The African champion completed the contest in 54.73, dipping under 55 seconds for the third time this year, with Janieve Russell of Jamaica securing victory in 54.02.
Elsewhere, a number of other South African athletes delivered impressive performances on the European circuit over the weekend.
Carina Horn won the 100m women's sprint in 11.05 at the European Classic Permit Meeting in Sotteville, France, clocking the fastest time of her career, though the SA record holder was aided by a +2.6m/s wind. Zarck Visser again sailed over the eight metre mark, winning the men's long jump with a leap of 8.07m.
In Kortrijk, Belgium on Saturday, Justine Palframan won the 200m women's race in a personal best of 22.84 and also secured victory in the 400m event in 52.47. Showing consistent form. The World Student Games one-lap champion had clocked a 400m season's best of 52.30 in Celle Ligure three days earlier.
The next day, Palframan went on to win the 200m race at the Brussels Grand Prix in 23.07.
Lebakeng Sesele was triumphant in the 200m men's race in Kortrijk, achieving a personal best of 20.27 seconds, becoming the sixth athlete to dip under the ASA A-standard qualifying time in the half-lap dash for the IAAF World Championships in London next month.
He also finished second in the 100m men's race in 10.20, with the benefit of a +3.2m/s wind.
Gena Lofstrand continued her breakthrough international campaign, setting another personal best to win the 800m women's race in 2:02.05, edging out Winnie Nanyondo of Uganda by 0.01 in a late sprint.
