Garcinia dulcis and Garcinia forbesii King fruit peel extract: Secondary metabolite composition, antioxidant, and elastase inhibitory activity evaluation

Garcinia dulcis and Garcinia forbesii King are native plants from Indonesia and have tremendous potential as a source of raw medicines based on local wisdom. However, scientific data for strengthening pharmaceuticals are still limited. Therefore, it is necessary to conduct a study to strengthen and develop the potential of both plants using the approach of traditional medicine. This study aimed to explore the secondary metabolite composition and biological activity (antioxidant and antielastase) of both plants. Both samples were extracted using 70% ethanol and microwave-assisted extraction with a microwave power of 120 watts for 15 min. The extract obtained was then screened for phytochemicals using specific reagents. The total phenolic content (TPC) was determined using spectrophotometry with a 96-well microplate reader method. The total flavonoid content (TFC) was determined using the colorimetric method, whereas metabolite profiling analysis was conducted using the UPLC-QToF-MS/MS system. Meanwhile, biological activity was tested for antioxidant activity and antielastase as measured by a microplate reader 96-well spectrophotometry method at specific wavelengths. According to the results, G. dulcis and G. forbesii fruit peel extracts showed positive detection of particular secondary metabolites. TPC and TFC values were 13.98 ± 1.90 mg GAE/g and 10.33 ± 1.90 mg QE/g for G. dulcis and 11.98 ± 2.04 mgGAE/g and 1.96 ± 0.36 mgQE/g for G. forbesii. Metabolite profiling detected some compounds from G. dulcis, including ephedrannin B, hinokiflavone, mahuannin J, and candidate mass C9H12O8, and G. forbesii, including 5-Hydroxy-7,8,2'- trimethoxyflavone, lucialdehyde B, candidate mass C21H39NO4, candidate mass C14H10O6, and candidate mass C14H12O6. Meanwhile, the biological activities (antioxidant and antielastase) were 137.721 μg/mL and 108.893 μg/mL for G. dulcis and 481.948 μg/mL and 250.611 μg/mL for G. forbesii, respectively. Both plants showed different profiles of secondary metabolites and biological activities (antioxidant and antielastase) according to their respective characteristics.