MID Semester

Name                   : Tiara

Student Number   : RSA1C110003

 

1. The way to convert a compound of natural products that don’t have potential (inactive) can be made into a  superior compound that have high potential of biological activity is through biosynthetic pathway. The reason why we use biosynthetic pathway are through biosynthetic we can convert starting compound into a new compounds which more useful and through biosynthetic also, secondary metabolites can be fed with a precursor to a better product.

Biosynthetic pathway: By addition of substrates, precursors, or enzymes that play a role.
One of the approach methods that can be used is addition of precursors. To enhance the desired compound can be done by manipulating the media and with the addition of precursor compounds / precursors. That addition will stimulate the activity of certain enzymes involved in the biosynthesis pathway, so it can increase the production of compounds that we want. The addition of precursors is also intended to streamline the process of biosynthesis.

Example: 

To make anthocyanins, we use some precursors and enzymes. Enzyme abbreviations: PAL, phenylalanine ammonia-lyase; C4H, cinnamate 4-hydroxylase; 4CL, 4-coumaroyl:CoA ligase; CHS, chalcone synthase; CHI, chalcone isomerase; F3H, flavanone 3-hydroxylase; DFR, dihydroflavonol 4-reductase; ANS, anthocyanidin synthase; UFGT, UDP glucose-flavonoid 3-o-glucosyl transferase.

  

2.      Natural products have long been a source of inspiration for many drugs in human use. But not all compounds of natural product can be used directly or can be used directly but  the results is not maximized. By total synthesis or semi-synthesis we can replace the inactive group or groups that have bad effect to other groups thus getting a better product.

3.      selection of solvent in isolation of natural product is done by considering several criteria such as:

• Selectivity
  Select the selective solvent that appropriate with polarity compounds that would essence in order to get a more pure extract.

• Chemical and thermal stability
  The selected solvent should be stable at operating conditions of extraction and downstream processing.

• Compatibility with solute
  The solvent shouldn’t react with the dissolved compounds.

• Viscosity
  If the low viscosity solvent diffusion coefficient will increase so that the rate of extraction was also increased.

• Solvent Recovery
  In order to increase the economic value of the process, the solvent needs to recovery so it can be reused. The solvent has a low boiling point, more economical for recovery and reuse.

• Non-flammable
  For the safety purposes, it is necessary to choose a non-flammable solvent

• Non-toxic
  Choose non-toxic solvent for product safety and safety for workers.

• Cheap and easy to obtain
  Choose a solvent that's cheap and easy to obtain.
  
  Crystallization and Recrystallization is a purification technique. One of the critical success factors of crystallization and recrystallization process is the selection of solvents. The solvent used in the process of crystallization and recrystallization should fulfill the following requirements:
•   Having a large temperature gradient in the solubility properties.
• Boiling point solvent should be below the melting point of the compound to be crystallized.
•  Low solvent boiling point very favorable at the time of drying.
• Equity inert (does not react) to the compound to be crystallized or recrystallized.
  
  At least we have to know the polarity of the compound to be crystallized or recrystallized. After we know the polarity of the compound is then chosen according to the polarity of the solvent compound. The table below sets forth some of the solvents used in the process of crystallization and recrystallization.

Some solvent polarity.

No.	Polarity	Solvent
1	low polarity	Petroleum ether, Toluene.
2	Medium polarity	Diethyl ether, acetone
3	high polarity	Ethanol, water

example:

Flavonoids form a large class of important naturally occurring bioactive compounds. Their isolation and purification from natural sources can sometimes be very difficult and time-consuming when traditional phytochemical techniques are used. The solvent system hexane-ethylacetate-methanol-water is proposed as a starting point for the separation of samples containing free flavonoids, as it was cited in more than 60% of the papers. The solvent system ethyl-acetate-butanol-water is proposed as the starting point for glycosylated flavonoids.

Some solvent that use in alkaloid isolation are methanol (lots), and a non polar solvent. Some people use ether - this is dangerous and doesn't dissolve everything. Dichloromethane is good because it is non-toxic, volatile, and a good solvent. It has a major drawback: separation is often very difficult once you have placed your gluggy plant muck in there.

For steroid, usually use ethanol as a solvent.

Usually solvent that used in terpenoid isolation is n-hexane-ethyl acetate-methanol-water.

4.      Natural product chemists mainly use mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR) for structure elucidation of the compounds isolated from various natural sources. A few other analytical methods, for instance, infrared spectroscopy, UV-Vis spectroscopy, and X-ray crystallography, are used to provide supplementary information to confirm the proposed chemical structure for the compound. Several compounds are not UV active, while others like glycosides are hard to crystallize to give good quality crystals for X-ray analysis. MS and NMR methods, however, are usually sufficient to elucidate the structure of the compound.

The IR Spectrum of Caffeine