Structure optimizing of flavonoids against both MRSA and VRE.

Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) cause more than 100,000 deaths each year, which need efficient and non-resistant antibacterial agents. SAR analysis of 162 flavonoids from the plant in this paper suggested that lipophilic group at C-3 was crucial, and then 63 novel flavonoid derivatives were designed and total synthesized. Among them, the most promising K15 displayed potent bactericidal activity against clinically isolated MRSA and VRE (MICs = 0.25-1.00 µg/mL) with low toxicity and high membrane selectivity. Moreover, mechanism insights revealed that K15 avoided resistance by disrupting biofilm and targeting the membrane, while vancomycin caused 256 times resistance against MRSA, and ampicillin caused 16 times resistance against VRE by the same 20 generations inducing. K15 eliminated residual bacteria in mice skin MRSA-infected model (>99 %) and abdominal VRE-infected model (>92 %), which was superior to vancomycin and ampicillin.

Mutations influence the conformational dynamics of the GDP/KRAS complex.

Mutations near allosteric sites can have a significant impact on the function of KRAS. Three specific mutations, K104Q, G12D/K104Q, and G12D/G75A, which are located near allosteric positions, were selected to investigate the molecular mechanisms behind mutation-induced influences on the activity of KRAS. Gaussian accelerated molecular dynamics (GaMD) simulations followed by the principal component analysis (PCA) were performed to improve the sampling of conformational states. The results revealed that these mutations significantly alter the structural flexibility, correlated motions, and dynamic behavior of the switch regions that are essential for KRAS binding to effectors or regulators. Furthermore, the mutations have a significant impact on the hydrogen bonding interactions between GDP and the switch regions, as well as on the electrostatic interactions of magnesium ions (Mg2+) with these regions. Our results verified that these mutations strongly influence the binding of KRAS to its effectors or regulators and allosterically regulate the activity. We believe that this work can provide valuable theoretical insights into a deeper understanding of KRAS function.Communicated by Ramaswamy H. Sarma.

Antimicrobial ingredients of Zanthoxylum motuoense and potential in fresh pork meat preservation.

Zanthoxylum motuoense (Tibetan prickly ash, MTHJ), different from the Chinese prickly ash species, is distributed only in the Tibet. Now the chemical characterization and antibacterial activity of MTHJ extracts were analyzed for the first time. As a result, Schinifoline (12), γ-Fagarine (8), (2E,7E,9E)-6 S-Hydroxy-N-(2-methylpropyl)-11-oxo-2, 7, 9-Dodecatrienamide (6), and Neoechinulin A (17) were found to be the major different factors by untarget LC-MS metabolomics together with quantitative analysis on target. These four compounds were also the major antibacterial constituents. Then, the antimicrobial activity of MTHJ fractions was evaluated with colony forming units (CFU), fluorescence microscopy imaging, SEM and investigating the potential food preservation. Nutritional composition, colour and sensory evaluation of extract-treated samples were evaluated along storage time. The results suggested the MTHJ may be used for meat products preservation, and the scores were significantly higher for its unique flavor, which offered a promising choice for food safety, preservation and reducing foodborne illness.

A dual mechanism with H2S inhibition and membrane damage of morusin from Morus alba Linn. against MDR-MRSA.

It's urgent to discover new antibiotics along with the increasing emergence and dissemination of multidrug resistant (MDR) bacterial pathogens. In the present investigation, morusin exhibited rapid bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) by targeting the phospholipid of bacterial inner membrane, increasing membrane rigidity and disrupting bacterial homeostasis together with the membrane permeability, which caused fundamental metabolic disorders. Furthermore, morusin can also accumulate ROS, suppress H2S production, and aggravate oxidative damage in bacteria. Importantly, morusin also inhibited the spread of wounds and reduced the bacterial burden in the mouse model of skin infection caused by MRSA. It's a chance to meet the challenge of existing antibiotic resistance and avoid the development of bacterial resistance, given the multiple targets of morusin.

Targeted quantitative analysis of monoterpenoid indole alkaloids in Alstonia scholaris by ultra-high-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry.

