A new flavane acid from the fruits of Illicium verum

Abstract A new compound, illiciumflavane acid (1), along with 13 known compounds (2–14), were isolated from the fruits of Illicium verum Hook. F. Their structures were elucidated through various spectroscopic methods, including 1D NMR (1H NMR, 13C NMR), 2D NMR (HMQC, HMBC and NOESY) and HRMS. The stereochemistry at the chiral centres was determined using CD spectrum as well as analyses of coupling constants and optical rotation data. Cytotoxicity evaluation of four compounds showed that illiciumflavane acid and (E)-1,2-bis(4-methoxyphenyl)ethene exhibited potential against A549 activities with IC50 values of 4.63 μM and 9.17 μM, respectively. The structure of a new compound isolated from the fruits of Illiciumverum has been determined by detailed spectroscopic analyses. Thecytotoxicity activities of four compounds were determined againstP-388, NUGC, HT-29 and A549 cancer cell lines. Illiciumflavane acid (1)and (E)-1,2-bis(4-methoxyphenyl)ethene (5) showed activites againstthe four cell lines that were comparable to cisplatin.


Introduction
The genus Illicium is the only member of the family Illiciaceae (Liu et al. 2014). Previous chemical investigations of the genus Illicium have resulted in the isolation of prenylated ABSTRACT A new compound, illiciumflavane acid (1), along with 13 known compounds (2-14), were isolated from the fruits of Illicium verum Hook. F. Their structures were elucidated through various spectroscopic methods, including 1D NMR ( 1 H NMR, 13 C NMR), 2D NMR (HMQC, HMBC and NOESY) and HRMS. The stereochemistry at the chiral centres was determined using CD spectrum as well as analyses of coupling constants and optical rotation data. Cytotoxicity evaluation of four compounds showed that illiciumflavane acid and (E)-1,2-bis(4-methoxyphenyl)ethene exhibited potential against A549 activities with IC 50 values of 4.63 μM and 9.17 μM, respectively.
The structure of a new compound isolated from the fruits of Illicium verum has been determined by detailed spectroscopic analyses. The cytotoxicity activities of four compounds were determined against P-388, NUGC, HT-29 and A549 cancer cell lines. Illiciumflavane acid (1) and (E)-1,2-bis(4-methoxyphenyl)ethene (5) showed activites against the four cell lines that were comparable to cisplatin. C 6 -C 3 compounds, neolignans and seco-prezizaane-type sesquiterpenes, which are characteristic chemical markers of Illicium species (Li et al. 2015;Liu et al. 2015). Illicium verum Hook. F. (I. verum), Illiciaceae family, commonly referred to as star anise, mainly grows in Guangxi, Yunnan and Guizhou provinces, China. Anise fruits, which are commercially called 'seeds' , are used as flavourings and crude drug (Orav et al. 2008). It has been used for treating inflammation and achiness for long time (Liang et al. 2012). The fruits of I. verum are rich in shikimic acid which is the main material for the synthesis of tamiflu (a kind of anti-influenza drug), which led to pharmacological effects caused attention of some researchers in recent years. In this paper, the isolation and structure elucidation of a new compound is described together with 13 known compounds from the fruit of I. verum. Cytotoxicity activity evaluation of some of the compounds is also reported here.
The HMBC spectrum showed that the methine proton H-2 is correlated to aromatic carbons C-1′, C-8a, to an oxygen-substituted methine carbon C-3 and to a methylene carbon C-4, respectively. The methine proton H-3 is correlated with aromatic carbons C-1′, C-4a, with an oxygen-substituted methine carbon C-2, and with a methylene carbon C-4, respectively. The protons at δ 3.63 and 3.70 are assigned as H-4 based on their correlations with aromatic carbons C-4a and C-5. The aromatic proton at δ 7.15 is assigned as H-5 based on its correlations with methylene carbon at C-4, with aromatic carbons C-4a, C-6, C-7, C-8a, and with an carboxyl group carbon C-9, indicating the carboxyl group is located at the C-6 position. The correlation of methoxy protons at δ 3.63 to aromatic carbon C-8, suggesting the methoxy is placed at the C-8 position. Based on the above analyses, the placement of a hydroxyl group is at the C-7 position. (Table S1 and Figure S1).

General
The optical rotations were measured on a PE-GZ050R14 digital polarimeter. Melting points were conducted on an X-6 micro-melting point apparatus. The UV spectra were recorded using a TU-1901 spectrophotometer. NMR spectra were recorded on a Bruker Advance 500 MHz spectrometer. HRESIMS were performed on a MAT 95XP mass spectrometer. The instrument for bioassay was a microplate reader (MPR A4i, Tosoh).

Plant material
The fruits of I. verum were collected in the Guangxi Province of China, in October 2014 and authenticated by Dr. Shao-Qing Tang, Professor of Life College, Guangxi Normal University. A voucher specimen (registration number: 20141002) has been deposited in the Natural Products Laboratory, Guangxi Normal University, China.

Anticancer activity
The activities against P-388, NUGC, HT-29 and A549 cancer cells were performed by MTT assay method.

Conclusion
In conclusion, the compounds isolated from the fruit of I. verum are structurally diverse. Cytotoxicity evaluation of some compounds suggested that illiciumflavane acid (1) has significant against A549 activity with IC 50 value of 4.63 μM and (E)-1,2-bis(4-methoxyphenyl) ethene (5) possessed medium cytotoxic effect against A549 cells. This report thereby provided a basis for the activity of this food and medicinal plant.

Disclosure statement
No potential conflict of interest was reported by the authors.