A Review on the Phytochemistry, Medicinal Properties and Pharmacological Activities of 15 Selected Myanmar Medicinal Plants

Medicinal plants are a reservoir of biologically active compounds with therapeutic properties that over time have been reported and used by diverse groups of people for treatment of various diseases. This review covers 15 selected medicinal plants distributed in Myanmar, including Dalbergia cultrata, Eriosema chinense, Erythrina suberosa, Millettia pendula, Sesbania grandiflora, Tadehagi triquetrum, Andrographis echioides, Barleria cristata, Justicia gendarussa, Premna integrifolia, Vitex trifolia, Acacia pennata, Cassia auriculata, Croton oblongifolius and Glycomis pentaphylla. Investigation of the phytochemical constituents, biological and pharmacological activities of the selected medicinal plants is reported. This study aims at providing a collection of publications on the species of selected medicinal plants in Myanmar along with a critical review of the literature data. As a country, Myanmar appears to be a source of traditional drugs that have not yet been scientifically investigated. This review will be support for further investigations on the pharmacological activity of medicinal plant species in Myanmar.


Introduction
Natural products, especially those derived from plants, have been used to help mankind sustain human health since the dawn of medicine. Traditional medicine has been in existence since time immemorial and has been well accepted and utilized by the people throughout history. Since ancient times, plants have been an exemplary source of medicines. Plant-derived medicinal products have attracted the attention of scientists around the world for many years due to their minimum side effects and positive effects on human health.
In the pharmaceutical landscape, plants with a long history of use in ethnomedicine can be a rich source of substances for the treatment of various ailments and infectious diseases.  We previously reported [3] the traditional uses, chemical constituents, the published the biological and pharmacological evidences of 25 medicinal plants from Kachin State, in Northern Myanmar. In Kachin State, the climatic conditions vary considerably, from warm to humid in the lowlands, to extremely cold in the highlands, and the mountains in the far north are snowcapped. The geographical and climate conditions of the central region in Myanmar are quite different from those of Kachin State. That region has a generally harsh climate and is extremely dry. Because of the geographical and climate differences the chemical constituents of the plants from that region have different medicinal uses, biological and pharmacological activities. Therefore, in this review, it is out intention to provide a complete account of the phytochemistry, medicinal and pharmacological uses of a few plants which grow in the central region of Myanmar, which is the tropical area of Myanmar. The traditional healers in central Myanmar use a lot of species of plants that serve as regular sources of medicine and there is a need to preserve the traditional knowledge on the uses of these medicinal plants.
A total of 15 medicinal plants, which belong to seven families and 15 genera were recorded in this review. The results are summarized in Table 1, which provides the following information for each species: scientific name, botanical family and local name. The most represented families are the Fabaceae with six species, followed by Acanthaceae (three species), Verbenaceae (two species), and Mimosaceae, Casealpiniaceae, Euphorbiaceae and Rutaceae were represented with one species each. The primary objective of this study is to present a database of the indigenous knowledge on medicinal We previously reported [3] the traditional uses, chemical constituents, the published the biological and pharmacological evidences of 25 medicinal plants from Kachin State, in Northern Myanmar. In Kachin State, the climatic conditions vary considerably, from warm to humid in the lowlands, to extremely cold in the highlands, and the mountains in the far north are snowcapped. The geographical and climate conditions of the central region in Myanmar are quite different from those of Kachin State. That region has a generally harsh climate and is extremely dry. Because of the geographical and climate differences the chemical constituents of the plants from that region have different medicinal uses, biological and pharmacological activities. Therefore, in this review, it is out intention to provide a complete account of the phytochemistry, medicinal and pharmacological uses of a few plants which grow in the central region of Myanmar, which is the tropical area of Myanmar. The traditional healers in central Myanmar use a lot of species of plants that serve as regular sources of medicine and there is a need to preserve the traditional knowledge on the uses of these medicinal plants.
A total of 15 medicinal plants, which belong to seven families and 15 genera were recorded in this review. The results are summarized in Table 1, which provides the following information for each species: scientific name, botanical family and local name. The most represented families are the Fabaceae with six species, followed by Acanthaceae (three species), Verbenaceae (two species), and Mimosaceae, Casealpiniaceae, Euphorbiaceae and Rutaceae were represented with one species each. The primary objective of this study is to present a database of the indigenous knowledge on medicinal plants used for various diseases among the local traditional healers of Myanmar, to  Glycomis pentaphylla Rutaceae Taw-shauk [4] Until now, few sources of information are available for some medicinal plants in the literature, and the sources of information in the literature make evident that additional new investigations and scientific reports are necessary.

