Ocimum gratissimum Essential oils Chemometric classification

This research focuses on the Multivariate Chemometric Classification of Ocimum gratissimum essential oils obtained from grasslands within three urban local government areas (LGAs) of Benin City Oredo, Egor, and Ovia north-east. The study aimed to determine the chemical variability and structural functional groups of O. gratissimum grown in different grassland environments and to understand how local environmental conditions influence the chemical profiles of the plant’s essential oils. The work involved plant collection, sample preparation, extraction of essential oils, analytical identification, and data interpretation. Fresh leaves of O. gratissimum were collected from uncontaminated bushy sites in the three LGAs, air dried for five days, oven-dried at 45°C for 30 minutes, blended, and stored in airtight brown bottles. Soxhlet extraction using analytical-grade n-hexane served to obtain the essential oils, which were then concentrated using a rotary evaporator. The extracts were analyzed using Gas Chromatography Mass Spectrometry (GCMS) and Fourier Transform Infrared Spectroscopy (FTIR). GCMS provided molecular identification and quantification of chemical compounds, while FTIR determined the functional groups present in the essential oils. Chemometric methods were employed to classify similarities and differences in the oils based on their chemical fingerprints across the study areas. A total of over forty compounds were detected across the three samples, with the most dominant being Decane (25.04%), Bis(2-ethylhexyl) phthalate (17.17%), and Thymol (12.65%), along with other bioactive components such as Caryophyllene, Squalene, Phytol, and several aromatic and aliphatic hydrocarbons. These compounds are known for their antimicrobial, anti-inflammatory, and antioxidant properties, indicating that O. gratissimum from all study sites retains medicinal relevance. Variations in compound concentrations were observed between locations, suggesting environmental or soilbased
influences on secondary metabolite biosynthesis. The FTIR results revealed prominent absorption peaks around 3350 cm⁻¹ (O–H), 2950 cm⁻¹ (C–H), and 1740 cm⁻¹ (C=O), indicating the presence of alcohols, alkanes, and esters common to essential oils
of Ocimum species. The results demonstrated that although the three O. gratissimum populations share core chemical identities, their quantitative differences are significant enough to allow chemometric differentiation