Displaying publications 41 - 60 of 106 in total

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  1. Fulltext Overview of Antagonists Used for Determining the Mechanisms of Action Employed by Potential Vasodilators with Their Suggested Signaling Pathways
    Loh YC, Tan CS, Ch'ng YS, Ahmad M, Asmawi MZ, Yam MF
    Molecules, 2016 Apr 15;21(4):495.
    PMID: 27092479 DOI: 10.3390/molecules21040495
    This paper is a review on the types of antagonists and the signaling mechanism pathways that have been used to determine the mechanisms of action employed for vasodilation by test compounds. Thus, we exhaustively reviewed and analyzed reports related to this topic published in PubMed between the years of 2010 till 2015. The aim of this paperis to suggest the most appropriate type of antagonists that correspond to receptors that would be involved during the mechanistic studies, as well as the latest signaling pathways trends that are being studied in order to determine the route(s) that atest compound employs for inducing vasodilation. The methods to perform the mechanism studies were included. Fundamentally, the affinity, specificity and selectivity of the antagonists to their receptors or enzymes were clearly elaborated as well as the solubility and reversibility. All the signaling pathways on the mechanisms of action involved in the vascular tone regulation have been well described in previous review articles. However, the most appropriate antagonists that should be utilized have never been suggested and elaborated before, hence the reason for this review.
  2. Orthosiphon stamineus: traditional uses, phytochemistry, pharmacology, and toxicology
    Ameer OZ, Salman IM, Asmawi MZ, Ibraheem ZO, Yam MF
    J Med Food, 2012 Aug;15(8):678-90.
    PMID: 22846075 DOI: 10.1089/jmf.2011.1973
    Orthosiphon stamineus Benth. (Lambiaceae) is an important plant in traditional folk medicine. This review is a comprehensive summary of the currently available chemical, pharmacological, and toxicological investigations as well as the traditional and therapeutic uses of this plant. Different in vitro and in vivo models have been addressed along with a survey of all phytochemicals identified in this plant, including flavonoids, terpenoids, and essential oils. Previous studies revealed that O. stamineus possesses several pharmacological activities, which are attributed to its phytochemical content. It was found that O. stamineus exhibits diuretic, hypouricemic, renal protective, antioxidant, anti-inflammatory, hepatoprotective, gastroprotective, antihypertensive, antidiabetic, antihyperlipidemic, antimicrobial, and anorexic activities. In conclusion, O. stamineus has wide traditional and pharmacological uses in various pathophysiological conditions. Therefore, it is an attractive subject for further experimental and clinical investigations.
  3. Orthosiphon stamineus leaf extract protects against ethanol-induced gastropathy in rats
    Yam MF, Ang LF, Salman IM, Ameer OZ, Lim V, Ong LM, et al.
    J Med Food, 2009 Oct;12(5):1089-97.
    PMID: 19857074 DOI: 10.1089/jmf.2008.0005
    Orthosiphon stamineus Benth., which is used as a gastroprotective herbal remedy in Malaysia, was assessed for its anti-ulcerogenic activity against ethanol-induced ulcers in rats. Fifty percent methanol was used to extract the oven-dried O. stamineus leaves. The extract was then lyophilized with a rotary evaporator and freeze-dried. Oral administration of O. stamineus methanolic extract (OSME) (125, 250, 500, and 1,000 mg/kg) was found to significantly decrease the ulcer index (P < .01, P < .001, P < .001, and P < .001, respectively). Histological study of a section of the rat stomach also showed a marked improvement in the gastric mucosal damage in groups receiving OSME. In order to further investigate the gastroprotective mechanism of OSME, mucus secretion and lipid peroxidation level were estimated in vitro and ex vivo. OSME exhibited dose-dependent stimulation of mucus secretion (r = 0.718, P < .001) and inhibition of lipid peroxidation in rat gastric mucosal homogenates (both in vitro [r = 0.819, P < .05] and ex vivo [r = 0.981, P < .05]). It was concluded that the gastroprotective mechanism of OSME was partly due to its ability to inhibit lipid peroxidation and stimulate gastric mucus secretion.
