An Overview: Pharmacognostic Properties of Phyllanthus amarus Linn.
Phyllanthus amarus (Euphorbiaceae) is a widely distributed small erect, tropical annual herbal whose stem has green capsule and grows upto 10-60 cm tall. The plant is bitter, astringent, cooling, diuretic, stomachic, febrifuge and antiseptic. It is popular in indigenious system of medicine like ayurveda, siddha, unani and homoeopathy and is used for its hepatoprotective, antitumour, antidiabetic, antihypertensive, analgesic, anti-inflammatory and antimicrobial properties. The plant is also used in dropsy, jaundice, diarrhoea, dysentery, intermittent fevers, diseases of urino-genital system, scabies, ulcers, wounds and cold. Its has a good anti-viral activity against hepatitis B virus. It also has anti- nociceptive and anti- inflammatory activities, antidiabetic and antilipidemic potentials. The present review is therefore, an effort to give a detailed survey of the literature on its pharmacological, traditional and phytochemical properties.
Received: July 13, 2010;
Accepted: August 21, 2010;
Published: November 16, 2010
The Phyllanthus genus of the family Euphorbiaceae was first identified
in Central and Southern India in 18th century. It is commonly called carry me
seed, stone-breaker, windbreaker,gulf leaf flower or gala of wind (Bharatiya,
1992).There are over 300 genera with over 5000 species in the Euphorbiaceae
worldwide. The Phyllanthus is one of the genus that falls under this
enormous family. Phyllanthus has about 750-800 species, found in tropical
and subtropical regions worldwide. Green medicine is safe and more dependable
than the costly synthetic drugs, many of which have adverse side effects (Joseph
and Raj, 2010a). The use of medicinal plants by man for the treatment of
diseases has been in practice for a very long time. Screening of compounds obtained
from plants for their pharmacological activity has resulted in the isolation
of innumerable therapeutic agents. P. amarus is an erect annual herb
of not more than one and half feet tall and has small leaves and yellow flowers.
In folk medicine P. amarus has reportedly been used to treat jaundice,
diabetes, otitis, diarrhoea, swelling, skin ulcer, gastrointestinal disturbances
and blocks DNA polymerase in the case of hepatitis B virus during reproduction
(Oluwafemi and Debiri, 2008). The beneficial medicinal
effects of plant materials typically result from the combinations of secondary
products present in the plant (Joseph and Raj, 2010b).
Several compounds including alkaloids, flavonoids, lignans, phenols and terpenes
were isolated from this plant and some of them interact with most key enzymes.
In traditional medicine, it is used for its hepatoprotective, anti-diabetic,
antihypertensive, analgesic, anti-inflammatory and antimicrobial properties
(Adeneye et al., 2006a, b).
Phyllanthus amarus leaf extract as a hepatoprotective agent. The plant
is also used in the treatment of stomach disorders, skin diseases and cold (Kokwaro,
1976; Iwu, 1993). It has anti-diarrhea effect (Odetola
and Akojenu, 2000). Its anti-viral activity against hepatitis B virus has
been established (Thyagarajan et al., 1988;
Wang et al., 1995) anti-carcinogenic (Joy
and Kuttan, 1998) and antimutagenic activities (Joy
and Kuttan, 1998). It also has anti-nociceptive and anti-inflammatory activities
(Kassuya et al., 2003) antidiabetic and antilipidemic
potentials (Adeneye et al., 2006a, b).
Phyllanthus amarus has been reported to include antioxidant, antiviral,
antibacterial, hypoglycemic, cancer suppressive and anthelmintic effects (Fig.
1). This study was aimed to present an overview of pharmacological, traditional
and phytochemical investigations of bioactive compounds present in this plant.
