Abstract
A growing body of evidence suggests that cellular damage or oxidative injury arising from production of free radicals or reactive oxygen species (ROS) are critical causative factors in the pathogenesis of many neurodegenerative disorders, inflammatory conditions, autoimmune diseases, diabetes, and gastrointestinal disorders. Results from biological and phytochemical studies indicate that medicinal plants have profound antioxidant potential that can be exploited further in the prevention and treatment of these devastating disorders. Here we have summarized the pharmacological and phytochemical investigations of 49 Bangladeshi medicinal plants representing 36 families with proven strong antioxidant properties. The medicinal plants were found to have profound antioxidant effect that can explain and justify some of their use in traditional medicine. These antioxidant medicinal plants may be considered as future leads to novel drug development for the management of various neurodegenerative and inflammatory disorders associated with oxidative cellular damage.
Introduction
Medicinal plants from time immemorial have been used in virtually all cultures as a source of medicine (CitationHoareau & Dasliva, 1999; CitationCragg & Newman, 2001; CitationFabricant & Fransworth, 2001). They are considered as the backbone of traditional medicine and are widely used to treat a plethora of acute and chronic diseases ranging from the common cold to complex human diseases all over the world. Research interest on screening of medicinal plants has intensified in recent years with a view to discovering potential antioxidants (CitationOlukemi et al., 2005; CitationAqil et al., 2006; Prakash et al., 2007). As an outcome of such an endeavor, several potential plant-derived antioxidants such as quercetin, carnosol, thymol, carnosic acid, hydroxytyrosol, gallic acid derivatives, tannins, catechins, rutin, morin, ellagic acid, eugenol, and rosemarinic acids have come to attention because of their extensive use in dietary supplementation, food preservation, and treating various free radical-mediated diseases (CitationHalliwell et al., 1995). Some known antioxidants of plant origin are summarized in .
Table 1. Phytochemical nature of plant-derived antioxidants.
Substantial evidence indicates that oxidative stress is one of the critical causative factors in the pathogenesis of major neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (CitationEbadi et al., 1996; CitationHall et al., 1998; CitationBehl, 1999; Markesbery & Lovell, 2006; CitationWang et al., 2006). In oxidative stress, production of highly reactive oxygen species (ROS) and reactive nitrogen species (RNS) overwhelms antioxidant defenses (CitationWang et al., 2006). Additionally, free radicals, ROS, and RNS are implicated in various diseases such as inflammation, atherosclerosis, and aging (CitationIssa et al., 2006; CitationPennathur & Heinecke, 2007). Antioxidants are thought to inhibit many oxidation reactions caused by these free radicals (CitationEbadi et al., 1996; CitationBehl, 1999). However, due to limitation of currently available therapeutics for the diseases associated with oxidative damage, there is a continuing interest and search for novel drug discovery and development for potent antioxidants from alternative sources.
Limited antioxidant-based formulations for the treatment of complex diseases, such as Alzheimer's disease, atherosclerosis, stroke, and diabetes, have previously been reported (CitationDevasagayam et al., 2004). Potential sources of antioxidant compounds have been looked for in several types of plant materials, such as vegetables, fruits, leaves, oilseeds, cereal crops, bark and roots, spices, herbs, and crude plant drugs (Ramarathnam et al., 1995). The traditional medicinal systems of Ayurveda and Unani are practiced in many South Asian countries, and several medicinal plants used in these treatment systems have been investigated (CitationScartezzini et al., 2000; Govindaranjan et al., 2005) and found to contain high amounts of antioxidants. Representative examples of plants used in Ayurvedic formulations with potent antioxidant activities are shown in .
Table 2. Representative examples of plants used in Ayurvedic formulations with potent antioxidant activities.
Bangladesh is a great resource with a myriad of medicinal plants that are yet to be fully explored. The uses of these plants are based on old and new experience and on clinical data, and many have no foundation whatsoever for their value. Their introduction into traditional medicine is rather empirical and only based on their beneficial effects on the patients (CitationKhanom et al., 2000). Proper scientific evaluation of the pharmacological properties of these plants used in different traditional formulations would carry enormous potential and promise for the 21st century (CitationRahman et al., 2001; CitationGhani, 2003). In this report, we have reviewed Bangladeshi medicinal plants with reported antioxidant principles in preclinical models (). Our focus was primarily on the published reports in Bangladesh and abroad on medicinal plants collected from different regions of Bangladesh. The reports available until 2007 are included in this review.
