Kidambi Srikanth bowed out of the tournament after losing to second-seeded Malaysian Lee Zii Jia 19-21, 14-21.
Two-time Olympic medallist Sindhu defeated Denmark's Christophersen 21-14 21-16.
In a repeat of last week's Indonesia Masters quarterfinal, Srikanth once again got the better of compatriot HS Prannoy.
Sindhu lost to Japanese top seed Akane Yamaguchi while Srikanth was outplayed by third seed Anders Antonsen of Denmark.
Kerala's HS Prannoy defeated Malaysia's Liew Daren 22-20 21-19 in the opening round.
Former champion Lakshya went down to Singapore's Loh Kean Yew 18-21, 12-21, while Srikanth was edged out by Malaysian Lee Zii Jia 21-19, 22-20.
Lakshya, ranked world No. 21, prevailed in a seesaw battle to notch up a 21-18, 12-21, 21-19 win over three-time junior world champion Vitidsarn.
Srikanth showed great determination to outwit NG Ka Long Angus in a hard-fought match.
Sen scored a 21-17, 21-15 victory to set up a clash with Kunlavut Vitidsarn of Thailand.
Sourabh Verma crashed out of the Super 500 tournament.