Amides and Flavonoids from the Fruit and Leaf Extracts of Melodorum siamensis

Two new dimethylpyranoflavanones from the roots of Melodorum fruticosum

Two previously unreported dimethylpyranoflavanones, pyronomelodorones A and B (1 and 2), along with five known compounds, 7-O-methyldihydrowogonin (3), 5,6,7-trimethoxyflavanone (4), 5,6-dihydroxy-7-methoxy-dihydroflavone (5), 5,7,8-trimethoxydihydroflavone (6), and pinostrobin (7), were isolated from the roots of Melodorum fruticosum. The structures of all isolates were fully characterized using spectroscopic data and comparison with the previous literature. All isolates were evaluated for their in vitro α-glucosidase inhibition and their cytotoxicity against KB, HepG2, and MCF7 cell lines. Among the isolates, compound 1 exhibited the most inhibitory activity against α-glucosidase and was superior to the positive control with an IC50 value of 1.32 μM. Compounds 1 and 2 showed weak cytotoxicity against the three human cancer cell lines, with IC50 values in the range of 53.3-79.0 μM.

Sarglamides A-E, Indolidinoid-Monoterpenoid Hybrids with Anti-neuroinflammatory Activity from a Sarcandra Species

Sarglamides A-E (1-5), representing the first example of heterodimers of a trans-N-cinnamoylindolidinoid and α-phelladrene derivatives, were isolated from Sarcandra glabra subsp. brachystachys. Particularly, compounds 4 and 5 possess unprecedented cagelike 6/6/5/6/5- and 6/6/6/6/5-fused pentacyclic scaffolds, respectively. Their structures were established by spectroscopic analysis, X-ray crystallography, quantum-chemical calculations, and chemical conversions. Plausible biosynthetic pathways of 1-5 involving the coisolated enantiomers 6a and 6b were proposed. Compounds 3-7 showed inhibitory activity against lipopolysaccharide-induced inflammation in BV-2 microglial cells.

Perplexing Polyphenolics: The Isolations, Syntheses, Reappraisals, and Bioactivities of Flavonoids, Isoflavonoids, and Neoflavonoids from 2016 to 2022

Flavonoids, isoflavonoids, neoflavonoids, and their various subcategories are polyphenolics-an extensive class of natural products. These compounds are bioactive and display multiple activities, including anticancer, antibacterial, antiviral, antioxidant, and neuroprotective activities. Thus, these compounds can serve as leads for therapeutic agents or targets for complex synthesis; they are coveted and routinely isolated, characterized, biologically evaluated, and synthesized. However, data regarding the compounds' sources, isolation procedures, structural novelties, bioactivities, and synthetic schemes are often dispersed and complex, a dilemma this review aims to address. To serve as an easily accessible guide for researchers wanting to apprise themselves of the latest advancements in this subfield, this review summarizes seventy-six (76) articles published between 2016 and 2022 that detail the isolation and characterization of two hundred and forty-nine (249) novel compounds, the total and semisyntheses of thirteen (13) compounds, and reappraisals of the structures of twenty (20) previously reported compounds and their bioactivities. This article also discusses new synthetic methods and enzymes capable of producing or modifying flavonoids, isoflavonoids, or neoflavonoids.

Antidiabetic and Cytotoxic Activities of Rotenoids and Isoflavonoids Isolated from Millettia pachycarpa Benth