Monoterpene indole alkaloids exhibit structural diversity in herbal resources and have been developed as promising drugs owing to their significant biological activities. Confidential identification and quantification of monoterpene indole alkaloids is the key to quality control of target plants in industrial production but has rarely been reported. In this study, quantitative performance of three data acquisition modes of ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry including full scan, auto-MS2 and target-MS2 , was evaluated and compared for specificity, sensitivity, linearity, precision, accuracy, and matrix effect using five monoterpene indole alkaloids (scholaricine, 19-epi-scholaricine, vallesamine, picrinine, and picralinal). Method validations indicated that target-MS2 mode showed predominant performance for simultaneous annotation and quantification of analytes, and was then applied to determine monoterpene indole alkaloids in Alstonia scholaris (leaves, barks) after extraction procedures optimization using Box-Behnken design of response surface methodology. The variations of A. scholaris monoterpene indole alkaloids in different plant parts, harvest periods, and post-handling processes, were subsequently investigated. The results indicated that target-MS2 mode could improve the quantitative capability of ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry for structure-complex monoterpene indole alkaloids in herbal matrices. Alstonia scholaris, monoterpene indole alkaloids, quadrupole time of flight mass spectrometry, qualitative and quantitative analysis, ultra-high-performance liquid chromatography.

Steroidal alkaloids from the roots of Veratrum stenophyllum.

Three new steroidal alkaloids, veratrasines A - C (1-3), along with ten known analogues (4-13) were isolated from the roots of Veratrum stenophyllum. Their structures were elucidated by NMR and HRESIMS data and comparison with the reported data in the literatures. A plausible biosynthetic pathway for 1 and 2 were proposed. Compounds 1, 3, and 8 showed moderate cytotoxic activity against MHCC97H and H1299 cell lines.

Significant anti-inflammatory aziridine-containing indole alkaloids from the Chinese medicinal plant Alstonia scholaris.

Two unique windmill-like aziridine-containing indole alkaloids, possessing an unprecedented 6/5/5/6/6/5/3 rigid ring system and an unusual azabicyclo[3.1.0]hexane core, were isolated from Alstonia scholaris. Their structures were established by spectroscopy, X-ray diffraction, and electronic circular dichroism calculations. The novel compounds exhibited significant anti-inflammatory bioactivity in vitro and alleviated LPS-induced acute lung injury in mice.

Steroidal alkaloid with unprecedented triheterocyclic architecture.

Veratrazine A (1), a steroidal alkaloid with a unique 6/5/5 triheterocyclic scaffold as the side chain, was isolated from Veratrum stenophyllum, and its structure was established via spectroscopic analyses and X-ray diffraction. A plausible biosynthetic pathway for 1 is proposed. Bioassy exhibits moderate anti-inflammatory activities in vitro and in vivo.

Bioguided isolation, identification and bioactivity evaluation of anti-MRSA constituents from Morus alba Linn.

ETHNOPHARMACOLOGY RELEVANCE: The root bark of Morus alba Linn. (M. alba), a traditional folk medicine, has been documented in the Chinese Pharmacopoeia, which has been widely used for asthma, fever, pneumonia, edema, vomit, colitis, bronchitis and keratitis diseases. Some of the diseases may be related to respiratory, digestive, urinary tract infections. Although Diels-Alder adducts (DAAs), flavonoids, 2-arylbenzofurans and stilbene compounds have been isolated from the root bark of M. alba, few compounds are reported for their antimicrobial efficacy in vivo and the mechanism. AIM OF THE STUDY: The aim of the study was to isolate and identify compounds of the root bark of M. alba in view of their anti-MRSA bioactivity, evaluate the anti-MRSA bioactivity of compounds and 60% ethanol elution (MA-6) in vitro and in vivo, and explore preliminary antibacterial mechanism in order to provide natural resources against MRSA infection. MATERIALS AND METHODS: Systematic phytochemical investigations were carried out according to the thin layer chromatography (TLC) of the active fraction MA-6 to find more anti-MRSA ingredients. The compounds of the root bark of M. alba were separated by column chromatography and identified by LC-MS/MS and NMR spectroscopy. The anti-MRSA efficacy of the active ingredients were evaluated by broth microdilution method and a murine infection model. The mode of action of compounds was explored by time-kill curve and post-contact effect. The preliminary mechanism of compounds against MRSA was explored by drug efflux pumps and bacterial biofilms. RESULTS: Chemical isolation resulted in twenty-nine known compounds, most with one or more geranyl and prenyl units exhibited superior anti-MRSA bioactivity, with MIC values of 2-16 µg/mL. In addition, the mode of action indicated that compounds presented persistent antimicrobial effect, which also produced concentration-dependent and time-dependent killing activity or property. Preliminary mechanism showed that the compound kuwanon O (29) damaged the bacterial cell membranes, leading to the accumulation of antibiotics inside bacterial cells, moreover, MA-6 and kuwanon O (29) inhibited the efflux of drugs by combining with methicillin or ethidium bromide (EtBr), resulting in the MICs of EtBr and methicillin were obviously decreased three-fold. The anti-MRSA efficacy in vivo indicated that the active fraction MA-6 could reduce bacteria in spleen, liver, kidney and mortality of acutely infectious mice, which was better than the positive drug berberine chloride. CONCLUSION: Experimental investigation showed that the MA-6 and compound 29 have promising bioactivity against MRSA in vitro and in vivo, which might be used as a potential source of new antibacterial medicine or a potential efflux pump inhibitor against MRSA infection.

