Natural Products Research Articles

Chloroformate-mediated ring cleavage of indole alkaloids leads to re-engineered antiplasmodial agents.

Natural product ring distortion strategies have enabled rapid access to unique libraries of stereochemically complex compounds to explore new chemical space and increase our understanding of biological processes related to human disease. Herein is described the development of a ring-cleavage strategy using the indole alkaloids yohimbine, apovincamine, vinburnine, and reserpine that were reacted with a diversity of chloroformates paired with various alcohol/thiol nucleophiles to enable the rapid synthesis of 47 novel small molecules. Ring cleavage reactions of yohimbine and reserpine produced two diastereomeric products in moderate to excellent yields, whereas apovincamine and vinburnine produced a single diastereomeric product in significantly lower yields. Free energy calculations indicated that diastereoselectivity regarding select ring cleavage reactions from yohimbine and apovincamine is dictated by the geometry and three-dimensional structure of reactive cationic intermediates. These compounds were screened for antiplasmodial activity due to the need for novel antimalarial agents. Reserpine derivative 41 was found to exhibit interesting antiplasmodial activities against Plasmodium falciparum parasites (EC50 = 0.50 μM against Dd2 cultures), while its diastereomer 40 was found to be three-fold less active (EC50 = 1.78 μM). Overall, these studies demonstrate that the ring distortion of available indole alkaloids can lead to unique compound collections with re-engineered biological activities for exploring and potentially treating human disease.

Penilumamide, a novel SIRT1 activator, protects UVB-induced photodamages in HaCaT cells

ABSTRACT Ultraviolet-B (UVB) radiation is a major physical factor that induces structural changes in human skin. The aim of this study was to determine whether the novel silent information regulator 1 (sirtuin 1 SIRT1) protein activator, penilumamide, exerted any protective effects against UVB-induced skin damage using human HaCaT keratinocytes as a model. Enzymatic assays were performed to determine the SIRT1-activating ability of penilumamide, which was compared with that of resveratrol, a potent natural product SIRT1 activator with antioxidant and anti-inflammatory properties. Penilumamide markedly activated SIRT1 enzyme activity compared to resveratrol. To further investigate the protective effect of penilumamide against UVB-induced cytotoxicity, HaCaT cells were pretreated with penilumamide (10 μM) for 24 hr followed by irradiation with UVB (40 mJ/cm2). UVB (40 mJ/cm2) irradiation significantly reduced cell viability in a time-dependent manner, whereas pretreatment with penilumamide blocked this effect. Further, penilumamide decreased the levels of intracellular reactive oxygen species (ROS) generated by UVB irradiation in HaCaT cells. Pretreatment with penilumamide also prevented UVB irradiation-induced changes in mitochondrial membrane potential (ΔΨ m). In addition, pretreatment with penilumamide significantly reduced the expression levels of pro-inflammatory cytokines, interleukin (IL)-6, IL-8, and IL-10 and phosphorylation of nuclear factor-kB (NF-kB). These results indicate that penilumamide protects HaCaT cells from UVB-induced inflammation. Taken together data demonstrate that penilumamide exerted protective effects against UVB-induced ROS generation in HaCaT cells. Therefore, penilumamide may be considered to be used as a new SIRT1 activator to protect human keratinocyte against UVB-induced damage.

Chromatographic fingerprinting of epiphytic fungal strains isolated from Withania somnifera and biological evaluation of isolated okaramine H.

Medicinal plants are "goldmines" of natural products, and continue to provide key scaffolds for drug development. They have immense therapeutic potential, encapsulating a plethora of metabolites within them, which have yet to be explored. Withania somnifera (L.) Dunal is one such medicinal plant known since time immemorial for its therapeutic activity in the Ayurveda system of medicine. Studies have revealed Nature's marvel of these medicinal plants harbouring endophytic and epiphytic microorganisms from phyllosphere to rhizosphere. Chromatographic fingerprinting was carried out using HPTLC and HPLC on five epiphytic strains isolated from the leaves, stem and fruits of Withania somnifera. Out of five filamentous fungi, one fungus identified as Aspergillus aculeatus S20 was well explored. An indole alkaloid, okaramine H, was isolated using systematic chromatographic investigation at a retention time of 26.278 min showing λmax at 206, 236, 284 and 370 nm. Confirmation was achieved using NMR and mass spectrometry (MS) as analytical techniques. Structure elucidation was done by studying the fragmentation pattern using MS/MS and an accurate mass was determined using HR-ESI-QTOF-MS showing m/z of 521.2546 [M + H]+. The percentage purity of isolated okaramine H was found to be >90. Well known for its insecticidal activity, okaramine H was explored for its antileishmanial activity against the Leishmania donovani parasite for the first time. Under in vitro conditions, the compound showed an inhibitory effect on Leishmania donovani promastigotes with an IC50 of 147 μg mL-1.

