Nepali chemists discovered two new compounds from Simal (Bombax ceiba L.)

Nepali chemists have discovered two new compounds from the stem bark of a plant popularly known in Nepal as Simal. The discovery of the new compounds (Simalin A and Simalin B) has recently been published in a journal Phytochemistry Letters. The plant material was collected from Darchula, Nepal and the research was carried out in Kumamoto University, Kumamoto, Japan.

Simal is a deciduous tree found in Nepal, India, West China and Malaysia.  Bark of this plant is used in wound healing; flowers and fruits are used in revitalizing sexual impotency and gum is used as remedy of diarrhea, dysentery, influenza and menorrhagia. 

Joshi et al., obtained Simalin A (molecular formula determined: C20H28O14) as a colorless gum with positive optical rotation, whereas Simalin B (molecular formula determined: C26H40O17) was obtained as colorless gum with negative optical rotation First author of the paper is pursuing PhD at
Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan with funding from Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan. He is an assistant professor of chemistry at Pokhara University, Pokhara, Nepal.

Fig. 1. Structure of newly discovered compounds 1. Simalin A and 2. Simalin B

According to a expert in natural product chemistry, further characterization and biological assays of these new compounds are necessary to understand the medicinal role of these compounds.  

Further reading: K.R. Joshi et al., Phytochemistry Letters 7 (2014) 26–29

 

Scientists discovered a simpler way to synthesize Aziridines

Dr. Mahesh Paudyal, co-author of the science paper

Chemists at University of Texas-Southwestern Medical Center have discovered a simpler route to synthesize aziridine, a three-membered nitrogen analogs of epoxide rings. Aziridines are present in a number of biologically active natural products and are very important synthetic building blocks because they are extensively used to introduce nitrogen atom into complex molecules, including medicinal drugs. The current aziridination methods always need a protecting group on the nitrogen atom. The protecting group groups provide stability to the molecule but the removal of such protecting group needs harsh conditions, and hence is problematic.

Jat et al. have developed a direct and simple one-step method for preparing N–H and N–Me aziridines from alkenes under mild conditions that avoids the need for an N-protecting group (Science,2014, 343, 61). This aziridination method involves the reaction of an alkene with the aminating agents DPH (dinitrophenyl-hydroxylamine) or N–Me–DPH in the presence of a rhodium catalyst, which produces N–H or N–Me aziridines at ambient temperature.

The simple route to aziridines can will help medicinal and natural products chemists © Science/AAAS

“The major challenge now is to develop an asymmetric version of this reaction that will selectively provide a single mirror-image form (enantiomer). This is extremely important in synthesizing drug molecules because two enantiomers of a molecule show different biological activities,” says Mahesh Paudyal, a co-author of the paper at the University of Texas Southwestern Medical Center.

[For detailed understanding and coverage: Please see “This week in Science (page 5) and Perspective (page 34)” of the same issue of Science, Chemistry World – January 9, 2014 (online), C&EN News- January 6, 2014 (online)]

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