T-SQL (SS2K8) :: First Occurrence Of The String From Text

I have text column .I want to find out first occurance of string based on logic.I defiend Text with examples and also mentioned expected result.I coloured the text in word document,due to some reasons not displaying same here.Attached as image below texts to understand more clear.

TEXT 1: 'ABNAGENDRACSURENDRADJITHENDRAXNARENDRABVEERNDARAXDRMNDRAXRVINDRABNAGENDRACSURENDRADJITHEN'

From the above text1, I want to get “AXNARENDR”.

Based on logic defined below:

First I have to search for string “A” Then next to ‘A’ it should not be “B” or “C” or “D”.It can be anything other thing these three.Combination of “A” otherthan “B” or “C” or “D”

In the example text I defined “A”,”X” defined three times .I want to capture few characters from the first occurrence of the string

i.e AXNARENDR (TEXT1 I defined “A” with 4th occur

TEXT 2:

'ABNAGENDRACSURENDRADJITHENDRABNAGENDRACSURENDRADJITHENABNAGENDRACSURENDRADJITHENABN
AGENDRACSURENDRADJITHENAYENDGHRABVEERNDARAXDRMNDRABNAGENDRACSURENDRADJITHENAYRVINDR'

From the above text2, I want to get “AYENDGHR”.

TEXT 3:

'ABNAGENDRACSURENDRADJITHENDRABNAGENDRACSURENDRADJITHENABNAGENDRACSURENDRADJITHENABNAGENDRACSURENDR
ADJITHENABNAGENDRACSURENDRADJITHENDRABNAGENDRACSURENDRADJITHENABNAGENDRACSURENDR
ADJITHENABNAGENDRACSURENDRADJITHABNAGENDRACSURENDRADJITHENDRABNAGENDRACSURENDRADJITHEN
ABNAGENDRACSURENDRADJITHENABNAGENDRACSURENDRADJITHAZENIVKHRABVEERNDARAXDRMNDRAYRVINDR AZNHKLMN'

From the above text3, I want to get “AZENIVKHR”.