Non-benzenoid N-aryl oxalamide: synthesis of troponyl-oxalamide peptides by Pd(II)-catalyzed C(sp3)-H functionalization of glycinamides.

Aryl oxalamides are constituents of various promising drug-like molecules. Their aryl groups are derived from the benzenoid aromatic moiety. However, non-benzenoid aromatic molecules, troponoids, are found in various bioactive natural products. It would be thought-provoking to explore non-benzenoid aryl oxalamide derivatives. This report describes the synthesis of N-troponyl-oxalamide peptides by Pd(II)-catalyzed C(sp3)-H functionalization of N-troponyl glycinate peptides. This is the first instance of β-hydride elimination at the palladium complex of N-troponyl glycinates that generates imine in situ, rendering the synthesis of oxalamides. Importantly, the crystal structures of representative oxalamide derivatives form distinctive foldameric structures, such as β-sheet type structures, owing to the presence of additional troponyl carbonyl groups. Hence, these non-benzenoid oxalamides are potential scaffolds for tuning the structure and function of N-troponyl peptides, which could provide innovative avenues of research in the development of emerging structural and functional peptides.

Morin overcomes doxorubicin resistance in human breast cancer by inducing DNA damage and modulating the LKB1/AMPK/mTORC1 signaling pathway.

Breast cancer chemoresistance hampers chemotherapy efficacy; researchers investigate the pharmacological activities of natural products for potential solutions. This study aimed to determine the effect of morin, a bioflavonoid isolated from Maclura pomifera, on two Dox-resistant human breast cancer cell lines MDA-MB-231 (MDA-DR) and MCF-7 (MCF-DR). Sulforhodamine B and colony-forming assays demonstrated the cytotoxic effect of morin on both cell lines. Morin induced DNA damage and reduced the DNA repair mechanism, a feature of chemoresistance. In addition, morin reduced the protein expressions of cell cycle regulators, such as cyclin D1, CDK4, cyclin E1, cyclin B1, and p-Rb, thereby halting cell cycle progression. Moreover, morin slightly reduced PARP and Bcl-xL expressions but left LC3-II and RIPK3 expressions unchanged. Annexin-V/7-AAD analysis showed morin increased 7-AAD positive cells and annexin-V positive cells among MDA-DR and MCF-DR cells, respectively. In addition, morin increased p-AMPK and p-LKB1 levels; and, thus, inhibited phosphorylation of the mTOR pathway, but decreased t-AMPK levels by inducing lysosomal degradation, and AICAR, an AMPK activator, reduced Raptor, cyclin D1, CDK4, cyclin E1 and phosphorylated, and total mTOR levels, indicating AMPK is a key player in inducing cell death. Also, morin modulated MAPK phosphorylation and attenuated p-Akt and p-GSK3αβ levels; and thus, inhibited cell survival. In addition, morin suppressed tumor growth in our MDA-DR xenografted mouse model. These findings indicate that morin is a potential treatment for Dox-resistant breast cancer and that it does so by inducing DNA damage and modulating the LKB1/AMPK/mTORC1 pathway, along with regulating the MAPK, and Akt/GSK3αβ signaling pathways.

Natural health product knowledge as a significant factor associated with health-promoting lifestyle in a low-income urban community in Kuala Lumpur

