Displaying publications 1 - 20 of 87 in total

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  1. A new sesquiterpenoid from the rhizomes of Homalomena sagittifolia
    Wong KC, Hamid A, Eldeen IM, Asmawi MZ, Baharuddin S, Abdillahi HS, et al.
    Nat Prod Res, 2012;26(9):850-8.
    PMID: 21999629 DOI: 10.1080/14786419.2010.551770
    A new sesquiterpenoid, 1α,4β,7β-eudesmanetriol (1), was isolated together with the known compounds 1β,4β,7β-eudesmanetriol (2) and oplopanone (3) from the rhizomes of Homalomena sagittifolia. The structures of these compounds were determined by extensive spectral analyses. The compounds 1 and 2 inhibited growth of Pseudomonas stutzeri with a MIC value of 117 µM when evaluated for antibacterial activity using the minimum concentration assay. Both these compounds showed remarkable activities against acetylcholinesterase enzyme with IC(50) values ranging between 25 and 26 µM. The isolation of these sesquiterpenoids and their biological activities observed in this study support the reported traditional uses of H. sagittifolia for the treatment of microbial related diseases and central nervous system disorders.
  2. Fulltext A simple isocratic HPLC method for the simultaneous determination of sinensetin, eupatorin, and 3'-hydroxy-5,6,7,4'-tetramethoxyflavone in Orthosiphon stamineus extracts
    Yam MF, Mohamed EA, Ang LF, Pei L, Darwis Y, Mahmud R, et al.
    J Acupunct Meridian Stud, 2012 Aug;5(4):176-82.
    PMID: 22898066 DOI: 10.1016/j.jams.2012.05.005
    Orthosiphon stamineus extracts contain three flavonoids (3'-hydroxy-5,6,7,4'-tetramethoxyflavone, sinensetin, and eupatorin) as bioactive substances. Previous reported high performance liquid chromatography- ultraviolet (HPLC-UV) methods for the determination of these flavonoids have several disadvantages, including unsatisfactory separation times and not being well validated according to International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) standard guidelines. A rapid, specific reversed-phase HPLC method with isocratic elution of acetonitrile: isopropyl alcohol: 20mM phosphate buffer (NaH(2)PO(4)) (30:15:55, v/v) (pH 3.5) at a flow-rate of 1ml/minute, a column temperature of 25°C, and ultraviolet (UV) detection at 340 nm was developed. The method was validated and applied for quantification of different types of O stamineus extracts and fractions. The method allowed simultaneous determination of 3'-hydroxy-5,6,7,4'-tetramethoxyflavone, sinensetin, and eupatorin in the concentration range of 0.03052-250 μg/ml. The limits of detection and quantification, respectively, were 0.0076 and 0.061 μg/ml for 3'-hydroxy-5,6,7,4'-tetramethoxyflavone, 0.0153 and 0.122 μg/ml for sinensetin and 0.0305 and 0.122 μg/ml for eupatorin. The percent relative standard deviation (% RSD) values for intraday were 0.048-0.368, 0.025-0.135, and 0.05-0.476 for 3'-hydroxy-5,6,7,4'-tetramethoxyflavone, sinensetin, and eupatorin, respectively, and those for intraday precision were 0.333-1.688, 0.722-1.055, and 0.548-1.819, respectively. The accuracy for intraday were 91.25%-103.38%, 94.32%-109.56%, and 92.85%-109.70% for 3'-hydroxy-5,6,7,4'-tetramethoxyflavone, sinensetin, and eupatorin, respectively, and those for interday accuracy were 97.49%-103.92%, 103.58%-104.57%, and 103.9%-105.33%, respectively. The method was found to be simple, accurate and precise and is recommended for routine quality control analysis of O stamineus extract containing the three flavonoids as the principle components in the extract.
  3. Fulltext Acute and Sub-Acute Toxicity Evaluation of the Methanolic Extract of Alstonia scholaris Stem Bark
    Bello I, Bakkouri AS, Tabana YM, Al-Hindi B, Al-Mansoub MA, Mahmud R, et al.
    Med Sci (Basel), 2016 Mar 08;4(1).
