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Publikationen - Natur- und Wirkstoffchemie

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Publikation

Zhang, H.; Lin, S.; Xie, R.; Zhong, W.; Wang, H.; Farag, M. A.; Hussain, H.; Arroo, R. R.; Chen, X.; Xiao, J.; Thermal degradation of (2R, 3R)-dihydromyricetin in neutral aqueous solution at 100 ℃ Food Chem. 435, 137560, (2024) DOI: 10.1016/j.foodchem.2023.137560

In the field of thermal degradation of flavonoids, current studies mainly focused on flavonols. However, the thermal degradation of dihydroflavonols in aqueous solution has received limited attention compared to flavonols. The single C2-C3 bonds of dihydroflavonols, which differs from the C2-C3 double bond in flavonols, may cause different degradation mechanisms. Dihydromyricetin (DMY) is a typical dihydroflavonol with six hydroxyl groups, and possesses various health effects. We explored the thermal degradation of DMY in neutral aqueous solution (pH 7) at 100 ℃. Ultra-performance liquid chromatography combined with photodiode array and electrospray ionization quadrupole-time-of-flight tandem mass spectrometric detection (UPLC-PDA-ESI-QTOF-MS/MS) provided suitable platform for exploring DMY degradation pathways, and negative ion mode was applied. Thermal treatment led to a decline in DMY level with time, accompanied by the appearance of various degradation products of DMY. Degradation mechanisms of DMY included isomerization, oxidation, hydroxylation, dimerization and ring cleavage. The pyrogallol-type ring B of DMY might be initially oxidized into ortho-quinone, which could further attack another DMY to form dimers. In addition, hydroxylation is likely to occur at C-2, C-3 of DMY or DMY dimers, which then further yields ring-cleavage products via breakage of the O1-C2 bond, C2-C3 bond, or C3-C4 bond. The 3-hydroxy-5-(3,3,5,7-tetrahydroxy-4-oxochroman-2-yl) cyclohexa-3,5-diene-1, 2-dione (m/z 333.0244) and unknown compound m/z 435.0925 were annotated as key intermediates in DMY degradation. Four phenolic acids, including 3,4,5-trihydroxybenzoic acid (m/z 169.0136, RT 1.4 min), 2,4,6-trihydroxyphenylglyoxylic acid (m/z 197.0084, RT 1.7 min), 2-oxo-2-(2,4,6-trihydroxyphenyl) acetaldehyde (m/z 181.0132, RT 2.4 min), and 2,4,6-trihydroxybenzoic acid (m/z 169.0139, RT 2.5 min) were identified as the major end products of DMY degradation. In addition, 5-((3,5dihydroxyphenoxy) methyl)-3-hydroxycyclohexa-3,5-diene-1,2-dione (m/z 261.0399, RT 11.7 min) and unidentified compound with m/z 329.0507 (RT 1.0 min) were also suggested to be end products of DMY degradation. These results provide novel insights on DMY stability and degradation products. Moreover, the heat treatment of DMY aqueous solution was found to gradually reduce the antioxidant activities of DMY, and even destroy the beneficial effect of DMY on the gut microbiota composition.
Publikation

Hussain, H.; How can we unlock the full potential of marine biological resources for novel drug discovery in an effective and ethical way? Expert Opinion on Drug Discovery 19, 125-130, (2024) DOI: 10.1080/17460441.2023.2285402

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Publikation

Feng, Q.; Yan, H.; Feng, Y.; Cui, L.; Hussain, H.; Park, J. H.; Kwon, S. W.; Xie, L.; Zhao, Y.; Zhang, Z.; Li, J.; Wang, D.; Characterization of the structure, anti-inflammatory activity and molecular docking of a neutral polysaccharide separated from American ginseng berries Biomedicine & Pharmacotherapy 174, 116521, (2024) DOI: 10.1016/j.biopha.2024.116521

