In summary, a practical and concise approach to the synthesis of biotinylated (−)-morphine (2) was developed. The sequence involves two synthetic steps with an overall yield of 23 %. As the C3 hydroxy group is a conserved functional group, this method could potentially be generalized to other opioid derivatives. Also, in silico simulation, NMR, and cellular assays were performed, showing that biotinylated (−)-morphine (2) binds to the same region of TLR4 as (−)-morphine (1) and that biotinylated morphine (2) acts on TLR4 with similar biological activities.
Meier J, Niessen S, Hoover H, Foley TL, Cravatt BF, Burkart MD. (2009) An orthogonal active siteidentification system (OASIS) for proteomic profiling of natural product biosynthesis.
ACS Chem Biol. 4(11):948-57.
There are commercially available suppositories of morphine,hydromorphone, and oxymorphone. Medications can also be placed in acolostomy or similar stoma, provided that the flow of effluent is slowenough to allow the drug to be absorbed via the mucosa Whenconverting from the oral to the rectal route, start with the same amountas the oral dose and titrate as needed.
Patricelli MP, Cravatt BF. (2001) Proteins regulating the biosynthesis and inactivation ofneuromodulatory fatty acid amides.
Vitam Horm. 62:95-131. Review
Hoover HS, Blankman JL, Niessen S, Cravatt BF. (2008)Selectivity of inhibitors of endocannabinoid biosynthesis evaluated by activity-based proteinprofiling.
Bioorg Med Chem Lett. 18(22):5838-41.
Adachi S, Cognetta AB 3rd, Niphakis MJ, He Z, Zajdlik A, St Denis JD, Scully CC, Cravatt BF, Yudin AK. Facile synthesis of borofragments and their evaluation in activity-based protein profiling. Chem Commun (Camb) 2015 Feb 12;51:3608-11.
Using AutoDock 4.0 (), in silico docking experiments were carried out to search for potential binding sites on TLR4 (). Lamarckian Generic Algorithm (LGA) and the torsion angles of the ligand were varied using AUTOTORS. First, the high-resolution structure of TLR4 was used as the target receptor after modification of Gasteiger charges and surface solvation. The full-length of TLR4 is split into two parts to which the opioid molecules were docked in order to carry out more accurate calculation. Both receptor and ligand were allowed flexibility when running morphine against TLR4. Energy minimized biotinylated (−)-morphine (2) was used in the docking and allowed to have seventeen of its bonds able to rotate within its structure to simulate realistic binding of this ligand to TLR4. A total of 100 runs were carried out and the results were grouped into clusters using an rmsd-tolerance of 2.0 Å. Finally, the resulted clusters were ranked using a force field scoring function (). The credibility of the docking results was evaluated by estimating binding energy and the distribution of the independent runs in clusters (fewer binding modes predicted is preferred). Among those, the highest ranked docked structure was used for molecular visualization.
A generally applicable strategy of chemically labeling (−)-morphine (1) is described. The synthesis starts from commercially available starting materials and can be completed in two steps with an overall yield of 23 %. In silico simulation and NMR results show that the binding of (−)-morphine to one of its molecular targets, toll-like receptor 4 (TLR4), was not affected by the modification. Secreted Embryonic Alkaline Phosphatase (SEAP) reporter assay results demonstrate that C3 biotinylated and unmodified (−)-morphine show similar biological activities in live cells. To our knowledge, these studies provide the first practical and concise method to label various opioid derivatives, a group of important therapeutics in pain management, for biochemical/pharmacological studies.
