Quantification of Carpaine and Antioxidant Properties of Extracts from Carica Papaya Plant Leaves and Stalks

Significance increase in dengue cases have been recorded worldwide every year and South East Asian countries have been badly affected. Currently, antiviral drug to treat dengue is still not available but papaya leaves extract (PLE) have been successfully used in treating dengue patients. Carpaine in PLE is the major active compounds that contributes to the anti-thrombocytopenic activity (raising platelet count in patient's blood). The PLE also contains polyphenols that contribute to antioxidant properties. Studies were carried out to extract and quantify carpaine from young leaves, old leaves and stalks of papaya plant. Carpaine crystalline powders were successfully purified and confirmed by 1H and 13C NMR (Nuclear Magnetic Resonance). Young papaya leaves recorded significantly higher amount of carpaine (P < 0.05) as compared with old leaves and stalks. Blending treatment showed significant effect (P < 0.05) on the amount of carpaine extracted from the young and old leaves and blended young leaves showed significantly much higher amount of carpaine as compared with the unblended samples (P < 0.05). In terms of total polyphenols content (TPC), young leaves (both unblended and blended samples) contained significantly higher amount of TPC (P < 0.05) followed by the old leaves and stalks. Results also showed relationship between the TPC and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay scavenging activities namely IC50 (R2 = 0.9743) and acid equivalent antioxidant capacity (AEAC) (R2 = 0.9581). Both young and old leaves also showed significantly higher (P < 0.05) DPPH scavenging activities as compared with the stalks in both unblended and blended samples. Young papaya leaves were recommended as source of material to extract carpaine for future development of drug in dengue treatment.