Correlation Between Acetogenin Content and Antiproliferative Activity of Pawpaw (Asimina triloba [L.] Dunal) Fruit Pulp Grown in Korea

The growth-inhibitory effects of pawpaw (Asimina triloba [L.] Dunal) roots, twigs, leaves, and fruit against human gastric (AGS) and cervical (HeLa) cancer cells and their anti-inflammatory activities

BACKGROUND

The pawpaw tree has several beneficial effects. However, no studies have been conducted to address the mechanisms underlying the cytotoxic effects of pawpaw extracts against cancer cells, and no study has investigated the anti-inflammatory effects. Hence, in this study, the growth-inhibitory effects of pawpaw (Asimina triloba [L.] Dunal) extracts against gastric (AGS) and cervical (HeLa) cancer cells and the inhibitory effects of pawpaw extracts against inflammatory factors (NO, TNF-α, IL-6, iNOS, and COX-2) were investigated.

METHODS AND RESULTS

The viability of AGS and HeLa cells, the analysis of cell cycle, and the expression of apoptosis marker protein were determined using MTT assay, FACS, western blotting, and TUNEL assays. The inflammatory factors were determined using Griess method, ELISA assay kit, and RAW 264.7 cells. The IC₅₀ values of twig and unripe fruit extracts for AGS cells were 82.01 and 100.61 µg/mL, respectively. For HeLa cells, pawpaw twig extracts exhibited the strongest ability to inhibit cervical cancer cell growth (IC_{50 =} 97.73 µg/mL). Analysis of the cell cycle phase distribution and expression of the apoptosis regulatory proteins BCL-2, BAX, caspase-3, and PARP showed that pawpaw twig, root, and unripe fruit extracts induced Sub G1 cell cycle arrest and apoptosis of AGS and HeLa cells. In addition, the twig, root, and unripe fruit extracts of pawpaw effectively inhibited the inflammatory makers NO, TNF-α, IL-6, and iNOS. Particularly, the twig, root, and unripe fruit extracts at concentrations of 50 µg/mL exhibited > 50% inhibition of TNF-α.

CONCLUSIONS

These findings indicate that pawpaw extracts are natural therapeutic agents that may be used for the prevention and treatment of gastric and cervical cancers, and encourage further studies on the anti-inflammatory potential of the pawpaw tree.

Phenolic Profiles, Antioxidant and Antimicrobial Activities of Pawpaw Pulp (Asimina triloba [L.] Dunal) at Different Ripening Stages

In this study, the phenolic components, as well as the antioxidant and antimicrobial activities, of the ripe and unripe fruit of pawpaw (Asimina triloba [L.] Dunal) extracted using five different solvents (distilled water, 95% methanol, 80% methanol, 95% ethanol, and 80% ethanol) were analyzed. The total phenolic content and total flavonoid content were the highest in the 95% ethanol (149.50 mg CAE/g) and 80% ethanol (5.62 mg RE/g) extracts of the unripe fruit, respectively. Analysis of 17 phenolic compounds in pawpaw extracts revealed that epigallocatechin, epicatechin, and p-coumaric acid were the as major compounds, and the amounts of all components significantly decreased with the ripening (P < 0.05). In all antioxidant assays, the 95% ethanol extract of the unripe fruit showed the highest antioxidant activity (EC₅₀ 0.22 to 0.93 mg/mL). The pawpaw extracts were more sensitive against Corynebacterium xerosis and Clostridium perfringens. In particular, the 95% ethanol extract of the ripe fruit notably inhibited C. xerosis growth, with minimum inhibitory concentration of 1.56 mg/mL. These results showed that the unripe fruit of pawpaw has abundant phenolic compounds and superior antioxidant activity, and that the 95% ethanol extract of the ripe fruit shows strong inhibitory activity against various microorganisms. Therefore, pawpaw fruit can be utilized as an attractive source of nutrients and therapeutic agents. PRACTICAL APPLICATION: In this study, we identified that the unripe fruit of pawpaw is rich in phenolic compounds and shows strong antioxidant activities. The 95% ethanol extract of the ripe fruit showed strong high inhibitory effect against various microorganisms. These results suggest that pawpaw fruit can serve as a source of antioxidants and delay the aging process. In addition, the fruit could also potentially be utilized as a potential antimicrobial agent.