Aim: American ginseng berries, grown in the aerial parts and harvested in August, are a potentially valuable material. The aim of the study was to analyze the specific polysaccharides in American ginseng berries, and to demonstrate the anti-inflammation effect through in vitro and in vivo experiments and molecular docking. Methods: After deproteinization and dialysis, the extracted crude polysaccharide was separated and purified. The structure of the specific isolated polysaccharide was investigated by Fourier Transform infrared spectroscopy (FT-IR), GC-MS and nuclear magnetic resonance (NMR), and anti-inflammatory activity was evaluated using in vitro and in vivo models (Raw 264.7 cells and zebrafish). Molecular docking was used to analyze the binding capacity and interaction with cyclooxygenase-2 (COX-2). Results: A novel neutral polysaccharide fraction (AGBP-A) was isolated from American ginseng berries. The structural analysis demonstrated that AGBP-A had a weight-average molecular weight (Mw) of 122,988 Da with a dispersity index (Mw/Mn) value of 1.59 and was composed of arabinose and galactose with a core structure containing →6)-Gal-(1→ residues as the backbone and a branching substitution at the C3 position. The sidechains comprised of α-L-Ara-(1→, α-L-Ara-(1→, →5)-α-L-Ara-(1→, β-D-Gal-(1→. The results showed that it significantly decreased pro-inflammatory cytokines in the cell model. In a zebrafish model, AGBP-A reduced the massive recruitment of neutrophils to the caudal lateral line neuromast, suggesting the relief of inflammation. Molecular docking was used to analyze the combined capacity and interaction with COX-2. Conclusion: Our study indicated the potential efficacy of AGBP-A as a safe and valid natural anti-inflammatory component.
Publikation

Eshboev, F.; Mamadalieva, N.; Nazarov, P.; Hussain, H.; Katanaev, V.; Egamberdieva, D.; Azimova, S.; Antimicrobial action mechanisms of natural compounds isolated from endophytic microorganisms Antibiotics 13, 271, (2024) DOI: 10.3390/antibiotics13030271

Infectious diseases are a significant challenge to global healthcare, especially in the face of increasing antibiotic resistance. This urgent issue requires the continuous exploration and development of new antimicrobial drugs. In this regard, the secondary metabolites derived from endophytic microorganisms stand out as promising sources for finding antimicrobials. Endophytic microorganisms, residing within the internal tissues of plants, have demonstrated the capacity to produce diverse bioactive compounds with substantial pharmacological potential. Therefore, numerous new antimicrobial compounds have been isolated from endophytes, particularly from endophytic fungi and actinomycetes. However, only a limited number of these compounds have been subjected to comprehensive studies regarding their mechanisms of action against bacterial cells. Furthermore, the investigation of their effects on antibiotic-resistant bacteria and the identification of biosynthetic gene clusters responsible for synthesizing these secondary metabolites have been conducted for only a subset of these promising compounds. Through a comprehensive analysis of current research findings, this review describes the mechanisms of action of antimicrobial drugs and secondary metabolites isolated from endophytes, antibacterial activities of the natural compounds derived from endophytes against antibiotic-resistant bacteria, and biosynthetic gene clusters of endophytic fungi responsible for the synthesis of bioactive secondary metabolites.
Publikation

Cheng, Y.; Zhao, H.; Cui, L.; Hussain, H.; Nadolnik, L.; Zhang, Z.; Zhao, Y.; Qin, X.; Li, J.; Park, J. H.; Wang, D.; Ultrasonic-assisted extraction of flavonoids from peanut leave and stem using deep eutectic solvents and its molecular mechanism Food Chem. 434, 137497, (2024) DOI: 10.1016/j.foodchem.2023.137497

Natural bioactive compounds extracted from agricultural by-products have received considerable attentions. Twenty-two kinds of deep eutectic solvents (DESs) with ultrasonic were screened to extract flavonoids from peanut leave and stem. ChCl-acetic acid (ChCl-Aa) with 1:2 M ratio resulted in more effective extraction of flavonoids compared to other solvents The best extraction conditions were found to be at a 27% water content in DES/H2O, for 43 min with 31:1 g/mL liquid/solid ratio, giving 2.980 mg/g dw of flavonoids through the response surface method. SEM showed that ChCl-Aa had a certain dissociation impact on the sample matrix, while 1H NMR analysis revealed the formation of hydrogen bonds between daidzein and ChCl-Aa. Changes in the H–bond length and number were observed by the B3LYP/6-31G (d,p) level of theory to confirm the experimental spectra. This study reveals that DESs are efficient for obtaining value-added products and could applied to other natural products.
Publikation