Dalbergia culrata Grah. (DC)
D. cultrata, locally known as Yin-daik, is widely distributed in Myanmar [4]. It is a moderate-sized deciduous tree indigenous to the forests of Burma that belongs to the family Fabaceae (or Leguminosae) [5]. This plant genus is mainly distributed in tropical and subtropical regions, such as South Africa and India, Laos, Myanmar, Thailand and Vietnam in Asia [6,7].
Prasad evaluated the antidiarrhoeal activity of the roots of ethanol extract, its fractions (chloroform, ethyl acetate and hexane) and lupinifolin isolated from the chloroform fraction of the roots. Lupinifolin showed moderate antidiarrhoel activity compared to the bioactive chloroform fraction [13].

Erythrina suberosa Roxb.
E. suberosa locally known as ka-thit and widely distributed in Myanmar. It belongs to the family Fabaceae, and is an ornamental tall tree also found occasionally on hills and moist slopes of India, Pakistan, Nepal, Bhutan, Burma, Thailand and Vietnam [15]. In traditional Myanmar medicine, the bark is used for dysentery, while the leaves are reported to be used in urinary diseases and inflammation. In India, E. suberosa has been used as a very important medicinal plant for the treatment of various ailments [16]. The bark is reported to be used in preparation of medicines for dysentery, as an astringent and febrifuge, and used for anorexia, liver troubles, helminthic manifestations, inflammations, intestinal worms, obesity and as a snake-bite antidote [17].
Molecules 2019, 24, 293 6 of 34 (36) and alpinumiso-flavone (37) from E. suberosa on apoptosis in human leukemia HL-60 cells and their potential to induce cancer cell death [19]. The ethanolic extract of the leaves of E. suberosa showed antitumor activity [23]. In addition, the ethanolic extract of the stem bark of E. suberosa induced apoptosis in human promyelocytic leukemia HL-60 cells [24]. It seems that E. suberosa has the potential for being selected for future anticancer therapeutics. M. pendula is locally called thin-win and is widely distributed in Myanmar. M. pendula also belongs to the family Fabaceae. Its timber is produced in Myanmar and Thailand [25]. In Myanmar traditional medicine, the root of M. pendula is applied for skin diseases, allergy, urinary diseases and inflammation, based on folklore medicine. Hayashi found the pterocarpan, maackiain and isoflavans, pendulone and claussenquinone in the heartwood of M. pendula and confirmed their identity and purification through NMR [26].
Serrano observed that acute p.o. treatment with the isolated alkaloids; erysodine (40) and erysotrine (41) produced anxiolytic effects in the elevated plus-maze and the light-dark transition model [15]. The anticancer potential and cytotoxic effect of some compounds from E. suberosa has been reported scientifically. Thus, Kumar studied the cytotoxic effects of 4 -methoxylicoflavanone (36) and alpinumiso-flavone (37) from E. suberosa on apoptosis in human leukemia HL-60 cells and their potential to induce cancer cell death [19]. The ethanolic extract of the leaves of E. suberosa showed antitumor activity [23]. In addition, the ethanolic extract of the stem bark of E. suberosa induced apoptosis in human promyelocytic leukemia HL-60 cells [24]. It seems that E. suberosa has the potential for being selected for future anticancer therapeutics.

