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Ethanolic extract of propolis exerts a strong anti-bacterial activity, in addition to antifungal, antiviral and antiprotozoal properties. In previous studies from these laboratories we have demonstrated that the intensity of the bactericidal activity of EEP is correlated with the virulence of the mycobacteria tested, and that EEP has a synergistic effect with antibiotics on growth of staphylococcus aureus. In the present study we investigated whether the same synergism and correlation exists between EEP and some anti-tuberculosis drugs on tuberculosis mycobacteria with different degrees of virulence. Six standard strains and 11 wild strains of mycobacteria were exposed for 30 days to EEP, with or without streptomycin, rifamycin, isoniazid or ethambutol. Out of the 17 strains, 8 were resistant to at least two standard antibiotics, and were considered "multi-resistant strains". The rest were either susceptible or resistant to only one of the antimycobacterial drugs. Antagonism was recorded only in one case, when Staphylococcus aureus were treated with a mixture of EEP and ethambutol, suggesting that a chemical bond could have been formed between this anti-tuberculosis antibiotic and one of the active components of the ethanol extract of propolis.

Ethanol extract of propolis (EEP) has antibacterial, antiviral, antiprotozoal and antifungal properties, in addition to many biological effects. Our laboratory has demonstrated a synergistic effect of EEP and antibiotics on the growth of Staphylococcus aureus, and suggested that the bactericidal effect of EEP was expressed mainly on virulent mycobacteria rather than on non-virulent (attenuated) ones. The present study was designed to reconfirm the latter finding, by subjecting 17 different mycobacteria strains to EEP, and evaluating whether there is a correlation between the virulence of the mycobacteria strains studied and their susceptibility to EEP. Our findings demonstrate that while the four non-virulent strains studied are not susceptible to EEP, out of the 13 virulent strains studied seven are susceptible and six are resistant to it. These results suggest that while there is no full correlation between virulence of the mycobacteria tested and their susceptibility to EEP, the few strains that were resistant to EEP were non-virulent.

Dolomite, a mineral composed of magnesium and calcium carbonates, potentiates the antitumoral activity of bleomycin: While 40 days after inoculation, no mice survived the Ehrlich ascites tumor burden, 44% of them survived it after bleomycin treatment, and 63% after a simultaneous treatment of bleomycin and dolomite. The beneficial antitumor effect of dolomite is probably related to its high content (12.8%) of magnesium.

The effect of 14 flavones on luminol-dependent chemiluminescence of neutrophils was studied in vitro. Chemiluminescence was used in this study as an indicator for the production of a reactive oxygen species by neutrophils, stimulated by phorbol myristate acetate. While flavone-8-acetic acid, and most of the compounds tested, inhibited chemiluminescence, flavone and its 5-hydroxy-7-methoxy derivatives enhanced it by up to 150%. The most active inhibitors of photon emission were the glycosides. These results indicate that lipophilicity and some structural determinants modulate the chemiluminescent capacity of neutrophils.

Fourteen derivatives of cinnamic and acrylic acids were evaluated for their ability to modulate chemiluminescence, evoked by neutrophils that had been exposed to luminol and phorbol-myristate-acetate. Compounds with one or two hydroxyl groups on the phenyl ring demonstrated significant inhibition of the chemiluminescence, but this inhibition was diminished by methoxylation. Saturation of the double bond in the aliphatic chain of cinnamic acid at C6-enhanced the chemiluminescence to a small degree. All three acrylic acid derivatives demonstrated a marked inhibition of the luminol chemiluminescence, indicating that characteristics of the heterocyclic ring is of utmost importance in this activity.

Antitumoral effect of ethanolic extract of propolis (EEP) was demonstrated in mature mice-bearing Ehrlich carcinoma. Survival rate after EEP treatment was compared to that of bleomycin, given alone or in combination every two days for 36 days and followed up for 14 additional days. The survival rate at 50 days was 55% after EEP and 40% after bleomycin, while all the mice-treated with EEP + bleomycin combination demonstrated shorter survival than the controls. It is concluded that while the in vivo activity of bleomycin is reduced in the presence of cytochrome-C-reductase inhibitors (like some of the EEP components are), the antitumoral property of EEP in the tumored animal model studied is significant and lasting.

Ethanolic extract of propolis (EEP) was tested as a protective agent against gamma irradiation in mice. The mice were exposed to 6 Gy gamma irradiation from a 60Co source, and were treated intraperitoneally with EEP, administered before and after their irradiation. While the non-treated mice expired within 12 weeks, the mice that received a series of EEP treatments survived the irradiation, and their leucocyte count as well as their spleens' plaque-forming activity returned to normal. It is suggested that an antioxidant and a free radical scavenger in the EEP are responsible for the radiation protective effect of the extract of this natural product.