Table 3. Medicinal plants of Bangladesh with reported antioxidant properties.
Discussion
In this report, we have included 49 Bangladeshi medicinal plants representing 36 families and claimed to have strong antioxidant properties (). The families are Acanthaceae, Anacardiaceae, Annonaceae, Apocynaceae, Asclepiadaceae, Asteraceae, Bignoniaceae, Caesalpinaeceae, Combertaceae, Dipterocarpaceae, Ebenaceae, Euphorbiaceae, Gentianaceae, Labiatae, Leguminosae, Liliaceae, Loranthaceae, Lythraceae, Manispermaceae, Meliaceae, Moraceae, Moringaceae, Myristaceae, Nyctaginaceae, Piperaceae, Ranunculaceae, Rhizophoraceae, Rubiaceae, Sapotaceae, Sonneratiaceae, Sterculiaceae, Umbelliferae, Verbenaceae, Vitaceae, Zingiberaceae, and Zygophyllaceae.
Numerous procedures have been used for determination of both the in vivo and in vitro antioxidant activity of either crude extracts and/or pure compounds of plant origin. Among them, ferric reducing/antioxidant power (FRAP) assay, total radical-trapping antioxidant potential (TRAP) assay, β-carotene–linoleic acid model system (β -CLAMS), oxygen radical absorption capacity (ORAC) method, thiobarbituric acid reactive substance (TBARS) method, trolox equivalent antioxidant capacity (TEAC) method, photochemiluminescence (PCL) method, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) assay, and superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal ion chelating activities are widely used (CitationDavalos et al., 2004; CitationTsao et al., 2004). The plants included in this report were investigated by either the DPPH assay or by superoxide anion free radical scavenging assay. The DPPH assay has been widely used to evaluate the free radical scavenging capacity of antioxidants (CitationBrand-Willams et al., 1995; CitationEspin et al., 2000; CitationYu et al., 2001). The method is considered to be a fast screening procedure for the determination of antioxidant activity of plant extracts. The method involves determination of the antiradical power of an antioxidant by measurement of the decrease in the absorbance of DPPH radical at 517 nm (CitationMatthaus et al., 2002). To determine superoxide-scavenging activity, two different assays were used: the enzymatic method with cytochrome C (CitationMcCord et al., 1969) and nonenzymatic method with nitroblue tetrazolium (NBT) (CitationZhang et al., 1990). With cytochrome C method, superoxide anions were generated by a xanthine and xanthine oxidase system. The superoxide scavenging activity was calculated by measuring the reduction rate of ferricytochrome C at 550 nm. With the NBT method, superoxide was generated by potassium peroxide. The inhibition rate was calculated by measuring the amount of the formazan that was reduced from NBT by superoxide at 560 nm.
