Lethal Concentration Determination of Fermented Carica papaya Leaf on Zebrafish (Danio rerio) Embryo Using Probit Regression with Arbitrary Slopes

Abstract Carica papaya Linn. (papaya plant) is a ubiquitous crop in tropical regions which is mainly harvested for its sweet-tasting fruit. Various parts of the papaya plant are used in folklore medicines to treat various ailments. This work presented the toxic and teratogenic effects of fermented Carica papaya leaf (CPL) on zebrafish (Danio rerio) embryos. The eggs from the spawning of the adult male and female zebrafish were collected and exposed to different concentrations of fermented CPL; 250, 125, 62.5, 31.25, 15.625 and 0 µg/ mL for six to 72 h post fertilisation (hpf). The survival and sublethal effects of these treatments on zebrafish embryos such as mortality and hatchability were calculated using microscopic observation while the heartbeat rate was measured using DanioScope. The toxic effects of fermented CPL on zebrafish embryos was found to be concentration dependent. The median lethal concentration (LC50) was 133.1 µg/mL as calculated from the probit-log (concentration) regression model using Microsoft Excel. This value fell into the category of less than toxic according to OECD guideline. The total flavonoid content (TFC) of the fermented CPL was also higher at the end of the fermentation as compared to onset of fermentation.