Profiling of Secondary Metabolites in Aerial Parts of Phanera bracteata

The flavonoid 4’,5,7-trihydroxy-6,8-dimethylflavanone (farresol) and 3’,4’,4trihydroxy chalcone (isoliquiritigenin) together with triterpenoid (friedelin) were isolated from the aerial parts of P. bracteata. The structure of these compounds was determined on the basis of spectroscopic data including UV, IR, 1-D and 2-D, NMR and mass spectral analysis. This is the first report on the occurrence of these compounds in this plant.


Introduction
One of the largest plant families is Fabaceae or Leguminosae dispersed in approximately 650 genera and 18,000 species [1], which are found in several areas of the world especially the tropics.There are three sub families of Fabaceae: Mimosoideae, Faboideae and Caesalpinoideae [1].Many of these species are applied as folk medicine and feed in remote areas all over the world [1].Phytochemical investigation of the Fabaceae family has been widely accomplished by different groups and the presence of flavonoids [1], alkaloids [2], stilbene [3], terpenoids [4], phenolic compounds [5], acylated triterpene glycosides [6] and nitro compounds [7] has been reported.Many of these constituents were found to show antimalarial [8], antitumour [9], anti-inflammatory [10] [11], antihyperlipidemic [12], anti-cancer [13], antibacterial [14], insecticidal [15] and antimicrobial activities [16].Phanera bracteata Benth or Bauhinia bracteata (Graham ex Benth.)Baker is a woody climber tree native of the tropical area, located mainly in the Southeast Asian region [17].The vine of P. bracteata is used in folk medi-cine for the treatment of irritated skin and as a rash ointment.There has been no previous report on the chemical investigation for this species.In the present study, we report herein the isolation and characterization of friedelin (1), farresol (2) and isoliquiritigenin (3) from the aerial parts of P. bracteata.

General Procedures
Melting points were determined on a Büchi 322 micro melting point apparatus and remain uncorrected.Infrared spectra (IR) were recorded on KBr pellets with a Shimadzu 8900 FT-IR spectrophotometer.Silica gel 60 H (E. Merck.70 -230 mesh ASTM, cat.No. 7734) and Sephadex LH-20 (20 -150 μm) were used for column chromatography.TLC analysis was performed on aluminium sheets of silica gel 60 PF 254 and the compounds were visualized under ultraviolet light. 1 Hand 13 C-NMR spectra were recorded in CDCl 3 and CD 3 OD solutions on a BrÜker AV-500 spectrometer.Chemical shifts are in δ (ppm) with tetramethylsilane (TMS) as an internal standard.Low resolution mass spectra were recorded on a Thermo Finnigan Polaris Q mass spectrometer at 70 eV (probe) and EIMS were measured with a BrÜker Esquire apparatus.

Plant Material
The aerial parts (fully grown trees) of P. bracteata were collected in May 2016 from tropical dry dipterocarp forest, Huai Yang Waterfall National Park, Prachuap Khiri Khan Province and authenticated by Mr. Narong Nuntasaen.The aerial parts were air-dried for one week and ground to a powder.A voucher specimen (BKF No. 147626) was deposited at the Forest Herbarium, Department of National Park, Wildlife and Plant Conservation, Ministry of Natural Resources and Environment, Bangkok, Thailand.

Extraction and Isolation
The air-dried powdered aerial parts of P. bracteata (12 kg) were percolated with hexane (25 litters × 3 days × 5 times) and then extracted with ethyl acetate (25 litters × 3 days × 5 times) at room temperature, respectively, followed by filtration (cotton wool).The filtrates were combined and evaporated under reduced pressure to afford the hexane (31.21 g) and ethyl acetate extracts (314.40 g) respectively.
The hexane extract was chromatographed on a silica gel column with gradient mixtures of hexane: ethyl acetate (100:0 to 70:30).Fractions were collected and combined on the basis of TLC characteristic technique.The solvents were evaporated to dryness to afford four fractions (F 1 -F 4 ).F 2 (2.88 g) was recrystallized from 95% ethanol to give compound (1) (470 mg) as white needles.
The ethyl acetate extract was subjected to column chromatography over silica gel, eluted with hexane, gradually enriched with ethyl acetate (100:0 to 0:100) to give fractions

Results
Chromatographic separations of the hexane and ethyl acetate extracts from the aerial parts of P. bracteata afforded compound (1)-( 3) respectively.The structure of these compounds was elucidated by comparison of 1 H and 13 C NMR spectral data with those in previous reports [18] [19] [20] [21] [22].
The occurrence of flavonoids and chalcones may be a characteristic useful for further chemotaxonomic studies of the genus Phanera.

Conclusion
Our study of the aerial parts of P. bracteata (Fabaceae) led to the isolation and characterization of three compounds.These results reinforce the previous studies showing that the genus Phanera is considered a good source of flavonoids.
We would like to note here that Friedelin (1), Farresol (2) and Isoliquiritigenin     Submit or recommend next manuscript to SCIRP and we will provide best service for you: Accepting pre-submission inquiries through Email, Facebook, LinkedIn, Twitter, etc.A wide selection of journals (inclusive of 9 subjects, more than 200 journals) Providing 24-hour high-quality service User-friendly online submission system Fair and swift peer-review system Efficient typesetting and proofreading procedure Display of the result of downloads and visits, as well as the number of cited articles Maximum dissemination of your research work Submit your manuscript at: http://papersubmission.scirp.org/Or contact ajps@scirp.org