Bose plucked three vital wickets conceding 67 runs in 14 overs while Saha claimed 3 for 56. Skipper Badri top-scored for South with a patient 57.
With this loss, their second consecutive one, South Zone are out of contention for a place in the finals with the final league match between East Zone and North Zone from Feb 11 to 14 at Rajkot becoming a virtual semifinal.
Resuming on 113 for 3 a lot depended for South Zone on their captain Badrinath but Bose and Saha had other plans.
Badrinath in the company of Prasad Reddy (39 off 125 balls 7X4s) played safely thro' the first 11 overs in the morning adding a further 30 runs before Ranadeb Bose struck twice in one over to put East in command.
He first got the prize scalp of Badri caught by S S Das at slips to leave South Zone on 143 for 4. Badri made 57 off 125 balls inclusive of seven boundaries.
Two balls later, R Ashwin was back in the pavilion nibbling at a delivery outside the off stump to get a faint edge to give a regulation catch to keeper Haldar Das. Ashwin did not disturb the scorers and South were in trouble at 143 for five.
Swapnil Asnodkar (15) then joined Prasad Reddy and the two played patiently trying to rebuild the innings. The duo took the score to 171 when Bose struck again getting Asnodkar to play away from his body outside the off stump and the edge going to slips where S S Das made no mistake.
S S Paul then removed the last big resistance, when he ended the marathon vigil of Prasad Reddy for a caught behind to leave South on seven for 184. The end came when Palash Jyoti Das in his first over grabbed two wickets in four balls to seal a 68 run victory for East and oust South Zone from the tournament.
East Zone 313&163 beat South Zone 204&204 (Badri 57, Ravi Teja 53, Prasad Reddy 39; Ranadeb Bose 3 for 67, Tushar Saha 3 for 56) by 68 runs.