Structure–Activity Relationship (SAR), Phytochemical Profiling, and Structural Characterization of Ethanolic Extracts and Oils from Black Seed, Baobab Seed, and Neem Seed
Aliyu Shehu
Okunola Oluwole Joshua
Uduma A. Uduma
Abstract
This study investigates the phytochemical composition, Physicochemical Liquid Chromatography Mass Spectrometry/Gas Chromatography Mass Spectrometry characterization, and structure–activity relationships (SAR) of bioactive compounds in ethanolic extracts and seed oils of Azadirachta indica (neem), Nigella sativa (black seed), and Adansonia digitata (baobab) and physicochemical parameters of the seed oils. Phytochemical screening revealed the presence of flavonoids, phenolics, tannins, glycosides, and stilbenoids. Black seed extract exhibited the highest concentration of phenolics and tannins, while neem extract contained all identified phytochemical classes, including stilbenoids. LC-MS analysis of the plant materials confirmed compounds such as dihydroquercetin, sinapic acid, polydatin, and malic acid corroborating the screening results. GC-MS profiling revealed 63 compounds in neem seed oil, 45 in black seed oil, and 44 in baobab seed oil. Neem oil was rich in azadirachtin, nimbin, gedunin, β-sitosterol, linoleic acid, and palmitic acid, known for antioxidant, antimicrobial, and anti-inflammatory properties. Black seed and baobab oils contained thymoquinone, carvacrol, tocopherols, sterols, 2,4-decadienal, and 2-pentylfuran also linked to therapeutic effects. SAR analysis connected these compounds to biological activities via mechanisms including radical scavenging, membrane disruption, and enzyme inhibition. Physicochemical analysis showed oil yields of neem (37.0 ± 2%), baobab (28.0 ± 2%), and black seed (24.0 ± 2%), alongside significant variations in saponification, iodine, and peroxide values. This multi-analytical approach highlights the chemical diversity and pharmacological potential of these underutilized seeds. The integration of SAR-based validation with LC-MS/GC-MS profiling enhances understanding of their bioactivity, supporting applications in cosmetic, nutraceutical, and pharmaceutical formulations.
References