Synthesis and evaluation of inhibitory activity in vitro of dihydrostilbenes against human neutrophil elastases.

Twelve dihydrostilbenes (including five new analogues) were prepared by the Witting-Hornor reaction from appropriate aromatic aldehydes and phosphonate esters, followed by hydrogenation in five steps. The in vitro inhibition activity against human neutrophil elastase (HNE) of these dihydrostilbenes was evaluated, and three 1,2-dihydroxylated dihydrostilbenes (6b, 6j, and 6l) exhibited stronger inhibitory activity against HNE than other analogues.

New Dihydrostilbene Derivatives from Chloraea chrysantha.

The study of the main components of the alcoholic extract obtained from Chloraea chrysantha Poepp. led to the isolation of two new dihydrostilbene derivatives together with the known gavilein (3). The new compounds have been assigned as 3-methoxy-5-{2-[3-methoxy-2-(3-methylbut-2-en-1-yl)phenyl]ethyl}phenol (1) and 1-[2-(3,5-dimethoxyphenyl)ethyl]-3-methoxy-2-(3-methylbut-2-en-1-yl)benzene (2). The presence of compounds 1-3 is perfectly in accordance with the current botanical classification of the genus.

Dihydrostilbenes and diarylpropanes: Synthesis and in vitro pharmacological evaluation as potent nitric oxide production inhibition agents.

An efficient synthesis of dihydrostilbenes (1-5) and diarylpropanes (6-10) is achieved from the commercially available starting materials and Wittig-Horner reaction, Claisen-Schmidt condensation and hydrogenation as key steps. Later, their nitric oxide (NO) production inhibition effects were evaluated in lipopolysaccharide (LPS)-induced RAW-264.7 macrophages as an indicator of anti-inflammatory activity. All the tested compounds significantly decreased NO production in a concentration-dependent manner except compounds 2, 6 and 8 and did not show notable cytotoxicity except compound 1. Two compounds i.e., compound 9 (hindsiipropane B) (100%; IC50=1.84µM) possessed the most potent NO inhibitory activity which was even stronger than the positive control, L-NMMA (90.1%; IC50=2.73µM) followed by compound 4 (75.5%; IC50=2.98µM) at 10µM concentration and this finding was also further correlated by suppressed expression of LPS stimulated inducible NO synthase. Our study revealed that compound 9, a 1,3-diarylpropane scaffold with 3″,4″-dimethoxyphenyl and 3',4'-dihydroxy-2'-methoxyphenyl motifs could be considered as potential compound or lead compound for further development of NO production-targeted anti-inflammatory agents.

Identification of dihydrostilbenes in Pholidota chinensis as a new scaffold for GABAA receptor modulators.

A dichloromethane extract of stems and roots of Pholidota chinensis (Orchidaceae) enhanced GABA-induced chloride currents (I(GABA)) by 132.75 ± 36.69% when tested at 100 µg/mL in a two-microelectrode voltage clamp assay, on Xenopus laevis oocytes expressing recombinant α1ß2γ2S GABA(A) receptors. By means of an HPLC-based activity profiling approach, the three structurally related stilbenoids coelonin (1), batatasin III (2), and pholidotol D (3) were identified in the active fractions of the extract. Dihydrostilbene 2 enhanced I(GABA) by 1512.19 ± 176.47% at 300 µM, with an EC50 of 52.51 ± 16.96 µM, while compounds 1 and 3 showed much lower activity. The relevance of conformational flexibility for receptor modulation by stilbenoids was confirmed with a series of 13 commercially available stilbenes and their corresponding semisynthetic dihydro derivatives. Dihydrostilbenes showed higher activity in the oocyte assay than their corresponding stilbenes. The dihydro derivatives of tetramethoxy-piceatannol (12) and pterostilbene (20) were the most active among these derivatives, but they showed lower efficiencies than compound 2. Batatasin III (2) showed high efficiency but no significant subunit specificity when tested on the receptor subtypes α1ß2γ2s, α2ß2γ2s, α3ß2γ2s, α4ß2γ2s, α5ß2γ2s, α1ß1γ2s, and α1ß3γ2s. Dihydrostilbenes represent a new scaffold for GABA(A) receptor modulators.

Dihydrostilbenes and flavonoids from whole plants of Jacobaea vulgaris.