A phytochemical investigation of the root and leaf extracts of Millettia pachycarpa Benth resulted in the isolation and identification of 16 compounds, including six rotenoids (1-6) and 10 prenylated isoflavonoids (7-16). Compound 4 was isolated as a scalemic mixture, which was resolved by chiral HPLC to afford (-)-(6aS,12aS)-12a-hydroxy-α-toxicarol (4) and (+)-(6aR,12aR)-12a-hydroxy-α-toxicarol (4). (+)-(6aR,12aR)-Millettiapachycarpin (3) and (-)-(6aS,12aS)-12a-hydroxy-α-toxicarol (4) were isolated as new compounds. The absolute configuration of (-)-(6R)-pachycarotenoid (2), (+)-(6aR,12aR)-millettiapachycarpin (3), (-)-(6aS,12aS)-4 and (+)-(6aR,12aR)-12a-hydroxy-α-toxicarol (4), (+)-(6aS,12aS)-(5), and (-)-(6aS,12aS,2″R)-sumatrol (6) were identified by electronic circular dichroism (ECD) data. (-)-(6aS,12aS,2″R)-Sumatrol (6) was also confirmed by X-ray diffraction analysis using Cu-Kα radiation. Antidiabetic activities, including α-glucosidase and α-amylase inhibitory activities, and cytotoxicities against lung cancer A549, colorectal cancer SW480, and leukemic K562 cells of some isolated compounds were evaluated. Of these, isolupalbigenin (11) exhibited the highest α-glucosidase inhibitory activity, with an IC₅₀ value of 11.3 ± 0.2 μM, whereas the scalemic mixture of 12a-hydroxy-α-toxicarol (4) displayed the best α-amylase inhibitory activity, with an IC₅₀ value of 106.9 ± 0.2 μM. Euchrenone b10 (15) exhibited the highest cytotoxicity against lung cancer A549, colorectal cancer SW480, and leukemic K562 cells, with IC₅₀ values of 40.3, 39.1, and 15.1 μM, respectively. In addition, molecular docking simulations of α-glucosidase inhibition of the active compounds were studied.

Silver-catalysed three-component reactions of alkynyl aryl ketones, element selenium, and boronic acids leading to 3-organoselenylchromones

An Ag-catalysed three-component reaction of alkynyl aryl ketones bearing an ortho-methoxy group, element selenium, and arylboronic acid, providing a facile route to selenofunctionalized chromone products has been developed. This protocol features high efficiency and high regioselectivity, and the use of selenium powder as the selenium source. Mechanistic experiments indicated that the combined oxidative effect of (bis(trifluoroacetoxy)iodo)benzene and oxygen in the air pushes the catalytic redox cycle of the Ag catalyst and the phenylselenium trifluoroacetate formed in situ is the key intermediate of the PIFA-mediated 6-endo-electrophilic cyclization and selenofunctionalization reaction of alkynyl aryl ketones.

Anticoronavirus and Immunomodulatory Phenolic Compounds: Opportunities and Pharmacotherapeutic Perspectives

In 2019, COVID-19 emerged as a severe respiratory disease that is caused by the novel coronavirus, Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). The disease has been associated with high mortality rate, especially in patients with comorbidities such as diabetes, cardiovascular and kidney diseases. This could be attributed to dysregulated immune responses and severe systemic inflammation in COVID-19 patients. The use of effective antiviral drugs against SARS-CoV-2 and modulation of the immune responses could be a potential therapeutic strategy for COVID-19. Studies have shown that natural phenolic compounds have several pharmacological properties, including anticoronavirus and immunomodulatory activities. Therefore, this review discusses the dual action of these natural products from the perspective of applicability at COVID-19.

Nitric oxide production inhibitory activity of clerodane diterpenes from Monoon membranifolium

A new clerodane diterpene, 2β-methoxyhardwickiic acid (1), and four known compounds (2-5) were isolated from the twigs of Monoon membranifolium. The structure of the new compound was determined by extensive spectroscopic methods and ESITOFMS data. The absolute configuration of 1 was established by a comparison of its ECD spectrum and specific rotation with those of related previously reported compounds. All compounds were evaluated for their nitric oxide (NO) production inhibitory activities in RAW264.7 macrophage cells. Compounds 3 and 5 inhibited NO production with IC₅₀ values of 16.1 and 28.9 μM, respectively, which were better than that of standard compound, indomethacin (IC₅₀ = 32.2 μM).

Helichrysetin and TNF‑α synergistically promote apoptosis by inhibiting overactivation of the NF‑κB and EGFR signaling pathways in HeLa and T98G cells