Our straightforward synthesis of biotinylated (−)-morphine (2) is outlined in . The intermediate 7 can be readily obtained in good yield (65 %) by the classical substitution reaction between deprotonated biotin (5) and commercially available 1,2-bis-(2-iodoethoxy)-ethane (6). It is observed that the choice of base is pivotal for this reaction since compound 6 is unstable under strong basic conditions. Compound 7 was then subject to react with (−)-morphine (1). We found that the conditions had to be carefully tuned to selectively alkylate the C3 phenolic hydroxyl group. It is also important to prevent elimination of HI from compound 7. Several bases (NEt3, KOH, or NaH) and solvents (Et2O, DMF, CHCl3, or DMSO) were tested (), each of which had different effects in promoting the reaction. Using weaker bases, such as K2CO3 and NEt3, and less polar solvents, no reaction occurred and the reactants could be recovered completely. When the reaction was subjected to the strong inorganic base KOH, compound 7 partly degraded due to the fragile nature of compound 7 under strong basic conditions. Finally, optimal conditions were obtained by using NaH to deprotonate the phenol of (−)-morphine (1) in DMSO which subsequently reacted with compound 7 to provide biotinylated (−)-morphine (2) in 35 % yield.
Germplasm refers to the sum total of all the genes present in a crop and its related species.
The conservation of germplasm involves the preservation of the genetic diversity of a particular plant or genetic stock for it’s use at any time in future. It is important to conserve the endangered plants or else some of the valuable genetic traits present in the existing and primitive plants will be lost. A global organization- International Board of Plant Genetic Resources (IBPGR) has been established for germplasm conservation and provides necessary support for collection, conservation and utilization of plant geneic resources through out the world. The germplasm is preserved by the following two ways:
(a) conservation- The germplasm is conserved in natural environment by establishing biosphere reserves such as national parks, sanctuaries. This is used in the preservation of land plants in a near natural habitat along with several wild types.
(b) conservation- This method is used for the preservation of germplasm obtained from cultivated and wild plant materials. The genetic material in the form of seeds or in vitro cultures are preserved and stored as gene banks for long term use.
In vivo gene banks have been made to preserve the genetic resources by conventional methods e.g. seeds, vegetative propagules, etc. In vitro gene banks have been made to preserve the genetic resources by non - conventional methods such as cell and tissue culture methods. This will ensure the availability of valuable germplasm to breeder to develop new and improved varieties.
The methods involved in the in vitro conservation of germplasm are:
(a) Cryopreservation- In cryopreservation (Greek-krayos-frost), the cells are preserved in the frozen state. The germplasm is stored at a very low temperature using solid carbon dioxide (at -790C), using low temperature deep freezers (at -800C), using vapour nitrogen (at- 1500C) and liquid nitrogen (at-1960C). The cells stay in completely inactive state and thus can be conserved for long periods. Any tissue from a plant can be used for cryopreservation e.g. meristems, embryos, endosperms, ovules, seeds, cultured plant cells, protoplasts, calluses. Certain compounds like- DMSO (dimethyl sulfoxide), glycerol, ethylene, propylene, sucrose, mannose, glucose, praline, acetamide etc are added during the cryopreservation. These are called cryoprotectants and prevent the damage caused to cells (by freezing or thawing) by reducing the freezing point and super cooling point of water.
(b) Cold Storage- Cold storage is a slow growth germplasm conservation method and conserves the germplasm at a low and non-freezing temperature (1-90C). The growth of the plant material is slowed down in cold storage in contrast to complete stoppage in cryopreservation and thus prevents cryogenic injuries. Long term cold storage is simple, cost effective and yields germplasm with good survival rate. Virus free strawberry plants could be preserved at 100C for about 6 years. Several grape plants have been stored for over 15 years by using a cold storage at temperature around 90C and transferring them in the fresh medium every year.
(c) Low pressure and low oxygen storage- In low- pressure storage, the atmospheric pressure surrounding the plant material is reduced and in the low oxygen storage, the oxygen concentration is reduced. The lowered partial pressure reduces the in vitro growth of plants. In the low-oxygen storage, the oxygen concentration is reduced and the partial pressure of oxygen below 50 mmHg reduces plant tissue growth. Due to the reduced availability of O2, and reduced production of CO2, the photosynthetic activity is reduced which inhibits the plant tissue growth and dimension. This method has also helped in increasing the shelf life of many fruits, vegetables and flowers.