Eucalyptus ash alters secondary protein conformation of human grey hair and facilitates anthocyanin dyeing

PLoS One. 2018 Jul 2;13(7):e0199696. doi: 10.1371/journal.pone.0199696. eCollection 2018.


Wood ashes infused with water have been traditionally used as hair cosmetics, but little or no research has examined the effects of ash on human hair. This study investigated the effect of eucalyptus ash on the structure and morphology of excised human grey hair and its potential use as a pretreatment in natural hair dyeing using anthocyanins extracted from purple cops of Zea mays. Tensile characteristics and surface morphology of ash-pretreated hair was monitored by texture analysis, scanning electron microscopy and atomic force microscopy. The biochemical characteristics of ash-treated hair were analyzed by synchrotron radiation-FTIR and sulfur K-edge X-ray absorption near edge. Dyeing with anthocyanins was analyzed by Lab color scale and adsorption of anthocyanins. Ash-treated hair was elastically and plastically deformed with microscopic alterations to the ridges of the cuticle cells, similar to ammonia-treated hair. The ash extract significantly changed the relative proportion of alpha-helices in the cuticle and cortex layers (p < 0.05), but did not affect the interaction of S-bonds with neighboring atoms (p > 0.05). Ash-treated hair showed significantly enhanced adsorption of anthocyanins (p < 0.05) which changed the color of the grey hair. The alteration of secondary proteins in the cuticle and cortex layers of the grey hair by ash extract pre-treatment, enhanced anthocyanin adsorption. The eucalyptus ash could potentially be useful as a natural hair dyeing pre-treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthocyanins / chemistry*
  • Eucalyptus / chemistry*
  • Hair / chemistry*
  • Hair Color*
  • Hair Dyes / chemistry*
  • Humans
  • Protein Conformation
  • Proteins / chemistry*
  • Zea mays / chemistry*


  • Anthocyanins
  • Hair Dyes
  • Proteins

Grant support

The Thailand Research Fund (TRF) and Mama Herb (99), through the management of TRF, were the partial co-sponsors that provided support in the form of salaries for an author [KS] and materials, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. All authors had no personal contact with Mama Herb (99). The specific roles of these authors are articulated in the ‘author contributions’ section.