  4. Fulltext Orthogonal Stimulus-Response as a Tool to Formulate Traditional Chinese Medicinal Herbal Combination: - New Scientific-Based TCM Herbal Formulating Method
    Loh YC, Tan CS, Yam MF, Oo CW, Omar WMW
    J Pharmacopuncture, 2018 Sep;21(3):203-206.
    PMID: 30283708 DOI: 10.3831/KPI.2018.21.024
    Objectives: There is an increasing number of complex diseases that are progressively more difficult to be controlled using the conventional "single compound, single target" approach as demonstrated in our current modern drug development. TCM might be the new cornerstone of treatment alternative when the current treatment option is no longer as effective or that we have exhausted it as an option. Orthogonal stimulus-response compatibility group study is one of the most frequently employed formulas to produce optimal herbal combination for treatment of multi-syndromic diseases. This approach could solve the relatively low efficacy single drug therapy usage and chronic adverse effects caused by long terms administration of drugs that has been reported in the field of pharmacology and medicine.

    Methods: The present review was based on the Science Direct database search for those related to the TCM and the development of antihypertensive TCM herbal combination using orthogonal stimulus-response compatibility group studies approach.

    Results: Recent studies have demonstrated that the orthogonal stimulus-response compatibility group study approach was most frequently used to formulate TCM herbal combination based on the TCM principles upon the selection of herbs, and the resulting formulated TCM formula exhibited desired outcomes in treating one of global concerned complex multi-syndromic diseases, the hypertension. These promising therapeutic effects were claimed to have been attributed by the holistic signaling mechanism pathways employed by the crude combination of herbs.

    Conclusion: The present review could serve as a guide and prove the feasibility of TCM principles to be used for future pharmacological drug research development.

  5. New flavonoid-based compound synthesis strategy for antihypertensive drug development
    Loh YC, Chan SY, Tew WY, Oo CW, Yam MF
    Life Sci, 2020 May 15;249:117512.
    PMID: 32145305 DOI: 10.1016/j.lfs.2020.117512
    Hypertension is one of the leading causes of mortality in relation to the cardiovascular conditions and easily the most overlooked and poorly managed disease in mankind. With well over 200 drugs available in the market globally, there is still an urgency to search for antihypertensive alternatives due to the subpar efficacy and unwarranted side effects of the current choices. Present studies reported over 250 types of plant-derived compounds were being investigated for potential pharmacological effects on the vasculature in the last 3 decades. There were numerous literatures that claimed various compounds exhibiting vasorelaxant properties to a certain extent with low numbers of these compounds being successfully adapted into the current medicinal practice for treatment of hypertension. The issue is the scarcity of reviews that summarizes the discovery of this field and the lack of thorough comparison of these compounds to identify which of these vasodilators should be the next face of hypertension management. Thus, this review is aiming towards identifying the relationship between a major class of plant-derived compounds, flavonoid's activity as a vasodilator with their signalling pathways and their structural characteristics according to their vasorelaxant properties. Interestingly, we found that both nitric oxide and voltage-operated calcium channels pathways, and two of the flavonoid's structural characteristics play crucial roles in eliciting strong vasorelaxant effects. We have faith that the insights of this review will serve as a reference for those researching similar topics in the future and potentially lead to the development of more promising antihypertensive alternative.
  6. Fulltext Modulation of interleukin-18 release produced positive outcomes on parasitaemia development and cytokines production during malaria in mice
    Basir R, Hasballah K, Jabbarzare M, Gam LH, Abdul Majid AM, Yam MF, et al.
    Trop Biomed, 2012 Sep;29(3):405-21.
