An extract from Taxodium distichum targets hemagglutinin- and neuraminidase-related activities of influenza virus in vitro.

Influenza virus remains an emerging virus and causes pandemics with high levels of fatality. After screening different plant extracts with potential anti-influenza activity, a water extract of Taxodium distichum stems (TDSWex) showed excellent activity against influenza viruses. The EC50 of TDSWex was 0.051 ± 0.024 mg/mL against influenza virus A/WSN/33. TDSWex had excellent antiviral efficacy against various strains of human influenza A and B viruses, particularly oseltamivir-resistant clinical isolates and a swine-origin influenza strain. We observed that the synthesis of viral RNA and protein were inhibited in the presence of TDSWex. The results of the time-of-addition assay suggested that TDSWex inhibited viral entry and budding. In the hemagglutination inhibition assay, TDSWex inhibited the hemagglutination of red blood cells, implying that the extract targeted hemagglutin-related functions such as viral entry. In the attachment and penetration assay, TDSWex showed antiviral activity with EC50s of 0.045 ± 0.026 and 0.012 ± 0.003 mg/mL, respectively. In addition, TDSWex blocked neuraminidase activity. We conclude that TDSWex has bimodal activities against both hemagglutinin and neuraminidase during viral replication.

Antifilarial activity of diterpenoids from Taxodium distichum.

BACKGROUND: Lymphatic filariasis caused by Wuchereria bancrofti, Brugia malayi and B. timori, is a debilitating disease with an adverse social and economic impact. The infection remains unabated in spite of treatment with existing antifilarial drugs diethylcarbamazine (DEC) and ivermectin which are chiefly microfilaricides. There is therefore, need for macrofilaricides, embryostatic agents and better microfilaricides. In the present study we explored the antifilarial potential of crude extract and its molecular fractions of the plant Taxodium distichum using in vitro assay systems and rodent models of B. malayi infection. METHODS: Ethanolic extract (A001) of aerial parts of T. distichum was solvent fractionated and sub-fractionated. Four molecules, 3-Acetoxylabda-8(20), 13-diene-15-oic acid (K001), Beta-sitosterol (K002), labda-8(20),13-diene-15-oic acid (K003) and Metasequoic acid A (K004) were isolated from the fractions and their structure determined by spectroscopic analysis. The extract, subfractions and molecules were evaluated for antifilarial activity against B. malayi by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reduction and motility assays in vitro and in two animal models, Meriones unguiculatus and Mastomys coucha, harbouring B. malayi infection. RESULTS: A001 was effective in killing microfilariae (mf) and adult worms in vitro. The diterpenoid K003 produced 100 % reduction in motility of both mf and adult worms and > 80 % inhibition in MTT reduction potential of adult female worms. In B. malayi-M. unguiculatus model, A001 killed all the adult worms in > 80 % of infected animals. K003 was embryostatic (> 95 %) in this model. In the B. malayi-M. coucha model, K003 killed ~54 % of adult worms (macrofilaricidal activity) and rendered > 36 % female worms sterile; it also stopped any further rise in microfilaraemia after day 42 post-initiation of treatment. CONCLUSION: Ethanolic extract of aerial parts of the plant T. distichum possesses potent antifilarial activity and the active principle was localised to K003 which showed significant macrofilaricidal activity and late suppression of peripheral microfilaraemia and some embryostatic activity. These findings indicate that labdane diterpenoid molecule(s) may provide valuable leads for design and development of new macrofilaricidal agent(s). To the best of our knowledge, this is the first report on antifilarial efficacy of products from the plant T. distichum.

Compositional and Enantiomeric Analysis of the Essential Oil of Taxodium distichum from India.

The leaf essential oil composition of Taxodium distichum L., collected from the foothills of Uttarakhand, India was analyzed using gas chromatography-flame ionization detection (GC-FID) and gas chromatography-mass spectrometry (GC-MS) equipped with DB-5 (5% diphenyl-95% dimethyl polysiloxane) and ß-cyclodextrin (6-tertiarybutyldimethylsiliyl-2,3-diethyl-ß-cyclodextrin) capillary columns. Seventeen constituents, representing 90.3 to 99.4% of composition were identified in the essential oils from different seasons, viz. spring, summer, rainy, autumn and winter. The essential oil composition was mainly dominated by monoterpene hydrocarbons, represented mainly by α-pinene (81.9-94.3%). Other constituents of the oil were myrcene (0.5-4.7%), ß-pinene (2.2-2.9%), limonene (0.5-1.5%), camphene (≤ 0.03-1.5%), and α-terpineol (upto 1.6%). Chiral analysis of T. distichum essential oil on an ethyl substituted ß-cyclodextrin capillary column revealed the presence of a-pinene in racemic form, with an enantiomeric ratio of 49.3% for (1R)-(+)- and 50.7% for (1S)-(-)-α-pinene.

Antibacterial activity of Taxodium ascendens diterpenes against methicillin-resistant Staphylococcus aureus.

One new and seven known diterpenes were identified from an antibacterial chromatographic fraction of Taxodium ascendens. Of these, demethylcryptojaponol (2), 6-hydroxysalvinolone (3), hydroxyferruginol (4), and hinokiol (5) demonstrated potent activity against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). These compounds represent a class of synthetically accessible compounds that could be further developed for treatment of drug-resistant bacterial infections.

A new norlignan from Taxodium ascendens.

A new norlignan, (2R,3R,4S,5S)-2,4-bis(4-hydroxyphenyl)-3,5-dihydroxy-tetrahydropyran (1), together with 9 known compounds were isolated from the branches and leaves of Taxodium ascendens. Their structures were mainly determined on the basis of MS, IR, 1D and 2D NMR spectral evidences. Methanol extract showed inhibitory activity on carbonic anhydrase II with an IC(50) value of 4.27 microg/ml, acetone extract and methanol extract inhibited activity of cathepsin B with IC(50) values of 2.12 and 3.71 microg/ml, respectively.

Natural biflavones as novel inhibitors of cathepsin B and K.

Cathepsin B and K, two important members in lysosomal proteases, involve in many serious human diseases, such as tumor and osteoporosis. In order to find their novel inhibitors, we performed the inhibition assays of cathepsin B and cathepsin K in vitro, randomly screened compounds from plants, and found six biflavones, named AMF1-5 and HIF, can potently inhibit cathepsin B and cathepsin K, especially AMF4 and HIF with IC(50) of 0.62 and 0.58 microM against cathepsin B. They are novel inhibitors for cathepsin B and K. Inhibition and flexible docking studies indicated that these biflavones are reversible inhibitors of cathepsin B, and their binding patterns and interaction modes with cathepsin B made them more specific to cathepsin B endopeptidase.