Why is my published article seemingly not indexed by Google or Google Scholar?

Although you asked a generic question, the answer is very particular to your own particular article. Most likely, @HoboSci, got the correct answer: you published in a journal of questionable ethical editorial policy that Google Scholar refuses to index. That is, "Journal of Chemical and Pharmaceutical Research" is probably such a journal (see https://bradleymonk.com/Beall%27s_List_of_Questionable_Journals).

I looked up the issue where your own article is published: JOCPR Volume 6 Issue 3: http://www.jocpr.com/archive/jocpr-volume-6-issue-3-year-2014.html. I searched Google Scholar for your article "Potential inhibitors against acetylcholinesterase and glutathione S-transferase associated with alzheimer's disease". I also searched for a couple other articles in that same special issue and none of them showed up in Google Scholar.

Unfortunately, I don't think there's anything you can do about it because once you've published in a journal like that, you can't republish the same article anywhere else. So,the lesson is to only publish your work in reputable journals, or else your published work might become almost invisible on the Web. :-(

This probably has nothing to do with predatory publishers or with the number of citations. Google Scholar has no quality requirements - it indexes anything and everything. This is unlike Web of Knowledge, which does have quality requirements, and also why Jeffrey Beall has said Google Scholar is full of junk science. What's likely is that the publisher didn't provide Google Scholar with what it needs.

Although Google Scholar has no quality requirements, it does have certain technical requirements before its bots can even crawl the journal's website. A key requirement is that Google users must see at least the complete abstract or the first full page. There are other technical requirements, as can be seen on this page.

Since it's not hard to get indexed by Google Scholar, it is something that authors should demand from publishers, and if the publisher does not do this, authors should approach another publisher. However since you can't retract the article, the next best thing to do is to host it on your institutional website (see the "Individual Authors" section in the last link for more details). If you don't have a website, you can also hand the article to your university repository. There's probably nothing you can do to get indexed by Web of Science however, other than hope the journal someday gets indexed by SCI.