    PMID: 23018504 MyJurnal
    The involvement of interleukin-18 (IL-18) and the effects of modulating its release on the course of malaria infection were investigated using Plasmodium berghei ANKA infection in ICR mice as a model. Results demonstrated that plasma IL-18 concentrations in malarial mice were significantly elevated and positively correlated with the percentage parasitaemia development. Significant expressions of IL-18 were also observed in the brain, spleen and liver tissues. Slower development of parasitaemia was observed significantly upon inhibition and neutralization of IL-18, whereas faster development of parasitaemia was recorded when the circulating levels of IL-18 were further augmented during the infection. Inhibition and neutralization of IL-18 production also resulted in a significant decrease of plasma concentrations of pro-inflammatory cytokines (TNFα, IFNγ, IL-1α and IL-6), whereas the anti-inflammatory cytokine, IL-10, was significantly increased. Augmenting the release of IL- 18 during the infection on the other hand resulted in the opposite. Early mortality in malarial mice was also observed when the circulating levels of IL-18 were further augmented. Results proved the important role of IL-18 in immune response against malaria and suggest that IL-8 is pro-inflammatory in nature and may involve in mediating the severity of the infection through a pathway of elevating the pro-inflammatory cytokine and limiting the release of anti-inflammatory cytokine.
  7. Fulltext Microencapsulation Curcuminoids for Effective Delivery in Pharmaceutical Application
    Ang LF, Darwis Y, Por LY, Yam MF
    Pharmaceutics, 2019 Sep 02;11(9).
    PMID: 31480767 DOI: 10.3390/pharmaceutics11090451
    Curcuminoids have been long proven to possess antioxidant, anti-inflammatory and antibacterial properties which are crucial in their role as a pharmacological active agent. However, its poor solubility, high oxidative degradation, light sensitivity and poor bioavailability have been huge hurdles that need to be overcome for it to be administered as an oral or even a topical medication. In this present study, a complex coacervation microencapsulation approach was used to encapsulate the curcuminoids using both gelatin B and chitosan (at the optimum ratio of 30:1% w/w) for a more efficient drug delivery system. Curcuminoids microcapsules (CPM) were developed to be spherical in shape, discrete and free flowing with a reduced color staining effect. The thick wall of the CPM contributes directly to its integrity and stability. Cross-linking increases the density of polymers' wall network, hence, further increasing the decomposition temperature of curcuminoids microcapsules. Microencapsulation demonstrated an increment in curcuminoids solubility, while chemical cross-linking allowed for sustained release of the drug from the microcapsules by lowering the swelling rate of the available polymer networks. Thus, the microcapsules complied with the zero order release kinetics with super case-II transport mechanism. On the basis of all that was discussed above, it can be safely concluded that CPM should be incorporated in delivery system of curcuminoid, especially in its topical delivery for controlled drug release purposes, for not only a more efficient drug delivery system design but also a more efficacious optimization of the pharmacological benefits of curcuminoids.
  8. Mechanisms of action of Panax notoginseng ethanolic extract for its vasodilatory effects and partial characterization of vasoactive compounds
    Loh YC, Tan CS, Ch'ng YS, Ng CH, Yeap ZQ, Yam MF
    Hypertens Res, 2019 02;42(2):182-194.
    PMID: 30464217 DOI: 10.1038/s41440-018-0139-9
    Panax notoginseng is the most valuable medicinal plant and has been used clinically for more than two thousand years to treat various diseases, including hypertension. Previous studies claimed that different isolated compounds from P. notoginseng are involved in different pathways for vasodilation. It is strongly believed that these vasodilating compounds might act synergistically in contributing vasodilatory effects via holistic signaling pathways. The present study aims to evaluate the vasodilatory effect and mechanism of action employed by the crude extract of P. notoginseng. The fingerprint of P. notoginseng was developed using tri-step FTIR and HPTLC. The contents of Rg1 and Rb1 in the active extract (PN95) were further quantified via HPTLC. The vasodilatory effect of PN95 was evaluated using an in vitro aortic ring model. The results showed that PN95 contains a high amount of Rg1 and Rb1, 25.9 and 13.6%, respectively. The vasodilatory effect of PN95 was elicited via the NO/sGC/cGMP and β2-adrenergic receptors pathways. Furthermore, PN95 could manage vascular tone by regulating action potentials via potassium and both VOCC and IP3R pathways. The results obtained fulfilled the expected outcome where the PN95 employed more signaling pathways than any of the single active compounds; hence, the holistic therapeutic effect could be achieved and would more easily translate to applications for the treatment of human diseases.