Millettia pendula BENTH.
M. pendula is locally called thin-win and is widely distributed in Myanmar. M. pendula also belongs to the family Fabaceae. Its timber is produced in Myanmar and Thailand [25]. In Myanmar traditional medicine, the root of M. pendula is applied for skin diseases, allergy, urinary diseases and inflammation, based on folklore medicine. Hayashi found the pterocarpan, maackiain and isoflavans, pendulone and claussenquinone in the heartwood of M. pendula and confirmed their identity and purification through NMR [26].
In 2006, three isoflavans: millettilone A (49), 3R-claussequinone (50) and pendulone (51), a 2-arylbenzofuran-millettilone B (52)-three pterocarpans: secundiflorol I (53), 3,8-dihydroxy-9-methoxypterocarpan (54) and 3,10-dihydroxy-7,9-dimethoxypterocarpan (55), and one isoflavone, formononetin (56), were isolated from a methanol extract of the powdered M. pendula timber [25] (Figure 5). Takahashi reported the vitro leishmanicidal activity of the methanolic timber extract of M. pendula [25]. Among the constituents of M. pendula pendulone (51), an isoflavan, showed significant leishmanicidal activity with an IC50 value of 0.07 μg/mL, while millettilone A (49, IC50 9.3 μg/mL), 3Rclaussequinone (50, IC50 1.2 μg/mL) and 3,8-dihydroxy-9-methoxypterocarpan (54, IC50 2.9 μg/mL) exhibited moderate activity and secundiflorol I (53, IC50 86 μg/mL) and 3,10-dihydroxy-7,9dimethoxypterocarpan (55, IC50 77 μg/mL) displayed weak leishmanicidal activity in vitro [25]. There are few chemical constituents and biological studies of this plant reported in the scientific literature, therefore, biologically active new chemical components from this plant might yet be found. S. grandiflora is a small, erect, fast-growing, and sparsely branched cultivated tree belonging to the family Fabaceae. It's locally known as paukpan-phyu in Myanmar. In folk medicine, the juice of the leaves and flowers is used as a popular remedy for catarrh, and headache. The bark of S. grandiflora is very astringent and the bitter bark is considered a tonic. Decoctions of leaves and flowers is used to treat leucorrhoea and vomiting of blood. The bark of S. grandiflora is used as an astringent and treatment of small pox, ulcers in the mouth and the alimentary canal, infant stomach disorders and scabies. The juice of the leaves of S. grandiflora has been reportedly used in the treatment of bronchitis, cough, vomiting, wounds ulcers, diarrhea, and dysentery. The flowers have reported antimicrobial activity. Powdered roots of this plant are mixed in water and applied externally as a poultice or rub for rheumatic swelling [27,28].
Remesh has reported that S. grandiflora has protective effects against cigarette smoke-induced oxidative damage in the liver and kidney of rats and protected the lungs from oxidative damage through its antioxidant potential [33,34]. Doddola reported the antiurolithiatic and antioxidant activities of the leaf juice of S. grandiflora [35]. The ethanol extract of the leaves and flowers of S. grandiflora exhibited anticancer activity against an Ehrlich ascites carcinoma tumor model [36]. The leaves of S. grandiflora showed a significant protection against erythromycin estolate-induced toxicity [27], antimicrobial [37], anticonvulsant and anxiolytic activity [38]. The alcoholic extract of S. Takahashi reported the vitro leishmanicidal activity of the methanolic timber extract of M. pendula [25]. Among the constituents of M. pendula pendulone (51), an isoflavan, showed significant leishmanicidal activity with an IC 50 value of 0.07 µg/mL, while millettilone A (49, IC 50 9.3 µg/mL), 3R-claussequinone (50, IC 50 1.2 µg/mL) and 3,8-dihydroxy-9-methoxypterocarpan (54, IC 50 2.9 µg/mL) exhibited moderate activity and secundiflorol I (53, IC 50 86 µg/mL) and 3,10-dihydroxy-7,9-dimethoxypterocarpan (55, IC 50 77 µg/mL) displayed weak leishmanicidal activity in vitro [25]. There are few chemical constituents and biological studies of this plant reported in the scientific literature, therefore, biologically active new chemical components from this plant might yet be found.

