Isoflavones from the leaves of Nicotiana tabacum and their anti-tobacco mosaic virus activities

Three new isoflavones, 4′,8-dihydroxy-6,7-dimethoxyisoflavone (1), 4′,6-dihydroxy-8-methoxycarbonyl-7-methoxyisoflavone (2), 4′,7-dimethoxy-8-hydroxymethyl-6-hydroxyisoflavone (3), together with three known flavones (4–6), were isolated from the leaves of Nicotiana tabacum. Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D NMR techniques. Compounds 1–3 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compounds 1–3 (at the concentration of 20 μM) exhibited anti-TMV activities with inhibition rates of 25.2, 22.6, and 27.4%, respectively.     

Three new prenylated xanthones from Comastoma pedunculatum and their anti-tobacco mosaic virus activity

Comastomaxanthones A–C (1–3), three new xanthones with a rare 2-oxoprenyl substituent, along with three known ones (4–6) were isolated from the aerial parts of Comastoma pedunculatum. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. In addition, compounds 1–6 were tested for their anti-tobacco mosaic virus activity. The results showed that all isolated compounds exhibited weak anti-TMV activity with IC₅₀ values ranging from 122.7 to 242.9 μM.     

Phenolic amides from the leaves of Nicotiana tabacum and their anti-tobacco mosaic virus activities

Three new phenolic amides, tabamides A–C (1–3), together with three known phenolic amides (4–6), were isolated from the leaves of Nicotiana tabacum. Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D NMR techniques. Compounds 1–6 were also tested for their anti-tobacco mosaic virus (anti-TMV) activity. The results showed that compound 1 exhibited high anti-TMV activity with inhibition rate of 38.6%, which is higher than that of positive control (ningnanmycin). The other compounds also showed potential anti-TMV activity with inhibition rates in the range of 15.3–26.5%, respectively.     

Anti-tobacco mosaic virus phenylpropanoids from the stems of Nicotiana tabacum

Three new phenylpropanoids, 3-(6-methoxy-3-oxo-1, 3-dihydroisobenzofuran-5-yl)-3-oxopropyl acetate (1), 3-hydroxy-1-(6-methoxy-1, 3-dihydroisobenzofuran-5-yl)propan-1-one (2), and 3-hydroxy-1-(6- methyl-1, 3-dihydroisobenzofuran-5-yl)propan-1-one (3), together with three known phenylpropanoids (4–6) were isolated from the stems of Nicotiana tabacum. Their structures were examined using different spectroscopic techniques, including extensive 1D- and 2D NMR. Compounds 1–6 were also evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The anti-TMV results demonstrated that compounds 1 and 6 exhibited high anti-TMV activities, with inhibition rates of 34.6 and 35.4%, both of which were higher than the positive control (32.5%). The other compounds (2–5) also had anti-TMV activities, with inhibition rates between 16.8 and 28.6%.     

Flavonoids from the bark and stems of Cassia fistula and their anti-tobacco mosaic virus activities

Two new flavonoids, fistulaflavonoids B and C (1–2), together with five known flavonoids (3–7) were isolated from the bark and stems of Cassia fistula. Their structures were determined by means of HRESIMS, extensive 1D and 2D NMR spectroscopic studies and chemical evidences. The anti-tobacco mosaic virus (anti-TMV) activity of the isolated flavonoids was also evaluated. The results showed that compounds 1 and 2 showed high anti-TMV activity with inhibition rate of 28.5% and 31.3%, which is higher than that of Ningnanmycin (24.7%). Compounds 4–7 showed modest anti-TMV activity with inhibition rate of 18.5%, 22.7%, 16.4%, and 15.3%, respectively.     

Three new flavones from the roots and stems of Tiandeng tobacco and their anti-TMV activities

Three new flavone derivatives, paranicflavones A–C (1–3), together with three known similar compounds (4–6), were isolated from their roots and stems of Tiandeng tobacco. Their structures were elucidated by spectroscopic methods, including extensive ¹H and ¹³C NMR techniques. Additionally, compounds 1–6 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities, and compound 2 exhibited anti-TMV activity with inhibition rate of 35.8%, which is higher than that of positive control, ningnanmycin.     

Three new alkaloids from the twigs of Cassia siamea and their bioactivities

Three new tricyclic alkaloid, siamalkaloids A–C (1–3), together with three known alkaloids (3–6) were isolated from the twigs of Cassia siamea. Their structures were determined by means of HRESIMS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1–6 were tested for their anti-tobacco mosaic virus (anti-TMV) activity, and compound 3 exhibited high anti-TMV activity with inhibition rate of 34.5%. This rate is higher than that of positive control. In addition, the cytotoxicity of compounds 1–6 were also tested, and compounds 2–6 showed weak activity with IC₅₀ values ranging from 2.8 to 9.4 μM for some tested human tumor cell lines.     