  9. Mechanisms of Action of Uncaria rhynchophylla Ethanolic Extract for Its Vasodilatory Effects
    Loh YC, Ch'ng YS, Tan CS, Ahmad M, Asmawi MZ, Yam MF
    J Med Food, 2017 Sep;20(9):895-911.
    PMID: 28771084 DOI: 10.1089/jmf.2016.3804
    Uncaria rhynchophylla is one of the major components included in Traditional Chinese Medicine prescriptions for hypertensive treatment. Previous studies have suggested that U. rhynchophylla might contain vasodilation-mediating active compounds, especially indole alkaloids. Hence, this study was carried out to determine the vasodilatory effects of U. rhynchophylla, which was extracted by different solvents. The most effective extract was then further studied for its signaling mechanism pathways. The authenticity of U. rhynchophylla was assured by using modernized tri-step Fourier transform infrared (FTIR), including conventional 1D FTIR, second derivative scanning combined with 2D-correlated IR spectroscopy. Results obtained proved that the fingerprint of U. rhynchophylla used was identical to the atlas. Isolated aortic rings from male Sprague-Dawley rats were preconstricted with phenylephrine (PE) followed by cumulative addition of U. rhynchophylla extracts. The signaling mechanism pathways were studied by incubation with different receptor antagonists before the PE precontraction. In conclusion, the 95% ethanolic U. rhynchophylla extract (GT100) was found to be most effective with an EC50 value of 0.028 ± 0.002 mg/mL and an Rmax value of 101.30% ± 2.82%. The signaling mechanism pathways employed for exerting its vasodilatory effects included nitric oxide/soluble guanylyl cylcase/cyclic guanosine monophosphate (NO/sGC/cGMP) and PGI2 (endothelium-derived relaxing factors), G protein-coupled M3- and β2 receptors, regulation of membrane potential through voltage-operated calcium channel, intracellular Ca2+ released from inositol triphosphate receptor (IP3R), and all potassium channels except the Kca channel.
  10. Mechanism of vasorelaxation induced by eupatorin in the rats aortic ring
    Yam MF, Tan CS, Ahmad M, Shibao R
    Eur J Pharmacol, 2016 Oct 15;789:27-36.
    PMID: 27370961 DOI: 10.1016/j.ejphar.2016.06.047
    Previous studies demonstrated that eupatorin content in Orthosiphon stamineus fractions correlated with their vasorelaxation activity. Even with previous studies, there is still very little information on the vasorelaxation effect of eupatorin, and not many scientific studies had been carried out. Therefore, the present study was designed to investigate the vasorelaxation activity and mechanism of action of eupatorin. The vasorelaxation activity and the underlying mechanisms of eupatorin was evaluated on thoracic aortic rings isolated from Sprague Dawley rats. Eupatorin caused the relaxation of aortic rings pre-contracted with phenylephrine with and without endothelium (pD2=6.66±0.13, EMAX=99.72±6.39%; pD2=6.10±0.22, EMAX=65.78±8.01%), and also the relaxation of endothelium-intact aortic rings pre-contracted with potassium chloride (pD2=6.20±0.30, EMAX=71.89±12.25%). In the presence of Nω-nitro-l-arginine methyl ester (pD2<4.60, EMAX=24.91±6.39%), methylene blue (pD2=6.05±0.38, EMAX=66.79±9.69%), ODQ (pD25.84±0.32, EMAX=60.47±9.6%), indomethacin (pD2=6.27±0.21, EMAX=76.03±9.45%), tetraethylammonium (pD2=6.09±0.35, EMAX=69.35±11.31%), 4-aminopyridine (pD2=6.34±0.12, EMAX=76±6.1%), barium chloride (pD2=6.47±0.14, EMAX=79.61±10.02%), atropine (pD2=6.36±0.29, EMAX=86.47±12.95%) and propranolol (pD2=6.49±0.26, EMAX=83.2±12.01%), relaxation stimulated by eupatorin was significantly reduced. Eupatorin was also found to be active in reducing Ca(2+) release from sarcoplasmic reticulum and in blocking calcium channels. The present study demonstrates the vasorelaxation effect of eupatorin involving NO/sGC/cGMP and indomethacin pathways, calcium and potassium channels, and muscarinic and beta-adrenergic receptors.
