Which of the components in royal jelly effect to grampositive bacteria? 

Thank you for your question. There are several studies have been reported that some proteins and lipid in royal jelly possess antimicrobial activity. Proteins in royal jelly that inhibit Gram positive bacteria were Major Royal Jelly Proteins (MRJPs) and royalactin. While lipid was trans-10-hydroxy-2-decenoic acid (10-HDA).

From the results of MIC and MBC, the sample no. 1,2, and 3 could inhibit and kill Corynebacterium spp. at concentration 18.75 mg/ml whereas the higher concentration of these sample (300 mg/ml) could not inhibit (inhibition zone = 0 mm.) this organims by agar well diffusion method, why?

Thank you for your answer in advance

Thank you for your question. In general, the method for antimicrobial evaluation has a limit of detection. The well diffusion method has a problem of diffusion. This might be due to the diffusion capacity of those royal jelly samples. Therefore, MIC and MBC could exhibit the positive results since the royal jelly was diluted with broth and could directly exposed to the bacterial inoculum.

1. What are benefits of ABTS assay for antioxidant activity, compared with DPPH assay?

2. Are antioxidant propoties of Royal Jelly associated with  inhibition of pathogenic bacteria?

I understand that royal jelly here is used for topical application. Can it be for bacterial infections inside the body/organs as well? How would you approach the manufacturing process and how would the medicine be introduced to the patient?

When I was a medical student, we occasionally applied  honey to the surgical wounds and the outcome was good.   To your knowledge, the effects in terms of antibacterial infection and antioxidant property of honey and royal jelly are similar or not?

Thank you for your question, Dr. Kanjana Suriyaprom

1. Both ABTS and DPPH are free radical that have color which provide an easy and rapid ways to evaluate antioxidant activity. The ABTS radical is soluble in water and organic solvents which allow the determination of antioxidant capacity of both hydrophilic and lipophilic samples. Moreover, ABTS assay is more sensitive than DPPH assay. However, the limitation of DPPH assay is that application of the conventional methanol and buffered methanol-based DPPH assay could not use to determine proteins and hydrophilic antioxidants because these are precipitated by the solvent. In addition, the DPPH assay could not use in this study due to the flocculation of royal jelly with the methanol in the reaction.
2. Yes, the antioxidant properties of royal jelly are associate with the antibacterial activity due to the phenolic and flavonoid compounds in royal jelly. However, the properties of royal jelly samples are different depend on the plant sources.

Thank you for question, Miss Melanie Lim

1. Normally royal jelly is widely use as a supplement so it can be used for antibacterial against bacterial infection inside the body.
2. The agar well or agar disc diffusion method can be used to determine the efficacy of royal jelly and change the group of tested bacteria into pathogenic enteric bacteria.
3. The patient can take the medicine directly or it can be developed into the nanoparticle which can specifically deliver to the target organs.

Thank you for your question, Professor Dr. Vorachai Sirikulchayanonta

The effects of honey and royal jelly might not similar since the bioactive compound in honey are different from royal jelly. Honey contains tocopherol, ascorbic acid, phenolic, flavonoid and enzymes. The main group of antioxidants in honey are the flavonoids, pinocembrin which unique in honey. On the other hand, the royal jelly contains phenolic, flavonoid and trans-10-hydroxy-2-decenoic acid (10-HDA) which found only in royal jelly. For the antibacterial activity, honey can inhibit both Gram positive and negative bacteria. The factors responsible for antibacterial activity in honey are hydrogen peroxide, low pH, phenolic, flavonoid, methylglyoxal and bee defensin-1. Royal jelly can inhibit Gram positive bacteria, but the efficacy decreases in Gram negative bacteria. The factors involve in antibacterial activity in royal jelly are major royal jelly proteins (MRJPs), royalactin, jelleines, 10-HDA, phenolic and flavonoid.