Three new xanthones from the stems of Garcinia oligantha and their anti-TMV activity

For more bioactive compounds, phytochemical investigations of the acetone extract of the stems of Garcinia oligantha resulted in the isolation of three new xanthones (1–3) and five known analogues (4–8). Structural elucidations of 1–3 were performed by spectral methods such as 1D and 2D (HMQC, HMBC, and ROESY) NMR spectroscopy, in addition to high resolution mass spectrometry. Compounds 1, 2, 6, 7, and 8 showed anti-tobacco mosaic virus (anti-TMV) activities with inhibition rates above 10%.     

Biphenyl derivatives from the twigs of Garcinia bracteata and their biological activities

Three new biphenyl derivatives, bractebiphenyls A–C (1–3), along with five known biphenyl derivatives (4–8) were isolated from the acetone extract of the twigs of Garcinia bracteata. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. The anti-tobacco mosaic virus (anti-TMV) activities of 1–8 were evaluated. Compound 3 showed high anti-TMV activities with inhibition rates of 28.4%, which is close to that of Ningnanmycin (30.2%). Compounds 1–3, 6 and 8 were also tested for their cytotoxicities against five human tumor cell lines (NB4, A549, SHSY5Y, PC3, and MCF7), and 3 showed high cytotoxicities against A549 and PC3 cell with IC₅₀ values of 3.6 and 2.7 μM, respectively.     

Three new 3-methyl-2-arylbenzofurans from the fermentation products of an endophytic fungus Phomopsis sp. and their anti-TMV activity

Three new arylbenzofurans, 7-methoxy-2-(4-methoxyphenyl)-3-methyl-5-(3-prenyl)-benzofuran (1), 2-(4-methoxyphenyl)-3-methyl-5-(3-prenyl)-benzofuran-7-ol (2), 2-(4-hydroxy-3,5-dimethoxyphenyl)-3-methyl-5-(3-prenyl)benzofuran-7-ol (3), along with four known arylbenzofurans (4–7) were isolated from the fermentation products of an endophytic Phomopsis sp. Their structures were elucidated by spectroscopic methods including extensive 1D- and 2D-NMR techniques. In addition, compounds 1–7 were tested for their anti-tobacco mosaic virus (anti-TMV) activity. The results showed that compound 3 exhibited obvious anti-TMV activity with inhibition rate of 35.2% better than that of positive control (31.8%). The other compounds also showed potential anti-TMV activity with inhibition rates in the range of 18.6–25.7%, respectively.     

Isoflavones from the roots and stems of Nicotiana Tabacum and their anti-tobacco mosaic virus activities

Two new isoflavones, 7-hydroxy-6,3′,4′,5′-tetramethoxy-isoflavone (1) and 6-hydroxy-7,3′,4′,5′-tetramethoxy-isoflavone (2), together with seven known isoflavones were isolated from the roots and stems of Nicotiana tabacum. Their structures were determined by means of HRESIMS, extensive 1D and 2D NMR spectroscopic studies and chemical evidences. The anti-tobacco mosaic virus (anti-TMV) activities of the isoflavones were also evaluated. The results reveal that compound 9 shows high anti-TMV activity, compound 2 shows moderate anti-TMV activity, and compounds 1, 3–8 show weak anti-TMV activities.     

Three new isobenzofurans from Lavandula angustifolia and their bioactivities

Three new isobenzofurans, lavandulactones A–C (1–3), together with three known ones (4–6), were isolated from the whole herb of Lavandula angustifolia. Their structures were established on the basis of detailed spectroscopic analysis (1D- and 2D-NMR, HRESIMS, UV, and IR) and comparison with data reported in the literature. New isolates were evaluated for their anti-tobacco mosaic virus (TMV) activities and cytotoxicity activities. The results revealed that compounds 1–3 showed high anti-TMV activity with inhibition rate of 31.8, 29.6 and 33.4%, respectively. These rates are higher than that of positive control. Compounds 1–3 also showed weak inhibitory activities against some tested human tumor cell lines with IC₅₀ values ranging from 1.5 to 5.7 μM.     

抗烟草黄瓜花叶病毒多糖筛选及其对烟草防御酶活性的影响

[目的]筛选出对烟草黄瓜花叶病毒病有良好抑制作用的多糖并探索其对烟叶防御酶活性的影响.[方法]采用半叶法,测定了安络小皮伞多糖等21种真菌多糖在枯斑三生烟上对CMV的钝化、预防及治疗效果,并测定了抗病毒多糖处理后普通烟NC-89体内防御酶的变化.[结果]安络小皮伞多糖对CMV具有较好的钝化及预防效果,其200倍液与等量供试病毒液混合30 min后接种,钝化效果为83.41%;喷施安络小皮伞多糖200倍液24 h后接毒处理,预防效果可高达93.15%.安络小皮伞多糖对CMV防治机理的研究表明,多糖处理后烟草相关防御酶POD、PAL和PPO活性增强,其中喷施安络小皮伞多糖24 h后接毒处理的酶活增加最为显著,该处理烟苗的POD、PAL和PPO的酶活峰值分别可增加至对照的2.74、3.45和2.82倍.[结论]安络小皮伞多糖通过增强烟草体内防御酶活性而提高烟草对烟草黄瓜花叶病毒病的抗性.     