  11. Mechanism of vasorelaxation induced by 3'-hydroxy-5,6,7,4'-tetramethoxyflavone in the rats aortic ring assay
    Tan CS, Yam MF
    Naunyn Schmiedebergs Arch Pharmacol, 2018 06;391(6):561-569.
    PMID: 29552696 DOI: 10.1007/s00210-018-1481-9
    Previous studies have demonstrated that 3'-hydroxy-5,6,7,4'-tetramethoxyflavone (TMF) content in Orthosiphon stamineus fractions correlate with its vasorelaxation activity. Even with the availability of previous studies, there is still very little information on the vasorelaxation effect of TMF, and few scientific studies have been carried out. Therefore, the present study was designed to investigate the vasorelaxation activity and mechanism of action of the TMF. The vasorelaxation activity and the underlying mechanisms of TMF were evaluated on thoracic aortic rings isolated from Sprague Dawley rats. TMF caused the relaxation of aortic rings with endothelium pre-contracted with phenylephrine. However, the vasorelaxant effect of TMF was significantly decreased in PE-primed endothelium-denuded and potassium chloride-primed endothelium-intact aortic rings. In the presence of Nω-nitro-L-arginine methyl ester, methylene blue, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, indomethacin, tetraethylammonium, 4-aminopyridine, barium chloride, atropine and propranolol, the relaxation stimulated by TMF was significantly reduced. TMF was also found to reduce Ca2+ release from sarcoplasmic reticulum (via IP3R) and block calcium channels (VOCC). The present study demonstrates the vasorelaxant effect of TMF involves NO/sGC/cGMP and prostacyclin pathways, calcium and potassium channels and muscarinic and beta-adrenergic receptors.
  12. Fulltext Investigation of antioxidant and hepatoprotective activity of standardized Curcuma xanthorrhiza rhizome in carbon tetrachloride-induced hepatic damaged rats
    Devaraj S, Ismail S, Ramanathan S, Yam MF
    ScientificWorldJournal, 2014;2014:353128.
    PMID: 25133223 DOI: 10.1155/2014/353128
    Curcuma xanthorrhiza (CX) has been used for centuries in traditional system of medicine to treat several diseases such as hepatitis, liver complaints, and diabetes. It has been consumed as food supplement and "jamu" as a remedy for hepatitis. Hence, CX was further explored for its potential as a functional food for liver related diseases. As such, initiative was taken to evaluate the antioxidant and hepatoprotective potential of CX rhizome. Antioxidant activity of the standardized CX fractions was determined using in vitro assays. Hepatoprotective assay was conducted against carbon tetrachloride- (CCl4-) induced hepatic damage in rats at doses of 125, 250, and 500 mg/kg of hexane fraction. Highest antioxidant activity was found in hexane fraction. In the case of hepatoprotective activity, CX hexane fraction showed significant improvement in terms of a biochemical liver function, antioxidative liver enzymes, and lipid peroxidation activity. Good recovery was observed in the treated hepatic tissues histologically. Hence, the results concluded that CX hexane fraction possessed prominent hepatoprotective activities which might be due to its in vitro antioxidant activity. These findings also support the use of CX as a functional food for hepatitis remedy in traditional medicinal system.
