the distribution of the phenolic metabolites of aloe ...directory.umm.ac.id/data...

*Corresponding author. Fax: #972-7659-6742.E-mail address: [email protected] (Y. Gutterman)

Biochemical Systematics and Ecology 28 (2000) 825}838

The distribution of the phenolic metabolitesbarbaloin, aloeresin and aloenin as a peripheral

defense strategy in the succulent leaf partsof Aloe arborescens

Yitzchak Gutterman*, Elena Chauser-VolfsonJacob Blaustein Institute for Desert Research and Dept. of Life Sciences, Ben-Gurion University of the Negev,

Sede Boker Campus 84990, Israel

Received 22 June 1999; accepted 25 November 1999

Abstract

Aloe arborescens is a large, multi-stemmed shrub. It is used as hedge plants to protectagricultural "elds or stock and as horticultural plants in gardens. In natural habitats it is one ofthe very common Aloe species along the Indian Ocean coast of southern Africa, from the Cape,in the south, to Zimbabwe and Malawi in the north. Secondary phenolic metabolites such asbarbaloin (Rf 0.31}0.35), aloeresin (Rf 0.25}0.3) and aloenin (Rf 0.51}0.55) have been found tobe distributed in the succulent leaves of Aloe arborescens in a peripheral defense strategy. Theyoungest leaves have the highest content. The terminal third of each leaf has the highest contentand the basal third, the lowest. Along the leaf margins, on the top third and adaxial side, thecontent is the highest and in the base third, the lowest along the leaf center on the abaxial side.Similar relative amounts of these three secondary phenolic metabolites were found in thedi!erent leaf locations. The leaf orientation may a!ect the total content of these three phenolsbut not their relative amounts in the di!erent parts of the leaves. It is possible that the moreoften the plant parts are damaged by consumption by animals such as elephants, kudu orinsects, the greater the increase of their phenolic metabolites. This increase may reduce orprevent further consumption when the content of the metabolites reaches a certain level. Theplants then have a chance to renew themselves. ( 2000 Elsevier Science Ltd. All rightsreserved.

Keywords: Aloenin; Aloeresin; Aloe; Barbaloin; Peripheral defense; Leaves; Phenolic metabolites

0305-1978/00/$ - see front matter ( 2000 Elsevier Science Ltd. All rights reserved.PII: S 0 3 0 5 - 1 9 7 8 ( 9 9 ) 0 0 1 2 9 - 5

1. Introduction

The genus Aloe contains about 150 species in South Africa of which the majority aredesert plants from the Karoo Desert, and there are many more on the Africancontinent (Reynolds, 1966, 1982; Court, 1981). Some of these species are trees that are5 m or taller, but the majority are shrubs 0.5}1.5 m high, and some are very smallplants measuring a few cm (van Wyk and Smith, 1996).

Aloe arborescens Miller (Aloaceae) (" Liliaceae) is very common in large areas ofnatural habitat. It is one of the very common Aloe species in natural habitats along theIndian Ocean coast of southern Africa, from the Cape, in the south, to Zimbabwe andMalawi in the north. It is probably the most widely cultivated species of the genusAloe in the world. It is used as hedge plants to protect agricultural "elds or stock andas horticultural plants in gardens (van Wyk and Smith, 1996).

This plant is a conglomerate of medium to large shrubs that are usually multi-stemmed, at or near ground level. The leaves are curved and are soft in texture withrather harmless marginal teeth (van Wyk and Smith, 1996). A. arborescens plants havebeen widely used for medicines and cosmetics and their chemical constituents havebeen studied (Hay and Haynes, 1956; Kudritskaya et al., 1985; Takayuki andToshifumi, 1983; Sato et al., 1990). The leaves of this plant were successfully used totreat X-ray burns in South Africa when A. vera was not available (Lowenthal, 1949).Barbaloin and aloenin may have an anti-allergic e!ect in addition to an anti-in#ammatory e!ect in vivo (Nakagomi et al., 1987).

