Studies on the chemical constituents of loquat leaves (Eriobotrya japonica)

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In Oriental Foods and Herbs; Ho, C., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2003.
Materials and Methods
Plant and Material Leaves of Eriobotrya japonica (Thunb.) Lindle. (Rosaceace) were collected from Anhui province, China, in Sept. 1994. Voucher specimens are deposited in
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New Use Agriculture and Natural Plant Products Program, Department of Plant Biology and Pathology, Cook College, Rutgers, The State University of New Jersey, 65 Dudley Road, New Brunswick, NJ 08901 Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100094, People's Republic of China Department of Food Science, Cook College, Rutgers, The State University of New Jersey, 65 Dudley Road, New Brunswick, NJ 08901
Downloaded by PENNSYLVANIA STATE UNIV on July 18, 2012 | Publication Date: August 5, 2003 | doi: 10.1021/bk-2003-0859.ch022
Loquat (Chinese name: Pi Pa), Eriobotrya japonica (Thunb.) Lindle is a subtropical tree belonging to the rose family. It is indigenous to southeastern China and the southern end of Japan. Now it is widely cultivated all over the world. The tree is evergreen, with distinctly ribbed leaves, and grows to 5 to 10 meters high. Thefruitis small (3 to 4 cm long), pale tangerine-colored, and pearshaped, sometimes with a single almost spherical stone in the center. The taste is quite delicate, but distinctive, with a pleasant tartness. The leaves are glossy, dark green above and whitish or rusty-hairy beneath. These characteristics of the tree have made the loquat an excellent specimen in the home landscape. The fruits, kernel and leaves of loquat are all used for medicinal purpose. The leaf of loquat is a well known Traditional Chinese Medicine used as anti­ tussive and anti-inflammatory agent for acute and chronic bronchitis. Phytochemical studies (7-5) with this species have led to the isolation of many natural products including flavonoids, triterpenes and sesquiterpene glycoside. Some of the components have been found to have antioxidant (2), antiviral (4), cytotoxic (7) and hypoglycemic (5) properties. In the course of ongoing search for anti-tussive and anti-inflammatory components from this plant, an ethanolic extract of the leaves of E. japonica was examined. We report here the isolation and structural determination of three new components as well as seventeen known compounds.
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Chemical study of Eriobotrya japonica leaves led to the isolation of three new compounds, linguersinol 9'-O-β-D­ -xylopyranoside, eriobotrin and isoeriobotrin, and together with seventeen known compounds, including three lignans, linguersinol, 2,6-dimethoxy-4-(2-propenyl)phenol and 2,6dimethoxy-4-(2-propenyl)phenol 1-Ο-β-D-glucopyranoside, eight megastigmane derivatives, and (6R,7E,9R)-9-hydroxy4,7-megastigmadien-3-one 9-O-β-D-apiofuranosyl-(1-->6)-βD-glucopyranoside, (6R,7E,9R)-9-hydroxy-4,7-megastigma­ -dien-3-one 9-O-β-D-xylopyranosyl-(1-->6)-β-D-glucopyrano­ -side, (6R,7E,9R)-9-hydroxy-4,7-megastigmadien-3-one 9-O-α -L-arabinopyranosy-(1-->6)-β-D-glucopyranoside, (6R,JE,9R)9-hydroxy-4,7-megastigmadien-3-one, (6R,7E,9R)-9-hydroxy4,7-megastigmadien-3-one 9-O-β-D-glucopyranoside, (6R,7E, 9S)-9-hydroxy-4,7-megastigmadien-3-one 9-O-β-D-gluco­ -pyranoside, (6S,7E,9R)-6,9-dihydroxy-4,7-megastigmadien-3one and (6S,7E,9R)-6,9-dihydroxy-4,7-megastigmadien-3-one
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Downloaded by PENNSYLVANIA STATE UNIV on July 18, 2012 | Publication Date: August 5, 2003 | doi: 10.1021/bk-2003-0859.ch022
Studies on the Chemical Constituents of Loquat Leaves(Eriobotryajaponica)
Qing-Li Wu , Mingfu Wang , James E. Simon , Shi-Chun Yu , Pei-Gen Xiao , and Chi-Tang Ho
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9-O-β-D-glucopyranoside, two flavonol glycosides, quercetin3-OP-D-glucoside and quercetin-7-ct-L-rhamnoside and four triterpenes, 2α,3α, 19a-trihydroxy-12-oleanen-28-oic acid, euscaphic acid, 2a-hydroxyoleanolic acid and oleanolic acid. Their structures were elucidated on the basis of spectral and chemical evidences.
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Extraction and Isolation Air-dried leaves (9.5 Kg) were extracted with 95% EtOH for three times. The ethanolic extract (1.33 Kg) was dissolved in water, and then extracted with petrol, CH C1 , EtOAc and H - B U O H . The w-BuOH soluble fraction was concentrated under reduced pressure to get 47 g extract. The H - B U O H extract was chromatographed on silica gel column using a step-gradient CHCl -MeOHH 0 and 1000 mL fraction was collected. Those fractions containing similar components as checked by TLC were combined and total 11 fractions were combined. Fr. 1 was further purified on Sephadex LH-20 (MeOH) to give compound 5 (15 mg). Fr. 2 was repeatedly re-chromatographed on Sephadex LH-20 (MeOH) and silica H to get compounds 2 (40 mg) and 10 (15 mg). Fr. 3 was repeatedly chromatographed on silica H and Sephadex LH-20 (MeOH) to get compound 14 (20 mg). Fr. 4 was further purified on Sephadex LH-20 (MeOH) to give pure compound 13 (230 mg). Fr. 5 was rechromatographed on Silica Gel (CHCl -AcOEt-MeOH-H 0) and followed by gel filtration column chromatography on Sephadex LH-20 (MeOH) to give compounds 6 (40 mg), mixture of 3 and 4 (60 mg), 11 (70 mg) and 12 (30 mg). Re-separation offr.6 on Silica Gel (CHCl -MeOH) and Sephadex LH-20 (MeOH) gave compound 1 (20 mg). Re-purification of fr. 9 on silica gel (CHCl -EtOAc-MeOH) and Sephadex LH-20 (MeOH) gave compounds 9 (15 mg), 15 (700 mg) and 16 (10 mg). Fr. 10 was rechromatographed on silica gel and Sephadex LH-20 (MeOH) to afford compounds 7 (330 mg) and of 8 (620 mg). The EtOAc extract (155 g) was chromatographed on silica gel column using step-gradient (CHCl -methanol) and totally 13 fractions were obtained. Rechromatography of fr. 4 on silica gel (petrol-CHCl ) gave compound 20 (30 mg). Fr. 6 was further purified on silica H (petrol: EtOAc) and Sephadex LH-20 (MeOH) to afford compounds 17 (35 mg) 18, (240 mg) and 19 (360 mg). The structures of compounds 1-14 are shown in Figure 1.