  13. Fulltext Interleukin-27 exhibited anti-inflammatory activity during Plasmodium berghei infection in mice
    Fazalul Rahiman SS, Basir R, Talib H, Tie TH, Chuah YK, Jabbarzare M, et al.
    Trop Biomed, 2013 Dec;30(4):663-80.
    PMID: 24522137 MyJurnal
    Interleukin-27 (IL-27) has a pleiotropic role either as a pro-inflammatory or anti-inflammatory cytokine in inflammatory related diseases. The role and involvement of IL-27 during malaria was investigated and the effects of modulating its release on the production of major inflammatory cytokines and the histopathological consequences in major affected organs during the infection were evaluated. Results showed that IL-27 concentration was significantly elevated throughout the infection but no positive correlation with the parasitaemia development observed. Augmentation of IL-27 significantly elevated the release of anti-inflammatory cytokine, IL-10 whereas antagonising and neutralising IL-27 produced the opposite. A significant elevation of pro-inflammatory cytokines (IFN-γ and IL-6) was also observed, both during augmentation and inhibition of IL-27. Thus, it is suggested that IL-27 exerts an anti-inflammatory activity in the Th1 type response by signalling the production of IL-10 during malaria. Histopathological examination showed sequestration of PRBC in the microvasculature of major organs in malarial mice. Other significant histopathological changes include hyperplasia and hypertrophy of the Kupffer cells in the liver, hyaline membrane formation in lung tissue, enlargement of the white and red pulp followed by the disappearance of germinal centre of the spleen, and tubular vacuolation of the kidney tissues. In conclusion, it is suggested that IL-27 may possibly acts as an anti-inflammatory cytokine during the infection. Modulation of its release produced a positive impact on inflammatory cytokine production during the infection, suggesting its potential in malaria immunotherapy, in which the host may benefit from its inhibition.
  14. Interleukin-18 Antagonism Improved Histopathological Conditions of Malaria Infection in Mice
    Jabbarzare M, Chin VK, Talib H, Yam MF, Adam SK, Hassan H, et al.
    Iran J Parasitol, 2015 Jul-Sep;10(3):389-401.
    PMID: 26622294
    Interleukin 18 (IL-18) exerts pleiotropic roles in many inflammatory-related diseases including parasitic infection. Previous studies have demonstrated the promising therapeutic potential of modulating IL-18 bioactivity in various pathological conditions. However, its involvement during malaria infection has yet to be established. In this study, we demonstrated the effect of modulating IL-18 on the histopathological conditions of malaria infected mice.
  15. Inhibitory effects of Cinnamomum burmannii Blume stem bark extract and trans-cinnamaldehyde on nasopharyngeal carcinoma cells; synergism with cisplatin
    Daker M, Lin VY, Akowuah GA, Yam MF, Ahmad M
    Exp Ther Med, 2013 Jun;5(6):1701-1709.
    PMID: 23837058
    Nasopharyngeal carcinoma (NPC) is a malignancy that occurs in the epithelium of the nasopharynx. The standard treatment of NPC patients with locoregionally advanced stages is problematic and is often associated with toxicities. Therefore, it is essential to screen for naturally occurring compounds with strong apoptosis-inducing activity and minimal toxicity. This study investigated the effects of the standardized methanol extract of Cinnamomum burmannii Blume stem bark and its main constituent, trans-cinnamaldehyde (TCA), on human NPC cell lines. The content of TCA in C. burmannii methanol extract was standardized to be 13.61% w/w by means of gas chromatography-mass spectrometry (GC-MS). NPC cell proliferation was clearly inhibited within 24 h of treatment, with TCA exhibiting greater activity than the methanol extract. TCA was more active against NPC cells compared with cisplatin. There was a pronounced downregulation of the proliferation markers, Ki67 and proliferating cell nuclear antigen (PCNA) in the TCA-treated cells; while morphological observation indicated the induction of apoptosis. Caspase activation and prominent DNA damage, which are markers of apoptosis induction were detected. TCA demonstrated the ability to scavenge nitric oxide. The simultaneous combination of TCA and cisplatin produced synergistic anti-proliferative effects. Collectively, these data indicate the potential use of TCA for the treatment of NPC.