The extracts of S. chirata, E. officinalis, Z. officinale, and M. malabarica showed higher concentrations and gave similar scores for superoxide scavenging activity in both assays, indicating strong superoxide scavenging activities of the plant extracts (CitationKhanom et al., 2000). Similar plants used in traditional Chinese medicines have also shown superoxide scavenging active components (CitationOkuda et al., 1995; CitationMiao et al., 1997). Potent superoxide scavenging activity was found from ginger (Zingiber officinale Roscoe), and the active antioxidant compound isolated was gingerol; its structure was confirmed as 3-decanone, 5-hydroxy-1 (4-hydroxy-3-methoxy phenyl)-3-one on the basis of spectral evidence (CitationKhanom et al., 2003). The aqueous 90% methanol and 1-butanol soluble fractions of the leaves of Calycopteris floribunda showed strong antioxidant activity, and two pure compounds, 3,8-di-O-methyl ellagic and 2,3,7-tri-O-methyl ellagic acids, were isolated from the 1-butanol soluble fraction of the parent extract (CitationDey et al., 2005). Twelve new compounds were separated (CitationSadhu et al., 2003) from Leucas aspera, a medicinal plant of Bangladesh comprising eight lignans and four flavonoids using antioxidant and anti-inflammatory effect as the isolation guide. Among them, nectandrin B, meso-dihydroguaiaretic acid, macelignan, acacetin, apigenin 7-O-[6″-O-(p-coumaroyl)-β-d-glucoside], chrysoeriol, apigenin, (−)-chicanine, (7R, 8R)- and (7S, 8S)-licarin A, erythro-2-(4-allyl-2, 6-dimethoxyphenoxy)-1-(4-hydroxy-3-methoxyphenyl)propan-1-ol, myristargenol B, and machilin C showed antioxidant activity by DPPH radical scavenging effect. Two flavonoids, luteolin and luteolin 7-O-β -glucoside, were isolated from Sonneratia caseolaris and found to possess antioxidant activity (CitationSadhu et al., 2006). In addition to the monomeric compounds, catechin and epicatechin, large amounts of procyanidins were isolated from a mangrove plant of Bangladesh named Xylocarpus granatum (CitationWangensteen et al., 2006a). The structures of the procyanidins were procyanidin B1 (epicatechin (4β → 8) catechin), epicatechin (4β → 8) epicatechin (4β → 8) catechin and epicatechin (4β → 8) epicatechin (4β → 8) epicatechin (4β → 8) epicatechin (4β → 8) catechin. The limonoids gedunin, xyloccensin O, xyloccensin P, and xyloccensin Q were isolated as well. The procyanidins showed antioxidant effect by highly scavenging DPPH free radical. In a separate study, catechins and procyanidins of this plant have been shown to have strong DPPH radical scavenging activity (CitationWangensteen et al., 2006b) and the procyanidin of the pentamer type has been found to be the most potent. CitationHasan et al. (2006) have reported strong DPPH free radical scavenging activity of the ethanol extract of Dendrophthoe falcata leaves and separated quercitrin (quercetin 3-O-α -rhamnoside) as the major component from the extract.
Overall, Bangladeshi medicinal plants reviewed in this report have shown enormous potential for antioxidant activity, which is important for novel drug discovery and therapeutic development for the treatment of numerous multiple human diseases. However, additional scientific studies are needed for structural elucidation of the active compounds followed by specific biomolecular evaluations. In so doing, compound(s) could be formulated as safe and effective drug candidates for the treatment of major neurodegenerative disorders and/or inflammatory conditions linked to oxidative stress and/or cellular damage.
Acknowledgements
The authors wish to thank Mr. Gazi Mosharof Hossain, Department of Botany, Jahangirnagr University, for his help in identifying scientific names with local names of the medicinal plants reported here. We are also grateful to the Department of Pharmacy, Jahangirnagar University, Dhaka, Bangladesh, for providing library facilities.
References
- F Ahmed, I Z Shahid, M A Razzak, M M Rahman, T Hoque, M T Rahman, and S K Sadhu. (2006). Free radical scavenging activity of some Mangroves available in Bangladesh. Oriental Pharm Exper Med 6:58–64.
- F Aqil, I Ahmed, and Z Mehmood. (2006). Antioxidant and free radical scavenging properties of twelve traditionally used Indian medicinal plants. Turk J Biol 30:177–183.
- C Behl. (1999). Alzheimer's disease and oxidative stress: Implications for novel therapeutic approaches. Prog Neurobiol 57:301–323.
- W Brand-Willams, M E Cuvelier, and C Berset. (1995). Use of a free radical method to evaluate antioxidant activity. Lebensmittel-Wissenschaft and Technologie 28:25–30.
- M G Cragg, and D J Newman. (2001). Natural product drug discovery in the next millennium. Pharm Biol 39 (Suppl):8–17.
- A Davalos, B Bartolome, and C Gomez-Cordoves. (2004). Inhibition of methyl linoleate autooxidation by phenolics and other related compounds under mild oxidative conditions. J Sci Food Agric 84:631–638.
- T P A Devasagayam, J C Tilak, and K K Boloor. (2004). Review: Free radicals and antioxidants in human health. Curr Stat Fut Prosp JAPI 52:794–804.