The rapid development of natural product chemistry has led to the isolation ofa wide variety of secondary metabolites, which in many cases were shown to be ofglycoside nature or glycosyl phenols. Thus, C-glycosyl phenols presently known haveonly been found in Aloe species, an observation of unique chemotaxonomic signi"-cance for Aloe species (Franz and GruK n, 1983).

In previous studies we have examined the distribution of the secondary phenolicmetabolites such as homonataloin in A. hereroensis, anthrone C-glycosides in theleaves of A. mutabilis and barbaloin in A. arborescens leaves. The distributiondepends on the leaf part, age and position of the leaf on the plant, the leaf orientationas well as seasonal in#uences (Chauser-Volfson and Gutterman, 1996, 1997, 1998;Gutterman and Chauser-Volfson, 2000). As a continuation of that investigationwe have now studied the distribution of the phenolic metabolites barbaloin, andaloeresin and aloenin in the leaves of A. arborescens according to leaf part andorientation.

The glycosyl phenols barbaloin, aloeresin and aloenin are considered to be the mostspeci"c secondary products in TLC screenings of Aloe plants (Fig. 1). Using TLC-analysis/separation, we determined the di!erent phenolic metabolites in developmen-tal solvent (Hirata and Suga, 1978; Speranza et al., 1985).

Barbaloin and aloeresin (C-glycosides) are found in Aloe species widely distributedin South Africa (Reynolds, 1985). It is known that aloeresin has a number of di!erentisomers, which is interesting from the scienti"c and applied point of view (Speranzaet al., 1986, 1988). Aloenin (O-glycoside) is found mainly in A. arborescens and in fewerAloe species than barbaloin and aloeresin. One of the main characteristics of

826 Y. Gutterman, E. Chauser-Volfson / Biochemical Systematics and Ecology 28 (2000) 825}838

C-glycosides is resistance to acid hydrolysis. Even after prolonged acid treatment, thesugar residue, which is attached by a carbon}carbon bond, remains attached to theaglycone. Cleavage of the C}C linkage is achieved only under drastic conditions.C-glycosidic bonds are always prior to O-glycosylation. Radioactivity was not incorp-orated in #avones containing C-glycosyl linkages (Franz and GruK n, 1983; Nakanoet al., 1985).

Barbaloin (Rf 0.31}0.35) was "nally characterized as 10b-D-glucopyranosyl-1,8-dihydroxy-3-hydroxymethyl-9(10-H)-anthracenone (Hay and Haynes, 1956; Conneret al., 1989; Yuko et al., 1990). Barbaloin gives o! yellow #uorescence. Aloeresin(Rf 0.25}0.3) is characterized as, 2-acetonyl-8-C-D-glycopyranosyl-7-hydroxy-5-methylchromone and aloenin (Rf 0.51}0.55) as, 4-methoxy-6[10-hyudroxy-12methyl-8-O-D-glycopyranosyl] phenyl-pyrone-2 (Speranza et al., 1985, 1986) and both giveblue-white #uorescence.

Barbaloin has been found to have a strong inhibitory e!ect on histamine releasefrom mast cells, while aloenin has a weak inhibitory e!ect. The inhibitory e!ect ofbarbaloin is much higher than that of a potent anti-in#ammatory drug, Indomethacin(Nakagomi et al., 1987). These results indicate that aloenin and barbaloin havedi!erent active sites at mast cells. Barbaloin demonstrates anti-in#ammatory andcathartic e!ects in vivo (Nakagomi et al., 1985)

The aim of this study was to determine the distribution and content of the threesecondary phenolic metabolites, barbaloin, aloeresin and aloenin, in A. arborescensleaves according to leaf part and orientation.

2. Materials and methods

The A. arborescens multi-branched shrubs, originating from South Africa, aregrowing in the Introduction Garden of the Jacob Blaustein Institute for DesertResearch at Sede Boker, in the Negev Desert of Israel (34346@ E 30351@ N, 460 m a.s.l.).The Aloe arborescens leaves used in these tests were taken from shrubs that haddeveloped from cuttings planted 15 years ago. They grow in loess soil with theaddition of cow manure and drip irrigation equivalent to 600 mm of rain, in additionto the annual average rainfall of about 100 mm.

