Dandruff is a dermatological, harmless, non-inflammatory, chronic scalp condition caused by Malassezia species and recognisable by the white flakes of dead skin in the hair. Mannosylerythritol lipids (MEL) are non-ionic glycolipid surfactants (biosurfactants) with excellent surface-active properties. Their skin compatibility, biocompatibility, biodegradability and remarkable antimicrobial properties make them a potential alternative to conventional surfactants. In the current study, an anti-dandruff shampoo was formulated with different concentrations of sodium lauryl sulphate (SLS) and MEL as surfactants. Two anti-dandruff agents, salicylic acid and benzoic acid, were used. The other ingredients used were xanthan gum, sodium EDTA, urea, Tween 80 and distilled water. The various physicochemical parameters evaluated were colour, clarity, odour, texture, pH, skin irritation, percentage of solid content, dispersibility for dirt, foam formation and foam stability, critical micelle concentration, washability, surface tension, visual stability and antimicrobial test using recommended procedures. The pH ranged from 5.15 to 6.5, the physical appearance was golden yellow, the solids content ranged from 25.1% to 28%, surface tension ranged from 30.64 mN m−1 to 38.00 mN m−1, CMC concentration ranged from 30.14 g/L to 30.16 g/L and foam value ranged from 190 mL to 105 mL. Antimicrobial activity was determined with Staphylococcus aureus (DSM 3463) and Malassezia furfur (ATCC14521). The zone of inhibition ranged from 10 mm to 17 mm (S. aureus) and 14.5 mm to 24 mm (M. furfur), respectively. The shampoo formulated with MEL only (formulation C) showed lower foaming and anti-dandruff activity than the synthetic shampoo (formulation A). However, the anti-dandruff activity increased when MEL was used in combination with SLS (formulation B). This shows that the antimicrobial properties of MEL and SLS together with other antimicrobial agents such as salicylic acid and benzoic acid enhance the properties of the shampoo. SLS can be completely replaced by a combination with biosurfactants to reduce the use of chemical surfactants and improve the anti-dandruff properties.