Ning, F.; Zhu, H.; Yan, H.; Liu, J.; Aziz, S.; Hussain, H.; Song, X.; Xie, L.; Meng, Z.; Cao, G.; Wang, D.; Separation and purification of quinolyridine alkaloids from seeds of Thermopsis lanceolata R. Br. by conventional and pH‐zone‐refining counter‐current chromatography J Sep Sci 46, 2300053, (2023) DOI: 10.1002/jssc.202300053

In this work, the preparative separation of quinolyridine alkaloids from seeds of T. lanceolata by conventional and pH-zone-refining counter-current chromatography. Traditional counter-current chromatography separation was performed by a flow-rate changing strategy with a solvent system of ethyl acetate-n-butanol-water (1:9:10, v/v) and 200 mg sample loading. Meanwhile, the pH-zone-refining mode was adopted for separating 2.0 g crude alkaloid extracts with the chloroform-methanol-water (4:3:3, v/v) solvent system using the stationary and mobile phases of 40 mM hydrochloric acid and 10 mM triethylamine. Finally, six compounds, including N-formylcytisine (two conformers) (1), N-acetycytisine (two conformers) (2), (-)-cytisine (3), 13-β-hydroxylthermopsine (4), N-methylcytisine (5), and thermopsine (6) were successfully obtained in the two counter-current chromatography modes with the purities over 96.5%. Moreover, we adopted nuclear magnetic resonance and mass spectrometry for structural characterization. Based on the obtained findings, the pH-zone-refining mode was the efficient method to separate quinolyridine alkaloids relative to the traditional mode.
Publikation

Lam, Y. T. H.; Hoppe, J.; Dang, Q. N.; Porzel, A.; Soboleva, A.; Brandt, W.; Rennert, R.; Hussain, H.; Davari, M. D.; Wessjohann, L.; Arnold, N.; Purpurascenines A–C, azepino-indole alkaloids from Cortinarius purpurascens: Isolation, biosynthesis, and activity studies on the 5-HT2A receptor J. Nat. Prod. 86, 1373-1384, (2023) DOI: 10.1021/acs.jnatprod.2c00716

Three previously undescribed azepino-indole alkaloids, named purpurascenines A−C (1−3), together with the new-to-nature 7-hydroxytryptophan (4) as well as two known compounds, adenosine (5) and riboflavin (6), were isolated from fruiting bodies of Cortinarius purpurascens Fr. (Cortinariaceae). The structures of 1−3 were elucidated based on spectroscopic analyses and ECD calculations. Furthermore, the biosynthesis of purpurascenine A (1) was investigated by in vivo experiments using 13C-labeled sodium pyruvate, alanine, and sodium acetate incubated with fruiting bodies of C. purpurascens. The incorporation of 13C into 1 was analyzed using 1D NMR and HRESIMS methods. With [3-13C]-pyruvate, a dramatic enrichment of 13C was observed, and hence a biosynthetic route via a direct Pictet−Spengler reaction between α-keto acids and 7-hydroxytryptophan (4) is suggested for the biosynthesis of purpurascenines A−C (1−3). Compound 1 exhibits no antiproliferative or cytotoxic effects against human prostate (PC-3), colorectal (HCT-116), and breast (MCF-7) cancer cells. An in silico docking study confirmed the hypothesis that purpurascenine A (1) could bind to the 5-HT2A serotonin receptor’s active site. A new functional 5-HT2A receptor activation assay showed no functional agonistic but some antagonistic effects of 1 against the 5-HT-dependent 5-HT2A activation and likely antagonistic effects on putative constitutive activity of the 5-HT2A receptor.
Publikation