Potent Antihyperuricemic Triterpenoids Based on Two Unprecedented Scaffolds from the Leaves of Alstonia scholaris.

Two rearranged triterpenoids, representing new subtypes of pentacyclic triterpenoids, with unique 6/6/6/7/5 and 6/6/5/6/6/6 ring systems were isolated from Alstonia scholaris. Their structures were established by spectroscopic analysis, single-crystal X-ray diffraction, and electronic circular dichroism calculations. Both compounds exhibited potent antihyperuricemic bioactivity in vitro and in vivo.

Migration of (non-) intentionally added substances and microplastics from microwavable plastic food containers.

Microwavable plastic food containers (MPFCs) are extensively used for food storage, cooking, rapid heating and as take-out containers. There is an urgent need to investigate whether MPFCs pose potential health risks, as a result of the migration of chemicals into foods. Herein, 42 intentionally added substances (IAS) and > 100 non-IAS (NIAS) migrating from MPFCs were identified in food simulants according to Regulation (EU). The migration of major IAS and NIAS was higher in 95% ethanol compared to other simulants, and gradually decreased following repeated use. NIAS, including Cramer class III toxic compounds, such as PEG oligomers of N,N-bis(2-hydroxyethyl) alkyl(C8-C18)amines, isomers of hexadecanamide and oleamide, and Irgafos 168 OXO were detected and exceeded the recommended limits in some MPFCs. Furthermore, microplastics (MPs) were detected with high values of over one million particles/L in some MPFCs in a single test, and migration behaviors of MPs in different MPFCs were diverse. Surprisingly, this rigorous migration might result in an annual intake of IAS/NIAS up to 55.15 mg and 150 million MPs particles if take-out food was consumed once a day. Multi-safety evaluation studies on the migration of various chemicals from MPFCs to foodstuffs during food preparation should be assessed.

A review of plant characteristics, phytochemistry and bioactivities of the genus Glechoma.

ETHNOPHARMACOLOGICAL RELEVANCE: Plants of the genus Glechoma have been abundantly used for thousands of years in China as folk treatments for cholelithiasis, urolithiasis, inflammation, and other conditions. AIM OF THE STUDY: This review discusses the potential application of Glechoma as an herbal medicine. The plant characteristics, ethnobotanical uses, phytochemistry, and pharmacological activities of Glechoma are summarized as a guide for phytochemical and pharmacological investigations. MATERIALS AND METHODS: Various search engines including SciFinder, Google Scholar, Scopus-Elsevier, Medline, Web of Science, and China National Knowledge Infrastructure were searched for publications on Glechoma using relevant keywords. Additionally, local records, books, and non-English journals were screened up to October 2020. RESULTS: The phytochemistry of several Glechoma plants has been systematically studied, and over one hundred different compounds have been isolated and identified. Terpenoids, flavonoids and polyphenols are the major secondary metabolites. Crude extracts and isolated compounds have been shown to exhibit various pharmacological activities including prevention of nephrolithiasis, anti-inflammatory, analgesic, anticomplement, antimicrobial, antioxidant, depigmenting, anticancer, and antiviral activities, among others. CONCLUSION: Glechoma species have been used as folk medicine to treat various diseases and have diverse biological activities, making them valuable starting materials for drug development. However, in most cases the pharmacological mechanisms, pharmacokinetics, toxicology, safety, and possible interactions with other drugs remain to be determined.

Development of a LC-HRMS based approach to boost structural annotation of isomeric citrus flavanones.

INTRODUCTION: The structural annotation of target relies on high-resolution mass spectrometry (HRMS) information resulting in dubious identities in most cases. The accurate annotation of isomeric structures is still challenging to be confirmed with significant bottleneck. OBJECTIVE: This study focused on the improvement of structural annotation of candidate structures via four pairs of isomeric flavanone-7-O-diglucosides and their basic flavanone aglycones commonly detected in citrus products. METHOD: An integrated liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) approach merging retention time, accurate mass, tandem mass spectrometry (MS/MS) information (diagnostic ions), ion ratio at selected collision energy was established successfully. RESULTS: Feasibility of this approach was validated confidently in biological samples with relative standard deviation (RSD) of ion ratio range from 3.91 to 12.28%. Differences of fragmentation patterns of citrus flavanones were illustrated reasonably. MS/MS fragments of (S)-hesperetin and (S)-isosakuranetin were complicated and showed typical radical ion [1,2 A - H]•- (m/z 164) in negative ESI mode due to the methoxyl group on B-ring, which showed huge difference with (R)-hesperetin and (R)-isosakuranetin. CONCLUSION: This study integrated multiple levels to boost the confidence of structural annotation relied on LC-HRMS, and provided important values in practice for precise identification of citrus flavanones in biological matrices.

