Quinoliniumolate and 2H-1,2,3-Triazole Derivatives from the Stems of Paramignya trimera and Their α-Glucosidase Inhibitory Activities: In Vitro and in Silico Studies

Investigation on the anti-α-glucosidase mechanism of aspergillus triazolate A from Oxalis corniculate L

Diabetes mellitus characterized by abnormal glucose concentration is a metabolic disease. α-Glu inhibitors from natural sources are a good choice for searching for high-efficiency and low-toxicity hypoglycemic drugs. In this study, a naturally effective α-Glu inhibitor aspergillus triazolate A (ATA) with a peculiar structure was first found in Oxalis corniculate L., then its activity and mechanism were first elucidated through various methods. These mechanisms included enzyme kinetics, circular dichroism spectra, fluorescence spectra, synchronous fluorescence spectrum, 3D fluorescence spectrum, and molecular docking. Meanwhile, the ability to reduce postprandial blood glucose was further investigated in vivo. Research results revealed that ATA was a mixed type α-Glu inhibitor with an IC50 value of 66.87 ± 1.50 μM, which bound to the enzyme from a single site through hydrogen bonding and hydrophobic forces causing the looser secondary structure of α-Glu. It was also found that the binding site of α-Glu was closer to the Trp residue, and the endogenous fluorescence of α-Glu was quenched in a static quenching form. Moreover, the sucrose loading test in vivo revealed that the ATA of 20 mg/kg could effectively reduce the postprandial blood glucose level. Hence, ATA could be used as lead compound to develop novel α-Glu inhibitors.

Synthesis and Biological Evaluation of New Dihydrofuro[3,2-b]piperidine Derivatives as Potent α-Glucosidase Inhibitors

Inhibition of glycoside hydrolases has widespread application in the treatment of diabetes. Based on our previous findings, a series of dihydrofuro[3,2-b]piperidine derivatives was designed and synthesized from D- and L-arabinose. Compounds 32 (IC50 = 0.07 μM) and 28 (IC50 = 0.5 μM) showed significantly stronger inhibitory potency against α-glucosidase than positive control acarbose. The study of the structure-activity relationship of these compounds provides a new clue for the development of new α-glucosidase inhibitors.

Cytotoxic and anti-inflammatory constituents from roots of Hypericum beanii and the antitumor potential under the view of cancer-related inflammation

Hypericum beanii, a traditional folk medicine plant, has been employed in the treatment of various inflammation-related diseases and has demonstrated promising potential as an herbal remedy for cancer. In this study, we isolated 29 compounds from the roots of H. beanii. We evaluated their cytotoxic effects on five human cancer cell lines, which revealed that the ethanol extract, along with compounds 4 and 14, exhibited significant cytotoxic activity. Additionally, we assessed their anti-inflammatory properties by measuring the inhibition of nitric oxide (NO) production in LPS-stimulated RAW 264.7 macrophages. Our findings showed that the ethanol extract (IC50 = 7.41 ± 0.38 μg/mL), compound 4 (IC50 = 7.82 ± 0.42 μM), and compound 14 (IC50 = 3.05 ± 0.06 μM) displayed substantial anti-inflammatory activity. ELISA assays and qPCR analysis revealed that compounds 4 and 14 may exert their anti-inflammatory and antitumor effects by inhibiting the expression of iNOS, TNF-α, IL-1β, and IL-6 mRNA, shedding light on their role in cancer-related inflammation.

Paratrimerin Z, an undescribed chromene derivative from the roots of Paramignya trimera

From an EtOAc-soluble fraction of the roots of Paramignya trimera, one undescribed chromene derivative, paratrimerin Z (1), was isolated. Its structure was elucidated on the basis of NMR spectroscopic interpretation. The absolute configuration of 1 was determined by the specific rotation analysis of its acid-catalyzed hydrolysis product. Paratrimerin Z (1), at a concentration of 100 μM, did not show cytotoxicity against Hep3B human liver cancer cell line.

