Bioactive Compounds of Fruit Parts of Three Eugenia uniflora Biotypes in Four Ripening Stages

Ripening stage impacts nutritional components, antiglycemic potential, digestibility and antioxidant properties of grumixama (Eugenia brasiliensis Lam.) fruit

This study aimed to determine the nutritional components (macronutrients ans minerals) and α-amylase inhibition capacity of freeze-dried grumixama (Eugenia brasiliensis Lam) seeds (S) and pulp/peel (P) portions, at ripe and mid-ripe stages. In vitro digestion was also performed on S and P from grumixama to assess the bioaccessibility of total phenolic compound (TPC), flavonoids (TFC), and anthocyanins (TAC), as well as to examine their impact on antioxidant activity (DPPH, ABTS, FRAP). The ripening process impacts the bioactive compounds and individual phenolics of S and P portions. The ripe S was source of myricetin and exhibited higher antioxidant activity, while mid-ripe S was high in flavonoids and cinnamic acid with higher antiglycemic potential. Ripe P showed higher soluble fiber, carbohydrate, TAC, and caffeic acid content, whereas mid-ripe P had increased mineral content (calcium, potassium, manganese), catechin, and TPC. After in vitro digestion, the P portion showed a bioaccessibility of total phenolic content (TPC) and total flavonoid content (TFC) exceeding 40% at intestinal phase. In contrast, the S portions had better release of TPC and TFC and antioxidant activity at gastric phase. Considering the outstanding nutritional and biological properties of grumixama fruit, freeze-dried S and P portions from both ripening stages possess could be explored as valuable sources of nutrients and antioxidant compounds.

Characterization of phenolic compounds in Eugenia uniflora leaves by ESI(-) FT-ICR MS, analysis of cytotoxic activity on gastric adenocarcinoma (AGS cells), and anti-Helicobacter pylori activity

Eugenia uniflora leaves are a source of flavonoids and ellagitannins, and the Brazilian population uses them to treat various diseases, including gastrointestinal disorders. This study aimed to determine if the ethanol extract and other derivatives are effective cytotoxic agents against gastric adenocarcinoma (AGS cells) and anti-H. pylori agent, its chemical composition, and mass spectrometry characterization of the more abundant compounds. The results were compared with the literature. The aqueous fraction, rich in Oenothein B and Gemin D/Hippomanin A, showed anti-H. pylori activity and higher cytotoxicity on AGS cells compared to the other samples analysed. Furthermore, the ESI(-) FT-ICR MS characterized the more abundant phenolic compounds, including Quinic Acid, Myricitrin, Gemin D/Hippomanin A, and Oenothein. Therefore, the activity of the ethanolic extract and aqueous fraction for gastric cancer and against H-pylori seems to originate from the antiproliferative and bacteriostatic effects of tannins and flavonoids.

New Hydrolyzable Tannin with Potent Antioxidant and α-Glucosidase Inhibitory Activity from Black Tea Produced from Camellia taliensis

Camellia taliensis (W. W. Smith) Melchior, belonging to the genus Camellia sect. Thea., is mainly distributed from northern Myanmar to western and southwestern Yunnan province of China, and its leaves have been used to make various teas by the locals of its growing regions. The chemical constituents of C. taliensis are significantly related to those of cultivated tea plants, C. sinensis and C. sinensis var. assamica. The HPLC-ESI-MS analysis of black tea prepared from the leaves of C. taliensis showed a rich existence of polyphenols. Further comprehensive chemical study led to the separation and recognition of 32 compounds (1-32), including one new hydrolyzable tannin, 1-O-galloyl-4,6-tetrahydroxydibenzofurandicarboxyl-β-D-glucopyranose (1), and one new natural product (24). The known compounds referred to seven hydrolyzable tannins (2-8), 10 flavonols and glycosides (9-18), and 14 simple phenolics (19-32). Their structures were elucidated by comprehensive spectroscopic analyses. Among them, 20 compounds (2, 3, 6, 7, 8, 15, 17, 18, 20-22, 24-32) were isolated from black tea for the first time. Most isolates displayed obvious antioxidant activities on DPPH and ABTS⁺ assays, and the hydrolyzable tannins 1, 3-5, 7, and 8 exhibited stronger inhibitory activities on α-glycosidase than quercetin and acarbose (IC₅₀ = 5.75 and 223.30 μM, respectively), with IC₅₀ values ranging from 0.67 to 2.01 μM.