Evaluation of bioactive compounds, antioxidant capacity and mineral elements in the leaves of guava (Psidium guajava L.) genotypes from China

Guava (Psidium guajava L.) is a medicinal tree species and its leaves are rich in beneficial bioactive compounds with antioxidant capacity. China has the second-largest planting area in the world however a comprehensive evaluation of the antioxidant capacity of guava genotypes in China has not yet been conducted yet. To identify the desirable genotypes with the greatest antioxidant capacity, 18 guava genotypes widely cultivated in China were collected in a germplasm garden. In this study, the antioxidant capacity, bioactive compound contents and mineral element contents of guava leaves were assessed. Genotypic variation was observed for antioxidant capacity, bioactive compound contents and mineral element contents in guava leaves. The bioactive compound contents were all significantly and positively correlated with the antioxidant capacity in guava leaves. Correlation analysis indicated that the total phenolic total triterpenoid contents were significantly related to the total phosphorus content. Principal component analysis and cluster analysis showed that DW was superior in antioxidant capacity (radical scavenging abilities of DPPH and ABTS) and total phenolic, total flavonoid and total triterpenoid contents, and the medicinal quality of superior guava genotypes was regulated by the leaf mineral element contents, especially phosphorus. This study is not only helpful for developing guava genotypes with superior medicinal quality in the future but can also provide theoretical support for fertilization management in the cultivation of superior guava genotypes to achieve higher medicinal quality.