|| Phyllanthus amarus
|| Jamgli amli, Jaramla
Habit and habitat: A herb that grows upto 10-60 cm tall, erect, stem
terete, younger parts rough, leaf 3.0-11.0x1.5-6.0 mm, elliptic oblong to obvate,
Flowers axillary, proximal 2-3 axils with unisexual 1-3 male flowers and all
succeeding axils with bisexual cymules. Male flowers -pedicel 1 mm long, calyx
5, oblong, elliptic, apex acute, hyaline with unbranched mid rib; disc segments
5, rounded, stamens 3, filaments connate. Female flowers-pedicel 0.8-1.0 mm
long, calyx lobes 5, lobes often toothed at apex, styles 3, free, shallowly
bifid at apex. seeds about 0.9 mm long, triangular with 6-7 longitudinal ribs
and many transverse striations on the back (Bagchi et
al., 1992). It is widely spread throughout the tropics and subtropics
in sandy regions as a weed in cultivated and wastelands (Ross,
Traditional uses: Phyllanthus has been used in Ayurvedic medicine for over 2,000 years and has a wide number of traditional uses. This includes employing the whole plant for jaundice, gonorrhea, frequent menstruation and diabetes and using it topically as a poultice for skin ulcers, sores, swelling and itchiness. The plant is bitter, astringent, cooling, diuretic, stomachic, febrifuge and antiseptic. It is useful in dropsy, jaundice, diarrhoea, dysentery, intermittent fevers, diseases of urino-genital system, scabies ulcers and wounds. The young shoots of the plant are administered in the form of an infusion for the treatment of chronic dysentery. Its efficacy in the field of gastro intestinal disorders like dyspepsia, colic, diarrhoea, constipation and dysentery is undisputed. In females it is used as a galactogogue, in leucorrhoea, menorrhagia and mammary abscess. In skin conditions, especially scabby or crusty lesions, bruises, wounds, scabies, offensive ulcers and sores, oedematous swellings, tubercular ulcers and ringworm, it has been utilized with good effect since many years. It is applied effectively in intermittent fevers and gonorrhoea as well as in ophthalmia and conjunctivitis. It has a urolithic property, dissolving renal calculi. Also, used in cough, asthma and other bronchial affections. Its antifungal, antiviral and anticancerous properties have also been demonstrated in experimental animals. The powdered leaves of Phyllanthus amarus (Bahupatra) were used in clinical studies evaluating its usefulness in patients suffering from chronic damage to the liver due to the protracted hepatitis B virus infection. This type of infection results in inability of the bodys immune system to eliminate the virus from the liver cells. This condition is described as a carrier state, because a continuously harbors the virus. Some of the components of the virus detectable in the carrier state in the blood are: HBsAg or the surface antigen of the virus and HBeAg or the envelope antigen of the virus. In addition, the carrier state may be confirmed by the presence of antibodies directed against the core of the virus or the anti-HBc antibodies. The powdered leaves of P. amarus were given in form of capsules to the patients with chronic viral hepatitis B in a dose of 200 mg three times a day for 30 days. P. amarus treated patients tested negative for the viral antigen 15-20 days after the end of the treatment. Due to its antiseptic, styptic, carminative, deobstruent, coolant, febrifugal, stomachic, astringent and diuretic properties of this plant it is very much utilized in traditional medicine.
Phytochemical properties: Phyllanthus amarus primarily contains
lignans (e.g., phyllanthine and hypophyllanthine) (Sharma
et al., 1993; Somanabandhu et al., 1993)
geraniin and 5 flavonaoids (quercertin, astralgin, quercertrin, isoquercitrin
and rutin). It also contains minor compounds like hydrolysable tannins like
phyllanthusiin D (Houghton et al., 1996), amariin
(Foo, 1993) amarulone (Rao and Bramley,
1971), amarinic acid and alkaloids like ent-norsecurinine, sobubbialine,
epibubbialine; diarylbutane, nyrphyllin and a neolignan, phyllnirurin.
Antioxidant activity: The Total Phenolic Content (TPC) and antioxidant
activity of fresh and dried Phyllanthus amarus were evaluated by Folin-Ciocalteau
method, 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity
and Ferric Reducing Antioxidant Power (FRAP) assays. Different drying treatments
led to significant reduction (p<0.05) in antioxidant properties of P.
amarus methanolic extracts, with microwave drying causing the highest decrease
in TPC and antioxidant activity exhibited by the reduction in both radical scavenging
activity and FRAP, the boiling water extracts appeared to exhibit stronger antioxidant
potentials (p<0.05) even in dried plant materials. This proves its strong
free radical scavenging activity (Lim and Murtijaya, 2007).
