Two new triterpenoids with antimicrobial activity from the leaves and twigs of Orophea yunnanensis.

Two new triterpenoids, 3-O-(4',5'-dihydroxybenzoyl)-lup-20(29)-en (1) and 3-O-(6'-desmethysyringyl)-13α-methyl-27-norolean-14-en-3ß-ol (2), were isolated from the leaves and twigs of Orophea yunnanensis. Their structures were identified by extensive spectroscopic experiments (NMR and MS) and comparison with literature data. Compounds 1 and 2 exhibited the moderate inhibitory activity against Sclerotinia sclerotiorum, Ceratocystis fimbriata and Verticillium dahliae Kleb with MIC values from 50 to 25 µg/mL, and also displayed the weak activity selectively against tested bacteria strains with MIC values from 100 to 50 µg/mL.

Differences between the binding modes of enantiomers S/R-nicotine to acetylcholinesterase.

Nicotine causes neurotoxic effects because it quickly penetrates the blood-brain barrier after entering the human body. Acetylcholinesterase (AChE) is a key enzyme in the central and peripheral nervous system associated with neurotoxicity. In this study, a spectroscopic method and computer simulation were applied to explore the mode of interaction between AChE and enantiomers of nicotine (S/R-nicotine). Fluorescence spectroscopy showed that the quenching mechanism of endogenous fluorescence of AChE by S/R-nicotine was static, as confirmed by the time-resolved steady-state fluorescence. The binding strength of both nicotine to AChE was weak (S-AChE: K a = 80.06 L mol-1, R-AChE: K a = 173.75 L mol-1). The main driving forces of S-AChE system interaction process were van der Waals force and hydrogen bonding, whereas that of R-AChE system was electrostatic force. Computer simulations showed that there were other important forces involved. S/R-Nicotine had a major binding site on AChE, and molecular docking showed that they bound mainly to the cavities enclosed by the active sites (ES, PAS, OH, AACS, and AP) in the protein. UV-vis spectroscopy and 3D spectroscopy indicated that nicotine significantly affected the microenvironment of Trp amino acids in AChE. The CD spectra indicated that S-nicotine increased the α-helical structure of AChE, but the overall conformation did not change significantly. By contrast, R-nicotine significantly changed the secondary structure of AChE. 5,5'-Dithiobis-2-nitrobenzoic acid (DTNB) method indicated that S and R nicotine produced different degrees of inhibition on the catalytic activity of AChE. Both experimental methods and computer simulations showed that R-nicotine had a significantly higher effect on AChE than S-nicotine. This research comprehensively and systematically analyzed the mode of interaction between nicotine and AChE for neurotoxicity assessment.

New isolates from leaves of Nicotiana tabacum and their biological activities.

Three new isolates (1-3) including one new sterol and two new flavonoids together with three known sterols (4-6) were isolated from the leaves of Nicotiana tabacum. Their structures were determined mainly by spectroscopic methods, including extensive 1D and 2D NMR techniques. All compounds were evaluated for their anti-tobacco mosaic virus and cytotoxic activities. The results showed that compounds 2 and 3 exhibited high anti-TMV activity with inhibition rate of 34.2 and 33.4%, respectively, which were roughly equivalent to that of positive control. The cytotoxicities of compounds 1 and 4-6 against five human tumour cell lines were also tested, and tested compounds showed weak inhibitory activities against some tested human tumour cell lines.

Three new sesquiterpenes from the stems of Nicotiana tabacum and their bioactivities.

Three new sesquiterpenes, methyl 4-isopropyl-7-methoxy-6-methylnaphthalene-1-carboxylate (1), methyl 2-hydroxy-4-isopropyl-7-methoxy-6-methylnaphthalene-1-carboxylate (2), and methyl 2-hydroxy-6-(hydroxymethyl)-4-isopropyl-7-methoxynaphthalene-1-carboxylate (3), together with three known sesquiterpenes (4-6), were isolated from the stems of Nicotiana tabacum. Their structures were determined by means of HRESIMS and extensive 1D and 2D NMR spectroscopic studies. The results showed that compounds 2, 3, and 5 exhibited high anti-TMV activity with inhibition rates of 33.6, 35.8, and 36.7%. Compounds 1-6 showed weak inhibitory activities against some tested human tumor cell lines (NB4, A549, SHSY5Y, PC3, and MCF7) with IC50 values in the range of 6.7-9.6 µM.