Jalil, K.; Ahmad, S.; Islam, N.; Ullah, R.; Jalil, Q.; Sulaiman, S.; Sajjad, A.; Ullah, R.; Alqahtani, A. S.; Bari, A.; Hussain, H.; Ali, E. A.; One pot synthesis, biological efficacy of AuNPs and Au-Amoxicillin conjugates functionalized with crude flavonoids extract of Micromeria biflora Molecules 28, 3320, (2023) DOI: 10.3390/molecules28083320

Amoxicillin is the most widely used antibiotic in human medicine for treating bacterial infections. However, in the present research, Micromeria biflora’s flavonoids extract mediated gold nanoparticles (AuNPs) were conjugated with amoxicillin (Au-amoxi) to study their efficacy against the inflammation and pain caused by bacterial infections. The formation of AuNPs and Au-amoxi conjugates were confirmed by UV–visible surface plasmon peaks at 535 nm and 545 nm, respectively. The scanning electron microscopy (SEM), zeta potential (ZP), and X-ray diffraction (XRD) studies reveal that the size of AuNPs and Au-amoxi are found to be 42 nm and 45 nm, respectively. Fourier-transform infrared spectroscopy (FT-IR) absorption bands at 3200 cm−1, 1000 cm−1, 1500 cm−1, and 1650 cm−1 reveal the possible involvement of different moieties for the formation of AuNPs and Au-amoxi. The pH studies show that AuNPs and Au-amoxi conjugates are stable at lower pH. The carrageenan-induced paw edema test, writhing test, and hot plate test were used to conduct in vivo anti-inflammatory and antinociceptive studies, respectively. According to in vivo anti-inflammatory activity, Au-amoxi compounds have higher efficiency (70%) after 3 h at a dose of 10 mg/kg body weight as compared to standard diclofenac (60%) at 20 mg/kg, amoxicillin (30%) at 100 mg/kg, and flavonoids extract (35%) at 100 mg/kg. Similarly, for antinociceptive activities, writhing test results show that Au-amoxi conjugates produced the same number of writhes (15) but at a lower dose (10 mg/kg) compared to standard diclofenac (20 mg/kg). The hot plate test results demonstrate that the Au-amoxi has a better latency time of 25 s at 10 mg/kg dose when compared to standard Tramadol of 22 s at 30 mg/ kg, amoxicillin of 14 s at 100 mg/kg, and extract of 14 s at 100 mg/kg after placing the mice on the hot plate for 30, 60, and 90 min with a significance of (p ≤ 0.001). These findings show that the conjugation of AuNPs with amoxicillin to form Au-amoxi can boost its anti-inflammatory and antinociceptive potential caused by bacterial infections.
Publikation

Hussain, H.; Xiao, J.; Ali, A.; Green, I. R.; Westermann, B.; Unusually cyclized triterpenoids: occurrence, biosynthesis and chemical synthesis Nat. Prod. Rep. 40, 412-451, (2023) DOI: 10.1039/d2np00033d

Covering: 2009 to 2021Biosynthetically, most of the syntheses of triterpenes follow the cascade cyclization and rearrangement of the acyclic precursors viz., squalene (S) and 2,3-oxidosqualene (OS), which lead to the very well known tetra- and pentacyclic triterpene skeletons. Aside from these, numerous other triterpenoid molecules are also reported from various natural sources and their structures are derived from \"S\" and \"OS\" via some unusual cyclization operations which are different from the usual tetra- and pentacyclic frameworks. Numerous compelling advances have been made and reported in the identification of these unusual cyclized mono-, di-, tri- and tetracyclic triterpenes between 2009 and 2021. Besides a dramatic increase in the newly isolated uncommon cyclized triterpenoids, substantial progress in the (bio)-synthesis of these triterpenes has been published along with significant progress in their biological effects. In this review, 180 new unusual cyclized triterpenoids together with their demonstrated biogenetic pathways, syntheses and biological effects will be categorized and discussed.
Publikation

Hussain, H.; Siddiqui, H.; Gerothanassis, I. P.; Prof. Dr. M. Iqbal Choudhary-A lifetime career dedicated to remarkable services in “natural products sciences” Frontiers in Pharmacology 14, 1119419, (2023) DOI: 10.3389/fphar.2023.1119419

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