Chemical composition, total phenol content, antioxidant and healing potential of geopropolis from Melipona subnitida bees

Abstract

In Brazil, Melipona subnitida, a species of stingless bee, endemic to northeastern Caatinga is popularly known as “Jandaira” and has the peculiarity of adding soil to propolis, forming geopropolis. This study aimed to establish the chemical profile, total phenol content, antioxidant activity and in vivo evaluation of the healing potential of 6 hydroethanolic (70%) extracts of Jandaira geopropolis (EGJ1 – 6) collected in the semiarid region at “Rio Grande do Norte”. These extracts were characterized by TLC and LC-UV/DAD, and submitted to total phenol content determination, using Folin-Ciocalteu method and gallic acid as standard, [1] and to the antioxidant potential evaluation using the DPPH free radical scavenging method and ascorbic acid as positive control [2]. EGJ1 healing activity was also evaluated on skin wounds surgically induced. Two groups of 12 male Wistar rats were used: Group 1, treated for 14 days with lanette® cream and Group 2, treated for 14 days with 10% EGJ1 in lanette® cream. Signs of inflammation and wound area [3] were daily macroscopically evaluated. Histological evaluations were assessed at days 3, 7 and 14 postoperative [4]. Obtained TLC and LC-UV/DAD results clearly showed two chemically distinct EGJ groups, one containing mainly flavones and flavonols and the other containing mainly hydrolysable tannins and phenolic acids, like gallic acid. All tested samples showed a total phenol content from 11.3 to 4.4%(m/m) of gallic acid equivalent and a concentration required to scavenge 50% of DPPH (IC50%) from 0.08 to 0.95 mg/mL. EGJ1 cream showed to be able to decrease the signs of inflammation, stimulate the process of re-epithelialization and promote angiogenesis and collagen production. In relation to the wound area, only at 14th postoperative day a statistically significant difference (p < 0.05) between groups were observed. In this extract hydrolysable tannins and phenolic acids were the main compounds.