Phytochemical Constituents of Indonesian Adlay (Coix lacrima-jobi L.) and Their Potential as Antioxidants and Crop Protection Agents

Adlay (Coix lacryma-jobi L.) is a cereal crop that has traditionally been used for medicinal purposes. It is processed into nutritious food in China and Southeast Asian countries. This study assesses the phytochemical constituents of this plant and their potential as antioxidants and crop protection agents. The methanolic extracts from seeds of Indonesian adlay (C. lacryma-jobi) varieties including Agrotis, Ma-yuen, and Aquatic, were tested against 2,2-diphnyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) to determine their free radical scavenging activity. The relationship between extraction solvents, phytochemical composition, and antioxidant activity was analyzed statistically using principal component analysis (PCA) to classify them based on the similarities among the components. The potential use of the phytochemicals as crop protection agents was also explored through a review of the literature. The Agrotis variety demonstrated the highest antioxidant activities (IC50 DPPH = 741.49 and ABTS =152.69 µg/mL). The ethyl acetate fraction of this variety showed the greatest antioxidant activity (IC50 DPPH and ABTS = 106.34 and 17.62 µg/mL, respectively), total phenolic content (275.16 mg GAE/g extract), and flavonoid content (37.41 mg QE/g extract). Fatty acids (FAs) and fatty acid methyl esters (FAMEs) accounted for 47.71 ± 0.02 and 41.73 ± 0.04%, respectively, and they were the major components of the extracts. The principal component analysis (PCA) revealed three different groups of phytochemical components in the seeds of Agrotis variety, including fatty acid methyl esters (FAMEs), such as methyl linoleate, methyl stearate, methyl vaccinates, and methyl palmitate, and fatty acids (FAs), including 7-hexadecanoid acid, bovinic acid, and 15-hydroxipentadecanoic acid. The final phytochemical group consisted of minor components, including uncategorized compounds such as decamethyl-tetrasiloxane and cycloalkenes. This study highlights the fact that C. lacrima-jobi is a promising source of natural antioxidants and agrochemicals.