# adding fake symbol so last word works as well
st = "asd)ae aef e'e'e'e asdasd".lower() + "#"

first_pos = None
words = []
alphabet = "qwertyuiopasdfghjklzxcvbnm"

# iterating through symbols in string
for i, ch in enumerate(st):
    if ch in alphabet and first_pos is None:
        # memorising first symbol of word
        first_pos = i
    if ch not in alphabet and first_pos is not None:
        # appending word
        words.append(st[first_pos:i])
        # forgetting first symbol of word
        first_pos = None
print(words)