    PMID: 29083368 DOI: 10.3390/medsci4010004
    Alstonia scholaris has been used by traditional medicine practitioners since the medieval ages for the treatment of diseases. The aim of this research was to evaluate the acute and sub-acute oral toxicity of its methanolic extract. The acute toxicity test was conducted using Sprague Dawley (SD) rats. The methanolic extract of Alstonia scholaris stem bark (ASME) was administrated in a single dose of 2000 mg/kg via oral gavage; and the animals were observed for any behavioral changes or mortality. In the sub-acute toxicity study, SD rats received three doses of ASME (250, 500 and 1000 mg/kg) for 28 days via oral gavage. During these 28 days of treatment, the rats were observed weekly for toxicity symptoms. Following the 28-day treatment, the rats were sacrificed for hematological, biochemical and histopathology studies. In the acute toxicity study, Alstonia scholaris was found to be non-toxic at a dose of 2000 mg/kg b.w. In the sub-acute toxicity study, significant variations in body weight, hematological and biochemical parameters were observed in the experimental groups at the dose of 500 and 1000 mg/kg with the death of two female rats being recorded at the highest dose (1000 mg/kg b.w.). Histopathological studies revealed slight degeneration (lesion) and centrilobular necrosis in the liver, which was most expressed in the highest-dose group. These results demonstrate that, while a single dose and short term oral intake of Alstonia scholaris bark extract caused no toxicity up to a dose of 2000 mg/kg b.w., toxic effects manifested in the long term treatment at the highest dose (500 and 1000 mg/kg). The long-term toxic effect was found to be associated with alterations in hematological compositions and end-organ damage to the liver. Thus, prolonged use of high doses of ASME orally should be discouraged and lower doses encouraged.
  4. Acute and subchronic oral toxicity of Coriolus versicolor standardized water extract in Sprague-Dawley rats
    Hor SY, Ahmad M, Farsi E, Lim CP, Asmawi MZ, Yam MF
    J Ethnopharmacol, 2011 Oct 11;137(3):1067-76.
    PMID: 21767625 DOI: 10.1016/j.jep.2011.07.007
    Coriolus versicolor, which is known as Yun Zhi, is one of the commonly used Chinese medicinal herbs. Recent studies have demonstrated its antitumor activities on cancer cells which led to its widespread use in cancer patient. However, little toxicological information is available regarding its safety. The present study evaluated the potential toxicity of Coriolus versicolor standardized water extract after acute and subchronic administration in rats.
  5. Acute and subchronic toxicity studies of methanol extract of Polygonum minus leaves in Sprague Dawley rats
    Christapher PV, Parasuraman S, Asmawi MZ, Murugaiyah V
    Regul Toxicol Pharmacol, 2017 Jun;86:33-41.
    PMID: 28229903 DOI: 10.1016/j.yrtph.2017.02.005
    Medicinal plant preparations may contain high levels of toxic chemical constituents to potentially cause serious harm to animals and/or humans. Thus, toxicity studies are important to assess the toxic effects of plant derived products. Polygonum minus is used traditionally for different ailments in Southeast Asia. This study was conducted to establish the acute and subchronic toxicity profile of the methanol extract of P. minus leaves. The acute toxicity study showed that the methanol extract of P. minus is safe even at the highest dose tested of 2000 mg/kg in female Sprague Dawley rats. There were no behavioural or physiological changes and gross pathological abnormalities observed. The subchronic toxicity study of methanol extract of P. minus at 250, 500, 1000 and 2000 mg/kg were conducted in both sexes of Sprague Dawley rats. There were no changes observed in the extract treated animal's body weight, food and water intake, motor coordination, behaviour and mental alertness. The values of haematological and biochemical parameters were not different between the treated and control animals. The relative organ weights of extract-treated animals did not differ with that of control animals. Based on the present findings, the methanol extract of P. minus leaves could be considered safe up to the dose of 2000 mg/kg.
