Esposito C, Garzarella EU, Bocchino B, et al. A standardized polyphenol mixture extracted from poplar-type propolis for remission of symptoms of uncomplicated upper respiratory tract infection (URTI): a monocentric, randomized, double-blind, placebo-controlled clinical trial. Phytomedicine. January 2021;80:153368. doi: 10.1016/j.phymed.2020.153368.
Upper respiratory tract infections (URTIs) are common illnesses caused by bacteria or viruses. Among the symptoms of URTIs are cough, sore throat, runny nose, nasal congestion, headache, low-grade fever, facial pressure, sneezing, malaise, and myalgia. Bacterial URTIs may be treated with antibiotic drugs, and if symptoms persist, nonsteroidal anti-inflammatory drugs are often used. Those drugs, however, can be associated with adverse effects. Propolis, a natural resinous substance found in tree exudates and secretions and used by bees to build and protect their hives, has been used worldwide as a traditional and ethnopharmacological medicine. Its many active components include polyphenols, which have anti-inflammatory properties. These authors conducted a randomized, single-center, double-blind, placebo-controlled clinical trial to evaluate the effectiveness of an oral spray containing M.E.D.® Propolis (B Natural srl; Corbetta, Italy) in the remission of URTI symptoms. M.E.D. Propolis is a hydro-alcoholic (6:4 per volume) solution obtained by extracting raw propolis from poplar (Populus balsamifera, Salicaceae) plants.
The oral spray contained M.E.D. Propolis, vegetal glycerine (10%) and natural flavors (< 1%). The placebo spray was a hydro-alcoholic (6:4 per volume) solution containing vegetal glycerin (10%), natural flavors (< 1%), and commercial caramel color. B Natural srl provided both sprays in 20 ml mouth spray bottles.
The total polyphenol content of the propolis oral spray was determined as galangin equivalents. Non-flavonoid compounds (caffeic, coumaric acid, ferulic, and isoferulic acids, and caffeic acid phenthyl ester), flavanols (galangin, quercetin, kaempferol, isorhamnetin), flavones (chrysin and apigenin), flavonones (pinocembrin and pinobanksin), and their derivatives were identified. The concentration of the main flavonoids (quercetin, pinobanksin, apigenin, chrysin, pinocembrin, and galangin) represented 39.7% of the total polyphenol content.
The trial began in December 2019 and was conducted by Samnium Medical Cooperative in Benevento, Italy. Of the 146 adults recruited for the trial, 24 were excluded for not meeting study criteria. Included adults had to have suffered from at least one of the following URTI symptoms on their first visit: sore throat, muffled dysphonia and swelling and redness of throat. Pregnancy, allergies, serious disease conditions, or the use of antibiotics/anti-inflammatory agents or immunological drugs within four weeks prior to the study were exclusion criteria.
The included 122 adults with uncomplicated forms of mild URTI were diagnosed by physical examination, including a throat swab. The patients had a mean age of 44 ± 14 years and had at least one of the following URTI symptoms: sore throat, muffled dysphonia, and swelling and redness of the throat. The patients visited the study site at baseline, at three and five days after the start of treatment, and after a follow-up period of 15 days after the end of treatment. At the baseline visit, 58 patients in the propolis group and 64 patients in the placebo group were administered two to four oral sprays. The patients were instructed to continue using the same dose three times daily for five days. The daily dose of 0.8-1.6 mL of propolis spray included 12-24 mg/mL of polyphenols.
At baseline, all patients had similar sociodemographic characteristics. Positive throat swabs were collected from seven patients in the propolis group and eight patients in the placebo group. The primary outcome measure was the remission of URTI symptoms. A secondary measure was the persistence of positive throat swabs after the follow-up period to determine the presence of antibiotic-resistant pathogen strains.
After three days of treatment, eight patients in the propolis group and seven patients in the placebo group had a positive throat swab. At the same time, 17% of the propolis group and 72% of the placebo group had at least one symptom (P < 0.001). Specifically, a sore throat was reported by 16% of the propolis group and 68% of the placebo group (P < 0.001); muffled dysphonia was seen in 10% of the propolis group and 71% of the placebo group (P < 0.05); and swelling and redness of the throat was observed in 18% of the propolis group and by 83% of the placebo group (P < 0.001). After five days of treatment, all patients reported no symptoms. After the follow-up period, all patients with bacterial URTIs had a negative throat swab. All patients completed the study, no adverse effects were recorded, and the sprays were well tolerated.
The authors conclude "propolis oral spray can be used to improve both bacterial and viral mild uncomplicated URTI symptoms in a lower number of days without the use of symptomatic treatment leading to a more immediate resolution." The main limitation of this study is the small number of patients with URTIs of bacterial origin, who all had a negative throat swab after the follow-up period; this prevented the assessment of significant differences between the treated and untreated patients.
Author V. Zaccario is an employee of B Natural srl. All other authors declare no conflicts of interest.