Abstract

Microbiologically influenced corrosion (MIC) of steel, primarily driven by bacterial activity, poses significant challenges across industrial environments. This study aimed to determine the phytochemical components present in extracts of Ocimum gratissimum (African Basil) and Chromolaena odorata (Siam weed) that could potentially inhibit bacteria associated with steel corrosion. Fresh leaves of both plants were harvested, authenticated, and subjected to extraction using ethanol and distilled water to obtain four distinct extracts: OGEE (O. gratissimum ethanol extract), OGAE (O. gratissimum aqueous extract), COEE (C. odorata ethanol extract), and COAE (C. odorata aqueous extract). The phytochemical profiles were analyzed using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS). Results revealed that the ethanol extracts contained markedly higher concentrations of key bioactive compounds. OGEE exhibited the highest levels of alkaloids (13.6 mg/g), glycosides (9.4 mg/g), flavonoids (17.3 mg/g), and phenolics (21.8 mg/g), followed by COEE, while the aqueous extracts displayed significantly lower concentrations but higher total amino acid contents. The moderate presence of tannins and oxalates in ethanol extracts further underscores their potential antimicrobial relevance. These findings suggest that especially the ethanol extracts of O. gratissimum and C. odorata are rich in phytochemicals known for their antimicrobial and antioxidant activities, indicating their promise as natural inhibitors against bacteria that accelerate steel corrosion. This study highlights the need for subsequent investigations to assess the direct anti-MIC efficacy of these extracts and to explore their applicability as eco-friendly alternatives to synthetic corrosion inhibitors.