Anti-Inflammatory activity: The Hexane Extract (HE), the Lignan-Rich
Fraction (LRF), or the lignans phyltetralin, nirtetralin, niranthin of P.
amarus when given orally inhibited carrageenan (Cg)-induced paw oedema and
neutrophil influx. The HE, the LRF or nirtetralin also inhibited the increase
of IL1-β tissue levels induced by Cg. Bradykinin (BK)-, Platelet Activating
Factor (PAF)- and endothelin-1 (ET-1)-induced paw oedema were significantly
inhibited by the HE or LRF. Finally, nirtetralin or phyltetralin caused inhibition
of paw oedema induced by PAF or ET-1. These results show that the HE, the LRF
and the lignans niranthin, phyltetralin and nirtetralin exhibited marked anti-inflammatory
properties (Kassuya et al., 2005).
Antinociceptive activity: The Hydroalcoholic Extract (HE) of 4 Phyllanthus
species, given intraperitoneally, produced significant inhibition of acetic
acid-induced abdominal constrictions, with mean ID (50) values of 0.3, 1.8,
7.4 and 26.5 mg kg-1 for P. amarus, P. orbiculatus,
P. fraternus and P. stipulatus, respectively. In the formalin
test, the 4 species produced graded inhibition against both phases of formalin-induced
licking, being more active in relation of the late phase. The HE of the species
elicited significant inhibition of the capsaicin-induced neurogenic pain. Orally
all HE of the Phyllanthus species were less potent and efficacious than
when given by intraperitoneally. This shows the pronounced antinociception when
assessed in chemical models of nociception, namely acetic acid-induced writhing
and formalin and capsaicin-induced licking (Santos et
Anti hepatotoxic activity: Albino rats were treated with ethanol orally
for 30 days and the control with sucrose. At the end of 30 days whole plant
powder was administered at a dosage of 200 mg/rat/day for 45 days. The increased
deposition of triglyceride, cholesterol and phospholipids are reduced in liver,
brain, kidney and heart due to ethanol administration (Tripathi
et al., 1992). Administration of whole plant powder for 7 days at
dosage of 35 and 70 mg kg-1 b.wt. helped in restoring the levels
of biochemical parameters within next 48 h in calves (Sane
et al., 1995).
Immunostimulant activity: When albino rats were treated with the extract
there is a dose-dependent decrease in Erythrocyte Sedimentation Rate (ESR) with
400 mg kg-1 significant increase in Red Blood Cell (RBC) count (100
mg kg-1) and Packed Cell Volume (PCV). P. amarus did not affect
the haemoglobin concentration, Total and differential count studies showed significant
increases in the number of circulating leucocytes and neutrophils respectively
especially with 100 mg kg-1 of extracts (p<0.05). The aminotransferases
(ALT) and (AST) gave significantly higher values in treated rats (p<0.05).
It was therefore suggested that the plant can serve as an immunostimulant (Taiwo
et al., 2009).
Antitumour and anticarcinogenic activity: Aqueous extract of P. amarus
exhibited potent anticarcinogenic activity against 20-methylcholanthrene induced
sarcoma and increased the survival of tumour harboring mice. The extract administration
(p.o.) was also found to prolong the life span of Dalton's Lymphoma Ascites
(DLA) and Ehrlich Ascites Carcinoma (EAC) bearing mice and reduced the volume
of transplanted solid tumours. The extract inhibited aniline hydroxylase, a
P-450 enzyme. The concentration required for 50% inhibition (IC50)
was found to be 540 μg mL-1. The extract also inhibit DNA topoisomerase
II of Saccharomyces cerevisiae mutant cell cultures and inhibited cell
cycle regulatory enzyme cdc 25 tyrosine phosphatase (IC5025
μg mL-1). Antitumour and anticancer activity of P. amarus
may be evident by the inhibition of metabolic activation of carcinogen as well
as the inhibition of cell cycle regulators (Rajeshkumar
et al., 2002).
Anti viral activity: Alcoholic, hexane, chloroform, butanol and water
extract of P. amarus were tested for in vitro effects on HbsAg,
HBeAg and HBV-DNA in serum samples positive for HBV antigen followed by the
screening of the respective antigen by Elisa. The extract were effective against
HBV antigen, the butanol extract being the most potent (Mehrotra
et al., 1991). Further studies were conducted on mice infected with
wood chuck hepatitis virus when administrated with extract was effective in
three animals in reducing the virus within 3-6 weeks eliminating both the surface
antigen titer and DNA polyemerase activity in serum. Venkateswaran
et al. (1987). An aqueous extract on human hepatocellular carcinoma
derived cell at 1 mg mL-1 concentration on a single dose. Inhibition
of the secretion of HBsAg for a period of 48 h was observed (Jayaram
and Thyagarajan, 1996; Yeh et al., 1993).