  6. Fulltext Adipocytokine Regulation and Antiangiogenic Activity Underlie the Molecular Mechanisms of Therapeutic Effects of Phyllanthus niruri against Non-Alcoholic Fatty Liver Disease
    Zarzour RHA, Alshawsh MA, Asif M, Al-Mansoub MA, Mohamed Z, Ahmad M, et al.
    Nutrients, 2018 Aug 09;10(8).
    PMID: 30096951 DOI: 10.3390/nu10081057
    The growth of adipose tissues is considered angiogenesis-dependent during non-alcoholic fatty liver disease (NAFLD). We have recently reported that our standardized 50% methanolic extract (ME) of Phyllanthus niruri (50% ME of P. niruri) has alleviated NAFLD in Sprague⁻Dawley rats. This study aimed to assess the molecular mechanisms of action, and to further evaluate the antiangiogenic effect of this extract. NAFLD was induced by eight weeks of high-fat diet, and treatment was applied for four weeks. Antiangiogenic activity was assessed by aortic ring assay and by in vitro tests. Our findings demonstrated that the therapeutic effects of 50% ME among NAFLD rats, were associated with a significant increase in serum adiponectin, reduction in the serum levels of RBP4, vaspin, progranulin, TNF-α, IL-6, and significant downregulation of the hepatic gene expression of PPARγ, SLC10A2, and Collα1. Concomitantly, 50% ME of P. niruri has exhibited a potent antiangiogenic activity on ring assay, cell migration, vascular endothelial growth factor (VEGF), and tube formation, without any cytotoxic effect. Together, our findings revealed that the protective effects of P. niruri against NAFLD might be attributed to its antiangiogenic effect, as well as to the regulation of adipocytokines and reducing the expression of adipogenic genes.
  7. An investigation of the anti-inflammatory and analgesic effects of Orthosiphon stamineus leaf extract
    Yam MF, Asmawi MZ, Basir R
    J Med Food, 2008 Jun;11(2):362-8.
    PMID: 18598181 DOI: 10.1089/jmf.2006.065
    Anti-inflammatory and analgesic activities of a standardized Orthosiphon stamineus methanol:water (50:50 vol/vol) leaf extract (SEOS) were evaluated in animal models. Oral administration of SEOS at doses of 500 and 1,000 mg/kg significantly reduced the hind paw edema in rats at 3 and 5 hours after carrageenan administration (P < .01 and P < .01; P < .01 and P < .05, respectively). SEOS (1,000 mg/kg, p.o.) also produced significant (P < .05) analgesic activity in both the acetic acid-induced writhing test and the formalin-induced licking test (late phase) in mice and rats, respectively. However, SEOS showed no effect on the tail flick and hot plate tests in mice. The results of the present study support the proposal that O. stamineus has anti-inflammatory and non-narcotic analgesic activities. These findings justify the traditional use of the plant for treating pain and inflammation.
  8. Anti-angiogenic activity of Gynura segetum leaf extracts and its fractions
    Seow LJ, Beh HK, Majid AM, Murugaiyah V, Ismail N, Asmawi MZ
    J Ethnopharmacol, 2011 Mar 24;134(2):221-7.
    PMID: 21167271 DOI: 10.1016/j.jep.2010.12.007
    Gynura segetum is a popular medicinal plant in Indonesia and Malaysia, known to possess various medicinal properties especially for treatment of cancer, diabetes and hypertension.
  9. Anti-angiogenic activity of Morinda citrifolia extracts and its chemical constituents
    Beh HK, Seow LJ, Asmawi MZ, Abdul Majid AM, Murugaiyah V, Ismail N, et al.
    Nat Prod Res, 2012;26(16):1492-7.
    PMID: 22292423 DOI: 10.1080/14786419.2011.562208
    Morinda citrifolia L. has been used for the treatment of a wide variety of diseases, including cancer. This study was undertaken to evaluate the anti-angiogenic effect of M. citrifolia fruits and leaves. Anti-angiogenic activity was evaluated in vivo using the chick chorioallantoic membrane assay. Bioactivity-guided fractionation and isolation were performed to identify the active constituent, and high-performance liquid chromatography analysis was then used to quantify the amount of this active constituent in the active extracts and fraction. The methanol extracts of fruits and leaves of M. citrifolia and the subsequent chloroform fraction of the fruit methanolic extract were found to have potential anti-angiogenic activity and were more potent compared to suramin. Scopoletin was identified as one of the chemical constituents that may be partly responsible for the anti-angiogenic activity of M. citrifolia fruits. The present findings further support the use of M. citrifolia in cancer or other pathological conditions related to angiogenesis.
