In Vitro Antioxidant, Anti-Platelet and Anti-Inflammatory Natural Extracts of Amphiphilic Bioactives from Organic...

Watermelon (Citrullus lanatus) processing generates substantial quantities of rind, seeds, and residual pulp that are typically discarded despite being rich in polyunsaturated fatty acids, polar lipids, carotenoids, and phenolic compounds. These amphiphilic bioactives are increasingly recognized for their roles in modulating oxidative stress, inflammation, and platelet activation; however, the lipid fraction of watermelon by-products remains insufficiently characterized. This study examined organic watermelon juice and its by-products to isolate, characterize, and evaluate extracts enriched in amphiphilic and lipophilic bioactives, with emphasis on their in vitro antioxidant, anti-inflammatory, and antithrombotic properties.

total lipids were extracted using a modified Bligh-Dyer method and fractionated into total amphiphilic compounds (TAC) and total lipophilic compounds (TLC) via counter-current distribution. Phenolic and carotenoid levels were quantified, and antioxidant capacity was assessed using DPPH, ABTS, and FRAP assays. Anti-platelet and anti-inflammatory activities were evaluated against ADP- and PAF-induced platelet aggregation. Structural characterization of polar lipids was performed using ATR-FTIR, and LC-MS was used to determine fatty acid composition and phospholipid structures.

Carotenoids were primarily concentrated in the TLC fractions with high ABTS values for antioxidant activity, while phenolics mostly in the juice, the TACs of which showed the strongest total antioxidant capacity based on DPPH. TAC fractions of both samples showed also higher FRAP values of antioxidant activity, likely due to greater phenolic content. TAC extracts also exhibited notable inhibition of PAF- and ADP-induced platelet aggregation, associated with their enriched ω-3 PUFA profiles and favorable ω-6/ω-3 ratios based on their LC-MS profiles.

Overall, watermelon products (juice) and by-products represent a valuable and sustainable source of amphiphilic bioactives with significant antioxidant, anti-inflammatory, and anti-platelet potential, supporting their future use in functional foods, nutraceuticals, and cosmetic applications.