- S K Dey, M Shoeb, T Rob, N Nahar, M Mosihuzzaman, and N Sultana. (2005). Biological and chemical studies on Calycopteris floribunda leaves. Dhaka Univ J Pharm Sci 4:103–106.
- M Ebadi, S K Srinivasan, and M D Baxi. (1996). Oxidative stress and antioxidant therapy in Parkinson's disease. Prog Neurobiol 48:1–19.
- J C Espin, C Soler-Rivas, and H J Wichers. (2000). Characterization of total free radical scavenger capacity of vegetable oils and oil fraction using 2,2-diphenyl-1-picrylhydrazyl radical. J Agric Food Chem 48:648–656.
- D S Fabricant, and N R Fransworth. (2001). The value of plants used in traditional medicine for drug discovery. Environ Health Perspec Suppl 1:69–75.
- A Ghani. (2003): Medicinal Plants of Bangladesh with Chemical Constituents and Uses. Dhaka, Bangladesh, Asiatic Society of Bangladesh.
- R Govindarajan, M Vijayakumar, and P Pushpangadan. (2005). Antioxidant approach to disease management and the role of ‘Rasayana’ herbs of Ayurveda. J Ethnopharmacol 99:165–178.
- R O Guerrero, M TH Khan, M B Casanas, and M M Morales. (2004). Specific bioassays with selected plants of Bangladesh. Rev Cubana Plant Med 9: Proc. 2
- E D Hall, P K Andrus, J A Oostveen, T J Fleck, and M E Gurney. (1998). Relationship of oxygen radical-induced lipid peroxidative damage to disease onset and progression in a transgenic model of familial ALS. J Neurosci Res 53:66–77.
- B Halliwell, R Aeschbach, J Loliger, and O I Aruoma. (1995). The characterization of antioxidants. Food Chem Toxic 33:601–617.
- M S Hasan, M M Masud, M I Ahmed, S Mondal, S J Uddin, S K Sadhu, and M Ishibashi. (2006). Antioxidant, antinociceptive activity and general toxicity study of Dendrophthoe falcata and isolation of quercitrin as the major component. Oriental Pharm Exper Med 6:355–360.
- K E Heim, A R Tagliaferro, and D J Bobilya. (2002). Flavonoids antioxidants: Chemistry, metabolism and structure-activity relationships. J Nutr. Biochem 13:572–584.
- L Hoareau, and E J Dasilva. (1999). Medicinal plants: A re-emerging health aid. Electronic J Biotechnol 2:56–70.
- A Y Issa, S R Volate, and M Wargovich. (2006). The role of phytochemicals in inhibition of cancer and inflammation: New directions and perspectives. J Food Composition Anal 19:405–419.
- F Khanom, H Kayahara, M Hirota, and K Tadasa. (2003). Superoxide scavenging and tyrosinase inhibitory active compound in ginger (Zingiber officinale Roscoe). Pakistan J Biol Sci 6:1996–2000.
- F Khanom, H Kayahara, and K Tadasa. (2000). Superoxide-scavenging and prolyl endopeptidase inhibitory activities of Bangladeshi indigenous medicinal plants. Biosci Biotechnol Biochem 64:837–840.
- B Matthaus. (2002). Antioxidant activity of extracts obtained from residues of different oilseeds. J Agric Food Chem 50:3444–3452.
- J M McCord, and I J Fridovich. (1969). Superoxide dismutase, an enzymic function for erythrocuprein (Hemocuprein). J Biol Chem 244:6049–6055.
- W R Merkesbery, and M A Lovell. (2006). DNA oxidation in Alzheimer's disease. Antioxidants Redox Signaling 8:2039–2045.
- Z Miao, H Kayahara, and K Tadasa. (1997). Superoxide-scavenging and tyrosinase-inhibitory activities of the extracts of some Chinese medicines. Biosci Biotechnol Biochem 61:2106–2108.
- O A Olukemi, I O Olukemi, S M Oluwatoyin, A O Austin, L B Mansurat, and T I Olufunmilola. (2005). Antioxidant activity of Nigerian dietary herbs. Electron J Environ Agric Food Chem 4:1086–1093.
