Perri Shakes-Drayton set a new personal best at the Anniversary Games but it was not enough for the Londoner to win the women's 400m hurdles.
The 24-year-old British champion posted a time of 53.67 seconds but was overhauled down the home straight by Czech Zuzana Hejnova.
Britain won the women's 4x100m relay in front of 60,000 partisan fans at the Olympic Stadium.
It was the fastest time by a British sprint relay team for 12 years.
The quartet of Dina Asher-Smith, Anyika Onuora, Annabelle Lewis and Ashleigh Nelson crossed the line in 42.69secs.
But it was a disappointing evening for many of Britain's athletes on a celebratory evening commemorating last year's Olympic Games.
Robbie Grabarz's indifferent season continued as the London 2012 bronze medallist came fourth in the high jump.
His best jump of 2.24m was 14 cm below the height jumped by winner Bohdan Bodarenko, who failed with a world record attempt of 2.47m.
Marilyn Okoro was fourth (2:00.35) in the women's 800m, some distance behind America's Brenda Martinez, who set a meeting record of one minute 58.19 seconds.
The Olympic Stadium was hosting an evening of athletics for the first time since last summer's memorable Olympics when gold medal-winning performances from the likes of Britons Mo Farah and Jessica Ennis had 80,000 spectators in a frenzy.
Despite all the nostalgia for London 2012, the night was also the first of a two-day Diamond League meeting - and the last track and field event before next month's World Championships in Russia.
Shakes-Drayton is widely regarded as a medal contender in Moscow and she enhanced her reputation with an impressive performance.
The Londoner, who failed to qualify for last year's Olympic final, set a quick pace through the first 300m and led coming into the home straight but could not prevent Hejnova, the leading athlete in the event this season, from taking the victory.
Hejnova broke the Czech national record and set a world leading time of 53.07secs, in addition to securing the Diamond League title.
"I've run my best, what more can you ask for?" Shakes-Drayton, a European indoor gold medallist, told BBC Sport.
"I did well - it was just that last little bit. I need to get stronger but that will come."
There was disappointment for Britain in the men's 200m, a race won by Jamaica's Warren Weir in 19.89secs, with Richard Kilty (20.57), James Ellington (20.62) and Delano Williams (20.74) all finishing in the bottom three.
Mukhtar Mohammed set a personal best of 1min 45.67secs in the men's 800m, but it was only good enough for 10th place.
The men's 400m was won by Grenada's Kirani James (44.65), one of 12 Olympic champions competing in the two-day meeting.
Britons Nigel Levine (45.58) and Conrad Williams (46.43) were sixth and ninth respectively.