The 20-year-old Castro had the upperhand after the referee gave Jarsenbayev Mirat of Kazakhstan mandatory standing eight counts in the second and third rounds only to be handed a 27-41 loss.
Castro settled for the bronze medal — a pitiful consolation for the six-man squad.
The hosts, which fielded in five teams in this world-ranking event which attracted 181 men boxers and 127 women pugilists, went on to bag four gold medals, the same number won by Azerbajian. Kazakhstan finished with two golds including Mirat and Ukraine had one.
Five other Team Philippines members —bantamweight Joan Tipon, lightweight Genebert Basadre, flyweight Warlito Parrenas, light welterweight Mark Jason Melligen and welterweight Reynaldo Galido — lost their bouts on hairline margins.
The participation of the team was made possible by Ginebra San Miguel, the First Gentleman Foundation and Pacific Heights.
It is a part of the Amateur Boxing Association of the Philippines (ABAP) eliminations for the composition of the RP team which will see action in The Manila Southeast Asian Games.