Sesbania grandiflora (L.) Poir.
S. grandiflora is a small, erect, fast-growing, and sparsely branched cultivated tree belonging to the family Fabaceae. It's locally known as paukpan-phyu in Myanmar. In folk medicine, the juice of the leaves and flowers is used as a popular remedy for catarrh, and headache. The bark of S. grandiflora is very astringent and the bitter bark is considered a tonic. Decoctions of leaves and flowers is used to treat leucorrhoea and vomiting of blood. The bark of S. grandiflora is used as an astringent and treatment of small pox, ulcers in the mouth and the alimentary canal, infant stomach disorders and scabies. The juice of the leaves of S. grandiflora has been reportedly used in the treatment of bronchitis, cough, vomiting, wounds ulcers, diarrhea, and dysentery. The flowers have reported antimicrobial activity. Powdered roots of this plant are mixed in water and applied externally as a poultice or rub for rheumatic swelling [27,28].
Molecules 2019, 24, x 8 of 34 grandiflora flowers at 250 and 500 mg/kg exhibited significant antidiabetic activity (p ˂ 0.01) in alloxaninduced diabetic rats [39]. The S. grandiflora flowers displayed significant hepatoprotective [40] and antimicrobial activity [28]. Silver nanoparticles synthesized using the leaf extract of this plant showed not only excellent antibacterial activity against clinically isolated multi-drug resistant human pathogens [41], but also antifungal activity against some selected microbial pathogens [42]. T. triquetrum (synonyms: Desmodium triquetrum (L.) DC.) belongs to the family Fabaceae, which is widely distributed throughout the tropical, subtropical and Pacific regions of the world. This shrub is commonly known as lauk-thay or shwe-gu-than-hlet in Myanmar and is distributed in the regions of Chin, Kachin, Kayin, Mandalay, Sagaing, Shan and Yangon [4] and the southern area of Yunan Province in China [43]. An infusion of the roots is taken to treat kidney complaints, and an infusion of the leaves is drunk for stomach discomfort in Myanmar. A daily glass of a decoction of the roots of this plant is considered beneficial for chronic coughs and tuberculosis.
In Myanmar, local people use T. triquetru leaves to cover local fish pastes to prevent the development of fly larvae. A study in Myanmar proved that the aqueous extract of T. triquetrum has bactericidal activity on some pathogenic bacteria [47]. Moe et al. reported that the leaves of T. triquetrum were used by tuberculosis patients in Myanmar. The family members of patients were also familiar with this plant. In the central region of Myanmar, the herbs are available in the forest fringes but sometimes available in local markets of rural areas [48]. The extract of T. triquetrum and tadehagenoside proved to display hypoglycemic activity [49], with in vivo immunoprotection effects because of its antioxygenic properties [50], and anti-inflammatory activity [51]. Moreover, tadehaginosin (69) and 3,4-dihydro-4-(4′-hydroxyphenyl)-5,7-dihydroxycoumarin (70) from T. triquetrum showed hypoglycemic activity in vitro on HepG2 cells [45]. The phenylpropanoid glucosides-tadehaginosides C-J (73-80) and tadehaginoside (81) isolated from T. triquetrum showed Remesh has reported that S. grandiflora has protective effects against cigarette smoke-induced oxidative damage in the liver and kidney of rats and protected the lungs from oxidative damage through its antioxidant potential [33,34]. Doddola reported the antiurolithiatic and antioxidant activities of the leaf juice of S. grandiflora [35]. The ethanol extract of the leaves and flowers of S. grandiflora exhibited anticancer activity against an Ehrlich ascites carcinoma tumor model [36]. The leaves of S. grandiflora showed a significant protection against erythromycin estolate-induced toxicity [27], antimicrobial [37], anticonvulsant and anxiolytic activity [38]. The alcoholic extract of S. grandiflora flowers at 250 and 500 mg/kg exhibited significant antidiabetic activity (p < 0.01) in alloxan-induced diabetic rats [39]. The S. grandiflora flowers displayed significant hepatoprotective [40] and antimicrobial activity [28]. Silver nanoparticles synthesized using the leaf extract of this plant showed not only excellent antibacterial activity against clinically isolated multi-drug resistant human pathogens [41], but also antifungal activity against some selected microbial pathogens [42]. T. triquetrum (synonyms: Desmodium triquetrum (L.) DC.) belongs to the family Fabaceae, which is widely distributed throughout the tropical, subtropical and Pacific regions of the world. This shrub is commonly known as lauk-thay or shwe-gu-than-hlet in Myanmar and is distributed in the regions of Chin, Kachin, Kayin, Mandalay, Sagaing, Shan and Yangon [4] and the southern area of Yunan Province in China [43]. An infusion of the roots is taken to treat kidney complaints, and an infusion of the leaves is drunk for stomach discomfort in Myanmar. A daily glass of a decoction of the roots of this plant is considered beneficial for chronic coughs and tuberculosis.
Molecules 2019, 24, x 9 of 34 the potential to be developed into antidiabetic compounds [46], providing the scientific evidence needed for developing new chemical candidates in treating diabetes. In Myanmar, there are more and more diabetes patients nowadays, and based on the literature review, the plant T. triquetrum could be a very useful and valuable plant for treating diabetes patients.