  10. Fulltext Anti-hyperglycaemic activity of swietenia macrophylla king (meliaceae) seed extracts in normoglycaemic rats undergoing glucose tolerance tests
    Hashim MA, Yam MF, Hor SY, Lim CP, Asmawi MZ, Sadikun A
    Chin Med, 2013;8(1):11.
    PMID: 23684219 DOI: 10.1186/1749-8546-8-11
    Swietenia macrophylla King (Meliaceae) is used to treat diabetes mellitus in Malaysia. This study aims to evaluate the anti-hyperglycaemic potential of petroleum ether (PE), chloroform (CE) and methanol (ME) extracts of S. macrophylla seeds, in normoglycaemic and streptozotocin (STZ)-induced diabetic rats.
  11. Anti-hypertensive and vasodilatory effects of amended Banxia Baizhu Tianma Tang
    Tan CS, Loh YC, Ng CH, Ch'ng YS, Asmawi MZ, Ahmad M, et al.
    Biomed Pharmacother, 2018 Jan;97:985-994.
    PMID: 29136777 DOI: 10.1016/j.biopha.2017.11.021
    Although Banxia Baizhu Tianma Tang (BBT) has been long administered for hypertensive treatment in Traditional Chinese Medicine (TCM), the ratio of the herbal components that makes up the formulation has not been optimized with respect to the anti-hypertensive effect that it inherently possesses. A newly amended BBT (ABBT) formulation was developed using the evidence-based approach of orthogonal stimulus-response compatibility model. The ABBT showed enhanced therapeutic effect while maintaining its traditional theoretical approach rooted in TCM. This study was designed to investigate the possible mechanism of actions involved in the vasodilatory activity of ABBT-50 by evaluating its vasodilative effect on isolated Sprague Dawley rats in the presence of absence of various antagonists. When pre-contracted with phenylephrine, relaxation was observed in endothelium intact (EC50=0.027±0.003mg/ml, Rmax=109.8±2.12%) and denuded aortic rings (EC50=0.409±0.073mg/ml, Rmax=63.15±1.78%), as well as in endothelium intact aortic rings pre-contracted with potassium chloride (EC50=32.7±12.16mg/ml, Rmax=34.02±3.82%). Significant decrease in the vasodilative effect of ABBT-50 was observed in the presence of Nω-nitro-l-arginine methyl ester (EC50=0.12±0.021mg/ml, Rmax=75.33±3.28%), 1H-[1,2,4] Oxadiazolo[4,3-a]quinoxalin-1-one (EC50=0.463±0.18mg/ml, Rmax=54.48±2.02%), methylene blue (EC50=0.19±0.037mg/ml, Rmax=83.69±3.19%), indomethacin (EC50=0.313±0.046mg/ml, Rmax=71.33±4.12%), atropine (EC50=0.146±0.013mg/ml, Rmax=77.2±3.41%), and 4-aminopyridine (EC50=0.045±0.008mg/ml, Rmax=95.55±2.36%). ABBT-50 was also suppressing Ca2+ release from sarcoplasmic reticulum and inhibiting calcium channels. Vasodilatory effects of ABBT-50 are mediated through NO/sGC/cGMP cascade and PGI2, followed by muscarinic pathways and calcium channels.
  12. Anti-inflammatory activity of Crinum asiaticum plant and its effect on bradykinin-induced contractions on isolated uterus
    Samud AM, Asmawi MZ, Sharma JN, Yusof AP
    Immunopharmacology, 1999 Sep;43(2-3):311-6.
