Asymmetric Total Syntheses of Hypoestin A, Albolic Acid, and Ceroplastol II.

The first asymmetric total synthesis of bioactive diterpenoid hypoestin A with an unprecedented [5-8-5-3] tetracyclic skeleton is accomplished in 15 steps from commercially available (R)-limonene. Furthermore, the second asymmetric total syntheses of sesterterpenoids albolic acid and ceroplastol II in 21 steps are also reported. The synthetically challenging and highly functionalized [X-8-5] (X = 5 or 7) tricarbocyclic ring systems found in hypoestin A, albolic acid, ceroplastol II, and schindilactone A, as well as other natural products, are efficiently and directly constructed via a unique intramolecular Pauson-Khand reaction of an allene-yne. This work represents the first reported use of the Pauson-Khand reaction to access synthetically challenging eight-membered-ring systems in natural product synthesis.

Facile synthesis of 9H-pyrrolo[1,2-a]indoles via Brønsted acid catalyzed cascade reactions.

An efficient Brønsted acid catalyzed Friedel-Crafts alkenylation/1,6-addition/condensation cascade reaction has been developed. This protocol enables effective access to various highly functionalized 9H-pyrrolo[1,2-a]indoles in moderate to high yields. Mechanistic studies indicate that the in situ vinylogous reactivity intermediate might be formed in the catalytic system.

Nickel-Catalyzed Intramolecular Direct Arylation of Imines toward Diverse Indoles.

An efficient nickel-catalyzed intramolecular direct arylation of imines with challenging aryl chlorides has been developed. The versatile nickel catalysis made use of easily accessible imines and delivered diversely decorated 2-arylindoles of considerable importance to biological and medicinal chemistry.

Identification of five highly priced tuna species by quantitative real-time polymerase chain reaction.

Tunas are economically important fishery worldwide, and are often used for commercial processed production. For effective fishery management and protection of consumers' rights, it is important to develop a molecular method to identify species in canned tuna products rapidly and reliably. Here, we have developed a duplex quantitative real-time PCR (qPCR) for identification of five highly priced tuna species (Thunnus maccoyii, Thunnus obesus, Thunnus albacares, Thunnus alalunga and Katsuwonus pelamis) from processed as well as fresh fish. After amplification and sequencing of seven genetic markers commonly used for species identification, 16S rDNA and control region (CR) of mitochondrial DNA were selected as the reference gene markers for genus Thunnus and tuna species identification, respectively. Subsequently, a 73 bp fragment of 16S rDNA and 85-99 bp fragment of CR were simultaneously amplified from each target species by qPCR. The qPCR efficiency of each reaction was calculated according to the standard curves, and the method was validated by amplification DNA extracted from single or mixed tuna specimen. The developed duplex qPCR system was applied to authenticate species of 14 commercial tuna products successfully, which demonstrated it was really a useful and academic technique to identify highly priced tuna species.

Microbiological changes and biodiversity of cultivable indigenous bacteria in Sanbao larger yellow croaker (Pseudosciaena crocea), a Chinese salted and fermented seafood.

Sanbao large yellow croaker is a kind of Chinese salted and fermented seafood processed by adding 50% of salt and fermenting at high temperature [around 30 °C] over 20 d. To get a comprehensive understanding of cultivable microorganism's diversity present in its fermentation, the chemical and microbial properties of this product, were detected initially, followed by identification of bacteria recovered from different fermentation periods using PCR-RFLP and 16S rRNA gene sequencing analysis. In total, 105 indigenous isolates were recovered with 3 different medium and majority of the isolates picked up from both MRS and MSA medium were finally clustered into the genus of Staphylococcus (S.). Among the 90 Staphylococci, S. xylosus, S. saprophyticus, and S. nepalensis were the most prevailing cultivable species recovered throughout the whole production process (70 isolates, 77.8%), while 5 other species, namely, S. aureus, S. vitulinus, S. sciuri, S. equorum, and S. succinus formed a minor fraction (20 isolates, 22.2%) of the Staphylococcus communities. Lactic acid bacteria, Pseudomonas, Proteus, and Bacillus constituted trivial populations in the initial period of the fermentation and then gave the way to the Staphylococcus immediately. High salt concentration used during the processing is like to have a pronounced influence on the microbial populations involved. Data obtained in this work could be referred in control and optimization of the fermentation process and selecting suitable strains for aquatic product fermentation.