Acute toxicity of palm oil mill effluent on zebrafish (Danio rerio Hamilton-Buchanan, 1822): Growth performance, behavioral responses and histopathological lesions

Evaluating the toxicity of Palm Oil Mill Effluent (POME) is critical as part of the effort to develop waste management regulations for the palm oil industry. In this study, we investigated the acute toxicity of POME on growth performance, behavioral response, and histopathology of gill and liver tissues of zebrafish (Danio rerio). In total, 550 adult male zebrafish were used for the toxicity experiment including range finding test, acute toxicity test, growth performance and behaviour test. Static non-renewal acute toxicity bioassays were conducted by exposing fish to POME (1.584-9.968 mL/L) for 96 h. Growth performance, behavior response, and histopathological lesions in untreated and POME treated (96-h LC50: 5.156 mL/L) fish were measured at 24, 48, 72 and 96 h. Time-dependent significant decline in body length and body weight of POME-exposed zebrafish was observed. Furthermore, several behavioral changes were recorded, including hyperactivity, loss of balance, excessive mucus secretion, and depigmentation. Decreasing operculum movement and oxygen consumption rate as well as alterations in gill tissues (i.e. hyperplasia, hypertrophy, hemorrhage, and necrosis) of POME-exposed zebrafish were observed, suggesting a dysfunction in respiratory performance. On the other hand, liver tissue alterations (congestion, hemorrhage, hyperplasia, shrinkage of hepatocytes, hydrophilic degeneration, and necrosis) indicated a disruption in detoxification performance. We conclude that exposure to POME at acute concentration caused histopathological lesions both in gill and liver tissue along with changes in fish behaviors which disrupted respiratory and detoxification performance, resulting in mortality and reduced growth of zebrafish. These findings might provide valuable information for guiding POME management and regulation.

In vivo Toxicity Assessment of Refined Red Palm-pressed Mesocarp Olein in Sprague-Dawley Rats

Refined red palm-pressed mesocarp olein (PPMO) is recovered from palm-pressed mesocarp fiber, which is a by-product from palm oil mill. Its utilization in food industry is extremely limited even though it contains various phytonutrients. Thus, this study aimed to evaluate its toxicity effects by using the male Sprague-Dawley rat model. The rats were administered with a single dose of 2 g/kg PPMO in an acute toxicity study while administered with 2, 1, or 0.5 g/kg PPMO daily for 28 days in a sub-chronic toxicity study. The mortality, oral LD50 value, clinical observation, body and organ weight, hematological and biochemical analyses, pathological and histopathological examinations were assessed. The overall outcomes indicated that PPMO is non-toxic up to 2 g/kg and considered safe to be used in food application, especially as functional food ingredient and supplement attributed to its phytonutrients. Besides, this study provides an insight in alternative utilization of the wastes from palm oil mill.

Biological safety of Syagrus coronata (Mart.) Becc. Fixed oil: Cytotoxicity, acute oral toxicity, and genotoxicity studies

ETHNOPHARMACOLOGICAL RELEVANCE

Syagrus coronata, popularly known as licuri, is a palm native to caatingas. The fixed oil extract of licuri nuts is used by the population of Northeast Brazil for therapeutic purposes, including as an antifungal, anti-inflammatory, and a cicatrizant agent. However, there is no scientific information on the possible harmful health effects of the oil and hence its medicinal usability is unknown.

AIM OF THE STUDY

We aimed to analyze the biological safety and possible antioxidant activity of fixed S. Coronata oil.

MATERIALS AND METHODS

Chemical analysis of the oil was performed using gas chromatography with flame ionization detection (CG-FID). The cytotoxicity of varying concentrations of the oil (12.5, 25, 50, 100, and 200 μg/mL) was evaluated using the tetrazolium reduction assay in three cell lines: HEK-293 kidney embryonic cells, J774.A1 macrophages, and the tumor line Sarcoma-180 (S-180). Oral toxicity, genotoxicity, and mutagenicity tests were performed in mice which were administered a single dose of 2000 mg/kg of fixed licuri oil, by gavage. For acute toxicity tests, changes in blood and biochemical parameters, behavior, and weight were analyzed; histomorphometric analyses of the liver, kidney, and spleen were also performed. The comet assay and micronucleus (MN) test were performed to analyze genotoxicity. The antioxidant potential was assessed by the total antioxidant capacity (AAT) and DPPH elimination activity.

RESULTS

Licuri oil consists predominantly of saturated fatty acids, and lauric acid is the major compound. The highest concentrations of the oil showed low levels of cytotoxicity; however, LC50 was not reached in any of the tests. The acute toxicity study did not reveal any evidence of adverse effects in animals treated with oil; biochemical investigation of blood showed a decrease in blood concentration of total proteins and uric acid. The kidneys, spleen, and liver showed no morphological changes indicative of a pathological process. Genotoxic or mutagenic activity was not detected through both the comet assay and MN test. In addition, the oil showed low antioxidant activity in both methods.

CONCLUSION

Licuri oil from the stem of S. coronata did not present significant toxic effects as well as absence of genetic damage when administered orally. Future studies are needed to investigate its pharmacological potential.

Dose-response analysis of toxic effect from palm oil mill effluent (POME) by-products on biohydrogen producing bacteria - A preliminary study on microbial density and determination of EC50

The stimulant and toxicity effects of reported organic (acetic acid, propionic acid, butyric acid, formic acid, oil & grease) and inorganic (copper) by-products presented in palm oil mill effluent on anaerobic bacterial population were examined in this paper. The toxicity test had shown that acetic, propionic and butyric acids tend to stimulate the bacterial density level (survival rate more than 50%), while formic acid, copper, oil and grease were shown to have suppressed the density level (survival rate less than 50%). The highest biomass recorded was 1.66 mg/L for the concentration of acetic acid at 216 mg/L and lowest biomass concentration, 0.90 mg/L for copper at 1.40 mg/L. Biohydrogen-producing bacteria have a favourable growth rate around pH 5.5. The comparison of half maximal effective concentration (EC₅₀) values between two test duration on the effects of organic and inorganic by-products postulate that bacteria had a higher tolerance towards volatile fatty acids. While acetic, butyric and propionic acids had exhibited higher tolerance EC₅₀ values for bacteria, but the opposite trend was observed for formic acid, copper and oil & grease.

Acute and Subchronic Oral Toxicity of Oil Palm Puree in Sprague-Dawley Rats

Palm puree is rich in antioxidants and is produced via blending various proportions of mesocarp fibre and crude palm oil. The aim of this study was to assess the acute and subchronic toxicity of palm puree in male and female Sprague–Dawley rats. For the acute toxicity study, animals administered single palm-puree doses (2000 mg kg⁻¹) by gavage were observed daily for 14 d. For the subchronic toxicity study, the rats were administered 500, 1000, or 2000 mg kg⁻¹ palm puree daily for 28 d. We evaluated body and organ weights; performed haematological, biochemical, and histopathological analyses of blood and organ samples during and after treatment; and calculated the oral no-observed-adverse-effect level (NOAEL). The toxicity studies showed no signs of toxicity or mortality. The haematological, biochemical, and histopathological analyses and body and organ weights indicated no evidence of substantial toxicity at any dose of palm puree. The oral lethal dose and NOAEL for the palm puree were greater than 2000 mg kg⁻¹ d⁻¹ over 28 d. To the best of our knowledge, the present study is the first to confirm the safety of palm puree as a novel functional food. These encouraging results warrant further studies to elucidate its potential for pharmaceutical formulations.