Phenolic profile and α-glucosidase inhibitory potential of wampee (Clausena lansium (Lour.) Skeels) peel and pulp: In vitro digestion/in silico evaluations.

To investigate the changes in phenolics, flavonoids, and their bio-activities of wampee (Clausena lansium (Lour.) Skeels) during digestion, the peel and pulp were subjected to simulated in vitro digestion, encompassing oral, gastric, small intestine, and large intestine digestion stages. The peel exhibited a total release of 91.93 mg GAE/g DW of phenolics and 61.86 mg RE/g DW of flavonoids, whereas the pulp displayed a release of 27.83 mg GAE/g DW of phenolics and 8.94 mg RE/g DW of flavonoids. Notably, the phenolics and flavonoids were mostly released during the oral digestion stage for peel, while they were mostly released during the small intestine digestion stage for pulp. The results of the targeted flavonoids analysis indicated that rutin and l-epicatechin were the two most widely released compounds in each digestion step. Moreover, myricetin has been identified as the best inhibitor against α-glucosidase, probably because it formed the most H-bonds, 8, with 6 catalytic residues, which was the highest number. Furthermore, the soluble substances released from the peel exhibited significantly higher antioxidant activities and inhibitory activity against α-glucosidase (p < 0.05) compared to those from the pulp. Positive correlations were observed between the total phenolic content or total flavonoid content and the antioxidant activities (r > 0.73 (peel), > 0.61 (pulp)), as well as α-glucosidase inhibitory activity (r <  - 0.48 (peel), < -0.64 (pulp)) of peel and pulp. In conclusion, these findings provide valuable insights into the digestive characteristics and health benefits of both wampee peel and pulp.

Comprehensive evaluation of aroma and taste properties of different parts from the wampee fruit.

Wampee is a tropical fruit having high medicinal value. To fully realize the fruit's potential, it is essential to reveal the flavor characteristics. In this study, a comprehensive analysis of the aroma and taste profiles of different parts from the wampee fruit was conducted. The aroma profile was analyzed by E-nose, and 67 volatile components were identified through HS-SPME-GC-MS. Among them, 11 were considered as crucial compounds. Additionally, 42 volatile components were identified by HS-GC-IMS, with 22 compounds showing a variable importance in projection scores greater than 1.0. Moreover, the taste profile and representative compounds were analyzed by E-tongue and HPLC, and 12 compounds were considered as important taste contributors based on taste activity value. These findings shed light on the various compounds responsible for the unique aroma and taste of the wampee fruit, providing theoretical foundation for exploring ways for its comprehensive utilization and development.

Free, Conjugated, and Bound Phenolics in Peel and Pulp from Four Wampee Varieties: Relationship between Phenolic Composition and Bio-Activities by Multivariate Analysis.

Free, conjugated, and bound phenolic fractions of peel and pulp in four wampee varieties from South China were analyzed for their contents, composition, antioxidant capacities, and inhibitory activities against α-glucosidase. We found that there were significant differences in phenolic/flavonoid contents among diverse varieties and different parts (peel and pulp), and the contents were highest in the peel's bound form. The results of UHPL-Q-Exactive HF-X and HPLC showed that chlorogenic acid, gentisic acid, and rutin were abundantly distributed over the three phenolic fractions in peel and pulp of all wampee samples, while isoquercitrin was the most abundant in the conjugated form of peel/pulp and myricetin had the richest content in the free form of peel/pulp. Wampee peel had stronger antioxidant capacities of ABTS+, DPPH, ·OH, and FRAP than the pulp, and the bound phenolic fraction of the peel/pulp had much higher antioxidant activities than FP and CP fractions. It is interesting that the same phenolic fraction of the wampee peel displayed roughly close IC50 values of α-glucosidase inhibition to those from the pulp samples. The relationship between individual phenolic and TPC/TFC/the bio-activities and the similarity among the free, conjugated, and bound phenolic fractions in peel and pulp samples were explored by using Pearson correlation analysis, principal component analysis, and hierarchical cluster analysis. This work provides a systematic and comprehensive comparison of the three phenolic fractions of diverse wampee varieties and different parts, and a rationale for applying phenolics from wampee fruits.