  16. In vitro study and structure-activity relationship analysis of stilbenoid derivatives as powerful vasorelaxants: Discovery of new lead compound
    Chan SY, Loh YC, Oo CW, Yam MF
    Bioorg Chem, 2020 11;104:104239.
    PMID: 33142420 DOI: 10.1016/j.bioorg.2020.104239
    The development of vasorelaxant as the antihypertensive drug is important as it produces a rapid and direct relaxation effect on the blood vessel muscles. Resveratrol (RV), as the most widely studied stilbenoid and the lead compound, inducing the excellent vasorelaxation effect through the multiple signalling pathways. In this study, the in vitro vascular response of the synthesized trans-stilbenoid derivatives, SB 1-8e were primarily evaluated by employing the phenylephrine (PE)-precontracted endothelium-intact isolated aortic rings. Herein we report trans-3,4,4'-trihydroxystilbene (SB 8b) exhibited surprisingly more than 2-fold improvement to the maximal relaxation (Rmax) of RV. This article also highlights the characterization of the aromatic protons in terms of their unique splitting patterns in 1H NMR.
  17. Fulltext In vitro pharmacodynamic profile of Loranthus ferrugineus: evidence for noncompetitive antagonism of norepinephrine-induced vascular contraction
    Ameer OZ, Salman IM, Najim HS, Abdullah GZ, Abdulkarim MF, Yam MF, et al.
    J Acupunct Meridian Stud, 2010 Dec;3(4):272-82.
    PMID: 21185543 DOI: 10.1016/S2005-2901(10)60048-9
    The mode by which Loranthus ferrugineus methanol extract antagonizes and/or modulates norepinephrine-induced vasoconstriction was investigated in rat aortic rings. The vascular effects of three different concentrations of this extract were challenged against cumulative additions of norepinephrine. Phentolamine, a nonselective α-adrenoceptor antagonist, verapamil, an L-type calcium channel blocker, and papaverine, a phosphodiesterase inhibitor, were used in three different concentrations as positive controls. Log concentration-response curves and double-reciprocal plots were constructed for the extract and each vasorelaxant. To characterize antagonism reversibility, the norepinephrine maximum contractile effect was examined before extract addition to the aortic ring chamber and after its removal. Phentolamine shifted the norepinephrine log concentration-response curve to the right with no significant depression in the maximum response. Similar to verapamil and papaverine, the extract produced a rightward shift in norepinephrine log concentration-response curve and a significant drop in maximum response. The double-reciprocal plots showed comparable y-intercept values for all phentolamine concentrations, a characteristic of competitive antagonism. In contrast, different y-intercept values on double-reciprocal plots were obtained for each concentration of extract, verapamil, and papaverine, typical of noncompetitive antagonism. The norepinephrine maximum contractile response was approximately similar before the addition of extract and after its removal. The data collectively showed that L. ferrugineus methanol extract exerted its vascular effect by reversible noncompetitive antagonism of norepinephrine-induced vasoconstriction. These findings add to the understanding of the cardiovascular mechanisms by which L. ferrugineus, a plant traditionally used for the management of hypertension, elicits its action.
  18. Fulltext In vitro permeation and in vivo anti-inflammatory and analgesic properties of nanoscaled emulsions containing ibuprofen for topical delivery
    Abdullah GZ, Abdulkarim MF, Salman IM, Ameer OZ, Yam MF, Mutee AF, et al.
    Int J Nanomedicine, 2011;6:387-96.
