Antifungal alkaloids from Mahonia fortunei against pathogens of postharvest fruit.

Postharvest pathogens can affect a wide range of fresh fruit and vegetables, including grapes, resulting in significant profit loss. Isoquinoline alkaloids of Mahonia fortunei, a Chinese herbal medicine, have been used to treat infectious microbes, which might be effective against postharvest pathogens. The phytochemical and bioactive investigation of this plant led to the isolation of 18 alkaloids, of which 9 compounds inhibited the growth of Botrytis cinerea and 4 compounds against Penicillium italicum. The antifungal alkaloids could change the mycelium morphology, the total lipid content, and leak the cell contents of B. cinerea. Furthermore, the two most potent antifungal alkaloids, berberine (13) completely inhibited effect on gray mold of table grape at 512 mg L-1, while jatrorrhizine (18) exhibited an inhibition rate > 90% on grape rot at the same concentration, with lower cytotoxicity and residue than chlorothalonil, which suggested that ingredients of M. fortunei might be a low-toxicity, low-residue, eco-friendly botanical fungicide against postharvest pathogens.

The chloroplast GATA-motif of Mahonia bealei participates in alkaloid-mediated photosystem inhibition during dark to light transition.

Mahonia bealei and Mahonia fortunei are important plant resources in Traditional Chinese Medicine that are valued for their high levels of benzylisoquinoline alkaloids (BIAs). Although the phytotoxic activity of BIAs has been recognized, information is limited on the mechanism of action by which these compounds regulate photosynthetic activity. Here, we performed comparative chloroplast genome analysis to examine insertions and deletions in the two species. We found a GATA-motif located in the promoter region of the ndhF gene of only M. bealei. K-mer frequency-based diversity analysis illustrated the close correlation between the GATA-motif and leaf phenotype. We found that the GATA-motif significantly inhibits GUS gene expression in tobacco during the dark-light transition (DLT). The expression of ndhF was downregulated in M. bealei and upregulated in M. fortunei during the DLT. NDH-F activity was remarkably decreased and exhibited a significant negative correlation with BIA levels in M. bealei during the DLT. Furthermore, the NADPH produced through photosynthetic metabolism was found to decrease in M. bealei during the DLT. Taken together, our results indicate that this GATA-motif might act as the functional site by which BIAs inhibit photosynthetic metabolism through downregulating ndhF expression during the DLT.

Green synthesis of silver nanoparticles from Mahonia fortunei extracts and characterization of its inhibitory effect on Chinese cabbage soft rot pathogen.

The pathogenic bacterium Pectobacterium carotovorum causes soft rot in cabbage and significantly reduces plant yield. In this study, we employed Mhonia fortunei extracts to synthesis silver nanoparticles (Mf-AgNPs) and investigated their functions against P. carotovorum. The results showed that the surface plasmon resonance (SPR) peak of AgNP was 412 nm under optimal synthesis conditions. Furthermore, the results of Scanning electron microscope-Energy dispersive spectrometer (SEM-EDS) and High-resolution transmission electron microscopy (HR-TEM) revealed that the Mf-AgNPs had a spherical structure with an average diameter of 13.19 nm and the content of Ag0 ions accounted for 82.68% of the total elemental content. The X-Ray diffraction (XRD) results confirmed that AgNPs had a face-centered cubic (FCC) crystal structure, while Fourier transform infrared spectroscopy (FTIR) results indicated the presence of various biomolecules as reducing and stabilizing agents on the AgNP surface. Antibacterial activity was first evaluated by an inhibitory zone test, which revealed that 500 µg ml-1 of AgNPs had antibacterial activity against P. carotovorum and four model bacteria including Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa, respectively with an antibacterial function comparable to 1 mM AgNO3 solution. The Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for P. carotovorum were 8 µg ml-1, respectively. Furthermore, AgNPs at 8 µg ml-1 completely inhibited the growth of P. carotovorum, decreased their tolerance to 0.25 mM H2O2 as well as considerably reduced colony formation after 1 h of treatment and thereafter. Treatment with Mf-AgNPs resulted in bacterial cell membrane destruction and biofilm formation inhibition, respectively. With an FIC (fractional inhibitory concentration) index of 0.174, AgNP and zhongshengmycin showed a significant synergistic effect. The infection of P. carotovorum to cabbage explants was significantly inhibited in vitro by a combination of 2 µg ml-1 Mf-AgNP and 5 µg ml-1 zhongshengmycin. In conclusion, the synthesized Mf-AgNP exhibited significant antibacterial activity against P. carotovorum.

First Report of Leaf Blight on Mahonia fortunei Caused by Botryosphaeria dothidea in China.

