What are molecular dynamics and MD simulation?

In computational chemistry, molecular dynamics (MD) simulations are when you simulate or model the motion s and behavior of individual atoms in a molecule or molecules of your choosing by applying the laws of classical mechanics to solve for parameters such as velocity, charge, position and so on. Inevitably the use of classical mechanics to describe such small particles means that one ends up relying on some parameters that should be measured (experimentally, or calculated through some ab initio method. More on this below) or known beforehand (from scientific literature). The collections of such parameters are known as forcefields. Examples for some forcefields that are used today are CHARMM and AMBER forcefields.

Molecular dynamics calculations can be less accurate than quantum mechanics calculations but are relatively a lot faster in most situations. Quantum mechanics calculations of the ab initio type don't suffer from the same crutch as MD simulations in that they calculate everything from scratch, and do not require you to provide experimental information.

Reference: https://www.quora.com/What-are-molecular-dynamics-and-MD-simulation

What are some interesting advancements in green chemistry in the pharmaceutical industry?

I think the most interesting, is in improving the manufacturing process of pharmaceuticals.  The end results are the same, but the environmental impacts of some pharmaceutical processing is really terrible, and new processes are much improved.

In particular, a lot of pharmaceuticals use some nasty solvents.  See Page on rowan.edu for a paper called "A method to characterize the greenness of solvents used in pharmaceutical manufacture."  This paper is from 2007, and there have been more improvements since then.  But the concept remains the same.

Reference: https://www.quora.com/What-are-some-interesting-advancements-in-green-chemistry-in-the-pharmaceutical-industry

Why do doctors only prescribe drugs instead of natural remedies? For instance, turmeric instead of an anti inflammatory drug like Advil?

Natural remedies fall into two categories, those with relevant active ingredients (ie. those containing chemicals that will treat the condition) and those without.

Those without don't work, full stop. Walnuts won't cure migraine just because they look like little brains, old wives tale, there's no point prescribing something that doesn't work. I take it we can agree to this? Cool.

Now, the other group, this does contain active ingredients, willow bark contains acetylsalicylic acid (ASA) and can relieve pain, fever and inflamation, (pretty good huh?), plants in the digitalis family contain cardiac glycosides that can control otherwise potentially fatal heart conditions (even better!), this isn't woo woo or superstition this is real, wow! So why don't doctors prescribe the plants?

Three main reasons, firstly, and by far the least important, price, convenience and palatability. Would you rather swallow a tablet of synthesized ASA or gather willow bark, brew a foul tasting tea and force yourself to swallow it while, btw, being in pain? Would a manufacturer sooner spend years growing willow trees (that require a very particular environment) in order to harvest the bark then ship it out complete with wood fibre, or synthesize the ASA and ship tiny tablets of the bit that works? Which gives you pain relief at pennies a dose?

The second reason is that natural remedies are taking advantage of chemicals that plants create for themselves, not us, they make a lot of chemicals. Some are beneficial to us, some aren't. Some will kill you in surprisingly small doses. Plants can also absorb chemicals from their environment. Would you sooner take a tablet containing only the relevant chemical, or do you want a pot luck of chemicals including the one you want plus potential toxins?

Thirdly, dosage. The concentration of your active ingredient will vary from plant to plant, between different parts of the same plant, and over the course of time. Most chemicals that may save your life in the correct dose will kill you if you take too much. Take too little and it won't help and your underlying condition might kill you. Add to that preparation variations: was the water hot enough and did you let your herbal tea steep long enough or too long; did you macerate it enough, too little, too much? Did you have the right bit of the plant, a bit that's too strong, one too weak, one picked at the wrong time of the year, one that grew next to a waste disposal site? Or would you sooner have a pill with a defined quantity of the chemical that could save or kill you?

Choosing ‘natural remedies' over ‘drugs' is like throwing out your cooker and roasting your dinner over an open fire in the middle of your living room. Sure it can cook the food and it's traditional, but it's less convenient, will fill the room with smoke and may get out of control, burn your house down and kill you. We do things the modern way for pretty good reasons.

ETA: It's been noted in the comments that willow bark actually contains just salicylic acid not acetylsalicylic acid. It has some of the same effects, but the acetyl group makes it safer, which is why the acetyl group is added chemically to the natural occurring salicylic acid. Thanks to Kasper Emil Feld for pointing this out (and adding another reason to prefer the pill!).

Reference: https://www.quora.com/Why-do-doctors-only-prescribe-drugs-instead-of-natural-remedies-For-instance-turmeric-instead-of-an-anti-inflammatory-drug-like-Advil

What is a chemical reaction?

Chemical Reactions are certain chemical processes that involve rearranging the molecular structure of a molecule. The atoms of the molecule do not change, but the arrangement of the atoms and the bonds holding the atoms together do change.