2.1. Method of analysis

After harvesting the A. arborescens leaves, the exudate was collected from each partof each leaf, using a hand press, and freeze-dried immediately (using Freezemobile`Virtisa) in vacuo. The freeze-dried powder was analyzed.

Samples (5}15 mg) of powder were dissolved in 1}1.5 ml methanol and were appliedto pre-coated TLC plates, silica gel on polyester (20]20 cm2). After drying, the plateswere placed in the TLC glass developing tank with solvent: ethyl acetate}meth-anol}water (100:16.5:13.5 v/v). After division and separation of barbaloin (Rf0.31}0.35), aloeresin (Rf 0.25}0.3) and aloenin (Rf 0.51}0.55) from the plates, these

Y. Gutterman, E. Chauser-Volfson / Biochemical Systematics and Ecology 28 (2000) 825}838 827

Fig. 1. Constitutional formula and absorption spectrum of phenolic secondary metabolites: (A) aloenin, (B)aloeresin, (C) barbaloin, at the wavelength range from 190 to 820 nm in MeOH (mg/ml). The concentrations(mg/bl) and absorption peaks are de"ned.

compounds were eluated with an exact volume of methanol, from 3}15 ml, dependingon the percentage of the compound in a tested sample. The absorbance was measuredat the j

.!9: 360}362 nm, 300}302 nm and 306}308 nm, respectively. The content of

the three compounds was determined using three calibration curves (Diode arraySpectrophotometer, Hewlett-Packard 8452-A) (Fig. 1).

Traces of two other secondary phenolic metabolites were also found but as theirhighest content was below 1% it was not determined quantitavely.

Signi"cance was determined by one-way ANOVA Fisher PLSD and Sche!e F-testsat 95% (Sokal and Rohlf, 1981).


Fig. 2. Leaf orientation and section; (I) All leaves are oriented upright when they start to grow; (II) Later,some leaves bend downwards; (III) and other leaves become horizontally oriented. Four leaves each ofupright- downward bending and horizontal-oriented leaves were harvested on 18 May 1998 and cut intothree parts: (T) terminal third; (M) middle third; (B) base third. Each of these parts was cut again into twolongitudinal parts: the adaxial (ad) and abaxial (ab). (In the horizontal leaf the adaxial side is the upper sideof the leaf). Each of these parts was weighed and the barbaloin content was determined (Fig. 3).

2.2. The content of the three phenolic metabolites in the adaxial and abaxial half of theleaf, in the terminal, middle and base parts and according to leaf orientation

Di!erently oriented leaves were harvested on 18 May 1998 (1) upright leaves, as allleaves are oriented when they start to grow, (2) leaves bending downwards and (3)leaves horizontally oriented. Each leaf was cut into 6 parts: (T) terminal third; (M)middle third; (B) base third. Each of these parts was cut again into two parts: theadaxial (ad) and abaxial (ab) (in the horizontal leaf the adaxial side is the upper side ofthe leaf) (Fig. 2).

Leaves of similar size and weight were chosen in each of the three groups of fourleaves used to obtain the results. Each part was weighed and the barbaloin, aloeresinand aloenin content was determined (Fig. 3).


Fig. 3. Average leaf weight (g$s.e.) and content (%) of barbaloin, aloeresin and aloenin of dry weight ofleaf exudate of four Aloe arborescens leaves according to section: T."tip, M."middle, B."base;ad."adaxial orientation; ab."abaxial orientation, of upright, downward or horizontally oriented leaves(Fig. 2).

2.3. The content of the three phenolic metabolites in the marginal and central parts of theleaf, in the terminal, middle and base parts in upright or downward leaf orientation

Five upright and "ve downward bending leaves were harvested on 9 June 1998for the second experiment. They were "rst cut into three parts: terminal (T),middle (M) and base (B). Each of these parts was cut into three parts:central (c) and two side parts (s) along the leaf margins (Fig. 4). Each of theseparts was weighed and the content of the three phenolic metabolites was determined(Fig. 5).

