

In episode **17** of **Monogatari Second Season** (the first episode of
**Onimonogatari** ), when Koyomi and Mayoi see the strange "darkness", an
image of the structure of a chemical compound is displayed, repeatedly:

![a structural formula](https://i.stack.imgur.com/zCAjxl.png)

Shortly afterwards, a number of different chemical compounds are displayed
(numbers not present in original):

![lots of structural formulae \(numbering
added\)](https://i.stack.imgur.com/1jjII.png)

What are these compounds?


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question
monogatari-series
What chemical compound is shown in episode 17 of Monogatari Second Season?


The first image is the structural formula of
[**epinephrine**](http://en.wikipedia.org/wiki/Epinephrine) (or **adrenaline**
, depending on where you live).

![structural formula of epinephrine](https://i.stack.imgur.com/Vk9kP.png)

Epinephrine is a neurotransmitter that plays a significant role in the fight-
or-flight response, and so its appearance here makes sense - Koyomi is
certainly about to take flight upon seeing the "darkness".

* * *

The second image contains the following compounds:

  1. [dopamine](http://en.wikipedia.org/wiki/Dopamine)
  2. [serotonin](http://en.wikipedia.org/wiki/Serotonin)
  3. [α-Neoendorphin](http://en.wikipedia.org/wiki/Alpha-Neoendorphin)
  4. epinephrine (again)
  5. [(Leu-)enkephalin](http://en.wikipedia.org/wiki/Enkephalin)
  6. [norepinephrine](http://en.wikipedia.org/wiki/Norepinephrine) (or noradrenaline)

All of these are neurotransmitters, as well, though none of them are as
localized to the fight-or-flight response as epinephrine is.


CC BY-SA 3.0
2013-10-28T02:19:42.003
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2013-10-28T02:50:13.067
2013-10-28T02:50:13.067
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answer