    PMID: 10596868
    Crinum asiaticum Linn plant is used in Malaysia as a rheumatic remedy and to relieve local pain. In the present study, we examined the anti-inflammatory effects of this plant extract on carrageenan-induced hind paw oedema in mice. C. asiaticum was serially extracted with petroleum ether, followed by chloroform and lastly, methanol. The chloroform and methanol extracts of the plant given orally (50 mg kg-1) caused significant (p < 0.05; n = 7) reduction in paw oedema but the petroleum ether extract did not induce significant effect (p > 0.05) on paw oedema. The methanol extract was then dissolved in water and extracted consecutively with chloroform, ethyl acetate and butanol. The chloroform fraction of methanol extract (CFME) treatment (50 mg kg(-1)) significantly reduced (p < 0.05; n = 7) the acute paw oedema. This may indicate that active anti-inflammatory compounds are present in the CFME. In an attempt to study the mechanism of action of its anti-inflammatory activity, the effects of CFME on BK- and histamine-induced contractions were investigated in isolated rat uterus and guinea-pig ileum preparations, respectively. It was found that CFME caused dose-dependent reduction (p < 0.05; n = 6) of the contractile response induced by BK and shifted the log dose-response curve of histamine to the right. The present findings suggest that C. asiaticum possessed an anti-inflammatory activity as suggested by its use in traditional medicine. The anti-inflammatory activity of this plant could not have been due to its anti-bradykinin activities as CFME non-specifically inhibited BK-induced contraction. It also suggest that CFME may contain compound(s) with anti-histaminic properties. The significance of these findings is discussed.
  13. Fulltext Anti-inflammatory and analgesic effects of Elephantopus tomentosus ethanolic extract
    Yam MF, Ang LF, Ameer OZ, Salman IM, Aziz HA, Asmawi MZ
    J Acupunct Meridian Stud, 2009 Dec;2(4):280-7.
    PMID: 20633503 DOI: 10.1016/S2005-2901(09)60069-8
    Elephantopus tomentosus is widely used in Asia, especially in Malaysia, for the treatment of pain and inflammation. In the present study, the analgesic and anti-inflammatory effects of a 95% ethanol extract of E. tomentosus were investigated in different experimental models. In the anti-inflammation study, 1000 mg/kg of extract significantly reduced carrageenan-induced hind paw edema (p < 0.05) and inhibited abdominal permeability compared with control (p < 0.01). The analgesic activity was assayed in several experimental models in mice: (1) hot plate, (2) tail flick, (3) writhing test; and rats: carrageenan-induced hyperalgesia pain threshold test. However, at the doses tested, no significant activity was found in the hot plate test and the tail flick test. E. tomentosus ethanol extract at 1000 mg/kg significantly (p < 0.05) increased hyperalgesia pain threshold and inhibited writhing activity. The results suggest that E. tomentosus ethanol extract at 1000 mg/kg dose is effective in anti-inflammatory and non-steroidal anti-inflammatory drug type anti-nociception activities.
  14. Anti-inflammatory and antioxidant activities of the methanol extract of Gynura segetum leaf
    Seow LJ, Beh HK, Umar MI, Sadikun A, Asmawi MZ
    Int Immunopharmacol, 2014 Nov;23(1):186-91.
    PMID: 25194675 DOI: 10.1016/j.intimp.2014.08.020
    Gynura segetum, family Compositae, is a cultivated species and can be found growing in the tropical regions of Indonesia and Malaysia. The plant is known for its use for the treatment of cancer, inflammation, diabetes, hypertension and skin afflictions. In the current study, in vivo anti-inflammatory effect of the methanol extract G. segetum leaf and its antioxidant effect in vitro have been investigated for the first time. The in vitro antioxidant activities of the methanol extract were measured using common methods including total phenolic content; total flavonoid content; scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and β-carotene bleaching assays. The in vivo anti-inflammatory activities were tested using the cotton pellet implanted animal model. The measurement of pro-inflammatory cytokine (TNF-α and IL-1) levels in the blood samples of the rats was carried out by using ELISA kits. The inhibitory activity on cyclooxygenase (COX) enzyme of methanol extract was also evaluated. The methanol extract exhibited good antioxidant activity which is associated with their total phenolic and flavonoid contents. Methanol extract strongly inhibited the granuloma tissue formation in rats and the anti-inflammatory potential was mediated through the inhibition of pro-inflammatory cytokines and COX-2 enzyme activities. Taken together, the present study suggests that G. segetum's leaf is a natural source of antioxidants and has potential therapeutic benefits against chronic inflammation.