Disruption of hepatitis B virus polymerase activity, mRNA transcription and
replication supported the role of Phyllanthus amarus being used as an
antiviral agent (Lee et al., 1996; Ott
et al., 1997).
Antibacterial activity: The antibacterial activity of extracts of the
root and leaf was assessed against extend spectrum lactamase (ESBL) producing
Escherichia coli isolated from the stool samples of HIV sero-positive
patients using Bauer disc diffusion method. The strains isolated from both HIV
sero-positive patients were susceptible to various concentrations of the extracts
(5, 10, 20, 40 and 80 mg mL-1). This proves the antibacterial activity
of the extract (Akinjogunla et al., 2010).
Hepatoprotective, nephroprotective and cardio protective activity: The
methanol extract of Phyllanthus amarus leaves (50-800 mg kg-1)
caused a statistically significant (p<0.05 students t-test) decrease
in the levels of total cholesterol, AST, ALT, urea, uric acid, total protein,
prostatic, alkaline and acid phosphatases. The highest reduction effect was
obtained with uric acid at 400 mg kg-1 of P. amarus extract
while the least effect was observed in total cholesterol. These effects were
dose- and time-dependent. This shows that the leaves of P. amarus have
hepatoprotective, nephroprotective and cardio protective properties (Obianime
and Uche, 2008).
Anti hyper glycemic activity: In a clinical trial conducted on nine
mild hypertensive patients (Diabetes Mellitus) were treated with a preparation
of the whole plant of Phyllanthus amarus for 10 days. The observations
indicated that Phyllanthus amarus as a potential diuretic hypotensive
and hypoglycaemic drug for human. Blood glucose was significantly reduced in
the treated group (Srividya and Periwal, 1995). In another
trial 25 patients in the age group of 35 - 55 with moderate and severe diabetic
blood sugar level (250-400 mg/100 mL) showed statistically significant (p<0.05)
lowering of blood sugar levels at a dose of 1 g thrice daily for a period of
3 months (Sivaprakasam et al., 1995).
The present study shows the pharmacological, traditional and phytochemical properties of various bioactive compounds present in the plant. The whole plant is used in India for the treatment of various diseases. The antioxidant potential of the extracts can be assessed by employing different in vitro assays. The antibacterial activity of extracts of the root and leaf was assessed against extend spectrum lactamase. Antitumour and anticancer activity of P. amarus may be evident by the inhibition of metabolic activation of carcinogen as well as the inhibition of cell cycle regulators. The whole plant powder helped in restoring the levels of biochemical parameters. P.amarus posses various phytochemical and pharmacological properties as discussed in present study. Further more Clinical and Pathological studies should be conducted to investigate the active potentials of bioactive compounds present in this plant.
Adeneye, A.A., A.S. Benebo and E.O Agbaje, 2006.
Protective effect of the aqueous leaf and seed extract of Phyllanthus amarus
on alcohol-induced hepatotoxity in rats. West Afr. J. Pharmacol. Drug Res., 22,23: 42-50.
Adeneye, A.A., O.O. Amole and A.K. Adeneye, 2006.
Hypoglycemic and hypocholesterolemic activities of the aqueous leaf and seed extract of Phyllanthus amarus
in mice. Fitoterapia, 77: 511-514.CrossRef | Direct Link |
Akinjogunla, O.J., N.O. Eghafona, I.O. Enabulele, C.I. Mboto and F.O. Ogbemudia, 2010.
Antibacterial activity of ethanolic extracts of Phyllanthus amarus
against extended spectrum β-lactamase producing Escherichia coli
isolated from stool samples of HIV sero-positive patients with or without diarrhoea. Afr. J. Pharm. Pharmacol., 4: 402-407.Direct Link |
Bagchi, G.D., G.N. Srivastava and S.C. Singh,1992 1992.
Distinguishing features of medicinal herbaceous species of Phyllanthus
occuring in Lucknow District (U.P.) India. Int. J. Pharmacognosy, 30: 161-168.CrossRef | Direct Link |
Bharatiya, V.B., 1992.
