(±)-6-3'a,7-6'-Isowallichilide: A pair of enantiomeric phthalide dimers from Ligusticum chuanxiong with new 6-3'a,7-6' dimerization sites

Five racemic phthalides from the aerial parts of Lycopodiastrum casuarinoides and their neuroprotective activities

Five racemic phthalides (1-5), including four undescribed phthalides monomers [(+)-1, (+)-2, (-)-2 and (-)-3], four undescribed phthalide dimers [(+)-4, (-)-4, (+)-5 and (-)-5], together with two known compounds [(-)-1 and (+)-3], were isolated from the aerial parts of Lycopodistrum casuarinoides. Their chemical structures were delineated by extensive spectroscopic data (UV, 1D/2D NMR, HRESIMS), in combination with the comparison of the experimental and calculated electronic circular dichroism spectra, calculated spin-spin coupling constants, and calculated NMR. All compounds were reported from Lycopodiaceae family for the first time. In addition, all isolates were tested for their neuroprotective effects on HT-22 cell injury induced by glutamate. Interestingly, among the five racemic phthalides, only the homologous dimers [(±)-5] displayed significant differences in neuroprotective effects, and (-)-5 exhibited the best neuroprotective activity against glutamate-induced HT-22 cells damage, with 29.3% increase rate in cell survival at 5 μM concentration. The neuroprotective effect of (-)-5 at different concentrations is equivalent to that of the positive control drug D/L-3-n-butylphthalide (racemic NBP). Furthermore, the biological evaluation revealed that (-)-5 could ameliorate glutamate-induced neuronal cell death via the Bax/Bcl-2 anti-apoptotic pathway.

Bioassay and NMR-HSQC-Guided Isolation and Identification of Phthalide Dimers with Anti-Inflammatory Activity from the Rhizomes of Angelica sinensis

Under the guidance of a bioactivity-guided approach and HSQC characteristic signals, nine pairs of phthalic dimers, angesilides A-I (1-9), with complex polycyclic skeletons featuring bridged, fused, and spiro ring systems were discovered from the rhizomes of Angelica sinensis. Their structures and absolute configurations were established by comprehensive spectroscopic methods, X-ray diffraction analysis, and chiral separation. Plausible biosynthetic pathway for 1-9 was proposed. Moreover, the anti-inflammatory activities of all isolates were evaluated in lipopolysaccharide (LPS) stimulated mouse leukemia cells of monocyte macrophages (RAW = 264.7). Among them, compound 9 showed a remarkable inhibitory activity with IC50 values of 425 nM and could significantly decrease IL-1β and IL-6 transcription levels. Interestingly, (+)-9 has superior NO inhibitory activity compared to that of (-)-9, which was verified by further molecular docking analysis. The findings provide new insights into A. sinensis as a functional food or for the development of new anti-inflammatory drug candidates.

Investigation of the ability of 3-((4-chloro-6-methyl pyrimidin-2-yl)amino) isobenzofuran-1(3H)-one to bind to double-stranded deoxyribonucleic acid

Phthalides represent a notable category of secondary metabolites that are prevalent in various plant species, certain fungi, and liverworts. The significant pharmacological properties of these compounds have led to the synthesis of a novel phthalide derivative. The current study focuses on investigating the binding interactions of a newly synthesized 3-substituted phthalide derivative, specifically 3-((4-chloro-6-methyl pyrimidine-2-yl)amino) isobenzofuran-1(3H)-one (Z11), with double-stranded deoxyribonucleic acid (dsDNA). Research in the pharmaceutical and biological fields aimed at developing more potent DNA-binding agents must take into account the mechanisms by which these newly synthesized compounds interact with DNA. This investigation seeks to explore the binding dynamics between dsDNA and our compound through a variety of analytical techniques, such as electrochemistry, UV spectroscopy, fluorescence spectroscopy, and thermal denaturation. The binding constant (Kb) of Z11 with DNA was determined using both spectroscopic and voltammetric approaches. The research revealed that Z11 employs a groove binding mechanism to associate with dsDNA. To further explore the interactions between Z11 and dsDNA, the study utilized density functional theory (DFT) calculations, molecular docking, and molecular dynamics simulations. These analyses aimed to ascertain the potential for a stable complex formation between Z11 and dsDNA. The results indicate that Z11 is situated within the minor groove of the dsDNA, demonstrating the ability to establish a stable complex. Furthermore, the findings imply that both π-alkyl interactions and hydrogen bonding play significant roles in the stabilization of this complex.