  15. Fulltext Antidiabetic and antioxidant activities of Nypa fruticans Wurmb. vinegar sample from Malaysia
    Yusoff NA, Yam MF, Beh HK, Abdul Razak KN, Widyawati T, Mahmud R, et al.
    Asian Pac J Trop Med, 2015 Aug;8(8):595-605.
    PMID: 26321511 DOI: 10.1016/j.apjtm.2015.07.015
    OBJECTIVES: To study the antidiabetic and antioxidant activities of nipa palm vinegar (NPV) used in traditional Malay medicine for treating diabetes.

    METHODS: NPV was extracted using liquid-liquid extraction method and the obtained samples were subjected to antidiabetic studies using normal and streptozotocin-induced diabetic rat models whereas antidoxidant activities were investigated via in vitro antioxidant tests namely 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azinobis-3-ethylbenzothiozoline-6-sulfonic acid free radicals scavenging activities and the reducing power assay.

    RESULTS: Single administration of NPV and its extracts were not effective in both normal and diabetic rats. In intraperitoneal glucose tolerance test, NPV and its aqueous extract showed significant blood glucose lowering effect. In the sub-acute study, compared with the diabetic control, aqueous extract of NPV showed the most notable blood glucose lowering effect (56.6%) and a significant improvement in serum insulin levels (79.8%, P 

  16. Fulltext Antidiabetic properties and mechanism of action of Orthosiphon stamineus Benth bioactive sub-fraction in streptozotocin-induced diabetic rats
    Mohamed EA, Yam MF, Ang LF, Mohamed AJ, Asmawi MZ
    J Acupunct Meridian Stud, 2013 Feb;6(1):31-40.
    PMID: 23433053 DOI: 10.1016/j.jams.2013.01.005
    Orthosiphon stamineus is a popular folk medicine widely used to treat many diseases including diabetes. Previous studies have shown that the sub-fraction of chloroform extract was able to inhibit the rise of blood glucose levels in a glucose tolerance test. This study was carried out to evaluate the chronic effect and possible mechanism of action of the bioactive chloroform sub-fraction of O. stamineus using streptozotocin-induced diabetic rats and in vitro methods. Administration of the chloroform extract sub-fraction 2 (Cƒ2-b) at a dose of 1 g/kg twice daily on diabetic rats for 14 days showed a significant lowering (p < 0.05) of the final blood glucose level compared to the pretreatment level. However, there were no significant differences in the plasma insulin levels post-treatment compared to the pretreatment levels for all doses of Cƒ2-b. Conversely, Cƒ2-b at a concentration of 2 mg/mL significantly increased (p < 0.001) the glucose uptake by the rat diaphragm muscle. The increase in glucose uptake was also shown when the muscle was incubated in a solution containing 1 IU/mL of insulin or 1 mg/mL of metformin. Furthermore, the effect of this sub-fraction on glucose absorption in the everted rat jejunum showed that Cƒ2-b at concentrations of 0.5 mg/mL, 1 mg/mL and, 2 mg/mL significantly reduced the glucose absorption of the jejunum (p < 0.05-0.001). Similarly, the absorption of glucose was also inhibited by 1 mg/mL and 2 mg/mL of metformin (p < 0.001). These results suggest that the effect of Cƒ2-b may be due to extra-pancreatic mechanisms. There was no evidence that the plant extract stimulated the release of insulin in order to lower the blood glucose level.
  17. Fulltext Antihyperglycaemic and Toxicological Evaluations of Extract and Fractions of Gynura procumbens Leaves
    Algariri K, Atangwho IJ, Meng KY, Asmawi MZ, Sadikun A, Murugaiyah V
    Trop Life Sci Res, 2014 Aug;25(1):75-93.