Mahonia fortunei belongs to Berberidaceae, and is often used as a potted plant in Chinese tradition medicine (Li et al. 2015). In March 2019, leaf blight was observed on this species in the campus of Anhui Agricultural University (31°51'51″N; 117°15'31″E) in Hefei City, Anhui Province, China. The average disease incidence was 35% over 20 m2 planting area. Symptoms of the disease are easily apparent, with irregular, dark brown necrosis at the edge of the leaves. To identify the pathogen, symptomatic leaves were collected from three symptomatic leaves from three plants and cut into small pieces. Leaf pieces from the margin of the diseased tissues were surface sterilized for 1 min in 75% ethanol, rinsed three times with sterile distilled water, and subsequently, plated onto potato dextrose agar (PDA) and incubated in dark at 28°C for 4 days. The colonies of three isolates were obtained and appeared morphologically similar in agar media. The cultures were initially white, gradually becoming dark gray, and could grow to the edges of plates (90mm diameter) four days after subculturing. After 7 days on media, the colony was induced for sporulation by UV for 15min, and conidia were observed after 2 weeks. Conidia were nonseptate, hyaline, and oval, measuring 16.9 to 25.3 µm (mean 21.4 µm) × 5.0 to 8.4 µm (mean 6.8 µm) (n = 50). The isolate was identified as Botryosphaeria dothidea preliminarily according to the morphological characteristics (Zhai et al. 2014). For accurate identification, DNA was extracted from the mycelia. The internal transcribed spacer (ITS), ß-tubulin (TUB) and Ef1-a were amplified and sequenced using primers ITS1/ITS4, Bt2a/Bt2b and 983f /2228r, respectively (Zhai et al. 2014). The 543-bp ITS (GenBank accession no. MK850215), 673-bp TUB (no. MN370930) and 1069-bp Ef1-a (no. MN598070) showed >99% identity with those of B. dothidea KP183180 (Xu et al. 2015), KU306116 (Lisboa et al. 2016) and DQ767637.1 (Schoch et al. 2006), respectively. Based on cultural characteristics and phylogenetic analysis, the current isolate associated with leaf blight of M. fortunei was identified as B. dothidea. The representative strain was deposited at the China Center for Type Culture Collection (CCTCC) as CCTCC AF 2019004 SX03. Pathogenicity test was performed on three healthy M. fortunei on campus. Three branches of each plant were selected and all leaves on branches were wounded with dissecting needle by puncturing, then inoculated with a spore suspension (105 conidia/mL) by a hand-held spray bottle, using sterile water as control (Huang et al. 2019). In order to maintain high relative humidity, the inoculated leaves were sealed with transparent plastic bags for 3 days. Fourteen days after inoculation, symptoms (leaf blight) were similar to those on infected leaves on campus, while the controls remained healthy. The experiments were conducted three times and the pathogen was reisolated from inoculated leaves and was confirmed as B. dothidea based on morphological and molecular analyses. To our knowledge, this is the first report of B. dothidea causing marginal leaf necrosis on M. fortunei in China. This study provides a preliminary basis for identifying the causal agent of this plant disease.

A strategy to discover lead chemome from traditional Chinese medicines based on natural chromatogram-effect correlation (NCEC) and natural structure-effect correlation (NSEC): Mahonia bealei and Mahonia fortunei as a case study.

Lead compound is an important concept for modern drug discovery. In this study, a new concept of lead chemome and an efficient strategy to discover lead chemome were proposed. Compared with the concept of lead compound, lead chemome can provide not only the starting point for drug development, but also the direction for structure optimization. Two traditional Chinese medicines of Mahonia bealei and Mahonia fortunei were used as examples to illustrate the strategy. Based on natural chromatogram-effect correlation (NCEC), berberine, palmatine and jatrorrhizine were discovered as acetylcholinesterase (AchE) inhibitors. Taking the three compounds as template molecules, a lead chemome consisting of 10 structurally related natural compounds were generated through natural structure-effect correlation (NSEC). In the lead chemome, the IC50 values of jatrorrhizine, berberine, coptisine, palmatine and epiberberine are at nanomolar level, which are comparable to a widely used drug of galantamine. Pharmacophore modeling shows that the positive ionizable group and aromatic rings are important substructures for AchE inhibition. Molecular docking further shows that pi-cation interaction and pi-pi stacking are critical for compounds to maintain nanomolar IC50 values. The structure-activity information is helpful for drug design and structure optimization. This work also expanded the traditional understanding of "stem is the medicinal part of Mahonia bealei and Mahonia fortunei". Actually, all parts except the leaf of Mahonia bealei exhibited potent AchE-inhibitory activity. This study provides not only a strategy to discover lead chemome for modern drug development, but also a reference for the application of different parts of medicinal plants.