2.4. The content of the three phenolic metabolites in upright- or downward-orientedleaves cut into 18 parts

Three upright and three downward bending leaves were harvested on 24 June 1998and cut into nine parts as in the experiment on 9 June (Fig. 4), but each of the 9 partswere also cut into two parts, the adaxial and abaxial, as in the "rst experiment (Fig. 6).


Fig. 4. Five upright leaves and "ve downward-bending leaves were harvested on 9 June 1998, and "rst cutinto three parts, as in Fig. 2: terminal (T), middle (M) and base (B). In this experiment, each of these partswas cut into three longitudinal parts: central (c) and two side parts (s) along the leaf margins. Each of theseparts was weighed and the barbaloin, aloeresin and aloenin content was determined (Fig. 5A}D).

These 18 parts were weighed and the content of the three phenolic metabolites wasdetermined (Fig. 7).

3. Results

3.1. The content of the three phenolic metabolites in the adaxial and abaxial half of theleaf, in the terminal, middle and base parts and according to leaf orientation

The content of all three phenolic metabolites, barbaloin, aloeresin and aloenin, inthe adaxial side of the leaves was higher than in the abaxial side, both in the upright,downward or horizontal oriented leaves.

In the upright leaves the phenolic metabolite content in all the parts was the highestcompared with the horizontal leaves in which it was the lowest. An intermediatephenolic metabolite content was found in all the respective leaf parts of the downwardbending leaves (Figs. 2 and 3).


Fig. 5. Average barbaloin, aloeresin and aloenin content (%) of dry weight of (A) "ve upright and (B) "vedownward-bending leaves. Average weight (g$s.e.) of (C) the "ve upright and (D) the "ve downwardbending leaves, as in Fig. 4.

The leaf orientation has an e!ect on the content of these three phenolic metabolitesin the whole leaf as well as the leaf parts; top vs. middle and base, as well as the adaxialvs. abaxial side. (Fig. 3).

In a previous study it was found that the terminal third of each leaf contained thehighest barbaloin content and the base third of each leaf the lowest (Gutterman andChauser-Volfson, 2000). In this study, the terminal parts were found to have signi"-cantly higher phenolic metabolite content (P"0.0001), reaching a maximum ofbarbaloin 23.2$1.1%, aloeresin 19.5$1%, aloenin 10.5$0.4% and the minimumcontent was found in basal leaf parts (barbaloin 2.7$0.1%, aloeresin 2.2$0.1%,aloenin 1.1$0.1%) (Figs. 2 and 3).


Fig. 6. As in Fig. 4, but three upright and three downward-bending leaves were harvested on 24 June 1998and each of the nine parts was also cut into two parts, to the adaxial and abaxial halves. The barbaloin,aloeresin and aloenin content of each of the 18 parts was determined (Fig. 7).

3.2. The content of the three phenolic metabolites in the marginal and central parts of theleaf, in the terminal, middle and base parts in upright or downward leaf orientation

In all the leaf parts, along the leaf margins (side parts) the content of phenolicmetabolite was signi"cantly higher according to the di!erent leaf parts (fromP"0.0034}0.0001), e.g. the top of the downward-oriented leaves contained barbaloin18.1$1.1%, aloeresin 15.0$0.9%, aloenin 11.6$0.8%) in comparison to the paral-lel central part (13.4$1.3%, 12.4$1.1% and 6.4$0.5%, respectively). In all theleaves tested, the content of all three phenolic metabolites was higher in the parts ofthe downward bending leaves in comparison with the respective leaf parts of theupright leaves. In the top marginal thirds (T.s.) the barbaloin content was highest andin the base center third (B.c.) the lowest (Figs. 4 and 5).

3.3. The content of the three metabolites in upright- or downward-oriented leaves cut into18 parts

In leaves that were cut into 18 parts (Fig. 6), a signi"cantly higher (P"0.0001)phenolic metabolite content was found in the side parts along the margins of theadaxial terminal parts. For example in downward oriented leaves the content was:barbaloin 18.8$0.8%, aloeresin 15.4$0.8%, aloenin 12.8$0.9%). The lowestcontent was found in the center base adaxial parts (barbaloin 2.4$0.2%, aloeresin2.4$0.2%, aloenin 1.0$0.3%) (Fig. 7).