Bioassay-guided isolation of anti-inflammatory diterpenoids with highly oxygenated substituents from kidney tea (Clerodendranthus spicatus).

The whole plant of Clerodendranthus spicatus (Thunb.) is one of popular functional food in south of China, named as "kidney tea" and used to ameliorate renal inflammation. In order to verify this potential function and explore the accurate compounds responsible for inflammation, the ethanol extract, fractions, and subfractions of this plant were prepared to evaluate anti-inflammation effect on xylene-induced acute inflammatory mice model, and the results indicated that two subfractions from EtOAc fraction show potential activities. Subsequent bioassay-guided isolation of the bioactive subfractions led to isolation of 25 compounds. Among them, compounds 2, 4, 5, 9-11, 13, 16, 17, and 20-22 inhibited the productions of pro-inflammation factors TNF-α, IL-1ß, and IL-8 in lipopolysaccharide (LPS) -induced renal epithelia (HK-2) cells, respectively. Further anti-inflammation evaluation in vivo indicated that the major bioactive compounds 1, 2, 5-7, 17, 21, and 22 from C. spicatus were even better than aspirin. PRACTICAL APPLICATIONS: C. spicatus as a healthy tea has been available in the Chinese market and as a medicine for various disorders such as nephritis, rheumatism, inflammation, gout, and diabetes. Previous pharmacological investigation of the plant revealed the potential anti-inflammatory activities, but the material basis of anti-inflammatory activity remains to be elucidated. In our study, the anti-inflammatory fractions and compounds were obtained by the bioassay-guide isolation and the results showed that the highly oxygenated diterpenoids were major anti-inflammatory compounds, in which 1, 2, 5-7, 17, 21, and 22 were even better than aspirin. This information supported kidney tea as a functional food for treatment of renal inflammation reasonably and may add a new dimension to biological activity of this plant in the field of agriculture as a functional food were cultivated.

Bioguided isolation, identification and activity evaluation of antifungal compounds from Acorus tatarinowii Schott.

ETHNOPHARMACOLOGY RELEVANCE: As a traditional folk medicine, Acorus tatarinowii Schott was used to treat digestive diseases, such as diarrhea, which may be related to Candida albicans infection; however according to literature surveys, there have been few studies of A. tatarinowii focusing on its antimicrobial activity, and almost all describe investigations using crude extracts or fractions. AIM OF THE STUDY: The aims of the current study were to isolate and identify antifungal fractions of A. tatarinowii based on their antifungal activity, explore the preliminary mechanism of 60% ethanol elution (AT60) by metabonomics, and evaluate the antifungal activity of AT60 in vivo and in vitro, to provide natural resources against fungal infections. MATERIALS AND METHODS: As a pilot evaluation of activity, A. tatarinowii fractions and compounds with antifungal bioactivity were isolated by bioactive-guided column chromatography, and identified by LC-QTOF-MS/MS and NMR spectroscopy. The antifungal effects of the active ingredients against resistant C. albicans were evaluated by in vivo and in vitro colony forming unit assays. The mechanism underlying the activity of AT60 against C. albicans was explored using an LC-QTOF-based metabonomics approach and fluorescence microscopy imaging. RESULTS: AT60 showed better activity against C. albicans than the same dose of the first line antifungal drugs, fluconazole and itraconazole (positive control drugs). Subsequent phytochemical investigation of AT60 identified twenty-five known compounds, six of which were isolated: asaraldehyde (7), 1-(2,4,5-trimethoxyphenyl)-1,2-propanediol (12), α-asarone (14), ß-asarone (15), γ-asarone (18), acotatarone C (19). Further, the compounds α-asarone (14) and acotatarone C (19) may be responsible for the antifungal activity, and exhibit synergistic effects. Metabonomics analysis indicated that AT60 can inhibit biofilm formation by regulating the C. albicans protein kinase C pathway. CONCLUSIONS: Our results show that A. tatarinowii has potent bioactivity against C. albicans in vitro and in vivo, and can be considered an antifungal botanic agent.