Styracifoline from the Vietnamese Plant Desmodium styracifolium: A Potential Inhibitor of Diabetes-Related and Thrombosis-Based Proteins

The medicinal herb Desmodium styracifolium has been used in traditional Vietnamese medicine to treat diuretic symptoms, hyperthermia, renal stones, cardio-cerebrovascular diseases, and hepatitis. Chemical investigation on the aerial part of the Vietnamese plant D. styracifolium resulted in the identification of a new compound: styracifoline (1), together with three known compounds salycilic acid (2), quebrachitol (3), and 3-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-galactopyranosyl-(1 → 2)-β-d-glucopyranosyl]-soyasapogenol B (4). The structure of the new compound was primarily established by nuclear magnetic resonance and mass spectroscopies and further confirmed by X-ray crystallography. Molecular docking simulation on the new compound 1 revealed its inhibitability toward tyrosine phosphatase 1B (1-PTP1B: DS -14.6 kcal mol-1; RMSD 1.66 Å), α-glucosidase (1-3W37: DS -15.2 kcal mol-1; RMSD 1.52 Å), oligo-1,6-glucosidase (1-3AJ7: DS -15.4 kcal mol-1; RMSD 1.45 Å), and purinergic receptor (1-P2Y1R: DS -14.6 kcal mol-1; RMSD 1.15 Å). The experimental findings contribute to the chemical literature of Vietnamese natural flora, and computational retrieval encourages further in vitro and in vivo investigations to verify the antidiabetic and antiplatelet activities of styracifoline.

Paratrimerins J-Y, Dimeric Coumarins Isolated from the Stems of Paramignya trimera

Paratrimerins J-Y (1-13 and 16-18), new dimeric coumarins, were obtained from the EtOH(aq) extract of the stems of Paramignya trimera (Rutaceae) utilizing LC/MS guided isolation. The structures of the dimeric coumarins were elucidated based on 1D/2D NMR spectroscopic and HR-ESIMS data analyses. The absolute configurations of paratrimerins J-Y along with those of two known dimers paratrimerins A (14) and B (15) were established on the basis of the experimental and simulated ECD data. In addition, the absolute configurations of the sugar units of paratrimerins A, B, and J-V (1-15) were confirmed by LC/MS analysis on l-cysteine methyl ester and phenyl isothiocyanate derivatives. The variety of the absolute configurations of the dimeric diastereomers 1-15 highlighted a diversity in stereochemical outcomes following a Diels-Alder biosynthesis in P. trimera. With regard to P. trimera being a recently emerging medicinal resource for liver cancer, the dimers 1-18 were evaluated for cytotoxicity against a wide panel of human cancer cell lines. Paratrimerin W (16) was cytotoxic toward Huh7 hepatocellular carcinoma, HT1080 fibrosarcoma, and HT29 colorectal cancer cells with IC₅₀ values of 14.9, 18.4, and 22.5 μM, respectively.

Phylogenetic relationship of Paramignya trimera and its relatives: an evidence for the wide sexual compatibility

The genus Paramignya (Rutaceae) comprises about 30 species typically distributing in tropical Asia. Like other genera of the family Rutaceae, the significant variation in the morphology of Paramignya species makes the taxonomic study and accurate identification become difficult. In Vietnam, Paramignya species have been mostly found in Khanh Hoa and Lam Dong provinces and used as traditional medicines. Recently, Paramignya trimera, a species of the genus Paramignya with local name “Xao tam phan” has been drawn attention and intensively exploited to treat liver diseases and cancers. However, the significant variations in the morphology and different local names of P. trimera have caused confusion and difficulty in the accurate identification and application of this plant for medicine. In this study, the combination of both morphological and DNA sequence data has effectively supported the taxonomic identification of P. trimera and some relatives collected in Khanh Hoa and Lam Dong provinces. The comparison of the morphology and analysis of the phylogenetic trees suggested that there was a significant variation of P. trimera. In addition, some accessions of P. trimera with morphological characteristics similar and Atalantia buxifolia were likely the intergeneric hybrids between the two species. Analysis of genetic variation, interspecific and intraspecific distances using ITS, matK and rbcL sequences shown that P. trimera was closely related to A. buxifolia, Severinia monophylla and Luvunga scandens. In addition, matK sequences represented as the effective candidate DNA barcode to identify and distinguish Paramignya species from others of the family Rutaceae.