The isolation of previously undescribed 12 compounds from the MeOH extract of Jacobaea vulgaris whole plants is disclosed, comprising 11 dihydrostilbenes (1-11) and one flavanone (12), and eight known compounds (six flavonoids, one dihydrostilbene, and one caffeoylquinic acid). Structural elucidation employed spectroscopic methods, including 1D and 2D NMR spectroscopy, HRESIMS, and ECD calculations. Evaluation of the compounds' effects on PCSK9 and LDLR mRNA expression revealed that compounds 1 and 3 downregulated PCSK9 mRNA while increasing LDLR mRNA expression, suggesting potential cholesterol-lowering properties.

Canniprene B, a new prenylated dihydrostilbene with cytotoxic activities from the leaves of Cannabis sativa.

A new, canniprene B (4), along with five known (1-3 and 5-6) dihydrostilbenes were isolated from the leaves of Cannabis sativa collected at CSIR - IIIM, Jammu, India. Structures of all isolated compounds were elucidated by spectroscopic data analysis, including 1D and 2D NMR, and HR-ESI-MS. Canniprene B is a new prenylated dihydrostilbenes, a positional isomer of the known compound canniprene (5). The cytotoxic activities of these compounds (1-6) were evaluated using the SRB assay against a panel of five human cancer cell lines. Notably, canniprene B (4) exhibited varying levels of cytotoxicity with IC50 values ranging from 2.5 to 33.52 µM, demonstrating the most potent activity against pancreatic cancer cells.

Development of Stilbenoid and Chalconoid Analogues as Potent Tyrosinase Modulators and Antioxidant Agents.

A number of stilbenoid and chalconoid derivatives were prepared by straightforward methods, and their ability to modulate tyrosinase activity and to scavenge free radicals were evaluated in vitro. The cell-free in vitro evaluation revealed two diarylpropanes, 24 and 25, as potent tyrosinase inhibitors, whereas diarylpropenoic acids seemed to enhance the enzymatic activity. An in silico evaluation of the binding affinity of the selected compounds with the crystal structure of tyrosinase was also conducted in order to obtain better insight into the mechanism. Representative synthetic compounds with inhibitory and activating properties were further evaluated in melanoma cell lines B16F1 and B16F10 for their ability to moderate tyrosinase activity and affect melanin production. Dihydrostilbene analogues I and II, exhibited a stronger anti-melanogenic effect than kojic acid through the inhibition of cellular tyrosinase activity and melanin formation, while diarylpropanoic acid 44 proved to be a potent melanogenic factor, inducing cellular tyrosinase activity and melanin formation. Moreover, the antioxidant evaluation disclosed two analogues (29 and 11) with significant free-radical-scavenging activity (12.4 and 20.3 µM), which were 10- and 6-fold more potent than ascorbic acid (122.1 µΜ), respectively.

Structures and In Vitro Antihepatic Fibrosis Activities of Prenylated Dihydrostilbenes and Flavonoids from Glycyrrhiza uralensis Leaves.

Glycyrrhiza uralensis is the major plant source of licorice. This study was to identify bioactive compounds from the plant's leaves in order to make better use of its aerial part. An ethanol extract of the leaves was subjected to repeated chromatography to yield 15 compounds. The structures were determined to be three novel dihydrostilbenes, based on their various spectroscopic data-glycypytilbene A (1), glycydipytilbene (2), and glycypytilbene B (3)-and 12 known compounds, α,α'-dihydro-3,5,4'-trihydroxy-4,3'-diisopentenylstilbene (4), α,α'-dihydro-3,5,3',4'-tetrahydroxy-2,5'-diisopentenylstilbene (5), 6-prenyleriodictyol (6), 5'-prenyleriodictyol (7), 6-prenylquercetin-3-Me ether (8), 5'-prenylquercetin (9), 6-prenylquercetin (10), 6-prenylnaringenin (11), 3'-prenylnaringenin (12), sigmoidin C (13), 8-[(E)-3-hydroxymethyl-2- butenyl]-eriodictyol (14), and quercetin-3-Me ether (15). Most of these chemical constituents inhibited α-glucosidase activity, with the two prenylated quercetin derivatives (9 to 10) being the greatest active (IC50 < 4.0 µg/mL). Compounds 1, 3 to 4, 6 to 7, 9 to 12 impeded the growth of human hepatic stellate cells, with the prenylated flavonoids (6 to 7, 9 to 12) being more robust than their unprenylated counterparts. PRACTICAL APPLICATIONS: This study found that Glycyrrhiza uralensis leaves contain prenylated dihydrostilbenes and flavonoids with inhibiting effects on α-glucosidase and on the proliferation of human hepatic stellate cells, which should prompt the development of G. uralensis leaves for healthy products with anti-diabetic or liver fibrosis-preventing effects.