Comparative evaluation of methanolic extracts from black pepper varieties: yield, GC-MS characterization, and antioxidant and antibacterial activities.

One of the most commonly used culinary spices, black pepper (Piper nigrum L.) is also a rich source of bioactive phytochemicals. The present study aims to investigate the oleoresin extracted from black and white pepper using a Soxhlet extraction system and describe its physicochemical characterization, GC-MS analysis, and antioxidant and antibacterial activity evaluation. The antioxidant capacity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay, and the antibacterial activity was determined by the agar well diffusion method. The extract had the highest antibacterial activity against Gram-positive Bacillus subtilis, with zones of 20 mm and 16 mm for black and white pepper extracts, respectively. The antioxidant activity of both extracts was found to be high, with DPPH radical scavenging activities of 86.80% for black pepper extract and 87.62% for white pepper extract. The oleoresin yield was 4.2% for black pepper and 3.2% for white pepper. GC-MS analysis showed a variety of phytochemical constituents such as alkaloids, terpenoids, fatty acids, and sterols. Major alkaloids of black pepper were found as piperine (8.54%) and yohimbine (12.27%), while the sterols were the most abundant class of compounds present in white pepper (28.67%). The total alkaloids present in the oleoresins of black pepper and white pepper were approximately 35%. This indicated that the oleoresins may serve as a natural source of biologically active compounds.