Tumor necrosis factor‑α (TNF‑α) has different effects on apoptosis depending on activation or inactivation of the nuclear factor‑κB (NF‑κB) and epidermal growth factor receptor (EGFR) signaling pathways. Helichrysetin, a natural chalcone, inhibits NF‑κB nuclear translocation in mouse pancreatic β cells. The present study aimed to identify the effect of helichrysetin on activation of the NF‑κB and EGFR signaling pathways induced by TNF‑α, and the synergistic effect of helichrysetin and TNF‑α on apoptosis of HeLa and T98G cells. Cell proliferation was measured by Cell Counting Kit‑8 assay, while apoptosis was measured by Hoechst 33258 and Annexin V/PI staining. NF‑κB activity was detected by luciferase assay, protein expression was measured by western blotting and mRNA expression was detected by quantitative PCR assay. The results revealed that in HeLa and T98G cells helichrysetin blocked the increased phosphorylation of NF‑κB p65 induced by TNF‑α. Although helichrysetin alone decreased cell viability, helichrysetin and TNF‑α synergistically decreased cell viability. Helichrysetin, not TNF‑α, promoted apoptosis, while the combination of helichrysetin and TNF‑α synergistically increased apoptosis. In addition, helichrysetin and TNF‑α synergistically enhanced the activation of caspase‑3 and poly‑(ADP‑ribose)‑polymerase compared with helichrysetin alone. Helichrysetin inhibited the phosphorylation of transforming growth factor‑β activated kinase (TAK1), IκB kinase‑α/β (IKK‑α/β), NF‑κB p65 and EGFR induced by TNF‑α. Consistent with the inhibition of NF‑κB activation, the increased TNF‑α‑induced mRNA expression levels of TNF‑α, IL‑1β, CCL2, CCL5 and CXCL10 were significantly downregulated by helichrysetin. Therefore, helichrysetin and TNF‑α synergistically promoted apoptosis by inhibiting TAK1/IKK/NF‑κB and TAK1/EGFR signaling pathways in HeLa and T98G cells, indicating a potential therapeutic strategy for cancer.

Important Flavonoids and Their Role as a Therapeutic Agent

Flavonoids are phytochemical compounds present in many plants, fruits, vegetables, and leaves, with potential applications in medicinal chemistry. Flavonoids possess a number of medicinal benefits, including anticancer, antioxidant, anti-inflammatory, and antiviral properties. They also have neuroprotective and cardio-protective effects. These biological activities depend upon the type of flavonoid, its (possible) mode of action, and its bioavailability. These cost-effective medicinal components have significant biological activities, and their effectiveness has been proved for a variety of diseases. The most recent work is focused on their isolation, synthesis of their analogs, and their effects on human health using a variety of techniques and animal models. Thousands of flavonoids have been successfully isolated, and this number increases steadily. We have therefore made an effort to summarize the isolated flavonoids with useful activities in order to gain a better understanding of their effects on human health.

Metal-free synthesis of 3-chalcogenyl chromones from alkynyl aryl ketones and diorganyl diselenides/disulfides mediated by PIFA

3-Selenyl/sulfenyl chromones/thiochromones were conveniently synthesized from the PIFA-mediated reactions between alkynyl aryl ketones bearing an ortho-methoxy/methylthio group and diorganyl diselenides/disulfides.

Dasymaschalolactams A-E, Aristolactams from a Twig Extract of Dasymaschalon dasymaschalum

Five new aristolactam alkaloids (1-5), dasymaschalolactams A-E, and the first isolation of dasymaschalolactone (17) as a natural product, together with 19 known compounds (6-16 and 18-25) were isolated from the twig extract of Dasymaschalon dasymaschalum. Their structures were elucidated by spectroscopic methods as well as comparisons made from the literature. Compounds 20 and 21 showed α-glucosidase inhibitory activities with IC₅₀ values of 4.5 and 24.7 μM, respectively.

Uvarialuridols A-C, three new polyoxygenated cyclohexenes from the twig and leaf extracts of Uvaria lurida

The first phytochemical investigation of Uvaria lurida resulted in the isolation and identification of three new polyoxygenated cyclohexenes, (+)-(1R,2S,3R,6S)-uvarialuridols A-C (1-3), together with 10 known compounds (4-13). All new structures were elucidated by spectroscopic methods and HRESIMS. The absolute configurations of compounds 1 and 5 were confirmed by X-ray diffraction analysis using Cu Kα radiation. The absolute configurations of compounds 2-4 were identified from comparisons of their specific rotations and ECD spectra with those of known compounds. Compound 11 showed α-glucosidase inhibitory activity with an IC₅₀ value of 30 μM which was better than the standard control, acarbose (74 μM) whereas, compound 10 exhibited nitric oxide (NO) production inhibitory activity with an IC₅₀ value of 37 μM.