Selected Medicinal Plants of India. Tafa Press, Bombay, pp: 235-237
Kassuya, C.A.L., F.P.L. Daniela, V.M. Lucilia, G.R. Vera-Lucia and B.C. Joao, 2005.
Anti-inflammatory properties of extract, fractions and lignans isolated from Phyllanthus amarus
. Planta Med., 71: 721-726.Direct Link |
Foo, L.Y., 1993.
Amariin, a di-dehydro hexahydroxy diphenoyl hydrolysable tannin from Phyllanthus amarus
. Phytochem., 33: 487-491.
Houghton, P.J., T.Z. Woldemariam, S. O`Shea and S.P. Thyagarajan, 1996.
Two securinega type alkaloids from Phyllanthus amarus
. Phytochem., 43: 715-717.CrossRef |
Taiwo, I.A., B.O. Oboh and P.N. Francis-Garuba, 2009.
Haematological properties of aqueous extracts of Phyllantus amarus
(Schum and Thonn.) and Xylopia aethiopica
(Dunal) A. rich in albino rats. Ethno-Med., 3: 99-103.Direct Link |
Iwu, M.M., 1993.
Modalities of Drug Administration: Hand Book of African Medicinal Plants. CRC Press Inc., Florida, pp: 309-330
Jayaram, S. and S.P. Thyagarajan, 1996.
Inhibition of HBsAg secrection from Alexander cell line by Phyllanthus amarus
. Indian J. Pathol. Microbiol., 39: 211-215.PubMed | Direct Link |
Joseph, B. and S.J. Raj, 2010.
Phytopharmacological properties of Ficcus racemosa
Linn - An overview. Int. J. Pharma. Sci. Rev. Res., 3: 134-138.Direct Link |
Joseph, B. and S.J. Raj, 2010.
Phytopharmacological and phytochemical properties of three Ficus
species - An overview. Int. J. Pharma Biosci., 1: 246-253.Direct Link |
Joy, K.L. and R. Kuttan, 1998.
Inhibition by Phyllanthus amarus
of hepatocarcinogenesis induced by N-nitrosodiethylamine. J. Clin. Biochem. Nutr., 24: 133-139.Direct Link |
Kassuya, C.A., A.A. Silerstre, V. Rehder and J.B. Calixto, 2003.
Anti allodynic and antioedematogeni properties of the lignan from Phyllanthus amarus
in models of persistent inflammatory and neuropathic pain. Eur. J. Pharm., 478: 145-153.
Kokwaro, J.O., 1976.
Medicinal Plants of East Africa. 1st Edn., East Africa Literature Bureau, Nairobi, pp: 58-59
Lee, C.D., M. Ott, S.P. Thayagarajan, D.A. Shafritz, R.D. Burk and S. Gupta, 1996. Phyllanthus amarus
down-regulates hepatitis B virus mRNA transcription and replication. Eur. J. Clin. Invest, 26: 1069-1076.CrossRef | Direct Link |
Lim, Y.Y. and J. Murtijaya, 2007.
Antioxidant properties of Phyllanthus amarus
extracts as affected by different drying methods. LWT-Food Sci. Technol., 40: 1664-1669.CrossRef |
Wang, M., H. Cheng, Y. Li, L. Meng, G. Zhao and K. Mai, 1995.
Herbs of the genus Phyllanthus amarus
in the treatment of Chronic Hepatitis B: Observations with three preparations from different geographic Sites. J. Lab. Clin. Med., 126: 350-352.PubMed |
Mehrotra, R., S. Rawat, D.K. Kulshreshtha, P. Goyal, G.K. Patnaik and B.N. Dhawan, 1991. In vitro
effect of Phyllanthus amarus
on Hepatitis B virus. Indian J. Med. Res., 93: 71-73.PubMed |
Obianime, A.W. and F.I. Uche, 2008.
The phytochemical screening and the effects of methanolic extract of Phyllanthus amarus
leaf on the biochemical parameters of male guinea pigs. J. Applied Sci. Environ. Manage., 12: 73-77.Direct Link |
Odetola, A.A. and S.M. Akojenu, 2000.
