Histatins (HTNs) is a family of small histidine-rich peptides (18-28 mol%) that present in the saliva and secreted by parotid, sub-mandibular and sub-lingual salivary glands (Oppenheim FG et al. 1988; Troxler RF 1990; Gornowicz A et al. 2014). The members of HTN family are structurally related peptides of which histatin 1 and 3 are full-length proteins encoded by closely related loci of two distinct genes, HTN1 and HTN3 (Oppenheim FG et al. 1988; Troxler RF 1990; Sabatini LM et al 1993). The smaller peptides are generated by proteolytic cleavage of parent HTN1 and HTN3 proteins by salivary proteases during secretion (Troxler RF 1990; Castagnola M et al. 2004).
HTNs exhibited antibacterial activity in vitro against various bacteria, including S. mutans, P. gingivalis, A. actinomycetemcomitans, P. aeruginosa and St. aureus (MacKay BJ et al. 1984; Murakami Y et al. 1991; Payne JB et al. 1991; Nishikata MH et al. 1991; Sajjan US et al. 2001; Murakami Y et al. 2002; Giacometti A et al. 2005; Welling MM et al. 2007). HTNs were also active against complex mixtures of bacteria, such as those present in saliva and plaque (Helmerhorst EJ et al. 1999). The antibacterial activity of HTNs is thought to rely on electrostatic interactions of cationic HTNs with anionic phospholipids, such as phosphatidylglycerol and cardiolipin on the bacterial cell surface (De Smet K & Contreras R 2005). HTNs have also been shown to possess a fungicidal activity (Oppenheim FG et al. 1988; Troxler RF 1990). HTN5 (a product of HTN3 gene) is the most potent among all histatin family members with regard to its antifungal activity against C.albicans and C.neoformans (Xu T et al. 1991; Tsai H & Bobek LA 1997; Helmerhorst EJ et al. 2001).