Article pubs.acs.org/JAFC New Benzophenones and Xanthones from Cratoxylum sumatranum ssp. neriifolium and Their Antibacterial and Antioxidant Activities † † ‡ § Cholpisut Tantapakul, Wisanu Maneerat, Tawanun Sripisut, Thunwadee Ritthiwigrom, ∥ ∥ ⊥ † † Raymond J. Andersen, Ping Cheng, Sarot Cheenpracha, Achara Raksat, and Surat Laphookhieo*, † Natural Products Research Laboratory, School of Science, Mae Fah Luang University, Tasud, Muang, Chiang Rai 57100, Thailand ‡ School of Cosmetic Science, Mae Fah Luang University, Tasud, Muang, Chiang Rai 57100, Thailand § Department of Chemistry, Faculty of Science, Chiang Mai University, Sutep, Muang, Chiang Mai 50200, Thailand ∥ Departments of Chemistry and Earth, Ocean & Atmospheric Sciences, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1 ⊥ School of Science, University of Phayao, Maeka, Muang, Phayao 56000, Thailand *S Supporting Information ABSTRACT: Two new benzophenones (1 and 2) and four new xanthones (4−6 and 17) together with 24 known compounds (3, 7−16, and 18−30) were isolated from the roots and twigs of Cratoxylum sumatranum ssp. neriifolium. Their structures were elucidated by spectroscopic methods. Compounds 5 and 26 showed antibacterial activity against Micrococcus luteus, Bacillus cereus, and Staphylococcus epidermis with minimum inhibitory concentrations ranging from 4 to 8 μg/mL, whereas compounds 7, 20, and 26 displayed selective antibacterial activities against Staphylococcus aureus (8 μg/mL), Salmonella typhimurium (4 μg/ mL), and Pseudomonas aeruginosa (4 μg/mL), respectively. The radical scavenging effects of some isolated compounds were investigated. Compounds 11 and 21 exhibited potent activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) with IC50 values of 7.0 ± 1.0 and 6.0 ± 0.2 μM, respectively. KEYWORDS: Cratoxylum sumatranum ssp. neriifolium, benzophenone, xanthone, antibacterial activity, antioxidant activity ■ INTRODUCTION nones,3 and some of them exhibited cytotoxicity.3 In the 1 investigation presented here, we report the isolation and Cratoxylum belongs to the Hypericaceae family that is widely fi distributed in South East Asian countries. In Thailand, only six identi cation of two new benzophenones (1 and 2)(Figure 1), 2 four new xanthones (4−6 and 17), and 24 known compounds species have been found, and some of them have been used as − − traditional medicines and cooking. The roots and stems of (3, 7 16, and 18 30)(Figure 2) from C. sumatranum ssp. Cratoxylum cochinchinense have been used in folk medicine to neriifolium roots and twigs. In addition, the antibacterial and − treat diuretic, stomachic, and tonic effects and diarrhea,3 5 antioxidant activities of some isolated compounds are reported. whereas the roots, bark, and leaves of Cratoxylum sumatranum Downloaded via UNIV OF PHAYAO on March 29, 2021 at 09:15:26 (UTC). ssp. neriifolium have been used for the treatment of rheumatoid ■ MATERIALS AND METHODS arthritis and musculoskeletal pain and also used as a protective General Experimental Procedures. Melting points were 6 α medicine for women after childbirth. Young leaves of C. determined on a Buchi B-540 visual thermometer. The [ ]D values sumatranum ssp. neriifolium as well as the flowers of Cratoxylum were measured with a Bellingham and Stanley ADP400 or Jasco P- See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles. formosum ssp. formosum are chewed for relief of coughs.7,8 The 1010 polarimeter. UV−vis spectra were recorded with a PerkinElmer latex of C. cochinchinense, C. formosum ssp. formosum, and C. UV−vis or BMG LABTECH/SPECTROstar Nano spectrometer. The formosum ssp. pruniflorum has been used to stop bleeding and IR spectra were recorded using a PerkinElmer FTS FT-IR − to treat wound infections.9 11 The fresh shoots, young leaves, spectrometer. Electronic circular dichroism spectra were recorded on fl a JASCO J-815 CD spectrometer. The NMR spectra were recorded and owers of some species of this genus, especially C. using a 400 or 600 MHz Bruker spectrometer. The HREIMS and ESI- formosum ssp. formosum, are traditionally consumed as TOF-MS data were measured on a MAT 95 XL or a Bruker-Hewlett- vegetables, and the taste is sour and slightly astringent because Packard 1100 Esquire-LC system mass spectrometer. Chiral