Antioxidant and toxicity tests of roasted noni (Morinda citrifolia) leaf infusion

Abstract

SummaryThe antioxidant properties and toxicity profile of roasted noni (Morinda citrifolia L.) leaf infusion were evaluated. The 2,2‐diphenylpicrylhydrazyl (DPPH) radical scavenging activity was greater than green tea infusion (81.6 ± 0.9% vs. 57.5 ± 1.8%, P < 0.001). The mean quercetin and kaempferol contents of roasted noni leaf infusion, as prepared by the consumer, were 0.24 ± 0.01 and 0.14 ± 0.01 μg mL−1, respectively. Tannic acid content was 10 ± 1 μg mL−1. The infusion was non‐mutagenic in the reverse mutation test in Salmonella typhimurium and did not induce primary DNA damage in E. coli PQ37. Further, no significant primary DNA damage was induced by 5,15‐dimethylmorindol, which was the only detectable anthraquinone in noni leaves. The infusion was not cytotoxic in the 24 h brine shrimp toxicity test (LC50 > 1 mg mL−1), nor was there any evidence of acute oral toxicity from the freeze–dried infusion in Sprague–Dawley rats (LD50 > 2000 mg kg−1 b.w.).