[Python] How can I remove the bracekts and parentheses in the end of words?

although I've read a lot of similar questions here, I couldn't find the absolute solution.
My task is to parse the protein names by removing the brackets and parentheses in the row.
In short, I want to retain the words in front of any parentheses and brackets.
But note that I need to keep symbols in the main words like H(+)/Cl(-) exchange transporter 6.

data = {
"Entry": ["A0A087X1C5", "A0A0B4J2F0", "O00468", "P51797", "O75164"],
"Reviewed": ["reviewed"] * 5,
"Entry Name": ["CP2D7_HUMAN", "PIOS1_HUMAN", "AGRIN_HUMAN", "CLCN6_HUMAN", "KDM4A_HUMAN"],
"Protein names": [
"Putative cytochrome P450 2D7 (EC 1.14.14.1)",
"Protein PIGBOS1 (PIGB opposite strand protein 1)",
"Agrin [Cleaved into: Agrin N-terminal 110 kDa subunit; Agrin C-terminal 110 kDa subunit; Agrin C-terminal 90 kDa fragment (C90); Agrin C-terminal 22 kDa fragment (C22)]",
"H(+)/Cl(-) exchange transporter 6 (Chloride channel protein 6) (ClC-6) (Chloride transport protein 6)",
"Lysine-specific demethylase 4A (EC 1.14.11.66) (EC 1.14.11.69) (JmjC domain-containing histone demethylation protein 3A) (Jumonji domain-containing protein 2A) ([histone H3]-trimethyl-L-lysine(36) demethylase 4A) ([histone H3]-trimethyl-L-lysine(9) demethylase 4A)"
],
"Gene Names": ["CYP2D7", "PIGBOS1", "AGRN AGRIN", "CLCN6 KIAA0046", "KDM4A JHDM3A JMJD2 JMJD2A KIAA0677"],
"Length": [515, 54, 2068, 869, 1064],
"STRING": [None, "9606.ENSP00000484893", "9606.ENSP00000368678", "9606.ENSP00000234488", "9606.ENSP00000361473"]
}

# Load into DataFrame
df = pd.DataFrame(data)


result = {
"Entry": ["A0A087X1C5", "A0A0B4J2F0", "O00468", "P51797", "O75164"],
"Reviewed": ["reviewed"] * 5,
"Entry Name": ["CP2D7_HUMAN", "PIOS1_HUMAN", "AGRIN_HUMAN", "CLCN6_HUMAN", "KDM4A_HUMAN"],
"Protein names": [
"Putative cytochrome P450 2D7",
"Protein PIGBOS1",
"Agrin",
"H(+)/Cl(-) exchange transporter 6",
"Lysine-specific demethylase 4A"
],
"Gene Names": ["CYP2D7", "PIGBOS1", "AGRN AGRIN", "CLCN6 KIAA0046", "KDM4A JHDM3A JMJD2 JMJD2A KIAA0677"],
"Length": [515, 54, 2068, 869, 1064],
"STRING": [None, "9606.ENSP00000484893", "9606.ENSP00000368678", "9606.ENSP00000234488", "9606.ENSP00000361473"]
}

# Expected result
result_df = pd.DataFrame(result)


When I tried the first approach, it removed all parentheses and brackets without considering the intermediate symbols.

df['Protein names'] = df["Protein names"].str.replace(r'\s*(\(|\[).*?(\)|\])\s*$', '', regex=True).str.strip()

# Before
# H(+)/Cl(-) exchange transporter 6 (Chloride channel protein 6) (ClC-6) (Chloride transport protein 6)
# After
# H


Also, I tried the step-by-step process using the second code, but it removed the intermediate symbols, too.

df["Protein names"] = df["Protein names"].str.split(' \(').str[0].str.strip()
df["Protein names"] = df["Protein names"].str.split(' \[').str[0].str.strip()

# Before
# Very-long-chain (3R)-3-hydroxyacyl-CoA dehydratase 1 (EC 4.2.1.134) (3-hydroxyacyl-CoA dehydratase 1) (HACD1) (Cementum-attachment protein) (CAP) (Protein-tyrosine phosphatase-like member A)
# After
# Very-long-chain


Thank you for reading this long question.
I'm looking forward to your tips.

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