Fig. 7. Barbaloin, aloeresin and aloenin content as a percentage of the dry weight of three A. arborescensleaves, (A) downward or (B) upward oriented, cut into 18 parts, according to Fig. 6.

In all the equivalent side parts along the margins, the phenolic metabolite contentof the adaxial parts was higher in comparison to their abaxial counterparts. Thisphenomenon was similar in the upright leaves and the down bending leaves. However,


in all the equivalent side parts in the down bending leaves the phenolic compoundcontent was higher (Fig. 7).

In all the central parts the opposite results were found. The content of thephenolic metabolites in the abaxial parts was signi"cantly higher (P"0.0001) thanthe parallel adaxial parts. Therefore, the terminal abaxial parts had the highestphenolic metabolite content of all the central parts (barbaloin 15.9$0.7%, aloeresin12.2$0.4%, aloenin 7.3$0.1%) and the basal adaxial parts the lowest (2.4$0.2%,2.3$0.1%, 1.0$0.03%, respectively), in upright- or down-bending leaves. In theparts from the center of the down-bending leaves the phenolic metabolite content washigher in the terminal and middle thirds either in the abaxial parts or in the adaxialparts in comparison with the parallel parts in the upright leaves. This was not found inthe basal parts (Figs. 6 and 7).

4. Discussion

The barbaloin or homonataloin content in di!erent Aloe species is higher in youngleaves than in older leaves (Birch and Donavan, 1955; Takayuki and Toshifumi, 1983;Nakagomi et al., 1985; Groom and Reynolds, 1987; Yamamoto et al., 1991; Chauser-Volfson and Gutterman, 1996, 1997, 1998). The terminal third of the leaves has thehighest percentages of these secondary metabolites and the leaf base third, the lowest(Chauser-Volfson and Gutterman, 1996, 1997, 1998).

By testing the barbaloin content in 18 leaf parts of Aloe arborescens, it was foundthat the localized barbaloin content in each particular leaf part di!ers signi"cantly.The barbaloin content is much higher along the leaf margins in all three thirds of theleaves in comparison with the centre counterparts. In the sides, along the margins, theadaxial part contains more barbaloin than the abaxial counterparts. The opposite istrue in the central parts of the leaves (Gutterman and Chauser-Volfson, 2000).

In the leaf vascular bundles there are aloin cells that are thin-walled secretory cellsthat surround the vascular bundles at the phloem side (Cutler, 1972; Cutler et al., 1980).Typically, in these cells yellowish globules are visible (Beaumont et al., 1986), which maycontain secondary metabolites. According to the results of the present study, barbaloin,aloeresin and aloenin are distributed in di!erent parts of the leaves in similar relativeamounts. In locations with signi"cantly higher barbaloin content, the amounts ofaloeresin and aloenin are also relatively higher. In leaf parts where the barbaloin contentis lower the content of aloeresin and aloenin is also relatively lower. In almost all the leafparts the barbaloin content was the highest and the aloenin the lowest (Figs. 2}7).

Some major questions have arisen from this study. What are the anatomicalstructures and functions enabling the pronounced peripheral distribution of thesecondary phenolic metabolites, barbaloin, aloeresin and aloenin? It is possible thatthese metabolites accumulate in the aloin cells (Cutler, 1972; Cutler et al., 1980;Beaumont et al., 1986), and, therefore, the content of barbaloin, aloeresin and aloeninvaries signi"cantly in di!erent close locations in the leaf. In some locations these threemetabolites together may reach 52% of the dry weight of the leaf and in otherlocations only 6%. Are these three phenolic metabolites connected to the same


biochemical cycles and located in the same aloin cells? What is the ecologicaladvantage of the massive production of all three of these metabolites rather than onlyone of them? Why are these three metabolites produced in similar relative amounts inthe di!erent locations within one leaf? (Figs. 1}7).