Structurally diverse phthalides from fibrous roots of Ligusticum chuanxiong Hort. and their biological activities

Falonolide A (1) and B (2), two novel polyyne hybrid phthalides resulting from unprecedented carbon skeleton polymerized by Z-ligustilide and falcarindiol, along with six new related phthalides (3-8), were isolated from Ligusticum chuanxiong Hort. Their structures were elucidated by spectroscopic analysis, computer-assisted structure elucidation (CASE) analysis, DP4+ probability analysis and electronic circular dichroism (ECD) calculations. A plausible biosynthetic pathway for 1-8 was proposed, and the production mechanism of 2 was revealed by density functional theory (DFT) method. Compounds 4 and 6 exhibited significant vasodilatory activity with EC50 of 8.00 ± 0.86 and 6.92 ± 1.02 μM, respectively. Compound 4 also displayed significant inhibitory effect of NO production with EC50 value of 8.82 ± 0.30 μM. Based on the established compounds library, structure-activity relationship analysis of phthalides was explored to provide insights into the drug development of vasodilators and anti-flammatory.

Discovery of a Potent Antiosteoporotic Drug Molecular Scaffold Derived from Angelica sinensis and Its Bioinspired Total Synthesis

Angelica sinensis, commonly known as Dong Quai in Europe and America and as Dang-gui in China, is a medicinal plant widely utilized for the prevention and treatment of osteoporosis. In this study, we report the discovery of a new category of phthalide from Angelica sinensis, namely falcarinphthalides A and B (1 and 2), which contains two fragments, (3R,8S)-falcarindiol (3) and (Z)-ligustilide (4). Falcarinphthalides A and B (1 and 2) represent two unprecedented carbon skeletons of phthalide in natural products, and their antiosteoporotic activities were evaluated. The structures of 1 and 2, including their absolute configurations, were established using extensive analysis of NMR spectra, chemical derivatization, and ECD/VCD calculations. Based on LC-HR-ESI-MS analysis and DFT calculations, a production mechanism for 1 and 2 involving enzyme-catalyzed Diels-Alder/retro-Diels-Alder reactions was proposed. Falcarinphthalide A (1), the most promising lead compound, exhibits potent in vitro antiosteoporotic activity by inhibiting NF-κB and c-Fos signaling-mediated osteoclastogenesis. Moreover, the bioinspired gram-scale total synthesis of 1, guided by intensive DFT study, has paved the way for further biological investigation. The discovery and gram-scale total synthesis of falcarinphthalide A (1) provide a compelling lead compound and a novel molecular scaffold for treating osteoporosis and other metabolic bone diseases.

Six pairs of enantiomeric phthalide dimers from the rhizomes of Ligusticum chuanxiong and their absolute configurations and anti-inflammatory activities

Six pairs of enantiomeric phthalide dimers (1-6) were isolated from the rhizomes of Ligusticum chuanxiong. Their structures and absolute configurations were elucidated by NMR spectroscopy, X-ray diffraction analyses, and electronic circular dichroism calculations. Compounds (+)-1 and (-)-1 are new phthalide dimers, featuring two classes of monomeric units (a phthalide and an unusual 2,3-seco-phthalide) with an uncommon linkage (3,6'/8,3'a). Compounds (+)-2 and (-)-3 are also novel phthalide dimers that had not been reported previously. Although (-)-2 and (+)-3 have been successfully isolated in previous studies, their absolute configurations were not unambiguously determined. As for compound 4, it was reported as a racemate in one study, and one of its enantiomers was identified in a subsequent study. Herein, all enantiomeric phthalide dimers were successfully separated, and their absolute configurations were determined. The inhibitory effects of all isolates against lipopolysaccharide-induced nitric oxide production were tested using RAW264.7 cells. The results show that compounds (+)-2, (-)-2, (+)-3, (-)-3, (+)-4, (-)-4, (+)-5, (+)-6, and (-)-6 have inhibitory activities, with compound (+)-5 being the most active (IC₅₀ value of 4.3 ± 1.3 μM).

Recent advances in natural phthalides: Distribution, chemistry, and biological activities

Phthalides, an important class of bioactive natural products, are widely distributed in plants, fungi, lichens, and liverworts. Amon them, n-butylphthalide, a phthalide monomer, has been approved to cure ischemic stroke. Owing to their good bioactivities in anti-microbial, anti-inflammatory, anti-tumor, anti-diabetic, and other aspects, a large number of researches have been conducted on phthalides from nature materials. In recent years, hundreds of novel natural phthalides were obtained. This review provides profiles of the advances in the distribution, chemistry, and biological activities of natural phthalides in 2016-2022.