Pressurized Hot Water Extraction of Mangosteen Pericarp and Its Associated Molecular Signatures in Endothelial Cells

Abstract

The mangosteen (Garcinia mangostana L.) pericarp is known to be rich in potent bioactive phytochemical compounds such as xanthones, which possess pharmacologically important antioxidant activity and beneficial cardiometabolic properties. Mangosteen pericarp is typically classified as unavoidable food waste and discarded, despite being rich in bioactive phytochemical compounds that therefore present an exciting opportunity for valorization. Thus, this study aims to extract phytochemical compounds from mangosteen pericarp using pressurized hot water extraction (PHWE) and determine its biological effects in endothelial cells using RNA sequencing. Liquid chromatography with MS/MS (LC/MSMS) and UV detection (LC/UV) was subsequently used to identify three key phytochemical compounds extracted from the mangosteen pericarp: α-Mangostin, γ-Mangostin, and Gartanin. Within the tested range of extraction temperatures by PHWE, our results demonstrated that an extraction temperature of 120 °C yielded the highest concentrations of α-Mangostin, γ-Mangostin, and Gartanin with a concomitant improvement in antioxidant capacity compared to other extraction temperatures. Using global transcriptomic profiling and bioinformatic analysis, the treatment of endothelial cells with mangosteen pericarp extracts (120 °C PHWE) for 48 h caused 408 genes to be differentially expressed. Furthermore, our results demonstrated that key biological processes related to "steroid biosynthesis and metabolism", likely involving the activation of the AMPK signaling pathway, were upregulated by mangosteen pericarp extract treatment. In conclusion, our study suggests a green extraction method to valorize phytochemical compounds from mangosteen pericarp as a natural product with potential beneficial effects on cardiometabolic health.

Keywords: PHWE; antioxidant; food waste; green extraction; mangosteen pericarp; sustainability.

Figure 1

(A) PCA score plot (PC1 X PC2) of LC-UV profile at UV 254 nm of MPE obtained from the different PHWE temperatures (60 °C, 80 °C, 100 °C, 120 °C). LC/UV analysis of the amount of standard compounds, (B) γ-Mangostin, (C) α-Mangostin, and (D) Gartanin extracted from different PHWE temperatures. Each bar is represented by mean ± SEM, n = 5–6. * Significantly different to 60 °C extraction temperature, # Significantly different to 80 °C extraction temperature, p < 0.05, one-way ANOVA, Tukey’s post-hoc test.

Figure 2

Antioxidant activity of MPE obtained from different extraction conditions was evaluated using two different assays, (A,B) DPPH and (C) ABTS. (A) Concentration response curve of MPE and (B) inhibitory concentration (IC₅₀) value and (C) CEAC of MPE (0.1 mg/mL) obtained from different PHWE temperature. Each bar is represented by mean ± SEM, n = 3–4. * Significantly different to 60 °C extraction temperature, # Significantly different to 80 °C extraction temperature, Φ Significantly different to 100 °C extraction temperature, p < 0.05, one-way ANOVA, Tukey’s post-hoc test.

Figure 3

GO biological processes for the DEGs from transcriptomics profiling of HMEC-1 treated with MPE (0.05 mg/mL) for 48 h. (A) Enrichment Plot of the GO BPs that correspond to respective upregulated genes. Significant biological clusters were associated with “response to external stimulus” (blue), and “steroid biosynthesis and metabolism” (red). (B) Dot plot showing the number of significant genes upregulated by MPE at 48 h. The x-axis represents the fold enrichment, and the GO BPs are on the y-axis. The number of genes is indicated by the size of the circle and the −log10(FDR) is represented in different colors. DEG was identified using adjusted p-value < 0.05 and log₂FC ≥ = |0.4| criteria, n = 3.

Figure 4

KEGG pathways for the DEG from the transcriptomics profiling of HMEC-1 treated with MPE (0.05 mg/mL) for 48 h. (A) Dot plot showing the DEGs upregulated in the respective KEGG pathways by MPE (0.05 mg/mL) at 48 h. The x-axis represents the fold enrichment, and the KEGG pathways are on the y-axis. The number of genes is indicated by the size of the circle and the −log10(FDR) is represented in different colors. DEG was identified using adjusted p-value < 0.05 and log₂FC ≥ = |0.4| criteria, n = 3. (B) Upregulated DEGs corresponding to KEGG pathways are shown. The enrichment FDR, number of genes involved in the pathway, fold enrichment, KEGG pathway, and the genes found in the pathway are represented.

Figure 5

“Steroid biosynthesis” was an upregulated KEGG pathway for the transcriptomics profiling of HMEC-1 treated with MPE (0.05 mg/mL) for 48 h. Gene hits are highlighted in red (upregulated). DEG was identified using adjusted p-value < 0.05 and log₂FC ≥ = |0.4| criteria, n = 3.

Figure 6

“PPAR signaling pathway” was an upregulated KEGG pathway for the transcriptomics profiling of HMEC-1 treated with MPE (0.05 mg/mL) for 48 h. Gene hits are highlighted in red (upregulated). DEG was identified using adjusted p-value < 0.05 and log₂FC ≥ = |0.4| criteria, n = 3.