BackgroundLow income communities are vulnerable to non-communicable diseases (NCDs), which affect their economy and disability status. An effective approach to address the NCD burden is through the multidimensional concept of health-promoting lifestyle. Another preferred approach by the population worldwide for NCD treatment is natural health product (NHP). Studies on NHP and health-promoting lifestyle among this vulnerable population, specifically the low-income urban community, are limited. Therefore, this study, aimed at investigating the NHP knowledge and health-promoting lifestyle, and to determine the factors associated with health-promoting lifestyle in a low income urban community in Cheras, Kuala Lumpur. This study has focused on sociodemographic characteristics, annual health monitoring activities, and health status, which are modifiable and non-modifiable factors.MethodsPhase 1 of the study involves developing the Malay-version NHP knowledge questionnaire, whereas Phase 2 involves a cross-sectional study of 446 randomly selected low-income respondents to determine their level of health-promoting lifestyle and the associated factors. The respondents’ sociodemographic, socioeconomic, health monitoring activity, health status, and NHP knowledge data were obtained using the newly developed Malay-version NHP questionnaire and the Health-Promoting Lifestyle Profile II (HPLP II) questionnaire. The independent variables include sociodemographic status, annual health monitoring activities, health status and NHP knowledge were analysed using simple and multiple linear regression.ResultsIn this study, the 10-item NHP knowledge questionnaire developed in the Malay version contains two domains [safe use (eight items) and point of reference (two items)] (total variance explained: 77.4%). The mean of NHP knowledge score was 32.34 (standard deviation [SD] 7.37). Meanwhile, the mean score of health-promoting lifestyle was 109.67 (SD 25.01). The highest and lowest scores of health-promoting lifestyles are attributed to spiritual growth and physical activity, respectively. Ethnicity is associated with a higher health-promoting lifestyle level, same goes to the occupational status − NHP knowledge interaction. “Unclassified” education status and annual blood glucose level monitoring are associated with a lower level of health-promoting lifestyle.ConclusionA new questionnaire in Malay version was developed to measure NHP knowledge. Compared to other subpopulations, the respondents’ health-promoting lifestyle levels in this study were low, associated with ethnicity, education status, and health monitoring activities. The findings provided insight into the interaction between NHP knowledge and occupational status, which is associated with a higher health-promoting lifestyle level. Accordingly, the future health-promoting lifestyle intervention programmes in healthcare delivery should target these factors.

Nonenzymatic Sequestering of Formaldehyde into the Antibiotic Methylene-Bridged Dimer Phaeochromycin F by Streptomyces sp. OUCMDZ-4982 as a Possible Multipronged Chemical Defense Mechanism.

Metabolites with high chemical reactivity serve important roles in chemical defenses of organisms. Formaldehyde, as a simple and highly reactive small molecule, can be produced by microorganisms, plants, and animals. Its toxicity is well known, but information about its other biological functions remains scarce. Here, we report that the natural product SEK34b produced by Streptomyces species can react nonenzymatically with formaldehyde in water to yield the methylene-bridged dimer phaeochromycin F. This process can eliminate the toxic substance formaldehyde produced by Staphylococcus aureus. Furthermore, there is a substantial inhibitory impact of phaeochromycin F on S. aureus. We hypothesize that these constitute an integrated system of defense and attack of Streptomyces species against competitors. Our study indicates that formaldehyde can react with vancomycin and tigecycline under mild conditions to generate the derivatives bearing an imidazolidin-4-one moiety, thereby reducing the antibacterial activity of these antibiotics. These data provide a possible chemical interaction mechanism of bacteria involving the nonenzymatic reactions of formaldehyde with highly reactive natural products.

Estimating the extent of adulteration of the popular herbs black cohosh, echinacea, elder berry, ginkgo, and turmeric - its challenges and limitations.

Covering: up to July 2023Botanical natural medicinal products and dietary supplements are utilized globally for their positive impacts on health and wellness. However, the effectiveness and safety of botanical products can be compromised by unintentional or intentional adulteration. The presence of adulterated botanical ingredients in the global market has been documented in the published literature but a key question, namely what the extent of adulteration is, remains to be answered. This review aims to estimate the prevalence of adulteration in preparations made from black cohosh rhizome, echinacea root or herb, elder berry, ginkgo leaf, and turmeric root/rhizome. According to the information provided in the 78 publications retrieved for this paper, 818 of 2995 samples were reported to be adulterated and/or mislabeled. Ginkgo leaf samples (n = 533) had the highest adulteration rate with 56.7%, followed by black cohosh rhizome (n = 322) samples with 42.2%, echinacea root/herb (n = 200) with 28.5%, elder berry (n = 695) with 17.1%, and turmeric root/rhizome (n = 1247) with 16.5%. Products sold as licensed or registered herbal medicines were found to have a lower risk of adulteration compared to products sold as dietary/food supplements. The data show that the adulteration rate substantially differs from one ingredient to the other. Due to the significant limitations of the available data upon which the estimated extent of adulteration is based, and the rapidly changing botanical dietary supplement market, conclusions from the five herbs examined in this publication cannot be applied to other botanicals traded in the global market. However, the data clearly show that a substantial portion of the botanical dietary supplements do not contain what is claimed on their labels.

Ferroptosis in Cognitive Impairment Associated with Diabetes and Alzheimer's Disease: Mechanistic Insights and New Therapeutic Opportunities.

