Natural Products and Bioprospecting最新文献

Our continuous study of the fruits of Garcinia xanthochymus and Garcinia subelliptica led to the isolation and structural characterization of six new polyprenylated acylphloroglucinols, xanthochymusones N and O (1 and 2), (–)-garciyunnanin L (3), and garsubelones C–E (4–6), together with two known analogues. Their structures were elucidated by interpretation of NMR and MS spectroscopic data. It was found that the Grossman-Jacobs rule is no longer applicable to determination of the C-7 configuration of compounds 1–3, as they possess a complex 6/6/6/6/6 fused ring system. The inhibitory activities of all the compounds against two human hepatocellular carcinoma cell lines Huh-7 and HepG2 were evaluated, and compound 1 exhibited moderate cytotoxic activities against HepG2 cells with IC₅₀ value 7.3 μM. Furthermore, the previous assignments of some polyprenylated acylphloroglucinols have been proved to be incorrect in this study, and analysis of NMR data enabled the structural revision of seven analogues: hyperselancins A and B, garcinielliptones F and G, garxanthochins A and B, and 13,14-didehydroxygarcicowin C. The revised structures of garcinielliptone F and garxanthochin A were shown to have the same structures of garsubelone B and xanthochymusone K, respectively, and the revised structures of other five compounds have not been reported.

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Otteacumienes G–K (1–5), five pairs of enantiomeric diarylheptanoids, along with one undescribed diarylheptanoid glycoside and one new lignan, were isolated from Ottelia acuminata var. acuminata. Compounds 1–5 were identified as five pairs of enantiomers and their structural configurations were determined through a combination of spectroscopic analysis, X-ray crystallography, and ECD calculation. Notably, compound 6 was the first diarylheptanoid glycoside isolated from this aquatic species, and its absolute configuration was unequivocally established through semi-synthesis. Biological evaluation demonstrated that compound 1 exhibited α-glucosidase inhibitory activity, with an inhibition ratio of 38.97% (acarbose as the positive control, inhibition ratio = 13.52%).

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Two concise and efficient synthetic routes were developed for the synthesis of three 1,7-diarylheptanoids (1–3) containing a 1,4-pentadiene unit, which were originally isolated from Ottelia acuminata var. acuminata. The first approach focused on the construction of linear diarylheptanoids 1 and 3 featuring a (1E,4E)-pentadiene moiety, via a Suzuki coupling reaction. The second strategy enabled the synthesis of sixteen-membered macrocyclic ether 2 with a (1Z,4E)-pentadiene unit. The challenging macrocyclization was successfully accomplished through an Ullmann coupling. Notably, the formation of the Z-olefin within the macrocyclic framework was promoted by the inherent ring strain of diarylether-type heptane system, which preferentially stabilizes this particular configuration.

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In this work, six pairs of undescribed enantiomeric prenylated flavonoids, ( ±)-epimesatines J–O (1a/1b–6a/6b), were isolated from the aerial parts of Epimedium sagittatum Maxim. Their structures and absolute configurations were determined based on spectroscopic data, quantum chemical calculations of electronic circular dichroism (ECD) and ¹³C NMR, as well as ECD experiments induced by Mo₂(OAc)₄ and Rh₂(OCOCF₃)₄. The cytotoxicity assay revealed that compounds 1a/1b, 2a/2b, and 4a/4b–6a/6b demonstrated significant inhibitory effects on the viability of human breast cancer cells MCF-7 while exhibiting no obvious toxicity towards human breast epithelial cells MCF-10A. Additionally, these compounds were found to decrease the expression of sphingosine kinase 1 (Sphk1) in MCF-7 cells. Notably, compounds 4a and 5b exhibited IC₅₀ values of 7.45 and 8.97 μM, respectively, in MCF-7 cells.

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Pseudomonas aeruginosa-induced bacterial keratitis is one of the most sight-threatening corneal infections associated with intense ocular inflammatory reactions that may lead to vision loss. Hence, this study investigated the efficacy of three nanocomposite chitosan-coated penetration enhancer vesicles (PEVs) to augment the ocular delivery of saponin(s), α-hederin (PEVI), hederacoside C (PEVII), or both (PEVIII) for treatment of Pseudomonas keratitis and its induced inflammatory response. The three formulations were prepared using the ethanol injection method and comprehensively characterized. In vitro, the antibacterial activity of the three formulations against P. aeruginosa was evaluated using agar well-diffusion method, pyocyanin production inhibition, and swarming and twitching motility inhibition assays. The therapeutic effect of the three formulations has been investigated in P. aeruginosa keratitis by gross lesion monitoring, determination of bacterial bioburden, biochemical markers, histopathological examination, and scoring after 7 days of topical treatment. Data revealed that PEVI, PEVII, and PEVIII nanocomposites showed particle size in the nanometer range, high entrapment efficiency, good stability, and sustained release of the saponins throughout 24 h. Among them, PEVIII exhibited notably strong in vitro antipseudomonal activity. Additionally, animals treated topically with PEVIII showed an appreciable gross lesion reduction, corneal tissue improvement, and formidable bacterial load reduction compared with untreated and gentamicin sulfate eye (GENTAWISE^®) ointment-treated groups. Moreover, PEVIII treatment showed the most significant reduction in TNF-α, NF-κB, ROS levels, and OPRL virulence gene expression while enhancing PI3K/Akt activation. Therefore, this study offers PEVIII as a promising treatment for P. aeruginosa keratitis.