Andrographis echioides Nees.
A. echioides is an annual medicinal plant of Acanthaceae family and the plants are seen mostly in dry places, such as South India, Sri Lanka and South Asian countries [52]. In Myanmar, it is distributed in the central region-Mandalay and Sagaing-and known by the common name se-gagyi-hmawe-tu. There is no traditional knowledge of A. echioides use in Myanmar till now based on folk medicine, but in Indian traditional medicine, the leaf juice of A. echioides is used to cure fevers [53]. The leaves of A. echioides boiled with coconut oil is applied to decrease the loss and graying of hair [54]. In Myanmar, local people use T. triquetru leaves to cover local fish pastes to prevent the development of fly larvae. A study in Myanmar proved that the aqueous extract of T. triquetrum has bactericidal activity on some pathogenic bacteria [47]. Moe et al. reported that the leaves of T. triquetrum were used by tuberculosis patients in Myanmar. The family members of patients were also familiar with this plant. In the central region of Myanmar, the herbs are available in the forest fringes but sometimes available in local markets of rural areas [48]. The extract of T. triquetrum and tadehagenoside proved to display hypoglycemic activity [49], with in vivo immunoprotection effects because of its antioxygenic properties [50], and anti-inflammatory activity [51]. Moreover, tadehaginosin (69) and 3,4-dihydro-4-(4 -hydroxyphenyl)-5,7-dihydroxycoumarin (70) from T. triquetrum showed hypoglycemic activity in vitro on HepG2 cells [45]. The phenylpropanoid glucosides-tadehaginosides C-J (73-80) and tadehaginoside (81) isolated from T. triquetrum showed the potential to be developed into antidiabetic compounds [46], providing the scientific evidence needed for developing new chemical candidates in treating diabetes. In Myanmar, there are more and more diabetes patients nowadays, and based on the literature review, the plant T. triquetrum could be a very useful and valuable plant for treating diabetes patients.
Basu reported not only the hepatoprotective and antioxidant activity of methanolic extract of the aerial parts of A. echioides against acetaminophen-induced hepatotoxicity in rats, but also the anti-inflammatory, analgestic and antipyretic activities of the ether, chloroform and ethyl acetate extracts of this plant [61,62]. The chloroform extract of the leaves of A. echioides exhibited significant diuretic activity [63]. The ethanol extract from the leaves of A. echioides showed antiulcer activity [64] and antifungal activity in vitro [65]. Rajkumar et al., in 2012 reported that the synergistic larvicidal activity of the leaf extracts of A. echioides against larvae of Aedes aegypti L [66]. Thus, we can say that A. echioides is a good source of antioxidant and antimicrobial compounds. The ethanolic extract of A. echioides has notable antibacterial activity against both Gram positive and negative bacteria in vitro [67] and the hydroalcoholic extract of this plant showed antimicrobial activity [54]. The methanol extract of A. echioides displayed potent antioxidant activity IC 50 values on the range of 1.14 ± 0.06 to 1.15 ± 0.45 mg/mL, as well as antibacterial activity (16 ± 1.527 mm) than the aqueous extract of this plant (20 ± 1.527 mm) [68]. While the phytochemical constituents and biological activities of the extracts of A. echioides have been reported, however, the pharmacological action of pure compounds from this plant has not been investigated yet, and therefore might represent an interesting research topic.
2,6-dihydrobenzoic acid, 132-hydroxy-(132-R)-phaeophytin, (E)-phytyl epoxide, phytol, phytene 1,2diol, (+)-dehydrovomifoliol, 3β-hydroxy-5α,6α-epoxy-7-megastigmen-9-one, β-sitosterol, βsitosteryl-3-O-β-glucopyranoside, squalene, 1H-indole-3-carbaldehyde, and loliolide were reported by Shen's group [58]. Moreover, a variety of chemical compounds isolated from the petroleum ether, ethyl acetate and methanol extracts of A. echioides were analysed by GC-MS [60].  Basu reported not only the hepatoprotective and antioxidant activity of methanolic extract of the aerial parts of A. echioides against acetaminophen-induced hepatotoxicity in rats, but also the antiinflammatory, analgestic and antipyretic activities of the ether, chloroform and ethyl acetate extracts of this plant [61,62]. The chloroform extract of the leaves of A. echioides exhibited significant diuretic activity [63]. The ethanol extract from the leaves of A. echioides showed antiulcer activity [64] and B. cristata or leik-tha-ywe-pya is a perennial shrub, belonging to the family Acanthaceae. It is found widely in subtropical Himalaya, Sikkim, Kashi Hills, and southern India at a height of 1350 m [69]. The bitter juice of the leaves of B. cristata is used as a diaphoretic and expectorant for serious catarrhal infections in the central region of Myanmar. In addition, an infusion of the roots and leaves is applied to boils and sores to reduce swelling. B. cristata is traditionally used for the treatment of a variety of diseases including anemia, toothache and coughs in Indian traditional medicine. Roots and leaves are used to reduce swelling and inflammation [70].
flavonoidal compounds, luteoline (105) and 7-methoxyluteoline (106), and iridodial glycosides, barlerin (107) and schanshiside methyl ester (108) from the leaves of B. cristata (Figure 9) [73]. Besides these compounds, researchers have found 4-hydroxy-trans-cinnamate derivatives and oleanolic acid (109) in this plant [74]. Biological investigations of this plant showed anti-inflammatory [69,75], and antioxidant properties [76,77]. There are few phytochemistry and biological studies of this species; therefore, it seems to be interesting for further investigation of new lead products.  J. gendarussa (Family: Acanthaceae) is a shade-loving, quick-growing, evergreen plant mostly found in moist areas. In Myanmar, it is commonly known as pha-wa-net and distributed in Bago, Kachin, Mandalay, Shan, Taninthayi and Yangon. J. gendarussa is native to China and is distributed widely across India, in tropical and subtropical areas of Asia, Sri Lanka and Malaysia [78]. In traditional medicinal systems, different parts of J. gendarussa have been used in a variety of diseases. The leaves and tender shoots are diaphoretic and used for chronic rheumatism. The juice of the fresh leaves is dropped into the ear for treating earache and an oil prepared from the leaves is used topically to treat oedema caused by beriberi. The plant has been used by the native medical practitioners and tribes to treat various ailments including liver disorders, tumours, inflammation and skin diseases [79].
Two diphyllin glycosides were obtained from the stems and the barks of J. gendarussa;  (HIV-1N) of the analogue nevaripine [80]. J. gendarussa had been reported to have a variety of pharmacological actions like hepatoprotective [83], antioxidant [84,85], anti-inflammatory and analgesic [85], antiangiogenic [86], anti-anxiety [87], anti-arthritic [88], anti-cancer [89,90], antibacterial [91], antifungal [92] and anthelmintic [93] effects based on folk medicine uses. The ethyl acetate soluble fraction isolated from the methanolic extract of the roots of J. gendarussa possessed anti-inflammatory activity in the carrageenan-induced paw edema model [94]. Scientific evidence for these pharmacological actions has not yet been found. It seems that J. gendarussa has the potential for being selected for further clinical studies. Moreover, relatively few chemical constituents of this plant are studied, hence it might be of interest to search for new bioactive compounds in its extracts.
antifungal [92] and anthelmintic [93] effects based on folk medicine uses. The ethyl acetate soluble fraction isolated from the methanolic extract of the roots of J. gendarussa possessed anti-inflammatory activity in the carrageenan-induced paw edema model [94]. Scientific evidence for these pharmacological actions has not yet been found. It seems that J. gendarussa has the potential for being selected for further clinical studies. Moreover, relatively few chemical constituents of this plant are studied, hence it might be of interest to search for new bioactive compounds in its extracts.

