Antioxidant Activity and a New Butanolide from the Primitive
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J.Natn.Sci.Foundation Sri Lanka 2014 42 (3): DOI: http://dx.doi.org/10.4038/jnsfsr.v42i3.7402 6+257&20081,&$7,21 $QWLR[LGDQW DFWLYLW\ DQG D QHZ EXWDQROLGH IURP WKH SULPLWLYH HQGHPLF genus Hortonia 5XNPDO5DWQD\DNH 1'DPLWK3HUHUD 1'1HGUD.DUXQDUDWQH 1'6\ULO$:LMHVXQGDUD 2*DYLQ&DUU3 'DYLG(:LOOLDPV 35D\PRQG-$QGHUVHQ 3DQG9HUDQMD.DUXQDUDWQH 1* 1 Department of Chemistry, Faculty of Science, University of Peradeniya, Peradeniya. 2 Royal Botanic Gardens, Peradeniya. 3 Department of Chemistry and Earth & Ocean Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1. 5HYLVHG-DQXDU\$FFHSWHG)HEXDU\ $EVWUDFW The antioxidant activity of MeOH and In this backdrop, further investigations of the chemical dichloromethane extracts of the leaves and their alkaloid and biological activity of the genus Hortonia , an fractions of the three representative species of the endemic endemic genus belonging to the family Monimiaceae genus Hortonia were evaluated using DPPH radical scavenging Juss, whose ancestors are considered to have bioassay. The results showed that the percentage yield of the RULJLQDWHG LQ *RQGZDQDODQG PLOOLRQ \HDUV basic compounds from all three species was very low. In ago (Somasekaram, 1997) have been reported in this general, the antioxidant activity of the leaf extracts and their study. Interestingly, its three representative species, H. acid washings was very low. It was also determined, contrary angustifolia , and H. ovalifolia exhibit to what had been reported, that the alkaloid boldine was + ÀRULEXQGD similar chemistry in addition to showing a similar leaf not found in detectable amounts in any of the acid washed fractions. Chemical investigations of the three species yielded morphology. However, a recent study based on the a new butanolide, which was characterized by NMR and mass evaluation of species of Hortonia E\ '1$ EDUFRGLQJ spectral data. KDVFRQ¿UPHGWKDWWKH\DUHLQGHHGWKUHHGLVWLQFWVSHFLHV (Rajapakse et al ., 2012). Previous studies have reported the .H\ZRUGV $QWLR[LGDQWDFWLYLW\EROGLQHEXWDQROLGH Hortonia presence of mosquito larvicidal lactones and butanolides angustifolia , +RUWRQLDÀRULEXQGD , Hortonia ovalifoli . (Ratnayake et al ., 2001; 2008a;b), antifungal ishwarane (Ratnayake et al ., 2008c) and cytotoxic hydrazulenones INTRODUCTION (Carr et al ., 2012) from all three species. It was recorded that the foliar parts of +ÀRULEXQGD The chemistry and biological activity of endemic plants contains boldine, which slows down the development DQGSODQWYDULHWLHVRI6UL/DQNDKDYHUHFHLYHGLQDGHTXDWH of fatty tissues (www.clarinsusa.com). Boldine, an DWWHQWLRQ $OWKRXJK 6UL /DQND SRVVHVVHV HQGHPLF aporphine alkaloid from Peumus boldus (Monimiaceae) SODQWV 'DVVDQD\DNH )RVEHUJ WKH is known for its antioxidant activity among the other progress on the evaluation of their therapeutic potential health promoting pharmacological properties. It has has been very slow (Bandara et al ., 1990; Hewage et al ., been reported in previous studies that compounds with 1997; 1998). The urgency for speedy investigations antioxidant activity were not isolated from all three was highlighted after the publication of hypoglycaemic Hortonia species. Hence it was decided to embark on activity of the plant Salacia reticulata Wight