In short, what a!ected the evolutionary responses to cause the development of theperipheral distribution of these three phenolic metabolites and what are the ecologicaladvantages for these plants? Are they to reduce the chance of adaptation of leaf eaterssuch as insects or attack by pathogens? The chance of the leaf consumer to adapt tothree di!erent metabolites is much lower than adaptation to only one (Feeny, 1992;Govindachari, 1992; Aerts and Mordue, 1997; Jarvis et al., 1997).

Bennett and Wallsgrove (1994) found that several classes of secondary products inplants are induced by wounding herbivory or infection. In Atropa acuminata(Solanaceae) the secondary metabolites have increased by 153% and up to 186% onrepeating the leaf damage (Khan and Harborne, 1991; Harborne, 1997). In Nicotianasylvestris (Solanaceae) the nicotine alkaloid production increases to 400% of controllevels after leaf damage and 286% after lepidopteran feeding (Baldwin, 1988). A sim-ilar phenomenon was found in A. arborescens. The more often a cutting was takenfrom the same leaf at intervals of one month, the gradually higher the content ofbarbaloin in the new growth of the leaf and the larger the new growth per month.Within three months the barbaloin content of the leaves growing from the same pointon the plant increased from 11.8 to 20% to 25.8 to 37%, more than three-fold(Gutterman and Chauser-Volfson, 2000).

This may prevent leaf eaters from consuming the leaves of plants that had pre-viously been damaged. Animals may prefer to eat leaves of plants that had not beentouched for a relatively long time and in which the barbaloin content is low. This givesthe plant time to recover between occasions when it is damaged by consumption. Ithas been seen that leaves originally palatable to feeding by a generalist insect, such asthe armyworm Spodoptera uridania become unpalatable a few days after such damage(Edwards and Wratten, 1983).

Plants develop secondary metabolites that accumulate as a response to pathogenicmicro-organisms and herbivory. It has been demonstrated that jasmonic acid and itsderivatives in the intracellular signal cascade begins with interaction of an elicitormolecule with the plant cell surface (Gundlach et al., 1992; Sembdner and Parthier,1993; Aerts et al., 1994; Staswik, 1995; Egan et al., 1996; Solecka, 1997).

The present study raises some further questions. Is there a response in A. arborescensto damage of one or some leaves, in a certain direction in the whole branch or plant, oris there only a local response in the new growth of a particular leaf or leaves that were cut?In order to answer these questions, further sets of experiments need to be carried out.

From Figs. 3, 5 and 7 it can be seen that the higher content of these three metabolitesis distributed in a peripheral defense strategy. The ecological signi"cance of the peri-pheral defense strategy of the distribution of the secondary phenolic metabolites in thesucculent leaves of A. arborescens needs to be studied in the natural habitats of theseplants in South Africa. The biochemical functions involved in the accumulation of thesemetabolites, as well as the anatomical structure of the aloin cells and tissues where thesethree di!erent metabolites are synthesized and accumulate, also require further study.


Acknowledgements

The authors wish to thank Frieda Gilmour for her comments and help in preparingthis paper.

References

Aerts, R.J., Gisi, D., De Carolis, E., De Luca, V., Baumann, T.W., 1994. Methyul jasmonate vapor increasesthe developmentally controlled synthesis of alkaloids in Catharanthus and Cinchona seedlings. PlantJournal 5, 635}643.

Aerts, R.J., Mordue, A.J., 1997. Feeding deterrence and toxicity of neem triterpenoids. J. Chem. Ecol. 23,2117}2132.

Baldwin, I.T., 1988. The alkaloidal responses of wild tobacco to real and simulated herbivory. Oecologia 77,378}381.

Bennett, R.N., Wallsgrove, R.M., 1994. Tansley review No. 72: Secondary metabolites in plant defencemechanisms. New Phyt. 127, 617}633.

Beaumont, J., Cutler, D.F., Reynolds, T., Vaughan, J.G., 1986. Secretory tissues in the East African shrubbyaloes. Bot. J. Lin. Soc. 92, 399}403.