Premna integrifolia L.
The plant P. integrifoia belongs to the family Verbenaceae, widely distributed in Vietnam, Laos and Cambodia [95]. In Myanmar, it is locally known by the names taung-tangyi or kywe-thwe and widely distributed in Mandalay, Rakhine and Taninthayi [4]. Traditionally, roots and stem barks are used as a laxative, carminative, and stomachic. Decoctions of the whole plant are used for fevers, rheumatism and neuralgia. The roots are used in the treatment of diabetes, inflammation, swelling, bronchitis, dyspepsia, liver disorders, piles, constipation and fever [96]. The decoction of the roots is used in gonorrhea and during convalescence from fever [97]. Two alkaloids, premnine and ganiarine, are isolated from the stem bark of P. integrifolia [97]. It is widely used by the traditional practitioners as a cardiotonic, antibiotic, anti-coagulant, stomachic, carminative, hepatoprotective and antitumor agent [98].

Vitex trifolia L.
V. trifolia belongs to the Verbenaceae family, a small shrub, is distributed widely in Southeast Asia, Micronesia, Australia, East Africa [106], and Yunan, Guangxi, and Guangdong provinces in mainland China [107]. It is commonly known in Myanmar as kyaung-ban. In Myanmar, dried fruit powder is orally taken with honey in a dose of 5-10 gm for diarrhoeal diseases. For menstrual disorders and urinary disorders, indigestion, the dried powder is orally taken with roasted common salt and warmed water in the same dose as above. Leaves is used as a curry ingredient. Root powder is slurried with alcohol and externally used for muscle cramps.
The ethanol extract of the leaves of V. trifolia displayed free radical scavenging activity [113]. The methyl-p-hydroxybenzoate (155), which is reported from V. trifolia possessed potential mosquito larvicidal activity with the LC 50 values of 5.77 ppm against Culex quinquefasciatus and 4.74 ppm against Aedes aegypti [115].
Essential oils of fresh leaves of V. trifolia, which was extracted by hydro-distillation in a Clevenger's apparatus, were evaluated against Vth instar larvae of Spilosoma obliqua, for insect growth regulatory activity [116]. According to Matsui et al. the leaves of V. trifolia showed the significant inhibitory activity on interleukin (IL)-1-β, IL-6 and inducible nitric oxide synthase (iNOS) mRNA synthesis and have a little effect on tumor necrosis factor (TNF) [117] and it acts on inflammatory activity related gene expression by inhibiting the NF-κB action [118]. The labdane-type diterpenoids [110] and flavonoids from the fruits of this plant [111] displayed anti-proliferative effects on cancer cells through the induction of the apoptosis and the inhibition of the cell cycle. Biological assays have been proved that the hexane and dichloromethane extracts of this plant are highly cytotoxic against several cancer cell lines [119]. The biological activities of V. trifolia have been reported scientifically, however, some traditional uses are still uninvestigated.

