Antimicrobial Activities And Physico-chemical Analyses Of Honeys

1.1. INTRODUCTION

Traditional medicine has been used to treat infections since the origin  of  mankind and honey is one of the oldest medicines considered as a remedy  for  microbial infections (Cooper et al., 2009). It was not until late 19th century that researchers discovered that honey has natural antimicrobial qualities  (Zumla  and  Lulat, 1989). Resistance to antibiotics continues to rise and few new therapies are on  the horizon, there is further increased interest in the antimicrobial potency of honey (Fahim et al., 2014). Previous studies showed that honey hadremarkable antimicrobial activity against fungi, bacteria,viruses and protozoa(Molan, 1992; Sherlock et  al.,  2010; Mohapatra et al., 2011; Fahim et al., 2014).

Honey is a natural sweet mixture produced by honey insects from the nectar of flowers or from living parts of plants. The insect transform the nectar into honey by combining this mixture with substances of their own. The  mixture  is  then  regurgitated, dehydrated and stored in the waxy honeycomb inside the hive to ripen   and mature for further use (Iurlina and Fritz, 2005). Honey is composed mainly of carbohydrates, smaller amount of water and a great number of minor components. Sugars are the main constituents of honey, constituting of about 95%. Honey characterization is based on the determination of its chemical, physical or biological properties (Gomes et al., 2010).

Even though honey is produced worldwide, its composition and antimicrobial activity can be variable, and are dependent primarily on their botanical origin, geographical and entomological source (Maryann, 2000). Other  certain  external factors, such as harvesting season, environmental factors, processing and storage condition, also play important roles (Gheldof and Engeseth, 2002).  Entomologically, the honey variety produced by honey bees (the genus Apis) is one most commonly referred to, as it is the type of honey collected by most beekeepers and consumed by most people in Nigeria. Honeys produced by other insects (stingless insects) have different properties (Sherlock et al., 2010).

Antimicrobial activity of honey is highly complex due to the involvement of multiple compounds and also due to large variations in the concentrations of these compounds among honeys. It depends on osmotic effect (sugar  concentration), hydrogen peroxide, and low pH, as well as more recently identified  compounds,  methyl glyoxal and antimicrobial peptide, bee defensin-1 (Fahim et al., 2014). 

Honey contains significant antioxidant contents including glucose oxidase, catalase, ascorbic acid, flavonoids, phenolic acids, carotenoid derivatives, organic  acids,  Maillard reaction products, amino acids and proteins. The biological properties that  make it  ideal as a medicine are: antibacterial, bacteriostatic, anti-inflammatory, wound and sunburn healing effects, antioxidant activity, radical scavenging activity and antimicrobial activity (Al-Mamary et al., 2002; Gheldof and  Engeseth,  2002;  Beretta et al., 2005; Aljadi and Kamaruddin, 2004; Fahim et al., 2014)

Generally, the darker the honey is the higher its phenolic content and its antioxidant power. Antioxidant activity depends on the botanical origin of honey and shows variations in different honeys acquired from different sources (Küçük et al., 2007). Furthermore, antimicrobial activity of honey is linked to hydrogen peroxide which is produced by glucose oxidase especially when honey is diluted. In the diluted form of honey, produced hydrogen peroxide is not tissue damaging and  is  an  important stimulant of the growth of tissues and has the potential for wound healing (Malik et al.,2010). The hydrogen peroxide activity of most of the honeys can be destroyed by heat or by the presence of catalase. However, some honeys retain their antimicrobial activity even in the presence of catalase which are known as “non- peroxidase honeys”. This activity is important especially in the context of topical antimicrobial and wound dressing fluids (Banget al., 2003; Malik et al.,2010).

Honey is considered among the possible alternatives, which is natural, non-toxic and with broad spectrum of action. This could be a  promising  substitute  or  supplement to antimicrobial agents, but some factors limits its use. Clinical  applicability of honey has been hindered by incomplete  knowledge  of  the antimicrobial activity and lack of precise mechanisms for determining the type of activity of honey, variations  of honey and its cost in some countries (Malik et al.,  2010; Mandal and Mandal, 2011).