Protective effects of polyphenolic extracts from longan seeds promote healing of deep second-degree burn in mice.

The objective of this study was to evaluate the ability of a polyphenolic extract from longan seeds as a wound-healing material for deep second-degree burn wounds. The total phenol content of the extract reached 45.28 ± 1.22 mg GAE per g DW when 70% ethanol was used as the extraction solvent, and then AB-8 resin was used for purification. Results from the antioxidant assay in vitro (DPPH˙ and hydroxyl radical scavenging activity) and antimicrobial activity assay (ZOI, MIC and MBC) showed that the fractions eluted by 30% ethanol tend to have greater antioxidant ability, as well as higher bactericidal and antibacterial activities, than the other elution fractions. Low-, middle-, and high-doses of the polyphenolic extract were applied for wound-healing of mice, and were compared with 30% ethanol solution (negative control) and 'Jing Wan Hong®' (positive control). The results showed that on the 11th day, the wound-healing rate and levels of hydroxyproline and protein indicated that wound healing in the high-dose polyphenolic group was similar to that of the positive control, which was higher than that in the other groups (p < 0.01). The histological results indicated that high-dose polyphenolic extracts are capable of leading to the formation of new blood vessels and capillaries, regenerating new dermal tissue and remodeling the newly formed tissue during the proliferative period. Our results provided first-hand information on the would-healing potential of the polyphenolic extract from longan seeds.