Concise Synthesis of the Terpene Core Structure of Suaveolindole Through a Time-Economic Route

The terpene core structure of suaveolindoles was synthesized through a concise route in a time-economical manner. A scalable synthetic route from pulegone delivered the desired α,β,γ,δ-unsaturated ester in a brief period. By way of Eschenmoser-Claisen rearrangement, carbon side chain moiety at the crowded double-allylic position was introduced stereoselectively.

Chromone Derivatives with α-Glucosidase Inhibitory Activity from the Marine Fungus Penicillium thomii Maire

The fungal strain YPGA3 was isolated from the sediments of the Yap Trench and identified as Penicillium thomii. Eight new chromone derivatives, named penithochromones M−T (1–8), along with two known analogues, 9 and 10, were isolated from the strain. The structures were established by detailed analyses of the spectroscopic data. The absolute configuration of the only chiral center in compound 1 was tentatively determined by comparing the experimental and the calculated specific rotations. Compounds 7 and 8 represent the first examples of chromone derivatives featuring a 5,7-dioxygenated chromone moiety with a 9-carbon side chain. Bioassay study revealed that compounds 6–10 exhibited remarkable inhibition against α-glucosidase with IC50 values ranging from 268 to 1017 μM, which are more active than the positive control acarbose (1.3 mmol).

What is Special about Silicon in Functionalised Organic Semiconductors?

A carbon side-chain analogue to the high-performance organic semiconductor triethylsilylethynyl difluoroanthradithiophene has been synthesised and characterized. Atomic substitution of carbon for silicon results in subtle changes to opto-electronic properties, which...

Natural and Synthetic Estrogens Regulate Human Health

Estrogen are very important chemical compounds very essential for our body functions. The cholesterol, what we eat through food, gets converted by the action of various enzymes. Scientists have synthesized estrogenic molecules in the laboratory and used them for oral contraceptives and other therapeutic purposes. Environmental estrogenic molecules (xenestrogen) played havocs in human life. Plants also make estrogenic substances (phytoestrogen); they are very useful for mankind. All steroid hormones, including estrogen are synthesized from cholesterol through a common precursor steroid, pregnenolone which is formed by the enzymatic cleavage of a 6-carbon side-chain of the 27-carbon cholesterol molecule. Cholesterol is a starting substance of group of estrogenic compounds [1]. On the other hand, synthetic estrogen are compounds obtained by chemical synthesis that possess estrogenic activity [2]. In addition to these estrogenic compounds there are some estrogenic action mimicking compounds known as xenestrogen and phytoestrogen (Figure 1).

Burkholderia thailandensis Methylated Hydroxyalkylquinolines: Biosynthesis and Antimicrobial Activity in Cocultures

ABSTRACT The bacterium Burkholderia thailandensis produces an arsenal of secondary metabolites that have diverse structures and roles in the ecology of this soil-dwelling bacterium. In coculture experiments, B. thailandensis strain E264 secretes an antimicrobial that nearly eliminates another soil bacterium, Bacillus subtilis strain 168. To identify the antimicrobial, we used a transposon mutagenesis approach. This screen identified antimicrobial-defective mutants with insertions in the hmqA, hmqC, and hmqF genes involved in biosynthesis of a family of 2-alkyl-4(1H)-quinolones called 4-hydroxy-3-methyl-2-alkenylquinolines (HMAQs), which are closely related to the Pseudomonas aeruginosa 4-hydroxy-2-alkylquinolines (HAQs). Insertions also occurred in the previously uncharacterized gene BTH_II1576 (“hmqL”). The results confirm that BTH_II1576 is involved in generating N-oxide derivatives of HMAQs (HMAQ-NOs). Synthetic HMAQ-NO is active against B. subtilis 168, showing ∼50-fold more activity than HMAQ. Both the methyl group and the length of the carbon side chain account for the high activity of HMAQ-NO. The results provide new information on the biosynthesis and activities of HMAQs and reveal new insight into how these molecules might be important for the ecology of B. thailandensis. IMPORTANCE The soil bacterium Burkholderia thailandensis produces 2-alkyl-4(1H)-quinolones that are mostly methylated 4-hydroxyalkenylquinolines, a family of relatively unstudied metabolites similar to molecules also synthesized by Pseudomonas aeruginosa. Several of the methylated 4-hydroxyalkenylquinolines have antimicrobial activity against other species. We show that Bacillus subtilis strain 168 is particularly susceptible to N-oxidated methylalkenylquinolines (HMAQ-NOs). We confirmed that HMAQ-NO biosynthesis requires the previously unstudied protein HmqL. These results provide new information about the biology of 2-alkyl-4(1H)-quinolones, particularly the methylated 4-hydroxyalkenylquinolines, which are unique to B. thailandensis. This study also has importance for understanding B. thailandensis secondary metabolites and has implications for potential therapeutic development.