There are many kinds of chemical reactions like synthesis reaction: where two molecules join together to form one molecule. The atoms don’t change but the molecular arrangement changes when both molecules merge into one.

Here is an image of a simple chemical reaction that produces water.

Reference: https://www.quora.com/What-is-a-chemical-reaction-2

How important is small molecule structure determination for drug development and discovery?

Very. Let’s say you have a compound that does something amazing to your cell culture. You know the structure, and have a pretty good idea how it binds to its target receptor, and the pharmacological mechanism(s) responsible for its amazing effects. Before you can consider this lead compound a drug candidate, you have to consider a few things, including (but not limited to):

• Solubility[1] - What kind of vehicle are you going to use to administer this compound? Good drug candidates are frequently poorly soluble in saline, but DMSO can be toxic.[2][3]
• Bioavailability - When administered via injection will it distribute into tissues, or get stuck on plasma proteins and never make it out of the blood stream?
• BBB permeability - Will it cross the blood-brain-barrier? Sometimes the answer you want is yes, sometimes it’s no.
• Off-target interactions - What are the chances this compound might preferentially bind to say, potassium channels? That wouldn’t be good.
• Metabolites - Might they be toxic? How about bioactive?
• Route of administration - Turns out that humans don’t like getting shots.[4] People much prefer pills. Is the compound something that could be absorbed through the GI tract?

Anyway, good drug candidates frequently have structures designed to address these and other issues.

Reference: https://www.quora.com/How-important-is-small-molecule-structure-determination-for-drug-development-and-discovery

Is a “vape” a drug delivery system and what besides nicotine might be delivered by it?
There are a lot of different forms of ¨vapes¨, but the main kind is designed to deliver nicotine in a safer and more effective way than cigarettes (or other nicotine delivery methods). They contain a thick liquid called e-juice, which is a mixture of propylene glycol and/or vegetable glycol, as well as flavoring and nicotine (Among others depending on the situation.) You can also suspend other drugs into a PG solution, really, anything that can be smoked will also be vape-able.

Reference: https://www.quora.com/Is-a-vape-a-drug-delivery-system-and-what-besides-nicotine-might-be-delivered-by-it

Inorganic Chemistry: What is the binding affinity of Iron (III) with EDTA and Deferoxamine?

EDTA has almost no affinity for iron and therefore no clinical benefit, deferoxamine is the treatment of choice for acute and chronic (e.g hemochromatosis) iron overload.  EDTA has been studied and used successfully to improve renal function in patients with impaired kidney function not due to lead toxicity(http://ndt.oxfordjournals.org/co...).  So while the mainstream medicine mantra is that EDTA is toxic to the kidneys, a double blind study has shown a  marked benefit in those with renal failure when treated with EDTA.

Reference: https://www.quora.com/Inorganic-Chemistry-What-is-the-binding-affinity-of-Iron-III-with-EDTA-and-Deferoxamine

How are Medicinal tablets  small yet powerful?

You do not chew poisonous or medicinal drugs. You eat fruits which are food - they mainly have carbohydrates. They lack medicinal properties. That is the bias.

Fruits & plants will work in the same way. If you eat poisonous mushroom definitely you’ll die if amount become more. They are for supplying energy, vitamins, minerals, hunger etc. If you do not easy so much bulk, you’ll jump out of hunger.

In the same way, we do prescribe specific foods as like medicine for vitamin, mineral deficiencies. Amla fruit is as good as taking vitamin C tablets, indeed far superior.

Medicine tablets has specific mechanism of action. They have the active ingredient in pure form in fully weighed manner. After taking it, the tablet breaks down, ultimately get absorbed. The molecules are designed or selected not to get destroyed. It pass the Liver and goes to blood of whole body. From blood, it can go to the targeted tissues in higher concentration.

There are other stuffs in a tablet apart from the real medicine. 0.5 mg weight is just small, there many other stuffs which makes the tablets big. What will be mixed, how much will much will mixed, that depends on the drug and that is of Pharmacy’s part, not really ours at this era.

Of course there are medicines which work quite simply. One of the example is Digene. Another example isabgol husk. It is too costly matter to eat Digene, isabgol husk instead of normal foods. Special formula actually given instead of oral food for too much sick persons.

You can eat Digene out of hunger but that is not quite recommendable. Magnesium content is huge, you may have diarrhea after such odd Digene meal.

Reference: https://www.quora.com/How-are-Medicinal-tablets-small-yet-powerful

Why can't we use the chemical compunds of our plastics to power things such as cars?

We can!!! It’s just a matter of cost, availability and motivation. Efficiency is always a consideration for the production of anything, including fuels. Having a market is always a consideration for developing a process for anything. It is virtually impossible to beat coal, natural gas, and petroleum feed stocks.

Reference:https://www.quora.com/Why-cant-we-use-the-chemical-compunds-of-our-plastics-to-power-things-such-as-cars