Chemical Composition and Antioxidant Activity of Essential Oil from Fruit of Schisandra perulata

Translated from Khimiya Prirodnykh Soedinenii, No. 4, July–August, 2022, pp. 643–645.

Plants of the genus Schisandra (Schisandraceae) grow in East Asia and number ~30 species [[1]]. They are rich sources of lignans and triterpenoids that are known to activate various useful biological processes [[2]–[4]]. In particular, fruit of several species of this genus are used as astringents, sedatives, and adaptogens and tonics for treating chronic cough, spontaneous sweating, tachycardia, and spermatorrhea [[4]].

S. perulata Gagnep. is an endemic species of the genus Schisandra found in Vietnam [[5]]. It is a deciduous woody vine that is often scattered in evergreen forests at elevations of ~1500 m. The chemical composition and biological activity of essential oils obtained from fruit of Schisandra were studied several times [[6]–[8]]. However, essential oil obtained from fruit of S. perulata has not been examined. In continuation of studies of the composition and biological activity of essential oils [[9]–[13]], we analyzed the composition and antioxidant activity of essential oil obtained from fruit of S. perulata.

Fresh fruit of S. perulata was collected in September 2019 in Lao Cai Province, Vietnam. The plant was identified by the University Botanist Hong Duc (Vietnam). A control sample was submitted for preservation in the herbarium (ID No. LC139). Fruit was dried in air at room temperature for one week, mechanically ground in a laboratory mill, and passed through a 0.5-mm sieve. Essential oils were separated by steam distillation using a Clevenger apparatus for 4 h at atmospheric pressure according to the method given in the Vietnam Pharmacopoeia [[14]] and in other studies [[9]]. Essential oils were collected, dried over anhydrous Na2SO4, and stored at 4°C for further analysis. Each extraction was performed in triplicate.

The chemical compositions of essential oils from fruit of S. perulata were determined by gas chromatography (GC) and GC-mass-spectrometry (GC-MS) using the published method [[10]]. GC analysis used an Agilent Technologies 7890A chromatograph equipped with an HP-5ms column (30 m × 0.25 mm i.d., film thickness 0.25 μm) and a flame-ionization detector (FID). The carrier gas was He (1.0 mL/min). The programmed operating conditions were as follows: initial column temperature increased from 60°C (2 min holding) to 220°C (10 min holding) at 4°C/min. The detector and injector temperatures were 260 and 250°C, respectively. The division coefficient was 10:1. Compounds were quantitatively determined using calibration curves obtained by analyzing representative standards of each class.

GC-MS analysis used an Agilent GC 7890A chromatograph equipped with the same column and the conditions described for GC analysis. The capillary column was connected directly to an HP 5973 MSD mass spectrometer (Hewlett Packard, USA). The injector temperature was 250°C; He carrier gas flow rate, 1.0 mL/min. All mass spectra were recorded under the following conditions: thermoelectric emission current 40 mA, ionization potential 70 eV, recording in scan range 35–350 amu at a rate of 1.0 scan/s.

Constituent parts of essential oils were identified by comparing retention indices (RI Exp.) of their GC-MS spectra with spectra obtained using a homologous series of n-alkanes under identical experimental conditions. Combined injections with known compounds under the same GC conditions were used in several instances. Mass spectral fragmentation patterns were compared with spectra of other essential oils of known composition that were recently reported in the literature [[10], [13], [15]].

The average yield of essential oil from fruit of S. perulata was 0.85 ± 0.02% (volume/mass), which was calculated from the ratio to the dry mass. The oil samples were light-yellow in color. Analysis of GC-MS spectra of the essential oil detected 46 compounds making up 90.25% of the oil (Table 1). The essential oil was dominated by sesquiterpenes (76.90%). Oxygen-saturated sesquiterpenes, monoterpenes, and oxygen-saturated monoterpenes made up 4.94, 4.86, and 3.55%, respectively. The main oil constituents were δ-cadinene (24.74%), α-ylangene (16.38), trans-α-bergamotene (7.84), β-elemene (6.91), and β-himachalene (6.27). This is the first report on the chemical composition of essential oil from fruit of S. perulata.

Table 1. Chemical Composition of Essential Oil from Fruit of Schisandra perulata

aElution order on HP-5ms column; bretention index on HP-5ms column.

Previous research showed that the compositions of essential oils obtained from fruit of Schisandra, namely species such as S. chinensis, S. grandiflora, S. rubriflora, S. sphenanthera, and S. propinqua were dominated by sesquiterpenes [[6]–[8]]. This agreed with the oil composition from fruit of S. perulata examined in the present work. However, the main compounds of the individual fruits varied, e.g., the main constituents of oil from fruit of S. chinensis were ylangene (37.72%), β-himachalene (10.46), and α-bergamotene (8.57) [[7]] while δ-cadinene (25.6%) was the main constituent in oil from fruit of S. sphenanthera [[8]].

The antioxidant activity of essential oil extracted from fruit of S. perulata was determined by two methods, i.e., by eliminating impurities from 2,2-diphenyl-1-picrylhydrazyl (DPPH) and by analysis of the ferric reducing antioxidant power (FRAP) test, as described before [[16]]. The DPPH analysis of the essential oil showed moderate antioxidant activity. The IC50 value was 0.571 ± 0.029 mg/mL as compared to 0.046 ± 0.002 mg/mL for BHT. The FRAP analysis of the essential oil found reducing activity for ferric ions with a trolox equivalent antioxidant concentration of 214.9 ± 13.7 μmol of trolox per gram. In general, essential oil from fruit of S. perulata could be a potential source of natural antioxidants. However, further research is necessary before this species is used for other pharmaceutical purposes.

We thank Mr. Ho A Minh for assistance with the field studies and sample collection.