In the other matches of the day, Malaysia beat Oman 7-0 and Korea defeated Bangladesh 6-1 in Pool B, while Japan thrashed hosts Indonesia 9-0 in Pool A.
It was the world No 6 Zii Jia's second title on the trot after winning the Asian crown in Manila earlier this month.
Titmus, 21, won the Australian 400m title with a swim of three minutes, 56.40 seconds on Sunday, shaving 0.06 seconds off Ledecky's previous mark of 3:56:46 set at the Rio Olympics.
India and Pakistan have won the tournament three times each, while South Korea are the most successful team, having clinched the title four times in the 10 previous editions.
Sindhu, a two-time Olympic medallist, lost 17-21, 16-21 to third seeded Chen in 43 minutes to end an impressive run in the Super 500 tournament.
The sixth seeded Indian prevailed 21-15 20-22 21-13 over the Japanese in 51 minutes.
The Telangana boxer out-punched her opponent from Thailand in the final of the Women's World Championships in Istanbul.
The world no took just 37 minutes to get the better of Sim Yu Jin, 21-16 21-13.
Nikhat, the 2019 Asian Championship bronze medallist, made short work of Brazil's Caroline De Almeida to notch up a dominant 5-0 win. She will take on Thailand's Jitpong Jutamas on Thursday.
Srikanth, seeded eighth in the BWF Super 500 tournament, won his first round match against Brice Leverdez of France 18-21, 21-10, 21-16 in 49 minutes.