Impact of Folic Acid Supplementation on Single- and Double-Stranded RNA Degradation in Human Colostrum and Mature Milk Gordana Kocic, 1 Ljiljana Bjelakovic, 2 Bojko Bjelakovic, 3 Tatjana Jevtoci-Stoimenov, 1 Dusan Sokolovic, 1 Tatjana Cvetkovic, 1 Hristina Kocic, 4 Svetlana Stojanovic, 1 Tomaz Langerholc, 4 and Marina Jonovic 5 1 Department of Biochemistry, Medical Faculty, University Nis, Nis, Serbia. 2 Department of Hygiene, Faculty of Physical Culture, University Nis, Nis, Serbia. 3 Pediatric Clinic, Medical Faculty, University Nis, Nis, Serbia. 4 Medical Faculty, University Maribor, Maribor, Slovenia. 5 Clinic for Gynecology and Obstetrics, Clinical Center Nis, Nis, Serbia. ABSTRACT Sufficient intake of folic acid is necessary for normal embryogenesis, fetal, and neonatal development. Folic acid facilitates nucleic acid internalization, and protects cellular DNA from nuclease degradation. Human milk contains enzymes, antimicrobial proteins, and antibodies, along with macrophages, that protect against infections and allergies. However, little to no information is available on the effects of folic acid supplementation on degradation of nucleic acids in human milk. In the present study, we aimed to determine the RNase activity (free and inhibitor-bound) in colostrum and mature milk, following folic acid supplementation. The study design included a total of 59 women, 27 of whom received 400 lg of folic acid daily periconceptionally and after. Folic acid supplementation increased the free RNase and polyadenylase activity following lactation. However, the increased RNase activity was not due to de novo enzyme synthesis, as the inhibitor- bound (latent) RNase activity was significantly lower and disappeared after one month. Folic acid reduced RNase activity by using double-stranded RNA as substrate. Data suggests that folic acid supplementation may improve viral RNAs degradation and mRNA degradation, but not dsRNA degradation, preserving in this way the antiviral defense. KEY WORDS:  colostrum  folic acid  human breast milk  RNase  RNase inhibitor INTRODUCTION L actogenic transmission of viruses such as HIV, hepatitis B, hepatitis C, HTLV-1, or CMV from the mother to the newborn is a significant health problem. 1 Almost one third of human HIV infections are transmitted via lacto- genic transmission. 2 Additionally, several thousand RNA transcripts for human proteins are present in human breast milk microvesicles (exosomes or lactosomes). These RNA transcripts in the human breast milk are comprised of cell- signaling proteins, enzymes involved in nucleic acid metab- olism and reverse transcription. Among non-coding RNA species, micro RNAs (miRNAs) were found in the vesicles. 3–5 The nucleic acid-induced immune response represents the first defense line of defense towards viral challenges by inducing the host antiviral response interactions and in- duction of type 1 Interferon synthesis. 6–8 RNases are also referred as ‘‘housekeeping enzymes,’’ involved in the con- trol of RNA splicing, organogenesis, carcinogenesis, an- giogenesis, and immune response. RNases may exert a number of protective roles in human milk including diges- tion of nucleic acids thus providing nutritive components via sufficient absorption of nucleosides, or degradation of viral RNAs. This observation come from the fact that the activity is considerably higher in milk than in serum, meaning that the enzyme may not be a product of simple diffusion from plasma, but rather a product of active secretion. Anti- microbial and antitumor properties of RNases appeared to be significant with the observation that the incidence of breast cancer was almost three times higher in women with low RNase content in milk. 9–12 One RNase form has been known as onconase. It was discovered that pregnant women produce a form of RNase that is secreted in the urine and has antiviral effects on type 1 HIV virus. Such RNase may also block the replication of HIV virus in cultured cells. 13–15 Structural analyses of milk enzyme have demonstrated en- zyme homology in terms of amino-acidic content and electrophoretic mobility with pancreatic RNase form, sug- gesting that this enzyme may appear in milk in the same way as in peripheral tissues, by the process of active uptake. 11 Experimental studies, epidemiological data, and clinical trials have documented that the intake of sufficient amounts of folic acid is necessary for normal embriogenesis and Manuscript received 21 March 2013. Revision accepted 3 January 2014. Address correspondence to: Gordana Kocic, MD, MSc, PhD, Department of Biochem- istry, Faculty of Medicine, University Nisˇ, Bul Dr Zorana Djindjica 81, 18000 Nisˇ, Serbia, E-mail: kocicrg@yahoo.co.uk JOURNAL OF MEDICINAL FOOD J Med Food 17 (7) 2014, 804–809 # Mary Ann Liebert, Inc., and Korean Society of Food Science and Nutrition DOI: 10.1089/jmf.2013.0093 804