- T Okuda. (1995): In: E Niki, H Shimasaki, and M Mino. eds. Antioxidants-Free Radicals and Biological Defense. Tokyo, Japan Scientific Press, pp. 263–275. (in Japanese).
- S Pennathur, and J W Heinecke. (2007). Mechanisms for oxidative stress in diabetic cardiovascular disease. Antioxidants Redox Signaling 9:955–966.
- D Prkash, S Suri, G Upadhyay, and B N Singh. (2007). Total phenol, antioxidant and free radical scavenging activities of some medicinal plants. Int J Food Sci Nutri 58:18–28.
- M S Rahman, M Sarder, J A Shilpi, and C M Hasan. (2006a). Antioxidant and analgesic activity of Clerodendrum viscosum leaf. Oriental Pharm Exper Med 6:319–323.
- M S Rahman, C M Hasan, and S K Sadhu. (2006b). The crude ethanol extract of the stem bark of Trewia polycarpa (Family: Euphorbiaceae). Oriental Pharm Exper Med 6:121–125.
- S Rahman, A Hasnat, C M Hasan, M A Rashid, and M Ilias. (2001). Pharmacological evaluation of Bangladeshi medicinal plants-A Review. Pharm Biol 39:1–6.
- N Ramarathnam, and M Takeuchi. (1997): Antioxidant defense system in vegetable extracts. In: F Shahidi. ed. Natural Antioxidants: Chemistry, Health Effects, and Applications. Champaign, IL, AOCS Press, pp. 76–87.
- C A Rice-Evans, N J Miller, and G Paganga. (1997). Antioxidant properties of phenolic compounds. Trends Plant Sci. 2:152–159.
- M A Z Sadek. (2004): Chemical and Biological Investigation of Kigelia pinnata. B. Pharm Thesis. Pharmacy Discipline, Khulna University, Khulna, Bangladesh.
- S K Sadhu, E Okuyama, H Fujimoto, and M Ishibashi. (2003). Separation of Leucas aspera, a medicinal plant of Bangladesh, guided by prostaglandin inhibitory and antioxidant activities. Chem Pharm Bull 51:595–598.
- S K Sadhu, F Ahmed, T Ohtsuki, and M Ishibashi. (2006). Flavonoids from Sonneratia caseolaris. J Nat Med 60:264–265.
- P Scartezzini, and E Speroni. (2000). Review on some plants of Indian traditional medicine with antioxidant activity. J Ethnopharmacol 71:23–43.
- I Z Shahid. (2004): Free radical scavenging activity of some Bangladeshi medicinal plants. B. Pharm Thesis, Pharmacy Discipline, Khulna University, Khulna, Bangladesh.
- R Tsao, and Z Deng. (2004). Separation procedures for naturally occurring antioxidant phytochemicals. J Chromatogr R B 812:85–99.
- S J Uddin, J A Shilpi, A Delazar, L Nahar, and S D Sarker. (2004). Free radical scavenging activity of some Bangladeshi plant extracts. Oriental Pharm Exp Med 4:187–195.
- H Wangensteen, G M Duong, M Alamgir, M Sarder, A B Samuelsen, and K E Malterud. (2006a). Antioxidants from Xylocarpus granatum. Planta Med 72:1051.
- H Wangensteen, G M Duong, M Alamgir, M Sarder, A B Samuelsen, and K E Malterud. (2006b). Biological activities of limonoids, catechins, procyanidins and extracts from Xylocarpus granatum. Nat Prod Commun 1:985–990.
- J Y Wang, L L Wen, Y N Huang, Y T Chen, and M C Ku. (2006). Dual effects of antioxidants in neurodegeneration: Direct neuroprotection against oxidative stress an indirect protection via suppression of glia-mediated inflammation. Curr Pharm Des 12:3521–3533.
- L Yu. (2001). Free radical scavenging properties of conjugated linoleic acids. J Agri Food Chem 49:3452–3456.
- H Y Zhang, and C S Lu. (1990). A study of the SOD-like activity of some copper (II)-small peptide and amino acid complexes. Acta Biochem Biophys Sinica (in Chinese) 22:593–594.