The resort worldwide to edible medicinal plants for medical care has increased significantly during the last few years. Currently, there is a renewed interest in the search for new phytochemicals that could be developed as useful anti-inflammatory and anti-allergic agents to reduce the risk of many diseases. The activation of nuclear transcription factor-kappa B (NF-κB) has now been linked to a variety of inflammatory diseases, while data from numerous studies underline the importance of phytochemicals in inhibiting the pathway that activates this transcription factor. Moreover, the incidence of type I allergic disorders has been increasing worldwide, particularly, the hypersensitivity to food. Thus, a good number of plant products with anti-inflammatory and anti-allergic activity have been documented, but very few of these compounds have reached clinical use and there is scant scientific evidence that could explain their mode of action. Therefore, this paper intends to review the most salient recent reports on the anti-inflammatory and anti-allergic properties of phytochemicals and the molecular mechanisms underlying these properties.

In order to assess their physicochemical and antioxidant properties as well as their antimicrobial potency, four varieties of honey from different botanical and geographical origins were used. The agar incorporation method was used to determine the antimicrobial potency of honeys. The total phenol content was determined by a modified Folin–Ciocalteu method and the free radical scavenging activity by the Fe³⁺ reducing power (FRAP) assay. Manuka honey was the most effective against Staphylococcus aureus Oxa R and S. aureus Oxa S with a Minimum Inhibitory Concentration (MIC) of 6% and 7%, respectively, whereas wild carrot honey was the most effective against Pseudomonas aeruginosa, with a MIC of 12%. Lavender honey was the least effective against all tested strains, even though was found to have the lowest pH and water content. Manuka honey had the highest content of polyphenols, with 899.09 ± 11.75 mg gallic acid/kg, whereas lavender honey had the lowest, with 111.42 ± 3.54 mg gallic acid/kg. A very significant correlation (r value was 0.9079 at P < 0.05) was observed between the total polyphenolic content and the Fe²⁺ content formed in the presence of the honey antioxidants. The differences between honey samples in terms of antibacterial and antioxidant activity could be attributed to the natural variations in floral sources of nectar and the different locations.

It is well established that honey contains substantial antioxidant compounds that could protect cell components from the harmful action of free radicals. One can speculate that these compounds may strengthen the organism defenses and consequently prevent oxidative stress in humans. Therefore, over time, impaired cells can accumulate and lead to age-related diseases. A comparative study was carried out to assess the antioxidant activity of three varieties of honey from different botanical and geographical (Manuka honey from New Zealand, Acacia Honey from Germany and Wild carrot honey from Algeria). Manuka honey had the highest phenolic content with 899.09 ± 11.75 mg gallic acid/kg. A strong correlation between the antioxidant activities of honeys and their total phenol contents has been noticed.

To evaluate the synergistic action of starch on the antifungal activity of honey, a comparative method of adding honey with and without starch to culture media was used. Candida albicans has been used to determine the minimum inhibitory concentration (MIC) of five varieties of honey. In a second step, lower concentrations of honey than the MIC were incubated with a set of concentrations of starch added to media to determine the minimum synergistic inhibitory concentration (MSIC). The MIC for the five varieties of honey without starch against C. albicans ranged between 40% and 45% (v/v). When starch was incubated with honey and then added to media, a MIC drop has been noticed with each variety. It ranged between 7% and 25%. A negative correlation has been established between the MIC drop and the diastase number (DN).

Six varieties of honey from different regions in Algeria were used to determine their potency against Pseudomonas aeruginosa . Four varieties originated from northern Algeria, and two from the Sahara. Three types of media were used. On nutrient agar the minimum inhibitory concentration (MIC) of the four northern varieties ranged between 30% (vol/vol) and 31% (vol/vol), while the MIC of the Sahara varieties was 11% (vol/vol) and 14% (vol/vol). On King A agar the MIC of the four northern varieties ranged from 25% (vol/vol) to 31% (vol/vol), whereas the MIC of the two varieties of Sahara honey was 12% (vol/vol) and 15% (vol/vol). On nutrient broth the MIC of the northern varieties ranged from 10% (vol/vol) to 21% (vol/vol), whereas the MIC of the two varieties of Sahara honey was 9% (vol/vol). The botanic flora of Sahara is known in Algeria for its medicinal uses, and thus the higher potency of the Sahara honey is most probably due to antibacterial substances in its plant derivates. These findings suggest that Sahara honey could be used for managing wounds and burns, which are mostly infected by P. aeruginosa .