Exploring the binding pattern between pepsin and deferasirox using detailed experimental and computer simulation methods.

Steady-state fluorescence spectroscopy indicated that a ground state complex was formed between deferasirox (DFX) and pepsin. The binding parameters and thermodynamic parameters of pepsin-DFX complex formation suggested the presence of only one high affinity binding site in the binding process of DFX and pepsin and that the binding process was hydrogen bond dominated. According to the MD simulation optimal pepsin-DFX binding model analysis, the binding force between DFX and pepsin was mainly hydrogen bonding, and the hydrophobic interaction was supplemented. Synchronous fluorescence spectroscopy and 3D fluorescence spectroscopy indicated that the binding of DFX to pepsin had minor effect on the protein structure and function. Circular dichroism spectra showed that DFX had no significant effect on the main secondary structure of pepsin. MD analysis also showed that DFX did not affect the looseness of pepsin and the overall secondary structure, but it affected the amino acid residue sequence Leu48-Ala49-Cys50-Ser51-Asp52. Pepsin enzyme activity test showed that the addition of DFX had a slight enhancement effect on the activity of pepsin. Combined with the MD results, DFX bound to pepsin and was closer to the pepsin active site Asp-215, which may affect the electrical environment of Asp-215 residues and enhance the activity of pepsin.

Three new isobenzofurans from the roots of Nicotiana Tabacum and their bioactivities.

Three new isobenzofurans (1-3), together with four known phenylpropanoids (4-7) were isolated from the roots of Nicotiana tabacum. 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) activities and cytotoxicity activities. The results showed that compounds 5 and 6 exhibited high anti-TMV activities with inhibition rates of 35.1 and 33.4%, respectively. The cytotoxicities of compounds 1-7 against five human tumor cell lines (NB4, A549, SHSY5Y, PC3 were also tested. Compounds 1-7 showed weak inhibitory activities against some tested human tumor cell lines with IC50 values in the range of 3.8-9.6 µM.

Three new phenylpropanoids from Lavandula angustifolia and their bioactivities.

Three new phenylpropanoids, 3-(3,4-dimethoxy-5-methylphenyl)-3-oxopropyl acetate (1), 3-hydroxy-1-(3,4-dimethoxy-5-methylphenyl)propan-1-one (2), and 3-hydroxy-1-(4-methylbenzo[d][1,3]dioxol-6-yl) propan-1-one (3), together with three known phenylpropanoids (4-6) were isolated from the whole plant of Lavandula angustifolia. Their structures were determined by means of HRESIMS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1-6 were tested for their anti-tobacoo mosaic virus (TMV) activities and cytotoxicity activities. The results revealed that compounds 1-3 showed high anti-TMV activity with inhibition rate of 35.2, 38.4 and 33.9%. These rates are higher than that of positive control. The other compounds also showed potential anti-TMV activities with inhibition rates in the range of 26.8-28.9%, respectively. Compounds 1-6 also showed weak inhibitory activities against some tested human tumour cell lines with IC50 values in the range of 3.8-8.8 µM.

Biodegradation and metabolic pathway of nicotine in Rhodococcus sp. Y22.