Cognitive impairment associated with diabetes and Alzheimer's disease has become a major health issue affecting older individuals, with morbidity rates growing acutely each year. Ferroptosis is a novel form of cell death that is triggered by iron-dependent lipid peroxidation. A growing body of evidence suggests a strong correlation between the progression of cognitive impairment and diabetes, Alzheimer's disease, and ferroptosis. The pharmacological modulation of ferroptosis could be a promising therapeutic intervention for cognitive impairment associated with diabetes and Alzheimer's disease. In this review, we summarize evidence on ferroptosis in the context of cognitive impairment associated with diabetes and Alzheimer's disease and provide detailed insights into the function and potential action pathways of ferroptosis. Furthermore, we discuss the therapeutic importance of natural ferroptosis products in improving the cognitive impairment associated with diabetes and Alzheimer's disease and provide new insights for clinical treatment.

Et3Al/Light-Promoted Radical-Polar Crossover Reactions of α-Alkoxyacyl Tellurides.

Here, we report new radical-polar crossover reactions of α-alkoxy carbon radicals for constructing highly oxygenated molecules with contiguous stereocenters. The method employs a 370 nm UV light-emitting diode (LED) for the photoexcitation of α-alkoxyacyl telluride, and Et3Al as the radical initiator and terminator. First, Et3Al and UV LED promoted radical coupling between the α-alkoxyacyl telluride and cyclopentenone via C-Te bond homolysis, CO expulsion, and C-C bond formation. Second, Et3Al converted the radical species to the corresponding aluminum enolate. Third, the second C-C bond formation occurred via a polar mechanism: intermolecularly with aldehydes/ketones and intramolecularly with epoxide, producing aldol and SN2 adducts, respectively. The present coupling reactions increase the molecular complexity in a single step by stereoselective formation of the two hindered C-C bonds. The devised method is expected to be useful for the expeditious assembly of densely oxygenated natural products.

Functional implications of unusual NOS and SONOS covalent linkages found in proteins.

The tertiary and quaternary structures of many proteins are stabilized by strong covalent forces, of which disulfide bonds are the most well known. A new type of intramolecular and intermolecular covalent bond has been recently reported, consisting of the Lys and Cys side-chains linked by an oxygen atom (NOS). These post-translational modifications are widely distributed amongst proteins, and are formed under oxidative conditions. Similar linkages are observed during antibiotic biosynthesis, where hydroxylamine intermediates are tethered to the sulfur of enzyme active site Cys residues. These linkages open the way to understanding protein structure and function, give new insights into enzyme catalysis and natural product biosynthesis, and offer new strategies for drug design.

Total Synthesis and Anti-inflammatory Activity of Asperjinone and Asperimide C.

Total syntheses of two γ-butenolide natural products, asperjinone (1) and asperimide C (2) in both racemic and chiral forms have been accomplished utilizing Basavaiah's one-pot Friedel-Crafts/maleic anhydride formation protocol as a key strategy. Our syntheses verified the revised structure of 1 proposed by Williams et al. and the structure and absolute configuration of 2 reported by the Li group. This work also discloses the unprecedented anti-inflammatory activity of 1. Synthetic 1 exhibited significant anti-inflammatory activity in renal proximal tubular epithelial cells (RPTEC) by suppression of gene expression of pro-inflammatory cytokines TNF-α, IL-1β and IL-6 under LPS-induced renal inflammation condition and was superior to (S)-1, rac-2, 2, and a positive drug control, indomethacin. Moreover, compound 1 inhibited downstream signaling of inflammation by significantly reducing iNOS and COX-2 gene expression and total NO production. The anti-inflammatory activity of asperjinone (1) renders it a potential and promising candidate for developing novel anti-inflammatory agents against inflammation worsening acute kidney injury.

Cobalt-Catalyzed Chemo- and Stereoselective Transfer Semihydrogenation of 1,3-Dienes with Water as a Hydrogen Source.