Acacia pennata (L.) Willd.
A. pennata, belonging to the family Mimosaceae, is a large woody prickly climber with bipinnate leaves. A. pennata (local name in Myanmar suyit or suboke-gyi) is widely distributed in regions of south and southeast Asia including Bangladesh, Butan, India, Sri Lanka, southwest China and Thailand [120]. In Myanmar, barks of A. pennata have been used in the treatment of asthma and bronchitis. It is reported to have some medicinal value. The leaf juice when mixed with milk is given to infants for indigestion. The A. pennata plant is used as an antiseptic for burning urine and for curing bleeding gums. The root bark can be used as antiflatulent and to cure stomach pain. It is also used in the treatment of bronchitis, cholera and asthma. A decoction of the leaves is used for general treatment of body aches, headaches and fevers [121].
From the leaves of A. pennata, two diterpenoids, a flavonoid glycoside together with another compounds were discovered: taepeenin D (156) (Figure 13 [122]. Biological activities of A. pennata were reported to include anti-parasitic [117] anti-nociceptive and anti-inflammatory [123,125], and antioxidant effects [126]. The phytochemical constituents and biological activities of A. pennata have been reported, however, further pharmacological studies are still needed to scientifically prove the basis of their actions.

Cassia auriculata Linn.
C. auriculata belongs to the family Caesalpiniaceae, which is an ethno-botanically important shrub with attractive yellow flowers. It is cultivated in Myanmar and commonly known as peik-thin-khet. The ethanolic extract of the roots of C. auriculata displayed the nephroprotective activity in cisplatin and gentamicin induced renal injury in male albino rats [127]. The plant has been reported to possess antipyretic, hepatoprotective, antidiabetic, antiperoxidative and antihyperglyceamic and microbicidal activity [128,129]. The flowers are used to treat urinary discharges, nocturnal emissions, diabetes and throat irritation. The leaves are anthelmintic and good for ulcers, skin diseases and leprosy [130].
Nakamura reported a benzocoumarin glycoside, avaraside I (175, Figure 14), along with other compounds such as av170araol I (176)  C. auriculata belongs to the family Caesalpiniaceae, which is an ethno-botanically important shrub with attractive yellow flowers. It is cultivated in Myanmar and commonly known as peik-thinkhet. The ethanolic extract of the roots of C. auriculata displayed the nephroprotective activity in cisplatin and gentamicin induced renal injury in male albino rats [127]. The plant has been reported to possess antipyretic, hepatoprotective, antidiabetic, antiperoxidative and antihyperglyceamic and microbicidal activity [128,129]. The flowers are used to treat urinary discharges, nocturnal emissions, diabetes and throat irritation. The leaves are anthelmintic and good for ulcers, skin diseases and leprosy [130].
Nakamura reported a benzocoumarin glycoside, avaraside I (175, Figure 14), along with other compounds such as av170araol I (176), luteolin, kaempferol, quercetin (177)   The ethanolic extract of C. auriculata flowers showed antihyperlipidemic activity [132]. The aqueous extract of the leaves of C. auriculata possessed antihyperglycemic and hypolipidemic activity in streptozotocin (STZ)-induced mild diabetic and severe diabetic rats [133]. The methanol extract of the root of this plant had significant hepatoprotective activities and antitubercular drug-induced hepatotoxicity [134]. , isolated from C. auriculata displayed hepatoprotective effects against cytotoxicity induced by D-GalM in primary cultured mouse hepatocytes [135]. C. auriculata leaf extract has a protective action against alcohol-induced oxidative stress to the cells as evidenced by the lowered tissue lipid peroxidation and elevated levels of the enzymic and non-enzymic antioxidants [135]. Polyphenols derived from the flowers of C. auriculata showed immunomodulatory effects on various immune cell compositions and their relevant functions [136]. The biological activities of chemical constituents and active principle(s) from this plant are still lacking thorough investigations.
C. oblongifolius (Euphorbiaceae), is popularly known as thetyin-gyi in Mynanmar. It is a medium sized tree widely distributed in the region of Mount Popa in Myanmar. Seeds are used as diarrhea and oedema, and very useful for inflammation, either taken orally or as an external application in Myanmar. Root bark and seeds are reported to be used as purgative, liver diseases and high blood pressure. It is used in gastric ulcers; the bark is used to treat dyspepsia and the roots to treat dysentery [137].
The methanolic extract of the aerial part of C. oblongifolius showed maximum antihepatotoxic activity, whereas, the other extracts (petroleum ether and acetone) showed lower activity [149]. Phytochemical constituents and biological activities of C. oblongifolius have been reported scientifically.