Nicotine in tobacco is harmful to health and the environment, so there is an environmental requirement to remove nicotine from tobacco and tobacco wastes. In this study, the biotransformation of nicotine by Rhodococcus sp. Y22 was investigated, and three metabolites (NIC1, NIC4 and NIC5) were isolated by column separation, preparative TLC and solid plate's method, respectively. NIC1 was identified as 6-hydoxynicotine based on the results of NMR, MS, HPLC-UV and HRESIMS analysis; NIC4 was a novel compound and identified as 5-(3-methyl-[1,3]oxazinan-2-ylidene)-5H-pyridin-2-one based on the results of NMR, MS and UV analysis; NIC5 was identified as nicotine blue based on the results of NMR and MS analysis. Meanwhile, two metabolites NIC2 and NIC3 were identified as 6-hydroxy-N-methylmyosmine and 6-hydroxypseudooxynicotine by HRESIMS analysis, respectively. According to these metabolites, the possible pathway of nicotine degradation by Rhodococcus sp. Y22 was proposed. The nicotine can be transformed to nicotine blue through two pathways (A and B), and 6-hydroxy-N-methylmyosmine is the key compound, which can be converted to 6-hydroxypseudooxynicotine (pathway A) and 5-(3-methyl-[1,3]oxazinan-2-ylidene)-5H-pyridin-2-one (pathway B), respectively. Moreover, the encoding gene of nicotine dehydrogenase, ndh, was amplified from Rhodococcus sp. Y22, and its transcriptional level could be up-regulated obviously under nicotine induction. Our studies reported the key metabolites and possible biotransformation pathway of nicotine in Rhodococcus sp. Y22, and provided new insights into the microbial metabolism of nicotine.

Two new sesquiterpenes from the leaves of Nicotiana tabacum and their anti-tobacco mosaic virus activities.

Two new sesquiterpenes, nicotianasesterpenes A and B (1 and 2), together with five known sesquiterpenes (3-7) were isolated from the leaves of Nicotiana tabacum. Their structures were determined mainly by spectroscopic methods, including extensive 1D- and 2D-NMR techniques. The anti-tobacco mosaic virus (anti-TMV) activities of compounds 1-7 were evaluated. The results revealed that compound 1 exhibited high anti-TMV activities with inhibition rates of 33.6%. This rate is high than that of positive control. The other compounds also showed potential activities with inhibition rates in the range of 18.8-28.4%, respectively.

Antiviral sesquiterpenes from leaves of Nicotiana tabacum.

Three unreported sesquiterpenes possessing two new skeletons, tabasesquiterpenes A-C (1-3), together with three known sesquiterpenes (3-6) were isolated from the leaves of Nicotiana tabacum. Their structures were determined mainly 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 that compound 2 exhibited high anti-TMV activity with inhibition rate of 35.2%, which were higher than that of positive control (ningnanmycin). The other compounds also showed potential anti-TMV activity with inhibition rates in the range of 20.5-28.6%.

Anti-TMV activity flavones from the leaves of Yunnan local air cured tobacco.

Four new flavones, tobaflavones E-H (1-4), together with two known flavones (5 and 6), were isolated from the leaves of Dali Tiandeng tobacco (a variety of Yunnan local air cured tobacco). Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D NMR techniques. Compound 2 is the first naturally occurring flavone bearing a (4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)methyl moiety. These compounds were also evaluated for their anti-tobacco mosaic virus (anti-TMV) activity. The results revealed that compounds 1 and 2 exhibited high anti-TMV activity with inhibition rate of 35.3% and 39.6%, respectively. The rates are higher than those of positive control. The other compounds also showed potential anti-TMV activity with inhibition rates in the range of 18.7-28.4%, respectively.

Biphenyls from Nicotiana tabacum and their anti-tobacco mosaic virus.

Five new biphenyls, tababiphenyls A-E (1-5), together with five known ones (5-10), were isolated from the leaves of Nicotiana tabacum, of which compound 1 possessed a seldom reported 6-carbons unit in biphenyls. Their structures were established on the basis of extensive spectroscopic analyses. All compounds were tested for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compounds 3 and 5 exhibited high anti-TMV activities with inhibition rate of 48.4% and 32.1%, respectively, which were higher than that of positive control (ningnanmycin). The other compounds also showed potential anti-TMV activities with inhibition rates in the range of 18.6-28.7%, respectively.

Phenolic compounds from Nicotiana tabacum and their biological activities.

Three new phenolic compounds, nicotphenols A-C (1-3), together with 14 known phenols (4-17), were isolated from the leaves of Nicotiana tabacum. Their structures were established by means of spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1-3 were tested for their anti-HIV-1 activities and cytotoxicities. They all showed significant cytotoxic abilities and modest anti-HIV-1 activities, respectively.