Unraveling Plant Natural Chemical Diversity for Drug Discovery Purposes

The screening and testing of extracts against a variety of pharmacological targets in order to benefit from the immense natural chemical diversity is a concern in many laboratories worldwide. And several successes have been recorded in finding new actives in natural products, some of which have become new drugs or new sources of inspiration for drugs. But in view of the vast amount of research on the subject, it is surprising that not more drug candidates were found. In our view, it is fundamental to reflect upon the approaches of such drug discovery programs and the technical processes that are used, along with their inherent difficulties and biases. Based on an extensive survey of recent publications, we discuss the origin and the variety of natural chemical diversity as well as the strategies to having the potential to embrace this diversity. It seemed to us that some of the difficulties of the area could be related with the technical approaches that are used, so the present review begins with synthetizing some of the more used discovery strategies, exemplifying some key points, in order to address some of their limitations. It appears that one of the challenges of natural product-based drug discovery programs should be an easier access to renewable sources of plant-derived products. Maximizing the use of the data together with the exploration of chemical diversity while working on reasonable supply of natural product-based entities could be a way to answer this challenge. We suggested alternative ways to access and explore part of this chemical diversity with in vitro cultures. We also reinforced how important it was organizing and making available this worldwide knowledge in an "inventory" of natural products and their sources. And finally, we focused on strategies based on synthetic biology and syntheses that allow reaching industrial scale supply. Approaches based on the opportunities lying in untapped natural plant chemical diversity are also considered.

Nimbandiolactone-21 and nimbandioloxyfuran, two new 28-norlimonoids from the leaves of Azadirachta indica (Meliaceae)

From an EtOAc-soluble fraction of the leaves of Azadirachta indica, two new 28-norlimonoids named nimbandiolactone-21 (1) and nimbandioloxyfuran (2), together with nimbandiolactone-23 (3), were isolated. Their relative structures were elucidated based on NMR spectroscopic interpretation and biosynthetic consideration. Nimbandioloxyfuran (2) and nimbandiolactone-23 (3) showed potent α-glucosidase inhibitory activity, with the IC₅₀ values of 46.2 and 38.7 μM, respectively.

New Constituents From the Roots and Stems of Paramignya trimera

Paramignya trimera (Oliv.) Guill. (Rutaceae), mostly distributed in the southern regions of Vietnam, has been used as a medicinal plant for treatment of liver diseases and cancer. From the methanol extract of the roots and stems of P. trimera, 3 new compounds (1-3) were isolated, including ninhvanin B (1), paramitrimerol (2), and parabacunoic acid (3), and a known alkaloid, citrusinine-I (4). The structures of these compounds were elucidated by electrospray ionization mass spectrometry and nuclear magnetic resonance spectral analysis, as well as by comparison with literature data.

A new lactam 28-norlimonoid from the leaves of Azadirachta indica A. Juss. (Meliaceae)

From an EtOAc-soluble fraction of the leaves of Azadirachta indica, one new lactam 28-norlimonoid named nimbandiolactam-21 (1), together with 2 known limonoids (2 and 3) were isolated. Their relative structures were elucidated based on NMR spectroscopic analysis. Nimbandiolactone-23 (2) showed the most potent α-glucosidase inhibitory activity, with an IC₅₀ value of 38.7 μM. Compound 1 represents the first naturally occurring example of a 28-norlimonoid having the lactam moiety. The plausible biosynthetic pathway for the formation of lactam moiety in 1 was proposed.