Antioxidant Properties and Chemical Profile of Passiflora foetida Extracts Determined by ATR-FTIR Metabolomics

Abstract

Passiflora foetida, which is also known in Malaysia as "Pokok Ulat Bulu", is widely found on the roadsides and coastal areas. The plant is traditionally used for hysteria, insomnia, diarrhea, fever and inflammation skin disease treatments. Considering the systematic way to prepare the P. foetida as herbal medicine has not been studied, this project was aimed to evaluate the potential of P. foetida as a natural source of antioxidant by using a rapid ATR-FTIR metabolomics method. The plant extracts were prepared and studied based on different postharvest treatments (fresh and dry samples), different extraction methods (maceration and sonication), different ethanol ratios (100%, 80%, 50%, and water), and different parts (leaf, stem, and fruit). All samples were evaluated for their antioxidant activities and chemical profiles by using ATR-FTIR metabolomics. The ATR-FTIR analysis detected metabolites such as phenolics and flavonoids, which were showed by the presence of functional groups at 3379 cm-1 (OH group), 1713 cm-1 (C=O group), 1651 cm-1 (C=C group) and 1034 cm-1 (C-O alkoxy group). Antioxidant properties results showed that 80% ethanol extract of leaf significantly exerted higher TPC (22.55±3.49 mg GAE/g sample) and TFC (69.11±13 mg QE/ g sample) as compared to 80% ethanol extracts from the stem and fruit. However, there was no significant difference in the DPPH scavenging activity of the different parts. Based on ATR-FTIR metabolomics, three different parts of the plant were clearly separated from each other, indicating that different metabolites were presented in the leaf, stem, and fruit. This study also indicated that the sonication method resulted in more uniform extracts as compared to maceration and freeze dry was the suitable postharvest treatment for maintaining the quality of herb.