(Z)-1,2-Disubstituted, trisubstituted, and tetrasubstituted alkenes are not only important units in medicinal chemistry, natural product synthesis, and material science but also useful intermediates in organic synthesis. Development of catalytic stereoselective transformations to access multisubstituted alkenes with various substitution patterns from easily accessible modular starting materials and readily available catalysts is a crucial goal in the field of catalysis. Water is an ideal hydrogen source for catalytic transfer hydrogenation despite of the high difficulty to activate water. Here, we report a cobalt-catalyzed protocol for regio- and stereoselective transfer semihydrogenation of 1,3-dienes to construct a broad scope of (Z)-1,2-disubstituted, (Z)-, (E)-trisubstituted, and tetrasubstituted alkenes in high stereoselectivity with H2O as the hydrogen source. Mechanistic studies revealed that the reactions proceeded through a unique Co(I)/Co(III) cycle and involved a 1,4-cobalt shift process, which is an unprecedented reaction pathway, providing a new platform for modular synthesis of multisubstituted alkenes as well as opportunities for designing novel reaction modes and pushing forward the advancement in organocobalt chemistry.

Neutrophil extracellular traps: Potential targets for the treatment of rheumatoid arthritis with traditional Chinese medicine and natural products.

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease. Abnormal formation of neutrophil extracellular traps (NETs) at the synovial membrane leads to the release of many inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Elastase, histone H3, and myeloperoxidase, which are carried by NETs, damage the soft tissues of the joints and aggravate the progression of RA. The balance of NET formation coordinates the pro-inflammatory and anti-inflammatory effects and plays a key role in the development of RA. Therefore, when NETs are used as effector targets, highly targeted drugs with fewer side effects can be developed to treat RA without damaging the host immune system. Currently, an increasing number of studies have shown that traditional Chinese medicines and natural products can regulate the formation of NETs through multiple pathways to counteract RA, which shows great potential for the treatment of RA and has a promising future for clinical application. In this article, we review the latest biological progress in understanding NET formation, the mechanism of NETs in RA, and the potential targets or pathways related to the modulation of NET formation by Chinese medicines and natural products. This review provides a relevant basis for the use of Chinese medicines and natural products as natural adjuvants in the treatment of RA.

Synthesis of C-Alkyl Glycosides from Alkyl Bromides and Glycosyl Carboxylic Acids via Ni/Photoredox Dual Catalysis.

C-Alkyl glycosides, an important class of C-glycosides, are widely found in various drugs and natural products. The synthesis of C-alkyl glycosides has attracted considerable attention. Herein, we developed a Ni/photoredox catalyzed decarboxylative C(sp3)-C(sp3) coupling reaction of stable glycosylcarboxylic acids with simple aliphatic bromides to generate C-alkyl glycosides. The method successfully linked several functional molecular fragments (natural products or drugs) to a sugar moiety, showing the extensive application prospects of this transformation. Controlled experiments and DFT calculations demonstrated that the reaction pathway contains a free radical process, and a possible mechanism is proposed.

Recent Advances on Catalytic Atroposelective Synthesis of Planar‐Chiral Macrocycles

Planar chiral skeletons widely exist in natural products, bioactive compounds, and other functional molecules. Although significant progress has been made in the field of asymmetric synthesis of central or axial chiral molecules over the past years, enantioselective constructing of planar chirality is still a big obstacle and numerous efforts have been made in this field. Previous works have mainly focused on the assembly of planar chiral [2,2]‐paracyclophanes and metallocenes. This Minireview describes the recent advancements on asymmetric catalytic synthesis of planar chiral macrocycles, including ansa chain construction, plane formation and asymmetric transformation strategies. It is anticipated that this Minireview will sever as a source of inspiration for developing new unconventional procedures for access to planar chiral skeletons.

SYNTHESIS AND REACTIVITY OF CARBOHYDRATES CONTAINING 3‐MEMBERED HETEROCYCLES, KEY PRECURSORS OF MODIFIED SUGARS AND MIMETICS

Molecules containing three‐membered heterocycles, including oxiranes (epoxides), thiiranes (episulfides) and aziridines, are considered privileged structures as they serve as key precursors or intermediates for the synthesis of a varied range of organic compounds, such as natural products, mimetics and pharmaceuticals. The principal advantage of this type of heterocycles is their reactivity towards the nucleophilic ring‐opening, which usually occurs in a regioselective manner, resulting in the formation of 1,2‐disubstituted products. When attached to a chiral scaffold, such as a carbohydrate molecule, the ring‐opening process is usually highly diastereoselective. Therefore, these compounds have been extensively employed in the field of carbohydrates for the synthesis of enantiomerically pure modified sugars that are useful as glycobiology tools. This review presents an overview of the recent methodologies developed for the construction of epoxide, thiirane, and aziridine rings from common or modified sugars. Due to their structural similarity to carbohydrates, three‐membered heterocyclic derivatives of cyclitols and carbasugars have been included. All these compounds, and their ring‐opening derivatives have shown to be crucial in the synthesis of glycomimetics, which display diverse biological activities. These include enzyme inhibition, binding to lectin receptors, and more recently, the use as probes for the diagnosis and monitoring of diseases.