    PMID: 21499428 DOI: 10.2147/IJN.S14667
    As a topical delivery system, a nanoscaled emulsion is considered a good carrier of several active ingredients that convey several side effects upon oral administration, such as nonsteroidal anti-inflammatory drugs (NSAIDs).
  19. Fulltext In vitro cholinomimetic effect of Loranthus ferrugineus in isolated guinea pig ileum
    Ameer OZ, Salman IM, Siddiqui MJ, Yam MF, Sriramaneni RN, Sadikun A, et al.
    J Acupunct Meridian Stud, 2009 Dec;2(4):288-93.
    PMID: 20633504 DOI: 10.1016/S2005-2901(09)60070-4
    This study aimed to elucidate the mechanism(s) of the spasmogenic action of Loranthus ferrugineus in isolated guinea pig ileum. Thus the contractile responses of guinea pig ileum to graded additions of either L. ferrugineus methanol extract or its n-butanol fraction were tested in the presence and absence of various pharmacological interventions. The data showed that L. ferrugineus methanol extract and the n-butanol fraction produced a concentration-dependent spasmogenic effect in isolated guinea pig ileum segments. These effects were significantly inhibited in the presence of 1 microM atropine. In contrast, the response to the lowest concentrations of L. ferrugineus methanol extract (0.25, 0.5 and 1 mg/mL) and n-butanol fraction of L. ferrugineus (0.125, 0.25 and 0.5 mg/mL) were considerably enhanced in the presence of 0.05 microM neostigmine. Neither L. ferrugineus methanol extract nor n-butanol fraction contractile responses were affected upon the incubation of the ileal segments with 100 microM hexamethonium. The results of this study show that the spasmogenic effect of L. ferrugineus is possibly mediated through a direct action on intestinal muscarinic receptors. It is suggested that the bioactive constituents of L. ferrugineus serve as a substrate for acetylcholinesterase.
  20. Fulltext In Vitro Antiplasmodium and Chloroquine Resistance Reversal Effects of Andrographolide
    Ibraheem ZO, Majid RA, Sidek HM, Noor SM, Yam MF, Abd Rachman Isnadi MF, et al.
    Evid Based Complement Alternat Med, 2019;2019:7967980.
    PMID: 31915453 DOI: 10.1155/2019/7967980
    The emergence of drug-resistant strains of Plasmodium falciparum is the worst catastrophe that has ever confronted the dedicated efforts to eradicate malaria. This urged for searching other alternatives or sensitizers that reverse chloroquine resistance. In this experiment, the potential of andrographolide to inhibit plasmodial growth and reverse CQ resistance was tested in vitro using the SYBRE green-1-based drug sensitivity assay and isobologram technique, respectively. Its safety level toward mammalian cells was screened as well against Vero cells and RBCs using MTT-based drug sensitivity and RBC hemolysis assays, respectively. Its effect against hemozoin formation was screened using β-hematin formation and heme fractionation assays. Its molecular characters were determined using the conventional tests for the antioxidant effect measurement and the in silico molecular characterization using the online free chemi-informatic Molinspiration software. Results showed that andrographolide has a moderate antiplasmodium effect that does not entitle it to be a substituent for chloroquine. Furthermore, andrographolide ameliorated the sensitivity of the parasite to chloroquine. Besides, it showed an indirect inhibitory effect against hemozoin formation within the parasite and augmented the chloroquine-induced inhibition of hemozoin formation. The study suggests that its chloroquine resistance reversal effect may be due to inhibition of chloroquine accumulation or due to its impact on the biological activity of the parasite. Overall, this in vitro study is a clue for the reliability of andrographolide to be added with chloroquine for reversal of chloroquine resistance and tolerance, but further in vivo studies are recommended to confirm this notion. In spite of its prominent and safe in vitro and in vivo growth inhibitory effect and its in vitro chloroquine resistance reversing effect, it is inapplicable to implement it in malaria chemotherapy to substitute chloroquine or to reverse its resistance.
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