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Sesquiterpenoids represent a structurally diverse class of natural products widely recognized for their ecological significance and pharmacological potential, including antimicrobial, anti-inflammatory, and anticancer properties. As part of our efforts to explore bioactive secondary metabolites from phytopathogenic fungi, we conducted a molecular networking-based analysis of Bipolaris sorokiniana isolate BS11134, which was fermented on a rice medium. This analysis led to the identification of three new seco-sativene-type sesquiterpenoids (1–3) and seven known analogues (4–10), with the NMR data of compound 4 being reported for the first time. The structures of these compounds were elucidated using HR-ESI-MS and extensive spectroscopic data analysis. Notably, compound 9 significantly inhibited nitrous oxide expression in lipopolysaccharide (LPS)-treated RAW264.7 cells in vitro (inhibition rate: 84.7 ± 1.7% at 10 μM), while compound 1 (10 μM) showed a weak inhibitory effect (inhibition rate = 28.0 ± 2.4%). Additionally, we proposed a biosynthetic pathway for these compounds. This study not only expands the chemical space of the helminthoporene class of molecules but also underscores the untapped potential of phytopathogenic fungi as promising sources of structurally unique and biologically active natural products.

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Antimicrobial resistance is one of the most pressing global health challenges, as many pathogens are rapidly evolving to evade existing treatments. Despite this urgent need for new solutions, natural plant-derived compounds remain relatively underexplored in the development of antimicrobial drugs. This report highlights an innovative approach to discovering potent antimicrobial agents through bioguided fractionation of numerous plant species from the rich Argentinean flora. By systematically screening 60 species (over 177 extracts) for antimicrobial activity against representative strains of gram-positive and gram-negative bacteria, we identified promising bioactive compounds within the Asteraceae family—particularly sesquiterpene lactones from the Xanthium genus. Building on this basis, we synthesized semi-synthetic derivatives by chemically modifying plant sub-extracts, focusing on structures incorporating heteroatoms and/or heterocycles containing oxygen and nitrogen (important for the bioavailability and bioactivity that they are capable of providing). These modifications were evaluated for their potential to enhance antimicrobial efficacy against bacteria and Candida species, including resistant strains. Our findings suggest that tailoring natural metabolites from Xanthium and related Asteraceae species can significantly improve their antimicrobial properties. This strategy offers a promising pathway for the development of novel therapeutic agents to combat bacterial and fungal infections in an era of rising drug resistance.

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Purpose

This study aimed to investigate the potential of corylin, a bioactive compound isolated from the aerial part of Pueraria lobata, as a novel skin-whitening agent. Specifically, the research sought to evaluate its effects on melanin synthesis, understand its underlying mechanisms, and validate its efficacy in mitigating hyperpigmentation.

Methods

Bioactive compound was isolated from Pueraria lobata through a systematic fractionation process involving activated carbon pigment removal, sequential solvent extraction, and resin-based chromatography. It was shown to inhibit melanin synthesis by targeting tyrosinase activation and modulating key signaling pathways. Its efficacy in reducing melanin production was validated through cellular assays and a UVB-stimulated 3D human skin model, highlighting its potential as a skin-whitening agent.

Results

Through fractionation, the bioactive compound was identified as corylin, which reduced melanin content and tyrosinase activity without cytotoxicity, modulated signaling pathways to downregulate MITF and melanogenic enzymes, and inhibited α-glucosidase, disrupted glycosylation. In a UVB-stimulated 3D skin model, it effectively decreased melanin production, confirming its potential to mitigate hyperpigmentation.

Conclusion

Corylin is a promising candidate for skin-whitening applications, effectively mitigating hyperpigmentation by targeting multiple stages of melanin synthesis, including enzymatic activity and regulatory pathways. Further clinical studies are needed to confirm its safety and therapeutic potential for dermatological use.

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Three pairs of enantiomeric phthalide dimers, including two new ones, angesicolides A (1) and B (2), and a new phthalide monomer (3), were obtained from the rhizomes of Angelica sinensis. Their structures were established through spectroscopic methods, quantum calculations, and chiral HPLC analysis. Compounds 1 and 2 were [2 + 2] and [4 + 2] cycloadducts of phthalide monomers, and their hypothetical biogenetic origin was proposed. Compounds 2, (+)-2, (−)-2, 4, (+)-4, and (−)-4 exhibited significant inhibitory activity against NO production with IC₅₀ values range from 1.23 to 5.55 μM.

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Natural products obtained from medicinal and aromatic plants are increasingly recognized as promising anticancer agents due to their structural richness, including terpene and flavonoid molecules, which induce apoptosis and modulate gene expression. These compounds offer an alternative to conventional treatments, often costly, which face challenges such as multidrug resistance. This review aims to provide a promising alternative approach to effectively control cancer by consolidating significant findings in identifying natural products and anticancer agent development from medicinal and aromatic plants. It synthesizes the findings of a comprehensive search of academic databases, such as PubMed and Springer, prioritizing articles published in recognized peer-reviewed journals that address the bioprospecting of medicinal and aromatic plants as anticancer agents. The review addresses the anticancer activities of plant extracts and essential oils, which were selected for their relevance to chemoprevention and chemotherapy. Compounds successfully used in cancer therapy include Docetaxel (an antimitotic agent), Etoposide VP-16 (an antimitotic agent and topoisomerase II inhibitor), Topotecan (a topoisomerase I inhibitor), Thymoquinone (a Reactive Oxygen Species-ROS inducer), and Phenethyl isothiocyanate (with multiple mechanisms). The review highlights natural products such as Hinokitiol, Mahanine, Hesperetin, Borneol, Carvacrol, Eugenol, Epigallocatechin gallate, and Capsaicin for their demonstrated efficacy against multiple cancer types, including breast, cervical, gastric, colorectal, pancreatic, lung, prostate, and skin cancer. Finally, it highlights the need for continued bioprospecting studies to identify novel natural products that can be successfully used in modern chemoprevention and chemotherapy.

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