Chemical composition of the essential oils of flowers of Rosa banksiae from China

Abstract

Rosa banksiae is a climber, growing to about 20 feet tall, and is very long lived. The flowers of Rosa banksiae have a lovely fragrance, similar to violets. It has no serious disease or insect problems. Rosa banksiae is an important and widespread woody plant in southwest China. It is reported that the flowers and leaves of this plant show free radical scavenging activity [1, 2]. Doctors of traditional Chinese medicine believe that the radical and leaves of this plant can stop pain and bleeding. However, it is noteworthy that the flowers of Rosa banksiae Ait.f. have a distinctive aroma. So far, there is no published scientific information in the literature on the chemical constituents of the volatiles of flowers of Rosa banksiae Ait.f. The objective of the present study is to provide qualitative and quantitative information on the volatiles present in flowers of Rosa banksiae Ait.f. from China. The flowers of Rosa banksiae Ait.f. were collected during flowering (April, 2006) in Enshi, Hubei Province, China, as identified by Prof. Kaigong Lu (School of Biological Science & Technology, Hubei Institute for Nationalities), and placed in the shade to dry. Two hundred grams of dried flowers was placed in a three-neck flask. Distilled water (1500 mL) was added and the contents distilled for 5h in an oil bath. The distillate was extracted with anhydrous ether (AR grade). The extracted solution was combined, dried over anhydrous sodium sulfate (AR grade) overnight, and concentrated by passing a slow stream of oxygen-free nitrogen gas (99.99%) to it without ether. A bright reddish-yellow essential oil (0.2612 g) was obtained and stored at 4°C until analysis. The yield was 0.13%. In total, 46 compounds were identified in flowers of Rosa banksiae Ait.f. from China (Table 1). These identified components constitute 94.15% of all identified peak areas using GC-FID with a DB-5 column. Of the total number of components identified, there are one acetal, 12 fatty hydrocarbons, three aromatic aldehydes, three carboxylic acids, five alcohols, two arenes, 17 terpenoids, and three phenols. As the main compounds (concentration higher than 1.0%), the following were found: octane (4.73%), phenylethyl alcohol (5.78%), 2-bornanone (26.34%), cis-verbenol (2.68%), borneol (3.78%), dodecane (41.01%), 6-methyldodecane (1.00%), elemicin (3.01%), and α-cadinol (1.06%). Among all the detected compounds in the flowers, we focus on the 17 terpenoids, which are responsible for the flowery odor.