var. diandra a careful investigation of the leaf extracts of all three by a Japanese group and the potent hypoglycaemic Hortonia species for antioxidant activity and for the compounds from the aqueous extracts were patented presence of boldine. Since a preliminary investigation (Yoshikawa et al ., 1997). However, the organic extracts of indicated the presence of low antioxidant potential S. reticulata have been investigated by several scientists of H. angustifolia , an extensive investigation of this in Sri lanka before the Japanese group (Premakumara claim for the presence of boldine (Perera et al ., 2009) et al *XQDWLODND et al .,1993; Tezuka et al .,1993; was undertaken. Herein, the results of a comprehensive 1994; Dhanabalasingham et al ., 1996). study of the antioxidant activities of all three species of Hortonia have been reported. * Corresponding author ([email protected]) 280 Rukmal Ratnayake et al. 0(7+2'6$1'0$7(5,$/6 5(68/76$1'',6&866,21 During this study in September 2005, specimens of The results (Table 1) showed that the percentage yield of H. angustifolia , + ÀRULEXQGD and H. ovalifolia were basic compounds in general from all three species was collected from Kanneliya, Hakgala and the foothills of YHU\ORZ,QDGGLWLRQWKHSUHOLPLQDU\7/&DQDO\VLVRI $GDP¶V3HDN6UL/DQND H. angustifolia was collected the crude CH 2Cl 2 and MeOH extracts gave a negative at an altitude of 700 m, +ÀRULEXQGD was collected in response against Dragendroff’s reagent, indicating the montane forests above 1300 m, and H. ovalifolia WKH DEVHQFH RI VLJQL¿FDQW FRQFHQWUDWLRQV RI DONDORLGDO above 1600 m. Voucher specimens ( H. angustifolia 3'$ constituents in the plant. Importantly, a careful 1H 526; +ÀRULEXQGD 3'$ H. ovalifolia 3'$ 105DQDO\VHVRIWKHVHFUXGHH[WUDFWV PJLQP/ were deposited at the National Herbarium, Peradeniya, of CDCl XVLQJ D 9$5,$1 0+] VSHFWURPHWHU 6UL/DQND 3 failed to show the OCH 3 signals of boldine between įH±,WZDVUDWLRQDOL]HGWKDWLIEROGLQHZDVLQGHHG $LUGULHGDQGJURXQGOHDYHV J RIHDFKRIWKH present in reasonable quantities, the HCl wash would three species of Hortonia were subjected to sequential exhibit antioxidant activity. Therefore the focus of the extraction with CH Cl followed by MeOH in a bottle 2 2 investigation was shifted to determining the antioxidant shaker. The basic (or alkaloidal) constituents in the activity of the extracts. It has been reported that a very CH Cl DQG 0H2+ H[WUDFWV ZHUH H[WUDFWHG E\ OLTXLG 2 2 low concentration of boldine (IC = from 5 x 10 to 15 liquid partitioning by the incorporation of 6 N HCl. 50 x 10 ) can protect red blood cell plasma membranes The basic constituents in the aqueous HCl layer were liberated by the addition of 1 N NaOH and extracted into from antioxidant sensitive oxygen uptake (Speisky et al ., 1991). CH 2Cl 2. The resulting brownish coloured crude extracts (Table 1) from CH 2Cl 2 and MeOH extracts were analyzed for alkaloids. 7DEOH $QWLR[LGDQW DFWLYLW\ RI OHDI H[WUDFWV DQG DFLG washed fractions $LUGULHG DQG SRZGHUHG OHDYHV RI H. angustifolia o (650 g) were extracted with CH 2Cl 2 [P/ DW C for 24 h. The combined CH Cl extracts were concentrated 2 2 Plant Total antioxidant activity in vacuo to obtain a black oil (37.4 g), which was subjected $2$ a WRPHGLXPSUHVVXUHOLTXLGFKURPDWRJUDSK\ 03/& RQ VLOLFDJHO HOXHQWVWHSJUDGLHQWIURPKH[DQHVWR(W2$F H. angustifolia extracts to provide six fractions. The second fraction after MeOH 10.01 ± 0.13 IXUWKHU SXUL¿FDWLRQ E\ VLOLFD JHO ÀDVK FKURPDWRJUDSK\ CH 2 Cl 2 1.43 ± 0.30 (W2$FKH[DQHV \LHOGHG FRPSRXQG 1 (15 mg). $FLGH[WUDFW Compound 1ZDVIXUWKHUSXUL¿HGE\& 18 UHYHUVHGSKDVH MeOH 1.03 ± 0.04 +3/& &+ CN/H O). 