LONG-CHAIN COMPOUNDS ISOLATED FROM LAC TIEN ( PASSIFLORA FOETIDA L . )

Three fatty acids, namely stearic acid (1), linoleic acid (2), linolenic acid (3) together with triacontan-1-ol (4), α-tocopherol (5) were isolated from the aerial parts of Passiflora foetida L. Their structure was elucidated using the spectroscopic methods, viz FT–IR, ESI–MS, NMR and by comparing with the published data. Compounds 4 and 5 were found for the first time from Passiflora genus.


Introduction
The genus Passiflora comprises about 500 species and is the largest in family Passifloraceae.The species of this genus are distributed in the warm temperate and tropical regions of the New World; they are much rarer in Asia, Australia, and tropical Africa [1,2].P. foetida is South American in origin, which has been spread to many tropical areas [2].In Vietnam, P. foetida is a plant growing wildly everywhere, especially in some provinces such as Hoa Binh, Thai Nguyen, Bac Giang, Quang Binh, Thua Thien Hue, Da Nang and Quang Nam [3].The ethnobotanical views of P. foetida reports that the decoction of leaves and fruits is used for the treatment of asthma and biliousness; leaf and root decoction is used for emmenagogue and hysteria; leaf paste is applied on the head for giddiness and headache [2,4,5].Bioactivity studies of P. foetida have indicated that it possesses analgesic, antidiarrhoeal, anti-inflammatory and cytotoxic activities.The phytoconstituents of this plant contain reducing sugars, alkaloids, flavonoids, tannins, steroids, gums, glycoside, cyanogenic compounds, and polyketides [4,5].
In the previous study, we reported the isolation and structural elucidation of some constituents from the methanol extract of P. foetida [6].In this paper, we report the isolation and identification of three fatty acids, one long-chain alcohol and α-tocopherol from the n-hexane and dichloromethane extracts of P. foetida.

General experimental procedures
The electrospray ionization (ESI) mass spectra were recorded on an Agilent LC-MSD-Trap SL spectrometer.The FT-IR spectra were recorded on a Shimadzu IR 8400 Prestige spectrometer with KBr discs.The 1 H-NMR (500 MHz) and 13 C-NMR (125 MHz) spectra were measured on a Bruker Avance 500 MHz; TMS was used as an internal reference.

Plant material, extraction and isolation
The aerial parts of P. foetida were collected in Phu Loc, Thua Thien Hue in January, 2016.The dried and powdered plant material (1.6 kg) was exhaustively extracted with n-hexane, dichloromethane, ethyl acetate and methanol at room temperature.After filtration, the solvents were removed using evaporation, and four crude extracts were obtained.
The molecular formula of 4 was established as C30H62O from the [M+H] + peak at m/z 439 in the positive ESI-MS.The FT-IR spectrum of compound 4 showed the absorptions of some functional groups: O-H (3421.7 cm -1 ), Csp3-H (2846.9,2916.4 cm -1 ), C-O (1060.9cm -1 ) and a longchain band of CH2 groups (721.4 cm -1 ).The 1 H-and 13 C-NMR spectra of compound 4 showed the presence of one oxygenated methylene group at H 3.64 (2H, t, 6.5 Hz, H-1) and C 63.12 ppm.The signal at H 1.57 (2H, t, 6.8 Hz, H-2) belonged to two methylene protons at C-2, corresponding to the signal of C-2, linked directly to the oxymethylene group, at C 32.85 (C-2).Besides, the resonance signal in the upfield at H 0.88 (3H, t, 6.0 Hz, H-30) belonged to the methyl protons at C-30 and at 1.26 (m, H-3~H29) of the overlapped methylene groups.Thus, compound 4 was identified to be triacontan-1-ol.

Conclusion
Five known compounds, namely stearic acid, linoleic acid, linolenic acid, triacontan-1-ol, and αtocopherol were isolated from the aerial parts of P. foetida.To the best of our knowledge, triacontan-1-ol and α-tocopherol were isolated for the first time from the genus Passiflora and stearic acid was isolated for the first time from P. foetida.The structural identification of the isolated compounds was conducted by using the combination of spectroscopic data including IR, MS, 1D-NMR, and the information from the literature.