Sajan Lal Shyaula,  PhD
Coordinator
Chief Scientific Officer
Tel:+977-1-5547715 (Ext: 269; 270; 273)
Email : [email protected]

Natural Products Chemistry Laboratory has been setup in academy from the beginning of establishment of Nepal Academy of Science and Technology in 1982. Since the establishment of this laboratory, aiming at solving key scientific problems in utilization of natural resources, NPCL carries out both basic and applied studies in chemical sciences and remained frontiers in solving the contemporary problems of nation. The laboratory has emphasized on the goal oriented research projects, problem based analytical service and quality training of scholars in the relevant fields of chemical and biochemical sciences. This laboratory is an integral part of NAST and has played a significant role in resources mobilization for the future growth of nation. 
The priorities of research area are: 

•    Isolation and characterization of natural constituents 
•    Quantitative, qualitative and biological evaluation of natural products 
•    Derivatization of natural bioactive compounds for activity enhancement
•    Optimization of extraction methods for commercially potential products from different medicinal plants
•    Development of industrial processes and green chemistry

Isolation and characterization of natural constituents 
With the help of the experiences gained by the people through many generations, the traditional medicinal practitioners, faith healers and ethnic groups have made use of herbal products for various purposes. The herbal plants are being consumed by the people for the treatment of infectious diseases like flu, measles, typhoid, diarrhea, wound, cold, cough and other microbial diseases. Many medicinal plants such as Aconitum, Acorus, Allium, Bergenia, Caragana, Mallotus, Picrorhiza, Rheum, Rhododendron, Usnea, Ramalina, Zanthoxylum, Zinziber, Tagetes and many more are currently under chemical and biological investigation in our laboratories. As depicted in the figure, three C-19 norditerpenoid alkaloids were isolated from the tubers of Aconitum spicatum and their antileshmanial activity was reported. Our works on natural products together with others have been described in several review articles.

Quantitative, qualitative and biological evaluation of natural products 
We perform standardization of plant materials and plant products through various physicochemical parameters, chemical tests and instrumental analyses. We evaluate the biological properties of the plant extracts and natural constituents isolated through various in vitro and in vivo biological assays such as antimicrobial susceptibility assay, anti-fungal assays, brine-shrimp lethality assay, antioxidant capacity assays, enzyme inhibition studies, assays on animal models, etc. 

Derivatization of natural bioactive compounds for activity enhancement
Medicinal plants mostly contain active secondary metabolites; have diverse physiological and pharmacological activities. Secondary metabolites show potent activities against the organisms and exhibit anititumor, antiallergic, anti-inflammatory, etc. properties. Selective functionalization by chemical methods at unactivated carbon atoms has been a major challenge in organic synthesis, and thus microbiological methods have frequently been used for this purpose. Biotransformations involve the use of enzymes or microorganisms to perform chemical reactions in which the starting substances and products are of comparable chemical complexity. On our studies, the secondary metabolites isolated from the medicinal plants, which showed the biological activities, are subjected for the biotransformation, and transformed products are purified and identified by spectroscopic analyses. Thus obtained transformed compounds are further screened for the biological activities.
We are working on derivatisation of natural secondary metabolites such as flavonoids and anthraquinones for enhancement of their bioactivities. For example, quercetin, a naturally occurring flavonoid, exhibits a high antioxidative property. Unfortunately its water insoluble property and the nature of rapid conjugation with glucuronosyltransferases and sulfotransferases present in the small intestine halts it to reach in the malignant organs through gastrointestinal tract in oral therapy. We have prepared several quercetin derivatives and compared their antioxidative property using the DPPH free radical scavenging assay. We also rationale the result obtained through the molecular calculations.

Optimization of extraction methods for commercially potential products from different medicinal plants
One of our major aim is the sustainable utilization of biological resources of Nepal. We are currently working on developing and designing the extraction protocols for industrial raw products. These raw products can be further used as the key ingredients in different herbal formulations. Recently, we have installed the first supercritical extraction system in Nepal for extracting valuable products from medicinal plants. Extraction of Lutein from Tagetes erecta and method optimization for efficient high yield of essential oil from Lindera neesiana are our successful achievements for commercial purpose.

Development of industrial processes and green chemistry
We are focusing on development of economic, industrial processes. Avoiding of organic solvents and hazardous reagents, development of high yielding and atom economic process, the use of mild conditions and ease work up protocols, microwave synthesis and short step total synthesis are the goals. Our achievements can be read in research articles and patents in the near future. 

Analytical services
We provide analytical services to our customers from the government, private and academic institutions under nominal charges and mutual collaborations. We are equipped with High performance liquid chromatograpy (HPLC), Medium pressure liquid chromatography (MPLC), Gas chromatography mass spectrometry (GC-MS), Liquid chromatography mass spectrometry (LC-MS), Fourier transform infrared spectroscopy (FT-IR), Ultra violet visible spectophotometer (UV), Recycling preparative high performance liquid chromatography, X-ray diffractometer (XRD), Atomic absorption spectroscopy (AAS), CHN elemental analyzer, Supercritical fluid extraction (SFE), High efficiency automatic fractional distillation system, Glove box, Elisa reader, etc. 

Team members
1. Dr Rosa Ranjit, [email protected], [email protected]
2. Mr Nishant Kumar Mishra