ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF CASTANEA SATIVA MILL. EXTRACT: NEW THERAPEUTIC PERSPECTIVES

Castanea spp. (Fagaceae) is a genus consisting of plants ranging from small shrubs to large trees in theforests and orchards in Europe, Asia and North America (1). Castanea sativa Mill. is the only one speciesexploited in Europe, particularly in the Mediterranean basin, for fruit and wood production. C. sativaattains a height of 20–35 m with a 2 m diameter trunk . The oblong-lanceolate, boldly toothed leaves are16–28 cm long and 5–9 cm broad. The flowers of both sexes are 10–20 cm long, in upright catkins, the maleflowers in the upper part and female flowers in the lower part; the female flowers develop into spinycupules containing 3-7 brownish nuts that are shed during October. The popularity of many Castanea spp.is based on several attributes of various species, including the production of nutritious, low fat nuts anddecay-resistant and high-quality wood. Chestnut fruits contain various nutrients (starch, free sugars,proteins, lipids/fat), vitamins and minerals important for health (2). Chestnut flowers have an outstandingantioxidant capacity, also displaying antimicrobial and antitumor effects. Studies on chestnut by-productsrevealed a good profile of bioactive compounds with antioxidant, anticarcinogenic and cardioprotectiveproperties (3). Recent studies on chemical composition revealed that C. sativa is characterized bybetaines, flavonoids, tannins, pentacyclic triterpenes (2, -5). Investigation of botanical folk medicines usedin the treatment of skin and soft tissue infections led us to study the plant for its potential antibacterialactivity (6, 7). Tannins, flavonoids, and antioxidants in shell extracts of Chinese chestnut (C. mollissimaBlume) appeared inhibitory to bacteria and fungi (8). Recently, Donis-Gonzalez reported that the greatestantimicrobial activity was found in the pellicle, a thin fibrous tissue found between the shell and kernel (9).When chestnut pellicle, shell, and nut kernel were directly placed on agar media, the pellicle tissue wasthe only tissue found to inhibit fungi (including yeast) and bacteria. In view of the interesting biologicalproperties reported for Castanea species, objective of this study was to determinate the total phenolicand flavonoid contents of extract of pellicle of C sativa and to investigate the in vitro antibacterialactivities of extract of the plant against pathogenic bacteria. Furthermore, being commonly acceptedthat reactive oxygen species play an important role in the pathogenesis of various diseases, theantioxidant activity of the same extract was also evaluated. Total phenolic and flavonoid contents of theextract was evaluated by spetctrophotometric assay; antiradical activity of C. sativa extract wasperformed by DPPH test and by superoxide anion scavenging capacity. The effects of chestnut extract onthe growth of pathogenic bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Enterococcusfaecium, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis) weredetermined using a microdilution method. Results obtained showed that the extract has both antioxidantin vitro activity and antimicrobial ability against Gram-positive and Gram-negative strains but with differenteffectiveness probably due to its active compounds. This study allowed us to enhance knowledge aboutthe type of chestnut by-products produced, their chemical composition and biological activities in orderto explore other possible applications of this extract.