    PMID: 25210589 MyJurnal
    The acute and sub-chronic antihyperglycaemic activity, safety margin evaluations and chemical composition of ethanol extract (EE) and fractions of Gynura procumbens (GP) were studied. Streptozotocin (STZ)-induced diabetic rats (SDRs) and the Organisation for Economic Cooperation and Development (OECD) guidelines 425 and 407 were used in the antidiabetic and toxicity studies, respectively. Biochemical and haematological data obtained from both acute and sub-chronic procedures suggest that the extract is safe at the limit test dose (2000 mg/kg); thus, the oral lethal dose (LD50) exceeds 2000 mg/kg. The acceptable daily intake (ADI) was determined to be 700 mg/kg/day. In the acute antihyperglycaemic study, the n-butanol fraction (n-BF) was found to consistently lower glucose levels the most effectively, which was also demonstrated in the 14-day study. Not only did the n-BF show the highest dose-dependent glucose-lowering action (51.2% and 62.0% at 500 mg/kg and 1000 mg/kg, respectively), its effect was the closest to that of metformin (63.6%, p<0.05). The estimated amount of flavonoids in n-BF were 62.90% and 79.68% higher than the ethyl acetate fraction (EAF) and aqueous fraction (AF), respectively (p<0.05), with a corresponding value of 61.22% and 49.33% for phenolics (p<0.05). GP leaves have a no-observed-adverse-effect-level (NOAEL) and antihyperglycaemic activity corresponding to the high content of phenols and flavonoids. Therefore, GP leaves are a promising source of new antidiabetic natural products.
  18. Fulltext Antihyperglycemic Effect of Methanol Extract of Syzygium polyanthum (Wight.) Leaf in Streptozotocin-Induced Diabetic Rats
    Widyawati T, Yusoff NA, Asmawi MZ, Ahmad M
    Nutrients, 2015 Sep;7(9):7764-80.
    PMID: 26389944 DOI: 10.3390/nu7095365
    Syzygium polyanthum (S. polyanthum), a plant belonging to Myrtaceae, is widely used in Indonesian and Malaysian cuisines. Diabetic patients in Indonesia also commonly use it as a traditional medicine. Hence, this study was conducted to investigate the antihyperglycemic effect of the methanol extract (ME) of S. polyanthum leaf and its possible mechanisms of action. To test for hypoglycemic activity, ME was administered orally to normal male Sprague Dawley rats after a 12-h fast. To further test for antihyperglycemic activity, the same treatment was administered to glucose-loaded (intraperitoneal glucose tolerance test, IPGTT) and streptozotocin (STZ)-induced diabetic rats, respectively. Hypoglycemic test in normal rats did not show significant reduction in blood glucose levels (BGLs) by the extract. Furthermore, IPGTT conducted on glucose-loaded normal rats also did not show significant reduction of BGLs. However, repeated administration of metformin and three doses of ME (250, 500 and 1000 mg/kg) for six days caused significant reduction of fasting BGLs in STZ-induced diabetic rats. The possible mechanisms of action of S. polyanthum antihyperglycemic activity were assessed by measurement of intestinal glucose absorption and glucose uptake by isolated rat abdominal muscle. It was found that the extract not only inhibited glucose absorption from the intestine but also significantly increased glucose uptake in muscle tissue. A preliminary phytochemical qualitative analysis of ME indicated the presence of tannins, glycosides, flavonoids, alkaloids and saponins. Additionally, Gas Chromatography-Mass Spectrometry (GC-MS) analysis detected squalene. In conclusion, S. polyanthum methanol leaf extract exerts its antihyperglycemic effect possibly by inhibiting glucose absorption from the intestine and promoting glucose uptake by the muscles.
  19. Fulltext Antihyperglycemic effect of orthosiphon stamineus benth leaves extract and its bioassay-guided fractions
    Mohamed EA, Mohamed AJ, Asmawi MZ, Sadikun A, Ebrika OS, Yam MF
    Molecules, 2011 May 04;16(5):3787-801.