Glycosmis pentaphylla Correa
G. pentaphylla is a shrub or small tree, ca. 1.5-5.0 m high, and is widely distributed from India, Malaysia, and Southern China to the Philippine Islands [150]. It is commonly known as taw-shauk or obok in Myanmar and is widely distributed in Bago, Magway, Mandalay and Yangon. In traditional Myanmar medicine, juice of the leaves of G. pentaphylla is used in fevers, liver complaints and as a vermifuge. A paste of the leaves mixed with ginger is applied for eczema and skin affections. A decoction of the roots is given for facial inflammation. G. pentaphylla is a species of plants belonging to the Rutaceae family, which has been used in several countries as a traditional medicinal plant for the treatment of various ailments. It is used for the treatment of cough, rheumatism, anaemia, and jaundice. Stems and roots of this plant are used for treatment of ulcer [151].

Glycosmis pentaphylla Correa
G. pentaphylla is a shrub or small tree, ca. 1.5-5.0 m high, and is widely distributed from India, Malaysia, and Southern China to the Philippine Islands [150]. It is commonly known as taw-shauk or obok in Myanmar and is widely distributed in Bago, Magway, Mandalay and Yangon. In traditional Myanmar medicine, juice of the leaves of G. pentaphylla is used in fevers, liver complaints and as a vermifuge. A paste of the leaves mixed with ginger is applied for eczema and skin affections. A decoction of the roots is given for facial inflammation. G. pentaphylla is a species of plants belonging to the Rutaceae family, which has been used in several countries as a traditional medicinal plant for the treatment of various ailments. It is used for the treatment of cough, rheumatism, anaemia, and jaundice. Stems and roots of this plant are used for treatment of ulcer [151].
The methanolic extract of the leaves and stems of G. pentaphylla showed antimicrobial, antioxidant and cytotoxic effects [166]. The acridone alkaloid arborinine, isolated from G. pentaphylla, showed significant inhibitory activity towards the growth of crown gall tumors produced by Agrobacterium tumefaciens in a potato disc bioassay [167]. The methanolic extract of the leaves of G. pentaphylla showed hepatoprotective activity against paracetamol-induced hepatotoxicity in Swiss albino mice [168].  [156]. G. pentaphylla ethanolic crude extract showed a significant antioxidant activity [169]. According to the literature, this plant seems to be a rich source of bioactive compounds. Various biological and pharmacological activities of selected medicinal plants and their products have been summarized in Table 2.

Conclusions
In this review, we have systematically summarized the structures and properties of 242 compounds isolated from 15 species of selected Myanmar medicinal plants. Among the 15 selected medicinal plants that have been described in this review, Erythrina suberosa might have potential as a future anticancer therapeutic based on the literature. The plants, Croton oblongifolius, Eriosema chinense, Premna integrifolia and Erythrina suberosa, their phytochemical constituents and biological activities are extensively investigated. Studies on the plants of Acacia pennata, Cassia auriculata, Glycomis pentaphylla and Tadehagi triquetrum have reported the presence of several bioactive compounds whose biological and pharmacological applications can further be investigated. The chemical and pharmacological action of Vitex trifolia have mainly emphasized on fruits, however, the chemical constituents of other parts of this plant and some traditional uses are still missing. On the other hand, the biological activities of the various extracts of Sesbania grandiflora, and Andrographis echioides have been reported scientifically but there have been a few reports on chemical constituents. There are few phytochemistry and biological studies of Dalbergia cultrata and Millettia pendula, Barleria cristata and Justicia gendarussa; Acacia pennata and Cassia auriculata, therefore, they seem to be interesting for investigation of new pharmaceuticals.
A vast reservoir of selected species remains untapped in terms of phytochemical constituents, as well as pharmacology, and this is the research gap for future studies. Further investigations of endemic plants in Myanmar and their phytochemical constituents are necessary to completely understand the molecular mechanisms of their action in vivo and in vitro and to assure the plant extracts are safe for human use.

Conflicts of Interest:
All authors declare to have no actual or potential conflict of interest.