#!/usr/bin/perl
use strict;
use warnings;
use feature 'say';

use Mojo::DOM;

my $html = '<div class="abstract-content selected" id="enc-abstract">
<p>Secondary bile acids (BAs) and short chain fatty acids (SCFAs), two
major types of bacterial metabolites in the colon...
</p>';

my $dom = Mojo::DOM->new( $html );
foreach my $abstract ( $dom->find('div.abstract-content > p')->each ){
  say $abstract->text;
}
[download]

Prints:

Secondary bile acids (BAs) and short chain fatty acids (SCFAs), two
major types of bacterial metabolites in the colon...
[download]

If this isn't what you want/expect please post (or link to) an HTML file you are working with, and clarify your requirements.