Evolutionary relationship of alfalfa mosaic virus with cucumber mosaic virus and brome mosaic virus

The amino acid sequences of the non-structural protein (molecular weight 35,000; 3a protein) from three plant viruses — cucumber mosaic, brome mosaic and alfalfa mosaic have been systematically compared using the partial genomic sequences for these three viruses already available. The 3a protein of cucumber mosaic virus has an amino acid sequence homology of 33.7% with the corresponding protein of brome mosaic virus. A similar protein from alfalfa mosaic virus has a homology of 18.2% and 14.2% with the protein from brome mosaic virus and cucumber mosaic virus, respectively. These results suggest that the three plant viruses are evolutionarily related, although, the evolutionary distance between alfalfa mosaic virus and cucumber mosaic virus or brome mosaic virus is much larger than the corresponding distance between the latter two viruses.     

Antiviral flavones from the leaves of Nicotiana tabacum

Three new flavones, tabaflavones A–C (1–3), together with three known flavones (4–6), were isolated from the leaves of Nicotiana tabacum. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1–6 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed compound 1 exhibited moderate anti-TMV activity with inhibition rate of 29.2%, which is close to that of the positive control. The other compounds also showed the anti-TMV activities with inhibition rates in the range of 14.2–20.8%.     

Chromones from the tubers of Eranthis cilicica and their antioxidant activity

Chemical studies on the constituents of Eranthis cilicica led to isolation of ten chromone derivatives, two of which were previously known. Comprehensive spectroscopic analysis, including extensive 1D and 2D NMR data, and the results of enzymatic hydrolysis allowed the chemical structures of the compounds to be assigned as 8,11-dihydro-5-hydroxy-2,9-dihydroxymethyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, 5,7-dihydroxy-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-2-methyl-4H-1-benzopyran-4-one, 5,7-dihydroxy-2-hydroxymethyl-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-4H-1-benzopyran-4-one, 7-[(β-d-glucopyranosyl)oxy]-5-hydroxy-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-2-methyl-4H-1-benzopyran-4-one, 7-[(β-d-glucopyranosyl)oxy]-5-hydroxy-2-hydroxymethyl-8-[(2E)-4-hydroxy-3-methylbut-2-enyl]-4H-1-benzopyran-4-one, 9-[(O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]methyl-8,11-dihydro-5,9-dihydroxy-2-methyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, 8,11-dihydro-5,9-dihydroxy-9-hydroxymethyl-2-methyl-4H-pyrano[2,3-g][1]benzoxepin-4-one, and 7-[(O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl)oxy]methyl-4-hydroxy-5H-furo[3,2-g][1]benzopyran-5-one, respectively. The isolated compounds were evaluated for their antioxidant activity.     

Isoprenylated chromones from the stems of Harrisonia perforata

Three new isoprenylated chromones, named harriforatins A−C (1−3), along with 13 known compounds (4−16) were isolated from the stems of Harrisonia perforata. Their planar structures were elucidated by spectroscopic measurements. The experimental and calculated ECD curves were used to determine their absolute configurations. Most isolated compounds were evaluated for inflammation inhibition against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages. Only compounds 5 and 6 showed inhibitory effects on NO production, with IC₅₀ values of 42.8 and 47.0 μM, respectively, that were stronger than that of the positive control, indomethacin (IC₅₀ = 68.6 μM).     

Tobacco mosaic virus: the first century

Tobacco Mosaic Virus: Pioneering Research for a Century, organized by The Royal Society of Edinburgh, in conjunction with The Royal Society, was held at The Royal Society of Edinburgh, UK, 7–8 August 1998.     

Homology between the proteins encoded by tobacco mosaic virus and two tricornaviruses

Summary A comparison was made of the amino acid sequences of the proteins encoded by RNAs 1 and 2 of alfalfa mosaic virus (A1MV) and brome mosaic virus (BMV), and the 126K and 183K proteins encoded by tobacco mosaic virus (TMV). Three blocks of extensive homology of about 200 to 350 amino acids each were observed. Two of these blocks are located in the A1MV and BMV RNA 1 encoded proteins and the TMV encoded 126K protein; they are situated at the N-terminus and C-terminus, respectively. The third block is located in the A1MV and BMV RNA 2 encoded proteins and the C-terminal part of the TMV encoded 183K protein. These homologies are discussed with respect to the functional equivalence of these putative replicase proteins and a possible evolutionary connection between A1MV, BMV and TMV.     

States of aggregation of the dahlemense strain of tobacco mosaic virus protein and their relation to crystal formation.

The aggregation of the protein of the dahlemense strain of tobacco mosaic virus has been studied by electron microscopy and ultracentrifugation. The aggregates formed are similar to those formed by the vulgare strain, although the particular conditions for their formation are often rather different. Helix formation by dialysis of A protein at pH 8 to acid pH is much more efficient if an intermediate step at pH 7 is introduced. The 20 S particle or two-layer disk is stable over a wide range of pH and ionic strength values. There is no tendency to form short stacks of disks at high ionic strength; instead, 30 S particles are formed that correspond to a pair of interlocked disks giving a “figure-of-eight” appearance in electron micrographs. These particles appear to be the “building blocks” of the protein crystal.