Birch, A.J., Donavan, F.W., 1955. Barbaloin. Austr. J. Chem. 8, 523}528.Chauser-Volfson, E., Gutterman, Y., 1996. The barbaloin content and distribution in Aloe arborescens

leaves according to the leaf part, age, position and season. Isr. J. Plant Sci. 44, 289}296.Chauser-Volfson, E., Gutterman, Y., 1997. Content and distribution of the secondary phenolic compound

homonataloin in Aloe hereroensis leaves according to leaf part, position and monthly changes. J. AridEnv. 37, 115}122.

Chauser-Volfson, E., Gutterman, Y., 1998. Content and distribution of anthrone C-glycosides in the SouthAfrican arid plant species, Aloe mutabilis, growing in direct sunlight and in shade in the Negev Desert ofIsrael. J. Arid Env. 40, 441}451.

Conner, J.M., Gray, A.I., Reynolds, T., Waterman, P.G., 1989. Anthracene and Chromone derivatives in theexudate of Aloe rabaiensis. Phytochem. 28, 3551}3553.

Court, D., 1981. Succulent Flora of Southern Africa. Balkema, Rotterdam.Cutler, D.F., 1972. Leaf anatomy of certain Aloe and Gasteria species and their hybrids. In: Ghouse, AK.M.,

Yunus, M. (Eds.), Research Trends in Plant Anatomy. Tata McGraw Hill, New Delhi, pp. 103}122.Cutler, D.F., Brandham, P.E., Carter, S., Harris, S.J., 1980. Morphological, anatomical, cytological and

biochemical aspects of evolution in East African shrubby species of AloeK L. (Liliaceae). Bot. J. Lin. Soc.80, 293}317.

Edwards, P.J., Wratten, S.D., 1983. Wound-induced defenses in plants and their consequences for patternsin insect grazing. Oecologia 59, 88}93.

Egan, T.P., Danielson, N.D., Gorchov, D.L., 1996. E!ects of wounding on taxol and baccatin III levels inTaxus media cv Hicksii. Ohio J. Sci. 96, 41}44.

Feeny, P., 1992. The evolution of chemical ecology: contributions from the study of herbivorous insects. In:Rosenthal, G.A., Berenbaum, M.R. (Eds.), Herbivores: their Interaction with Secondary Plant Metab-olites, 2nd Edition. Academic Press, San Diego, pp. 1}44.

Franz, G., GruK n, M., 1983. Chemistry, occurrence and biosynthesis of C-glycosyl compounds in plants.Planta Med. 47, 131}140.

Govindachari, T.R., 1992. Chemical and biological investigations on Azadirachta indica (the neem tree).Current Sci. (Bangalore) 63, 117}122.

Groom, Q.J., Reynolds, T., 1987. Barbaloin in Aloe species. Planta Med. 53, 345}348.Gundlach, H., Mueller, M.J., Kutchan, T.M., Zenk, M.H., 1992. Jasmonic acid is a signal transducer in

elicitor-induced plant cell cultures. Proc. Nat. Acad. Sci. USA 89, 2389}2393.Gutterman, Y., Chauser-Volfson, E., 2000. A peripheral defense strategy by varying barbaloin content in the

succulent leaf parts of Aloe arborescens Miller (Liliaceae). Bot. J. Lin. Soc. (in press).


Harborne, J.B., 1997. Plant secondary metabolism. In: Crawley, M.J. (Ed.), Plant ecology, 2nd Edition.Blackwell Science, Oxford, pp. 132}155.

Hay, J.E., Haynes, L.J., 1956. The aloins. Part 1. The structure of barbaloin. J. Chem. Soc., 3141}3147.Hirata, T., Suga, T., 1978. Structure of Aloenin, new biologically-active bitter glucoside from Aloe

arborescens var. natalensis. Bull. Chem. Soc. Japan 51, 842}849.Jarvis, A.P., Johnson, S., Morgan, E.D., Simmonds, M.S.J., Blaney, W.M., 1997. Photooxidation of nimbin

and salannin, tetranortriterpenoids from the neem tree (Azadirachta indica). J. Chem. Ecol. 23, 2841}2860.Khan, M.B., Harborne, J.B., 1991. Induced alkaloid defence in Atropa acuminata in response to mechanical

and herbivore leaf damage. Chemoecology 1, 77}81.Kudritskaya, S.E., Fishman, G.M., Zagorodskaya, L.M., Chikovani, D.M., 1985. Aloe arborescens caro-

tenoids. Khimia Prirodnich Soedinenies 4, 573.Lowenthal, L.J.A., 1949. Species of Aloe (other than Aloe vera) in the treatment of Roentgen dermatitis. J.