Effects of mrpigG on Development and Secondary Metabolism of Monascus ruber M7

Monascus pigments (MPs) have been used as food colorants for several centuries in Asian countries and are now used throughout the world via Asian catering. The MP biosynthetic pathway has been well-illustrated, but the functions of a few genes, including mrpigG, in the MP gene cluster are still unclear. In the current study, in order to investigate the function of mrpigG in M. ruber M7, gene deletion (ΔmrpigG), complementation (ΔmrpigG::mrpigG) and overexpression (M7::PtrpC-mrpigG) mutants were successfully obtained. The morphologies and biomasses, as well as the MP and citrinin production, of these mutants were analyzed. The results revealed that the disruption, complementation and overexpression of mrpigG showed no apparent defects in morphology, biomass or citrinin production (except MP production) in ΔmrpigG compared with M. ruber M7. Although the MP profiles of ΔmrpigG and M. ruber M7 were almost the same—with both having four yellow pigments, two orange pigments (OPs) and two red pigments (RPs)—their yields were decreased in ΔmrpigG to a certain extent. Particularly, the content of rubropunctatin (an OP) and its derivative rubropunctamine (an RP) in ΔmrpigG, both of which have a five-carbon side chain, accounted for 57.7%, and 22.3% of those in M. ruber M7. On the other hand, monascorubrin (an OP) and its derivative monascorubramine (an RP), both of which have a seven-carbon side chain, were increased by 1.15 and 2.55 times, respectively, in ΔmrpigG compared with M. ruber M7. These results suggest that the MrPigG protein may preferentially catalyze the biosynthesis of MPs with a five-carbon side chain.

Burkholderia thailandensis methylated hydroxy-alkylquinolines: biosynthesis and antimicrobial activity in co-cultures

ABSTRACTThe bacterium Burkholderia thailandensis produces an arsenal of secondary metabolites that have diverse structures and roles in the ecology of this soil-dwelling bacterium. In liquid co-culture experiments, B. thailandensis secretes an antimicrobial that nearly eliminates another soil bacterium, Bacillus subtilis. To identify the antimicrobial, we used a transposon mutagenesis approach. This screen identified antimicrobial-defective mutants with insertions in the hmqA, hmqC and hmqF genes involved in biosynthesis of a family of 2-alkyl-4(1H)-quinolones called 4-hydroxy-3-methyl-2-alkenylquinolines (HMAQs), which are closely related to the Pseudomonas aeruginosa 4-hydroxy-2-alkylquinolines (HAQs). Insertions also occurred in the previously uncharacterized gene BTH_II1576. Results confirm that BTH_II1576 is involved in generating N-oxide derivatives of HMAQs (HMAQ-NO) in B. thailandensis and that HMAQ-NOs are sufficient to eliminate B. subtilis in co-cultures. Moreover, synthetic HMAQ-NO is ∼50-fold more active than HMAQ. Both the methyl group and the length of the carbon side chain account for high activity of HMAQ-NO against B. subtilis. The results provide new information on the biosynthesis and activities of HMAQs and reveal new insight into how these molecules might be important for the ecology of B. thailandensis.IMPORTANCEThe soil bacterium Burkholderia thailandensis produces 2-alkyl-4(1H)-quinolones, mostly methylated 4-hydroxy-alkenylquinolines, a family of relatively unstudied metabolites similar to molecules also synthesized by Pseudomonas aeruginosa. Several of the methylated 4-hydroxy-alkenylquinolines have antimicrobial activity against other species. We show that N-oxidated methyl-alkenylquinolines are particularly antimicrobial and sufficient to kill Bacillus subtilis in co-cultures. We confirmed their biosynthesis requires the previously unstudied protein HmqL. These results provide new information about the biology of 2-alkyl-4(1H)-quinolones, particularly the methylated 4-hydroxy-alkenylquinolines, which are unique to B. thailandensis. This study also has importance for understanding B. thailandensis secondary metabolites and has implications for potential therapeutic development.

A Ruthenium-Catalyzed C–H Activation Strategy as an Efficient Shortcut in the Total Synthesis of 6,8-Dimethoxy-1,3-dimethyl­isoquinoline

A short and convenient total synthesis of 6,8-dimethoxy-1,3-dimethylisoquinoline, employing a C–H activation/alkenylation strategy, is reported. The approach involves the CeCl3·7H2O-promoted methoximation of 2,4-dimethoxyacetophenone and a methoxime-directed ruthenium-catalyzed allylation. This was followed by a one-pot, ruthenium-catalyzed allyl to propenyl isomerization and a microwave-assisted 6π-azaelectrocylization to complete the sequence. This approach, which entails a shortcut in the synthetic management of the three-carbon side chain, is an improved and more efficient route toward the natural product, which facilitated its access in just three steps and 27.3% overall yield.

Synthesis of cashew Mannich polyol via a three step continuous route and development of PU rigid foams with mechanical, thermal and fire studies

Renewable, biodegradable, agricultural resources are gaining increasing attention of many researchers because of growing environmental awareness and their potential to replace petrochemical derivatives. Cardanol obtained from cashew nut shell liquid (CNSL) is a renewable resource of immense potential. Cardanol, obtained as a byproduct of the cashew processing industry, is an important renewable resource and a unique phenolic compound carrying a 15-carbon side chain in the meta position, with varying degrees of unsaturation. The current research work describes the synthesis of new bio-based cashew Mannich polyols via the stepwise oxazolidine route and confirmed by spectral analysis. The foaming characteristics were studied and the polyols were successfully used in making rigid polyurethane (PU) foams with good mechanical, thermal and fire properties. The foams were characterized for density, flexural strength, morphology and limiting oxygen index (LOI) properties.