Lamium purpureum L. (Labiatae) together with seven known compounds (6-12). On the basis of chemical and spectral analyses, the structures of the new compounds were elucidated to be 2-(3,4-dihydroxyphenyl)ethyl-O-beta-D-galactopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->3)-(4-O-trans-caffeoyl)-beta-D-glucopyranoside (1), 2-(3,4-dihydroxyphenyl)ethyl-O-beta-D-galactopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->3)-(4-O-trans-feruloyl)-beta-D-glucopyranoside (2), 2-(3,4-dihydroxyphenyl)ethyl-O-beta-D-galactopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->3)-(6-O-trans-caffeoyl)-beta-D-glucopyranoside (3), 2-(3,4-dihydroxyphenyl)-R,S-methoxy-ethyl-O-beta-D-galactopyranosyl-(1-->2)-alpha-L-rhamnopyranosyl-(1-->3)-(4-O-trans-caffeoyl)-beta-D-glucopyranoside (4) and 2-(3-hydroxy-4-methoxyphenyl)ethyl-O-alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucopyranosyl-(1-->6)-(4-O-cis-feruloyl)-beta-D-glucopyranoside (5). In addition, the radical-scavenging activities of compounds 1-4 on 1,1-diphenyl-2-picrylhydrazyl radical were examined.

Three new dimeric benzofuran derivatives from the roots of Ligularia stenocephala MATSUM. et KOIDZ.

Three new dimeric benzofuran derivatives, ligulacephalins A (1), B (2) and C (3), were isolated from the roots of Ligularia stenocephala MATSUM. ET KOIDZ. (Compositae) together with three known compounds, 5,6-dimethoxy-2-isopropenylbenzofuran (4), euparin (5) and (R)-(-)-hydroxytremetone (6). The structures of the new compounds were determined by spectroscopic evidence. The chiral HPLC analysis demonstrated that 1-3 occurred as a racemate. The absolute configurations of each enantiomer from 1-3 were elucidated on the basis of circular dichroism (CD) data.

Two new aromatic compounds from Hericium erinaceum (BULL.: FR.) PERS(1).

Two new aromatic compounds, erinacerins A (1) and B (2), were isolated from the fruiting bodies of Hericium erinaceum (BULL.: FR.) PERS. (Hericiaceae) together with a known compound, hericenone A (3). The structures of the new compounds were elucidated on the basis of their spectral data. It was found that 1 occurred as a racemate.

Secoiridoid glycosides from Gentiana scabra.

Six new secoiridoid glycosides, gentiascabraside A (1), 6beta-hydroxyswertiajaposide A (2), 1-O-beta-d-glucopyranosyl-4-epiamplexine (3), and scabrans G3 (4), G4 (5), and G5 (6), have been isolated from the rhizomes and roots of Gentiana scabra together with a known compound, swertiajaposide A (7). The structures of the new compounds were determined by spectroscopic (NMR, MS) and chemical means.