Anti-diarrhoeal and gastro-intestinal potentials of the aqueous extracts of Phyllanthus amarus
(Euphorbiaceae). Afr. J. Med. Sci., 29: 119-122.PubMed | Direct Link |
Oluwafemi, F. and F. Debiri, 2008.
Antimicrobial effect of Phyllantus amarus
and Parquetina nigrescens
on Salmonella typhi
. Afr. J. Biomed. Res., 11: 215-219.Direct Link |
Ott, M., S.P. Thyagarajan and S. Gupta, 1997. Phyllanthus amarus
suppresses hepatitis B virus by interrupting interaction between HBV enhancer I and cellular transcription factors. Eur. J. Clin. Invest., 27: 908-915.PubMed | Direct Link |
Rao, G.S. and R. Bramley, 1971.
Hypophyllanthin. Tetrahedron Lett., 34: 3175-3178.
Ross, I.A., 1999.
Medicinal Plants of the World, Chemical Constituents, Traditional and Modern Medicinal Uses. Humana Press Inc., Totowa, New Jersey, pp: 249-254
Sane, R.T., V.V. Kuber, S.C. Mary and S. Menon, 1995.
Hepatoprotection by Phyllanthus amarus
and Phyllanthus debilis
-induced liver dysfunction. Curr. Sci., 68: 1243-1246.
Santos, A.R., R.O. De Campos, O.G. Miguel, V.C. Filho, A.C. Siani, R.A. Yunes and J.B. Calixto, 2000.
Antinociceptive properties of extracts of new species of plants of the genus Phyllanthus
(Euphorbiaceae). J. Ethnopharmacol., 72: 229-238.CrossRef |
Sharma, A., R.T. Singh and S.S. Handa, 1993.
Estimation of phyllanthin and hypophyllanthin by high performance liquid chromatography in Phyllanthus amarus
. Phytochem. Anal., 4: 226-229.CrossRef |
Sivaprakasam, K., R. Yasodha, G. Sivanandam and G. Veluchamy, 1995.
Clinical evaluation of Phyllanthus amarus
Schum and Thonn. in diabetes mellitus. Proceedings of the Seminar on Research in Ayurveda and Siddha, Mar. 20-22, CCRAS, New Delhi, pp: 7-7
Somanabandhu, A. and S. Nitayangkura, C. Mahidol, S. Ruchirawat and K. Likhitwitayawuid et al
1H- and 13C-nmr assignments of phyllanthin and hypophyllanthin: Lignans that enhance cytotoxic responses with cultured multidrug resistant cells. J. Nat. Prod., 56: 223-239.PubMed | Direct Link |
Srividya, N. and S. Periwal, 1995.
Diuretic, hypotensive and hypoglycaemic effect of Phyllanthus amarus
. Indian J. Exp. Biol., 33: 861-864.PubMed | Direct Link |
Thyagarajan, S.P., S. Subramanian, T. Thirunalasundari, P.S. Venkateswaran and B.S. Blumberg, 1988.
Effects of Phyllanthus amarus
on the chronic carriers of hepatitis B virus. Lancet., 2: 764-766.Direct Link |
Tripathi, S.C., G.K. Patnaik, P.K.S. Visen and B.N. Dhawan, 1992.
Evaluation of hepatoprotective activity of Phyllanthus amarus
against experimentally induced liver damage in rats. Proceedings of the 25th Indian Pharmacology Society Conference, Dec. 5-8, Muzaffarpur, Bihar, India, pp: 82-82
Venkateswaran, P.S., I. Millman and B.S. Blumberg, 1987.
Effect of an extract from Phyllanthus niruri
on hepatitis B and woodchuck hepatitis viruses: In vitro
and in vivo
studies. Proc. Natl. Acad. Sci. USA, 84: 274-278.Direct Link |
Yeh, S.F., C.Y. Hong, Y.L. Huang, T.Y. Liu, K.B. Choo and C.K. Chou, 1993.
Effect of an extract from Phyllanthus amarus
on hepatitis B surface antigen gene expression in human hepatoma cells. Antiviral Res., 20: 185-192.PubMed | Direct Link |
Rajeshkumar, N.V., K.L. Joy, G. Kuttan, R.S. Ramsewak, M.G. Nair and R. Kuttan, 2002.
Antitumor and anticarcinogenic activity of Phyllanthus amarus
extract. J. Ethnopharmacol., 87: 17-22.CrossRef | Direct Link |