Identification and quantification analysis of the chemical constituents from Mahonia fortune using Q­Exactive HF Mass Spectrometer and UPLC-ESI-MS/MS.

In this research, a comprehensive and innovative method was established for the qualitative and quantitative analysis of the main components in Mahonia fortune (MF). On the one hand, comprehensive insight of the constituents in MF extracts was achieved with a Q­Exactive HF Mass Spectrometer using data-independent acquisition method. The identification of 17 compounds was based on comparison with authentic reference standards and the deduction of 119 additional compounds both in positive and negative modes was using the MS-dial strategy and comparison with literature data. The proportion of alkaloids and phenols were the most in MF. On the other hand, an ultra-performance liquid chromatographic-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method for the quantification of 25 components in MF extract were developed and validated. The method established provided satisfactory precision and accuracy; acceptable recovery and stability; a good linearity and a reasonable limit of detection. The MF samples from 11 different sources were detected, and relative principal component analysis were applied to discriminate these samples. The variations of Columbamine, Jatrorrhizine, Palmatine and Berberine were suggested as important indicators of MF quality. This study supplies a novel and comprehensive method for the quality evaluation of MF. This research presents a MS based analytical strategy which shows an application potential in the analysis of the chemical constituents in Traditional Chinese Medicine (TCM).

Chemical constituents of lipophilic parts in water extrct from stem of Mahonia fortunei / 中草药

Objective To study the chemical constituents of lipophilic parts in water extracts from the stem of Mahonia fortunei. Methods The compounds were isolated and purified by repeated column chromatography on silica gel and high performance liquid chromatography, and their structures were determined by spectroscopic data analysis. Results Thirty-eight compounds were obtained from lipophilic parts in water extracts from the stem of M. fortunei and identified as maltol (1), 3-hydroxy-4-methoxyphenylethanol (2), syringylethanone (3), 1-hydroxy-3-(4-hydroxy-3-methoxyphenyl)-2-propanone (4), α-hydroxypropiosyringone (5), corydaldine (6), zhebeiresinol (7), vanillic acid (8), springic acid (9), noroxyhydrastinine (10), (+)-syringaresinol (11), episyringaresinol (12), schisandrin (13), neoechinulin A (14), 8-oxyjatrorrhizine (15), 8-oxyberberine (16), 5-hydroxymaltol (17), methyl-5- hydroxy-2-pyridinecarboxylate (18), vomifoliol (19), 2,3-dihydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-propanone (20), oleracein E (21), acortatarin A (22), 5-epi-acortatarin A (23), 5-(methoxymethyl)-1H-pyrrole-2-carbaldehyde (24), (+)-lyoniresinol (25), (−)-secoisolariciresinol (26), ciwujiatone (27), protocatechuic acid (28), adenosine (29), 3,4,5-trimethoxyphenyl-1-O-β-D- glucopyranoside (30), 2-(4-hydroxy-3-methoxyphenyl) ethyl-O-β-D-glucopyranoside (31), tortoside B (32), oldhamioside (33), (+)-syringaresinol-4′-O-β-D-glucopyranoside (34), episyringaresinol-4′-O-β-D-glucopyranoside (35), berberine (36), 3,4,5-trimethoxyphenyl-(6′-O-syringoyl)-O-β-D-glucopyranoside (37), and salidroside (38), respectively. Conclusion Compounds 3—7, 13—15, 17—19, 21—27, 29, 31, 33, and 38, are isolated from the genus Mahonia for the first time. Moreover, the nuclear magnetic resonance data of compound 15 is assigned for the first time.

Secondary metabolites from Colletotrichum fioriniae F18, an endophytic fungus isolated from the medicinal plant Mahonia fortunei / 药学学报

Chemical investigation on the rice culture of an endophytic fungus Colletotrichum fioriniae F18, inhabiting in the stems of the medicinal plant Mahonia fortunei, led to the isolation of nine compounds. They included a new indole alkaloid, makomotindoline B (1), and two known indole derivatives, 3-indoleacetic acid methyl ester (2) and N-acetyltryptamine (3), together with six known aromatic compounds, 2-(4-hydroxyphenyl) acetic acid (4), 4-(2-hydroxyethyl)phenol (5), 2-(4-methoxyphenyl)acetic acid (6), 4-hydroxyphenethyl 2-(4-hydroxyphenyl)acetate (7), regiolone (8) and N-phenethylacetamide (9). The structures of these compounds were elucidated based on the analysis of spectroscopic data including MS and NMR. The absolute configuretion of compound 1 was determined by electronic circular dichroism (ECD) calculation. Antibacterial activity assay indicated that compounds 1-9 had no antibacterial activities against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, as well as no quorum sensing inhibitory (QSI) activity for Chromobacterium violaceum.