    PMID: 21544041 DOI: 10.3390/molecules16053787
    Preliminary investigations were carried out to evaluate the antidiabetic effects of the leaves of O. stamineus extracted serially with solvents of increasing polarity (petroleum ether, chloroform, methanol and water); bioassay-guided purification of plant extracts using the subcutaneous glucose tolerance test (SbGTT) was also carried out. Only the chloroform extract, given at 1 g/kg body weight (b.w.), significantly reduced (P < 0.05) the blood glucose level of rats loaded subcutaneously with 150 mg/kg (b.w.) glucose. The active chloroform extract of O. stamineus was separated into five fractions using a dry flash column chromatography method. Out of the five fractions tested, only chloroform fraction 2 (Cƒ2), at the dose of 1 g/kg (b.w.) significantly inhibited (P < 0.05) blood glucose levels in SbGTT. Active Cƒ2 was split into two sub-fractions Cƒ2-A and Cƒ2-B, using a dry flash column chromatography method. The activities Cƒ2-A and Cƒ2-B were investigated using SbGTT, and the active sub-fraction was then further studied for anti-diabetic effects in a streptozotocin-induced diabetic rat model. The results clearly indicate that Cƒ2-B fraction exhibited a blood glucose lowering effect in fasted treated normal rats after glucose-loading of 150 mg/kg (b.w.). In the acute streptozotocin-induced diabetic rat model, Cƒ2-B did not exhibit a hypoglycemic effect on blood glucose levels up to 7 hours after treatment. Thus, it appears that Cƒ2-B functions similarly to metformin, which has no hypoglycemic effect but demonstrates an antihyperglycemic effect only in normogycemic models. The effect of Cƒ2-B may have no direct stimulatory effects on insulin secretion or on blood glucose levels in diabetic animal models. Verification of the active compound(s) within the active fraction (Cƒ2-B) indicated the presence of terpenoids and, flavonoids, including sinensitin.
  20. Antihypertensive activity and vascular reactivity mechanisms of Vitex pubescens leaf extracts in spontaneously hypertensive rats
    Al-Akwaa AA, Asmawi MZ, Dewa A, Mahmud R
    Heliyon, 2020 Jul;6(7):e04588.
    PMID: 32775735 DOI: 10.1016/j.heliyon.2020.e04588
    Background: Vitex pubescens has been used traditionally in hypertension treatment but not yet scientifically assessed. The objective of the study is to investigate the antihypertensive and vasorelaxant activities of V. pubescens, study its underlying pharmacological mechanisms, and identify the relevant vasoactive compounds.

    Methods: Successive extractions of V. pubescens leaf were carried out to produce petroleum ether (VPPE), chloroform (VPCE), methanol (VPME), and water (VPWE) extracts. Spontaneously hypertensive rats (SHRs) received a daily oral administration of the extracts (500 mg/kg/day; n = 6) or verapamil (15 mg/kg/day; n = 6) for 2 weeks, while the systolic and diastolic blood pressures were measured using non-invasive tail-cuff method. Vasorelaxation assays of the extracts were later conducted using phenylephrine (PE, 1 μM) pre-contracted aortic ring preparation. Mechanisms of vasorelaxation by the most potent fraction were studied using vasorelaxation assays with selected blockers/inhibitors. GC-MS was conducted to determine the active compounds.

    Results: VPPE elicited the most significant diminution in systolic and diastolic blood pressure of treated SHRs and produced the most significant vasorelaxation in the aortic rings. Vasorelaxant effects of F2-VPPE were significantly reduced in endothelium-denuded aortic rings by glibenclamide (1 μM), whereas calcium chloride and PE-induced contractions were significantly suppressed. Endothelium removal of the aortic rings or incubation with indomethacin (10 μM), atropine (1 μM), methylene blue (10 μM), propranolol (1μM) and L-NAME (10 μM) did not significantly alter F2-VPPE-induced vasorelaxation. Seven compounds were identified using GC-MS, including spathulenol.

    Conclusion: F2-VPPE exerted its endothelium-independent vasorelaxation by inhibition of vascular smooth muscle contraction induced by extracellular Ca+2 influx through trans-membrane Ca+2 channels and/or Ca+2 release from intracellular stores, and by activation of KATP channels. The vasorelaxation effects of V. pubescens could be mediated by the compound, spathulenol.

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