Invest. Derm. 12, 295}298.Nakagomi, K., Oka, S., Tomizuka, N., Jamamoto, M., Masui, T., Nakazawa, H., 1985. Novel biological

activities of aloe components. E!ects on mast-cell degranulation and platelet aggregation. KenkyuHokoku } Kogyo Gijutsuin Bisibutsu Kogyo 63, 3}9 (Japan).

Nakagomi, K., Yamamoto, M., Tanaka, H., Tomizuka, N., Masui, T., Nakazawa, H., 1987. Inhibition ofaloenin and barbaloin of histamine release from rat peritoneal mast cells. Agric. Biol. Chem. 51,1723}1724.

Nakano, M., Yamagishi, T., Takahashi, T., Kaneshima, H., 1985. Analysis of plant components incosmetics. 1. Determination of aloenin, a component of Aloe arborescence Mill., in lotion. Hok-kaidoritsu Eisei Kenkyushoho 35, 98}101 (Japan).

Reynolds, G.W., 1966. The Aloes of Tropical Africa and Madagascar. The Aloes Book Fund, Mbabane,Swaziland.

Reynolds, G.W., 1982. The Aloes of South Africa, 4th Edition. Balkema, Rotterdam.Reynolds, T., 1985. Observations on the phytochemistry of the Aloe leaf-exudate compounds. Bot. J. Lin.

Soc. 90, 179}199.Sato, Y., Ohta, S., Shinoda, M., 1990. Studies on chemical protectors against radiation. XXXI. Protection

e!ects of Aloe arborescens on skin injury induced by x-irradiation. Yakugaku Zasshi 110, 876}884.Sembdner, G., Parthier, B., 1993. The biochemistry and the physiological and molecular actions of

jasmonates. Ann. Rev. Plant Phys. & Plant Biol. 44, 569}589.Sokal, R.R., Rohlf, E.J., 1981. Biometry. Freeman, San Francisco, CA.Solecka, D., 1997. Tole of phenylpropanoid compounds in plant responses to di!erent stress factors. Acta

Physiol. Plant. 19, 257}268.Speranza, G., Dada, G., Lunazzi, L., Gramatica, P., Manitto, P., 1986. Aloenin B, a new diglucosylated

6-phenyl-2-pyrone from Kenya Aloe. J. Nat. Prod. 49, 800}805.Speranza, G., Gramatica, P., Dada, G., Manitto, P., 1985. Aloeresin C, a bitter C,O-diglucoside from Cape

Aloe. Phytochem. 24, 1571}1573.Speranza, G., Martignoni, A., Manitto, P., 1988. Iso-Aloeresin A, a minor constituent of Cape Aloe. J. Nat.

Prod. 51, 588}590.Staswik, P.E., 1995. Jasmonate Activity in Plants. Kluwer, Dordrecht.Takayuki, S., Toshifumi, H., 1983. The e$cacy of the Aloe plants, chemical constituents and biological

activities. Cosmetics and Toiletries 98, 105}108.van Wyk, B.-E., Smith, G., 1996. Guide to the Aloes of South Africa. Briza Publications, Pretoria.Yamamoto, M., Masui, T., Sugiyama, K., Yokota, M., Nukagomi, K., Nakazawa, H., 1991. Anti-in#ammat-

ory active constituents of Aloe arborescens Mill. Agric. Biol. Chem. 55, 1627}1629.Yuko, A., Toshiniko, H., Asuka, N., Kenji, Y., 1990. Development of crude drug analysis by liquid

chromatography, and UV and MS spectrometers. J. Liq. Chrom. 13, 2449}2464.


the distribution of the phenolic metabolites of aloe ...directory.umm.ac.id/data...

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