Several approaches to the synthesis of penicillin from 2-iminothioazolidine
50, from 2-thiothiazolidine 66 and by photocyclization of
77 and 78 were investigated. 2-Iminothiazolidine 50 was prepared
from dibromoester 45 by the action of benzylamine followed by treatment
of aziridine 46 with potassium or ammonium thiocyanate. Attempted
introduction of a two-carbon...
Asukamycin, a member of the manumycin family of antibiotics, exhibits strong antibacterial, antifungal, and anti-neoplastic activities. However, its production in the wild-type strain of Streptomyces nodosus subsp. asukaensis ATCC 29757 is relatively low. Recently, the biosynthetic gene cluster for asukamycin was identified in the producing organism and among the 36...
The prevalence of obesity and diabetes in the United States and globally has been rising in the last few decades and it continues to climb. One of the causes for this increase is the over consumption of sugars and/or carbohydrates. Among medications available to treat obesity and diabetes are the...
The purpose of this project was to isolate gabosines and other compounds through chemical screening of secondary metabolites of Streptomyces cellulosae subsp. griseorubiginoses strain S1096. Two different media were used to cultivate S. cellulosae. The first contained soybean and mannitol. The other contained oatmeal and trace element solution. After cultivation...
Among the myriad of naturally occurring bioactive compounds are the aminocyclopentitol-containing natural products that represent a family of sugar-derived microbial secondary metabolites, such as the antibiotics pactamycin, allosamidin, and trehazolin. Pactamycin, a structurally unique aminocyclitol antibiotic isolated from Streptomyces pactum, consists of a 5-membered ring aminocyclitol (cyclopentitol) unit, two aromatic...
Natural products (a.k.a. secondary metabolites) are produced by living organisms that are not essential for their growth, development, or reproduction, but may play a role in their survival or adaptability in nature. Many secondary metabolites isolated from plants and microbes have found use as molecular probes, drug leads, or medicine...
Pactamycin, a potent antitumor antibiotic produced by the soil bacterium Streptomycespactum, is a structurally unique aminocyclopentitol-containing natural product. Itconsists of a highly functionalized cyclopentitol core unit, two aromatic rings [3-aminoacetophenone (3AAP) and 6-methylsalicylic acid (6MSA)], and a 1,1-dimethylurea moiety. Despite its potent biological activity, the development of thisantibiotic was hampered...
Gamma Ray Bursts (GRBs) are the most energetic explosions in the Universe, producing up to $\sim10^{53}$ ergs of energy in the first few seconds of their emission -- the so-called prompt phase that is dominated by high energy X-ray and $\gamma$-ray photons. The very large luminosities released in these events...
Among the myriad of natural products are pseudosugar-containing secondary metabolites, e.g., the C7-pseudosugar-containing oligosaccharide acarbose, the C6- pseudosugar-containing aminoglycoside antibiotics, and the five-membered ring pseudosugar-containing antibiotic pactamycin. The C7-pseudosugars are normally derived from sedoheptulose 7-phosphate catalyzed by a family of enzymes called sedoheptulose 7-phosphate cyclases (SH7PCs). This family of enzymes...
Simultaneous speech translation (SimulST) is widely useful in many cross-lingual communication scenarios, including multinational conferences and international traveling. Since text-based simultaneous machine translation (SimulMT) has achieved great success in recent years. The conventional cascaded approach for SimulST uses a pipeline of streaming ASR followed by simultaneous MT but suffers from...