In vitro antioxidant, anti-inflammatory and anticancer activities of ethyl acetate soluble proanthocyanidins of the inflorescence of Cocos nucifera L

Background: Proanthocyanidins belong to a class of polyphenolic compounds called flavonoids and have been reported to exhibit important biological activities. The immature inflorescence of Cocos nucifera L. is used by Ayurvedic and traditional medical practitioners for the treatment of menorrhagia in Sri Lanka. Our studies have shown that the inflorescence of Cocos nucifera L. predominantly contains proanthocyanidins.

Objective: To determine the antioxidant, anti-inflammatory and anticancer activities of ethyl acetate soluble proanthocyanidins (EASPA) of immature inflorescence of Cocos nucifera L.

Methods: EASPA fraction of an acetone/water (7:3) extract of Cocos nucifera L. inflorescence was purified on Sephadex LH-20 and was used for the study. Antioxidant activity of EASPA was determined using DPPH and SOR scavenging assays. Anti-inflammatory activity of EASPA was determined by oxidative burst assay using chemiluminescence technique. MTT colorimetric assay was used to evaluate the cytotoxicity of EASPA to both PC3 and HeLa cells.

Results: EASPA showed radical scavenging activity against both DPPH and superoxide radicals with IC50 values of 11.02 ± 0.60 μg/mL and 26.11 ± 0.72 μg/mL. In both assays, EASPA showed less antioxidant activity than the standards used. It exhibited similar anti-inflammatory activity (IC50 = 10.31 ± 1.11 μg/mL) to ibuprofen (IC50 = 11.20 ± 1.90 μg/mL) (P ≥ 0.05). EASPA also showed stronger cytotoxic activity towards Hela cells (IC50 = 18.78 ± 0.90 μg/mL) than tamoxifen (IC50 = 28.80 ± 1.94 μg/mL) (P ≤ 0.05), while low cytotoxicity was observed against PC3 cells (IC50 = 44.21 ± 0.73 μg/mL) compared to doxorubicin (IC50 = 1.38 ± 0.16 μg/mL).

Conclusion: EASPA showed antioxidant, anti-inflammatory and anticancer activities.