HPLC 12 of the phenolic components. In addition, C. cochinchinense was performed on a CHIRALPAK IA column (10 mm × 250 mm) young leaves and fruits are commonly used as a spice for attached to a Waters 2487 dual λ absorbance detector. Silica gel C60 cooking and a substitute for tea, respectively.13 (Silicycle, 0−20 μm) and silica gel G60 (Silicycle, 60−200 μm) were Cratoxylum species produce various types of secondary used to perform quick column chromatography (QCC) and column metabolites, including anthraquinones,14 benzophenones,15 chromatography (CC), respectively. Analytical thin-layer chromatog- flavonoids,16 xanthones,3,14,17 and triterpenoids,15 and many of them exhibited interesting biological activities as well as Received: August 15, 2016 antioxidant activity.17,18 Previous phytochemical investigations Revised: October 24, 2016 of C. sumatranum leaves and stem bark resulted in the Accepted: October 27, 2016 identification of xanthones17,19 and anthraquinonebenzophe- Published: October 27, 2016 © 2016 American Chemical Society 8755 DOI: 10.1021/acs.jafc.6b03643 J. Agric. Food Chem. 2016, 64, 8755−8762 Journal of Agricultural and Food Chemistry Article Figure 1. Compounds isolated from C. sumatranum roots. Figure 2. Compounds isolated from C. sumatranum twigs. raphy (TLC) was performed with the precoated plates of silica gel 60 Extraction and Isolation. Air-dried roots of C. sumatranum ssp. F254. neriifolium (2.75 kg) were macerated with CH2Cl2 and acetone, Plant Material. The roots and twigs of C. sumatranum ssp. successively. The crude extract (47.88 g) was subjected to QCC over neriifolium were collected from Mae Hong Son Province, Thailand, in silica gel, eluting with an EtOAc/hexanes solvent gradient (100% June 2010. The plant was identified by J. Maxwell, and the voucher hexanes to 100% EtOAc) to give compounds 6 (94.3 mg) and 10 specimen (MFU-NPR0008) was deposited at the Natural Products (18.9 mg) and 13 fractions (1A−1M). Fraction 1B (1.84 g) was Research Laboratory of Mae Fah Luang University. further separated by QCC (100% hexanes to 100% acetone) to give 8756 DOI: 10.1021/acs.jafc.6b03643 J. Agric. Food Chem. 2016, 64, 8755−8762 Journal of Agricultural and Food Chemistry Article 1 13 Table 1. H (400 MHz) and C (100 MHz) NMR Spectroscopic Data of 1 and 2 in CDCl3 cratosumatranone A (1) cratosumatranone B (2) δ δ δ δ position C H [J (Hz)] HMBC C H [J (Hz)] HMBC 1 104.5 −−105.2 −− 2 161.0 −−164.7 −− 3 93.0 6.06 s 1, 2, 4, 5, 7, 1‴ 92.9 6.12 s 1, 2, 5, 7, 1‴ 4 163.8 −−163.7 −− 5 108.8 −−99.1 −− 6 158.7 −−154.3 −− 7 197.9 −−199.9 −− 1′ 140.2 −−142.7 −− 2′ 127.9 7.63 dd (7.2, 1.3) 7, 4′,6′ 127.2 7.45 br d (6.8) 7, 4′ 3′ 129.0 7.50 dd (7.6, 7.2) 1′,5′ 127.5 7.39 br d (6.8) 1′ 4′ 132.0 7.57 m 2′,6′ 130.1 7.44 m 4′,6′ 5′ 129.0 7.50 dd (7.6, 7.2) 1′,3′ 127.5 7.39 br d (6.8) 1′ 6′ 127.9 7.63 dd (7.2, 1.3) 7, 4′,2′ 127.2 7.45 br d (6.8) 7, 4′ 1″ 65.4 4.57 d (6.4) 4, 2″,3″ 65.5 4.58 d (6.4) 4, 2″,3″ 2″ 118.9 5.47 t (6.4) 1″,4″ 118.7 5.45 t (6.4) 1″,4″,9″ 3″ 141.5 −−141.6 −− 4″ 39.4 2.10 m 5″,9″ 39.5 2.10 m 2″,3″,4″,5″,9″ 5″ 26.0 2.10 m 4″ 26.1 2.10 m 3″,4″,6″,7″ 6″ 123.7 5.10 br t (6.8) 4″,5″,8″ 123.6 5.10 br t (6.4) 4″,5″,8″ 7″ 131.8 −−131.9 −− 8″ 25.8 1.68 s 10″ 25.8 1.68 s 6″,7″,10″ 9″ 16.6 1.73 s 4″ 16.7 1.73 s 2″,3″,4″ 10″ 17.7 1.61 s 8″ 25.7 1.61 s 6″,8″ 1‴ 21.6 3.28 d (6.8) 4, 5, 6, 2‴,3‴ 17.7 2.76 dd (17.2, 5.2), 2.55 dd (17.2, 5.2) 4, 5, 6, 2‴,3‴ 2‴ 122.2 5.17 br t (6.8) 1‴,5‴ 68.6 3.58 t (5.2) 5, 4‴ 3‴ 132.6 −−76.7 −− 4‴ 17.8 1.73 s 5‴ 20.9 0.85 s 2‴,3‴ 5‴ 25.6 1.67 s 4‴ 23.9 0.92 s 2‴,3‴ OH-2 9.07 br s 1, 2, 3 − 12.37 br s 1, 2, 3 OH-6 8.60 br s 1, 5, 6 −− − five fractions (1BA−1BE). Compound 4 (8.1 mg) was obtained from Purification of subfraction 2GB (57.1 mg) by CC (10% acetone/ subfraction 1BA (737.1 mg) by Sephadex LH-20 (10% CH2Cl2/ hexanes) gave compound 26 (6.0 mg). Fraction 2H (3.51 g) was MeOH). Fraction 1C (4.39 g) was obtained by repeated QCC (15% further separated by QCC (100% hexanes to 100% CH2Cl2) to give acetone/hexanes) to yield four subfractions (1CA−1CD). Subfraction compounds 22 (9.8 mg) and 25 (7.7 mg) and eight subfractions 1CA (126.6 mg) was purified by CC (15% acetone/hexanes), yielding (2HA−2HH). Compound 29 (8.1 mg) was obtained from subfraction compound 1 (79.6 mg).