Safety and bioactivity assessment of aqueous extract of Thai Henna (Lawsonia inermis Linn.) Leaf

ABSTRACT

The worldwide demand for a natural dye by the cosmetic and food industry has recently gained interest. To provide scientific data supporting the usage of Thai henna leaf as a natural colorant, the phytochemical constituents, safety, and bioactivity of aqueous extract of the henna leaf by autoclave (HAE) and hot water (HHE) were determined. HAE contained a higher amount of total phenolic and flavonoid contents than HHE. The major constituents in both extracts were ferulic acid, gallic acid, and luteolin. The extracts displayed no marked mutagenic activity both in vitro and in vivo mammalian-like biotransformation. HAE and HHE also exhibited non-cytotoxicity to human immortalized keratinocyte cells (HaCaT), peripheral blood mononuclear cells (PBMCs), and murine macrophage RAW 264.7 cell line with IC₂₀ and IC₅₀ > 200 μg/ml. The extracts exhibited antioxidant and anti-inflammatory activity as evidenced by significant scavenging of ABTS and DPPH radicals and decreasing NO levels in LPS-induced RAW 264.7 cells. The antioxidant and anti-inflammatory properties of the extracts might be attributed to their phenolic and flavonoid contents. In conclusion, the traditional use of henna as a natural dye appears not to exert toxic effects and seems biosecure. Regarding safety, antioxidant, and anti-inflammatory properties, the aqueous extract of Thai henna leaf might thus serve as a readily available source for utilization in commercial health industries.

KEYWORDS:

• Thai henna
• Salmonella typhimurium
• Drosophila melanogaster
• antioxidant
• anti-inflammation

Acknowledgments

This work was supported by Faculty of Medicine Research Fund, Chiang Mai University, Thailand (Grant No. 088-2561). The authors gratefully thank Mrs. Jennifer Nguyen for proofreading and the Family Comes First Co., Ltd. (Bangkok, Thailand) for providing Thai henna leaf powder.

Author contributions

Khantamat, O. performed the experiments, analyzed the data, and prepared the manuscript; Dukaew, N. and Karinchai, J. performed the experiments; Pitchakarn, P., Chewonarin, T. and Temviriyanukul, P. participated in data analysis.

Disclosure statement

The authors declare no conflict of interest.

Ethical review

The Drosophila study was approved by Institute of Nutrition, Mahidol University-Institute Animal Care and Use Committee (INMU-IACUC) (COA. No. INMU-IACUC 2020/02).

Additional information

Funding

This work was supported by the Faculty of Medicine Research Fund, Chiang Mai University, Thailand [Grant No. 088-2561].