First method, you are missing the second parameter for `get_the_author_meta`, which is the ID of the author.  

Second method, you are using undefined variables.. Check this code, should get you what you want.  

	// Method 1
	<ul class="authpcom">
		<?php
			$queried_object = get_queried_object();
			$author_email = get_the_author_meta( 'user_email', $queried_object->ID ); 

			$args = array(
				'author_email' => $author_email
			);
			$comments = get_comments($args);
			foreach($comments as $comment) :
				echo '<a href=" ' . get_permalink( $comment->comment_post_ID ) . ' " rel="external nofollow" title=" ' . get_the_title( $comment->comment_post_ID ) . ' ">' . get_the_title( $comment->comment_post_ID ) . '</a><br />' . $comment->comment_date . '<br /><li>' . $comment->comment_content . '</li>';
			endforeach;
		?>
	</ul>


	// Method 2
	<?php
		$comments = get_comments();
	?>
	<ul id="recent_comments">
	<?php foreach ($comments as $comment) { ?>
	<li>
		<p>
			<strong>
			<?php
				echo get_avatar( $comment->comment_author_email, '45' );
				echo strip_tags($comment->comment_author);
			?>
			</strong>
			&nbsp;commented on <a href="<?php echo get_permalink( $comment->comment_post_ID ); ?>#comment-<?php echo $comment->comment_ID; ?>" rel="external nofollow" title="<?php echo get_the_title( $comment->comment_post_ID ); ?>"> <?php echo get_the_title( $comment->comment_post_ID ); ?></a>: <?php echo wp_html_excerpt( $comment->comment_content, 45 ); ?> (...)
		</p>
	</li>
	<?php }  ?>
	</ul>