3 2 CH 2 Cl 2 1.52 ± 0.13 +ÀRULEXQGD extracts 7DEOH Percentage yield of extracted basic material MeOH 9.03 ± 0.12 CH 2 Cl 2 1.83 ± 0.20 $FLGH[WUDFW a Plant extract Weight of Weight of <LHOG MeOH 1.10 ± 0.06 extract (g) crude basic CH 2 Cl 2 1.42 ± 0.03 extract (g) H. ovalifolia extracts H. angustifolia MeOH 8.64 ± 0.22 CH Cl 1.63 ± 0.10 CH2Cl 2 20.1 0.065 0.32 2 2 MeOH 19.2 0.300 1.58 $FLGH[WUDFW +ÀRULEXQGD MeOH 1.20 ± 0.12 CH Cl 18.4 0.048 2.60 2 2 CH 2Cl 2 1.33 ± 0.33 MeOH 16.2 0.249 1.53 $VFRUELFDFLG 78.74 ± 0.42 H. ovalifolia a The activities shown are the mean ± SD of 500 mg dm CH2Cl 2 21.7 0.077 0.35 MeOH 20.3 0.320 1.57 (ppm) concentrations of analyte solutions (concentration of DPPH used 1 × 10 mol dm ). a <LHOGEDVHGRQSODQWH[WUDFW September 2014 Journal of the National Science Foundation of Sri Lanka 42(3) Antioxidant activity and a new butanolide from genus Hortonia 281 Interestingly, it was observed that while the leaf MeOH >į & & + & extract of the plants exhibited moderate antioxidant + & + & @ DQG D activity (Table 2) in the DDPH radical scavenging assay GRXEOHERQG>į + & + /HH et al ., 2004), the acid wash of the plant extracts, & @FRQMXJDWHGWRDWHUPLQDOHWK\Q\OJURXS>į which would have contained boldine if it was present in & + & @ ERWK RI ZKLFK isolable quantities, showed negligible activity. Based on had been reported previously in the butenolide and the foregoing, it is reasonable to assume that the leaves butanolide compounds (Ratnayake et al ., 2001; 2008a). of the three species of the genus Hortonia do not contain 1DWXUDOO\ RFFXUULQJ ¿YH PHPEHUHG ULQJ FRPSRXQGV boldine at levels detectable by 1H NMR or revealed by continue to be of interest as synthetic targets (Piers & antioxidant activity. Karunaratne, 1983). Examination of the 2D NMR data for 1 7DEOH FRQ¿UPHGWKHVHDVVLJQPHQWVDQGVKRZHG In addition to reporting the lack of alkaloids with WKDWWKHĮȕXQVDWXUDWHGȖODFWRQHZDVFRQQHFWHGDWWKHĮ antioxidant activity such as boldine, we also describe SRVLWLRQ & WRWKHǻ 14,15ROH¿QWKURXJKDQDON\OFKDLQ the isolation of a new butenolide from the leaves of which had to contain 8 methylene carbons to satisfy the H. angustifolia . molecular formula of 17KH FRQ¿JXUDWLRQ RI WKHǻ 14,15 doubleҏ bond was determined to be Z based on both the The structures of a series of butenolides (Ratnayake coupling constant ( J = 10.9 Hz) and a strong NOESY et al ., 2001) and butanolides (Ratnayake et al ., 2008a;b) FRUUHODWLRQ EHWZHHQ + į DQG + į from extracts of the same three species of Hortonia Compound 1 was isolated from the CH 2Cl 2 extracts of have been reported previously. While butenolide 1 was the other two species, + ÀRULEXQGD and H. ovalifolia different from those reported previously it was noted under the same chromatographic conditions (as described that the molecular formula of C 17 H24 O2 consistent with above) in comparable yields. DQ >0 1D@ + ion at m/z 283.1673 in the HRESIMS, differed from that of (2 E,3 R,4 R,9’Z GRGHF¶ O 6 HQ¶\Q\OLGHQH K\GUR[\PHWK\OEXWDQROLGH 17 16 1 6 2 (Ratnayake et al ., 2008a) by the loss of an oxygen atom.