Antimicrobial Activities And Physico-chemical Analyses Of Honeys

1.5.5.2. Anti-Inflammatory Activity

Although inflammation is a vital part of the normal response to infection or injury, when it is excessive or prolonged it can prevent healing or even cause further damage. The most  serious consequence  of excessive  inflammation is the production  of free radicals in the tissue. These free radicals are initiated by certain leucocytes that are stimulated as part of the inflammatory process (van den Berg et al., 2008), as inflammation is what triggers the cascade of cellular events that give rise to the production of growth factors which control angiogenesis and  proliferation  of fibroblasts and epithelial cells (Simon et al., 2009).

They can be extremely damaging and break down lipid, proteins and nucleic acids that are the essential components of the functioning of all cells. However, the anti-inflammatory properties of honey have been well established in a clinical setting (Subrahmanyam et al., 2003) and its action is free from adverse side effects.

1.5.5.3. Anti-Oxidant Activity

Antioxidant capacity is the ability of honey to reduce  oxidative  reactions  within the human body. It has been found to have a significant antioxidant content measured as its capacity to scavenge free radicals (Gheldof et al., 2002). This anti- oxidant activity may be at least partly what is responsible for its anti-inflammatory action because oxygen free radicals are involved in various aspects of inflammation (Henriques et al., 2006). Even when the antioxidants in honey do not directly suppress the inflammatory process, they can be expected to scavenge free radicals in order to reduce the amount of damage that would otherwise have resulted.

Honey exerts its anti-oxidant action by inhibiting the formation  of  free  radicals, catalyzed by metal ions such as iron and copper. Flavonoids and other polyphenols, common constituents of honey have the potential  to  impound  these  metal ions in complexes, preventing the formation of free radicals in the first place (Makawi et al., 2009).

Honey contains a variety of phytochemicals (as well  as  other substances such as organic acids, vitamins, and enzymes) that may serve as sources of dietary antioxidants. The amount and type of these antioxidant compounds depends largely upon the floral source/ variety of the honey. In general, darker honeys  have  been shown to be higher in antioxidant content than lighter honeys (Gheldof et al. 2002).

Researchers at the University of Illinois Champaign/Urbana examined the antioxidant content (using an assessment technique known as Oxygen Radical Absorbance Capacity or ORAC) of 14 uni-floral honeys compared to  a  sugar  analogue.  ORAC values for the honeys ranged from 3.0 ?mol TE/g for acacia honey   to 17.0 ?mol TE/g for Illinois buckwheat honey. The sugar analogue displayed no antioxidant activity (Alvarez-Suarez et al., 2013). Free radicals and reactive oxygen species (ROS) have been implicated in contributing to the processes of aging and disease. Humans protect themselves from these damaging compounds, in part, by absorbing antioxidants from high-antioxidant foods (Makawi et al., 2009). This report describes the effects of consuming 1.5 g/kg body weight of corn syrup or buckwheat honey on the antioxidant and reducing capacities of  plasma in healthy human adults.    It can be speculated that these compounds may augment defences against oxidative stress and that they might be able to protect humans from oxidative stress. Given that the average sweetener intake by humans is estimated to be in excess of 70 kg per year, the substitution of honey in some foods for traditional sweeteners could result in an enhanced antioxidant defense system in healthy adults (Henriques et al., 2006).

Antioxidant properties shown by volatile oil of propolis  (VOP)  from  India were investigated by spectrophotometric methods and a photochemiluminescence method and it was found that from IC50 values it could be concluded that  the  efficiency of scavenging ABTS radicals by the VOP was more pronounced as  compared to scavenging other radicals (Kwakman et al., 2010).

1.5.5.4. Boosting of Immune System

As well as having a direct antibacterial action, honey may clear infection through stimulating the body’s immune system to fight infections. It has been reported that honey stimulates B60 lymphocytes and T-lymphocytes in cell culture to multiply, and activate neutrophils (Tonks et al., 2003). Furthermore, Jones et al. (2000) in their study reported the stimulation of monocytes in cell cultures to release the cytokines TNF-alpha, IL-1 and IL-6, the cell “messengers” that activate the many facets of the immune response to infection. Recently, Tonks et al. (2007) discovered a 5.8k DA component of Manuka honey which stimulates the production of TNF-? in  macrophages via Toll-like receptor. In addition, honey provides a supply of glucose, which is essential for the “respiratory burst” in macrophages that produce hydrogen peroxide, the dominant component of their bacteria-destroying activity (Molan, 2001).

Moreover, it provides substrates for glycolysis, the major mechanism  for  energy production in the macrophages, and thus allows them to function in damaged tissue and exudates where the oxygen supply is often poor. The acidity of honey may also assist in the bacteria destroying action of macrophages, as an acid pH inside the phagocytic vacuole is involved in killing ingested bacteria (Molan, 2001).

1.5.6. Clinical Conditions for Treatment with Honey

1.5.6.1. As Remedy for Diarrhoea

Infections of the intestinal tract are common throughout the world, affecting people of all ages (Badawy et al., 2004). The infectious diarrhoea exacerbates nutritional deficiencies in various ways,  but as in any infection, the calorific demand    is increased. Pure honey has bactericidal activity against many enteropathogenic organisms, including those of the Salmonella and Shigella species, and  enteropathogenic E. coli(Badawy et al., 2004; Agbagwa et al., 2010).

In vitro studies of Helicobacter pylori isolates which cause gastritis have been shown to be inhibited by a 20% solution of honey. Even isolates that exhibited a resistance to other antimicrobial agents were susceptible (Chattopadhyay et al., 2009). In a clinical study, the administration of a bland diet and 30 mL of honey three times a day was found to be an effective remedy in 66% of patients and offered relief to a further 17%, while anaemia was corrected in more than 50% of the patients (Ndip  et  al., 2007).

1.5.6.2. As Medicine for Gastric  Ulcers

Gastric ulcers have been successfully treated by the use of honey as a dietary supplement (Ali, 1991). Honey administered subcutaneously or orally before oral administration of ethanol affords protection against gastric damage and  reverses changes in pH induced by ethanol (French et al., 2005).

Honey consumption delayed the postprandial ghrelin response (p = 0.037), enhanced the total PYY (p=0.007) response, and blunted the glucose response  (p=0.039) compared with consumption of the  sucrose-containing meal (Larson-Meyer et al., 2010).

1.5.6.3. As Medicine for Canine Recurrent Dermatitis The antibacterial activity of honeydew honey and propolis was evaluated in  vitro against Staphyococcus aureus strains isolated from canine  patients  with dermatitis and found that the honey showed bactericidal effects against the bacterial tested S. aureus stains, but was less efficient than the  propolis  at  certain  concentrations (Iulia et al., 2007; Moussa et al., 2012).