Recent Advances on Catalytic Atroposelective Synthesis of Planar-Chiral Macrocycles.

Planar chiral skeletons widely exist in natural products, bioactive compounds, and other functional molecules. Although significant progress has been made in the field of asymmetric synthesis of central or axial chiral molecules over the past years, enantioselective constructing of planar chirality is still a big obstacle and numerous efforts have been made in this field. Previous works have mainly focused on the assembly of planar chiral [2,2]-paracyclophanes and metallocenes. This Minireview describes the recent advancements on asymmetric catalytic synthesis of planar chiral macrocycles, including ansa chain construction, plane formation and asymmetric transformation strategies. It is anticipated that this Minireview will sever as a source of inspiration for developing new unconventional procedures for access to planar chiral skeletons.

Structural Simplification of Podophyllotoxin: Discovery of γ-Butyrolactone Derivatives as Novel Antiviral Agents for Plant Protection.

Natural products are a valuable resource for the discovery of novel crop protection agents. A series of γ-butyrolactone derivatives, derived from the simplification of podophyllotoxin's structure, were synthesized and assessed for their efficacy against tobacco mosaic virus (TMV). Several derivatives exhibited notable antiviral properties, with compound 3g demonstrating the most potent in vivo anti-TMV activity. At 500 μg/mL, compound 3g achieved an inactivation effect of 87.8%, a protective effect of 71.7%, and a curative effect of 67.7%, surpassing the effectiveness of the commercial plant virucides ningnanmycin and ribavirin. Notably, the syn-diastereomer (syn-3g) exhibited superior antiviral activity compared to the anti-diastereomer (anti-3g). Mechanistic studies revealed that syn-3g could bind to the TMV coat protein and interfere with the self-assembly process of TMV particles. These findings indicate that compound 3g, with its simple chemical structure, could be a potential candidate for the development of novel antiviral agents for crop protection.

Harnessing in vivo synthesis of bioactive multiarylmethanes in Escherichia coli via oxygen-mediated free radical reaction induced by simple phenols

BackgroundXanthenes and multi-aryl carbon core containing compounds represent different types of complex and condensed architectures that have impressive wide range of pharmacological, industrial and synthetic applications. Moreover, indoles as building blocks were only found in naturally occurring metabolites with di-aryl carbon cores and in chemically synthesized tri-aryl carbon core containing compounds. Up to date, rare xanthenes with indole bearing multicaryl carbon core have been reported in natural or synthetic products. The underlying mechanism of fluorescein-like arthrocolins with tetra-arylmethyl core were synthesized in an engineered Escherichia coli fed with toluquinol remained unclear.ResultsIn this study, the Keio collection of single gene knockout strains of 3901 mutants of E. coli BW25113, together with 14 distinct E. coli strains, was applied to explore the origins of endogenous building blocks and the biogenesis for arthrocolin assemblage. Deficiency in bacterial respiratory and aromatic compound degradation genes ubiX, cydB, sucA and ssuE inhibited the mutant growth fed with toluquinol. Metabolomics of the cultures of 3897 mutants revealed that only disruption of tnaA involving in transforming tryptophan to indole, resulted in absence of arthrocolins. Further media optimization, thermal cell killing and cell free analysis indicated that a non-enzyme reaction was involved in the arthrocolin biosynthesis in E. coli. Evaluation of redox potentials and free radicals suggested that an oxygen-mediated free radical reaction was responsible for arthrocolins formation in E. coli. Regulation of oxygen combined with distinct phenol derivatives as inducer, 31 arylmethyl core containing metabolites including 13 new and 8 biological active, were isolated and characterized. Among them, novel arthrocolins with p-hydroxylbenzene ring from tyrosine were achieved through large scale of aerobic fermentation and elucidated x-ray diffraction analysis. Moreover, most of the known compounds in this study were for the first time synthesized in a microbe instead of chemical synthesis. Through feeding the rat with toluquinol after colonizing the intestines of rat with E. coli, arthrocolins also appeared in the rat blood.ConclusionOur findings provide a mechanistic insight into in vivo synthesis of complex and condensed arthrocolins induced by simple phenols and exploits a quinol based method to generate endogenous aromatic building blocks, as well as a methylidene unit, for the bacteria-facilitated synthesis of multiarylmethanes.