Lipase-catalysed chemoselective monoacetylation of hydroxyalkylphenols and chemoselective removal of a single acetyl group from their diacetates

Anti-neuroinflammatory Activity of New Naturally Occurring Benzylated Hydroxyacetophenone Analogs from the Endophytic Fungus Alternaria sp. J030

Chemical studies on the culture broth of the endophytic fungus Alternaria sp. J030 led to the identification of three benzylated hydroxyacetophenone derivatives, bauvaroalterins A-C (1-3), and 34 structurally diverse metabolites (4-37). The new structures were elucidated by extensive spectroscopic analyses including UV, IR, 1D and 2D NMR, HRESIMS, and further confirmed using single crystal X-ray diffraction. The in vitro anti-neuroinflammatory effects of the co-isolated metabolites were evaluated in lipopolysaccharide (LPS)-stimulated microglial cells. Compounds 1-3 were shown to significantly reduce LPS-induced NO production by inhibiting the expression of iNOS, as well as inhibiting LPS-induced production of the inflammatory factors TNF-α, IL-1β and IL-6. Further studies revealed that 1-3 were capable of down-regulating the expression of NF-κB subunits p50 and p65, thereby suppressing the activation of NF-κB by inhibiting the LPS-induced phosphorylation of IκB-α. Together these findings demonstrate that bauvaroalterins A-C (1-3) exert anti-neuroinflammatory effects via inhibition of the NF-κB/iNOS signalling pathway in LPS induced BV-2 cells.

Antifibrotic compounds from Liriodendron tulipifera attenuating HSC-T6 proliferation and TNF-α production in RAW264.7 cells

The inhibition of hepatic stellate cell (HSC) proliferation has been considered as an effective therapeutic target for the treatment of liver fibrosis. The methanolic extract of Liriodendron tulipifera showed significant inhibitory activity against the proliferation of HSCs. Bioactivity-guided isolation afforded twelve compounds including (-)-sesamin (1), (-)-syringaresinol (2), (+)-dihydrodehydrodiconiferyl alcohol (3), salvinal (4), (+)-guaiacylglycerol-8-O-4'-dihydroconiferyl ether (5), (±)-guaiacylglycerol-8-O-4'-sinapyl alcohol ether (6), tanegool (7), (+)-5,5'-dimethoxy-7-oxolariciresinol (8), 3-hydroxy-4-methoxyacetophenone (9), 4-acetoxymethylphenol (10), (-)-paramicholide (11), and blumenol A (12). Among the compounds isolated, 2, 3 and 4 significantly attenuated the proliferation of the activated HSC-T6 cells. The maximal dose of these compounds, however, showed no cytotoxicity in primary cultured rat hepatocytes. Collagen deposition in the activated HSC-T6 cells was reduced by 2, 3 and 4. Also, the increased production of the pro-inflammatory cytokine tumor necrosis factor (TNF)-α induced by lipopolysaccharide was decreased by 3 and 4 in RAW264.7 macrophage cells. Collectively, (-)-syringaresinol (2), (+)-dihydrodehydrodiconiferyl alcohol (3), and salvinal (4) isolated from L. tulipifera leaves and twigs exhibited selective antifibrotic activities toward the activated HSCs and suppressed TNF-α production in RAW264.7 macrophages. These compounds may be useful candidates for developing therapeutic agents for the prevention and treatment of hepatic fibrosis.

Chemoselective acylation of (hydroxyalkyl)phenols catalyzed by Candida antarctica lipase B

Acylation of (hydroxyalkyl)phenols with vinyl esters by lipase B from Candida antarctica proceeded smoothly in a highly chemoselective manner, affording their alkyl esters exclusively or at least predominantly. The enzyme therefore discriminates between an alcoholic hydroxyl from a phenolic hydroxyl in addition to having versatile catalytic abilities for organic synthesis.

Six compounds from marine fungus Y26-02

Two new compounds, together with four known compounds, have been isolated from the ethyl acetate extract of the fermentation broth of the marine fungus Y26-02. Their structures were elucidated, respectively, as 5-(ethynyloxy)-3-hydroxy-3,6-dihydro-2H-pyran-2-one (1), 4-(butoxymethyl)benzene-1,2-diol (2), 4-(methoxymethyl)benzene-1,2-diol (3), 2-acetoxymethylphenol (4), N-(2-phenylethyl)acetamide (5), and 4-hydroxyphenethyl acetate (6) on the basis of their spectroscopic and physico-chemical properties.

Hydroxytyrosol lipophilic analogues: Enzymatic synthesis, radical scavenging activity and DNA oxidative damage protection

The olive oil phenol hydroxytyrosol (3), as well its metabolite homovanillic alcohol (4), were subjected to chemoselective lipase-catalysed acylations, affording with good yield 10 derivatives (5-14) bearing C(2), C(3), C(4), C(10) and C(18) acyl chains at C-1. Hydroxytyrosol (3) and its lipophilic derivatives showed very good DPPH. radical scavenging activity. Compounds 3, 4 and their lipophilic analogues 5-14 were subjected to the atypical Comet test on whole blood cells: 3 and its analogues 5 and 6, with little hydrophobic character (logP<or=1.20), showed a good protective effect against H(2)O(2) induced oxidative DNA damage. The homovanillic alcohol 4 and its analogues 10-14 resulted scarcely effective both as radical scavengers and antioxidant agents.

Syntheses of acetylated steroid glycosides and selective cleavage of O-acetyl groups in sugar moiety

Acetylated 3beta-O-beta-glycosyl steroid derivatives were synthesized by the reaction of a new polyhydroxysteroid 3beta,5alpha,6beta-trihydroxypregn-16-en-20-one (2) with the peracetylated 1-bromo derivatives of d-glucose and d-galactose, respectively. Subsequent protection by excess acetic anhydride in pyridine selectively gave the 6beta-O-acetylated steroid glycosides. Deprotection of the acetylated steroid glycosides separately with moderate catalysis dibutyltin oxide in methanol selectively removed all acetyl groups of sugar moiety, whereas the acetyl group of the steroid part was retained. The structures of the steroid glycosides were confirmed by mass spectrometry, NMR and IR. The complete protocol was shown to be non-destructive at all stages to the sugar moieties and the steroid nucleus. These regioselective reactions open a route to the synthesis of a series of closely related isomers of 2 and other widespread polyhydroxysteroids and steroid glycosides in marine organisms and some terrestrial species.

Reactions on a Solid Surface. A Simple, Economical, and Efficient Acylation of Alcohols and Amines over Al2O3

Al(2)O(3) brings about a rapid acylation of a range of alcohols and amines with acid chlorides and acid anhydrides, respectively. Amines are easily Boc- and Cbz-protected on reaction with Boc-anhydride and Cbz-Cl, respectively. The acylation of phenols is slow enough to allow chemoselective acylation of alcohols and amines in the presence of phenols.

A mild and selective method for cleavage of O-acetyl groups with dibutyltin oxide

A mild and efficient neutral method for the cleavage of O-acetyl groups with dibutyltin oxide has been developed. This method is especially useful in the synthesis of glycosides containing base- or acid-sensitive multifunctional groups.