Activity-Guided Isolation of Bioactive Constituents with Antinociceptive Activity from Muntingia calabura L. Leaves Using the Formalin Test

Encapsulation of Dicranopteris linearis extract using cellulose microparticles for antiulcer medication

Dicranopteris linearis (DL) is a fern in the Gleicheniaceae family, locally known as resam by the Malay community. It has numerous pharmacological benefits, with antiulcer and gastroprotective properties. Peptic ulcer is a chronic and recurring disease that significantly impacts morbidity and mortality, affecting nearly 20 % of the world's population. Despite the effectiveness of peptic ulcer drugs, there is no perfect treatment for the ailment. Encapsulation is an advanced technique that can treat peptic ulcers by incorporating natural sources. This work aims to encapsulate DL extract using different types of cellulose particles by the solvent displacement technique for peptic ulcer medication. The extract was encapsulated using methyl cellulose (MC), ethyl cellulose (EC), and a blend of ethyl methyl cellulose through a dialysis cellulose membrane tube and freeze-dried to yield a suspension of the encapsulated DL extracts. The microencapsulated methyl cellulose chloroform extract (MCCH) has a considerably greater level of total phenolic (84.53 ± 6.44 mg GAE/g), total flavonoid (84.53 ± 0.54 mg GAE/g), and antioxidant activity (86.40 ± 0.63 %). MCCH has the highest percentage of antimicrobial activity against Escherichia coli (2.42 ± 107 × 0.70 CFU/mL), Bacillus subtilis (5.21 ± 107 × 0.90 CFU/mL), and Shigella flexneri (1.25 ± 107 × 0.66 CFU/mL), as well as the highest urease inhibitory activity (50.0 ± 0.21 %). The MCCH particle size was estimated to be 3.347 ± 0.078 μm in diameter. It has been proven that DL elements were successfully encapsulated in the methyl cellulose polymer in the presence of calcium (Ca). Fourier transform infrared (FTIR) analysis indicated significant results, where the peak belonging to the CO stretch of the carbonyl groups of methyl cellulose (MC) shifted from 1638.46 cm-1 in the spectrum of pure MC to 1639.10 cm-1 in the spectrum of the MCCH extract. The shift in the wavenumbers was due to the interactions between the phytochemicals in the chloroform extract and the MC matrix in the microcapsules. Dissolution studies in simulated gastric fluid (SGF) and model fitting of encapsulated chloroform extracts showed that MCCH has the highest EC50 of 6.73 ± 0.27 mg/mL with R2 = 0.971 fitted by the Korsmeyer-Peppas model, indicating diffusion as the mechanism of release.

Flavonoids as dual inhibitors of cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX): molecular docking and in vitro studies

Background

Inflammation is known to involve in many pathological processes of different diseases, but the current therapy causes adverse effects. Thus, there is a great interest for the discovery of flavonoids as a valuable alternative to classical analgesic and anti-inflammatory agent with dual-inhibitory action, especially on both COX-2 and 5-LOX which can minimize or overcome this problem.

Results

In the present work, drug-likeness properties of the synthesized flavonoids via Lipinski’s Rule of Five were predicted using QikProp prior to evaluation of their COX and LOX inhibitory activities using enzyme assays. Subsequently, molecular docking was performed using GLIDE to analyse their binding behaviour. The results showed that all compounds obeyed the Lipinski’s Rule of Five. NPC6 and NPC7 had displayed better selectivity towards COX-2 as compared to Indomethacin with less than 50% inhibition against COX-1. In addition, these compounds also inhibited activity of 5-LOX. Their selectivity to COX-2 was due to the binding to hydrophobic region and extends to lobby region near the entrance of COX binding site forming hydrogen bond with Ser530. Interestingly, these compounds showed a similar binding mode as Zileuton in the active site of 5-LOX and formed hydrogen bond interaction with Ala424.

Conclusion

NPC6 and NPC7 had potential as dual inhibitor of COX-2 and 5-LOX. The scaffolds of these chemical entities are useful to be as lead compounds for the dual inhibition of COX-2 and 5-LOX.

Determination of Total Phenolic Content, Analysis of Bioactive Compound Components, and Antioxidant Activity of Ethyl Acetate Seri (Muntingia calabura L.) Leaves from North Sumatera Province, Indonesia

BACKGROUND: Seri (Muntingia calabura L.) leaves are a plant that is often found and have not been used in various treatments even though it is reported to have various groups of bioactive compounds such as phenolic, flavonoids, tannins, saponins, steroids, and triterpenoids. AIM: This study aimed to determine the total phenolic content, antioxidant activity and identify the content of potential bioactive compounds contained in the ethyl acetate fraction from M. calabura leaves. METHODS: M. calabura L. leaves fraction was carried out by maceration method using ethanol followed by partition starting with n-hexane, chloroform, and finally ethyl acetate as solvent. The ethyl acetate fraction was continued for phytochemical screening for the content of bioactive compounds using standard reagents, determination of total phenol content by colorimetric method, determination of antioxidant activity using the DPPH method, and analysis of bioactive compounds using gas chromatography–mass spectroscopy. RESULTS: The results showed that the ethyl acetate fraction of M. calabura leaves was positive for phenolic content which was indicated by the formation of a turquoise color after 5% FeCl3 reagent was added (in ethanol), phenolic content was 0.0727 mg GAE/g dry fraction, indicating antioxidant activity (IC50) amounted to 54.437 including strong categories as antioxidants and the results of GC–MS analysis obtained various kinds of compounds and it is suspected that compounds that provide potential as antioxidants are phytol. CONCLUSION: The bioactive compound of ethyl acetate fraction of seri (M. calabura) leaves contained phenolic components and has strong antioxidant activity.

In Vitro Anti-Diabetic Activities and UHPLC-ESI-MS/MS Profile of Muntingia calabura Leaves Extract

Anti-diabetic compounds from natural sources are now being preferred to prevent or treat diabetes due to adverse effects of synthetic drugs. The decoction of Muntingia calabura leaves was traditionally consumed for diabetes treatment. However, there has not been any published data currently available on the processing effects on this plant’s biological activity and phytochemical profile. Therefore, this study aims to evaluate the effect of three drying methods (freeze-drying (FD), air-drying (AD), and oven-drying (OD)) and ethanol:water ratios (0, 50, and 100%) on in vitro anti-diabetic activities of M. calabura leaves. In addition, an ultrahigh-performance-liquid chromatography–electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) method was used to characterize the metabolites in the active extract. The FD M. calabura leaves, extracted with 50% ethanol, is the most active extract that exhibits a high α-glucosidase and α-amylase inhibitory activities with IC₅₀ values of 0.46 ± 0.05 and 26.39 ± 3.93 µg/mL, respectively. Sixty-one compounds were tentatively identified by using UHPLC-ESI-MS/MS from the most active extract. Quantitative analysis, by using UHPLC, revealed that geniposide, daidzein, quercitrin, 6-hydroxyflavanone, kaempferol, and formononetin were predominant compounds identified from the active extract. The results have laid down preliminary steps toward developing M. calabura leaves extract as a potential source of bioactive compounds for diabetic treatment.

Metabolite variations and antioxidant activity of Muntingia calabura leaves in response to different drying methods and ethanol ratios elucidated by NMR-based metabolomics

INTRODUCTION

Muntingia calabura from the Muntingiaceae family has been documented for several medicinal uses. The combinations of drying treatment and extracting solvents for a plant species need to be determined and optimised to ensure that the extracts contain adequate amounts of the bioactive metabolites.

OBJECTIVE

Evaluate the metabolite variations and antioxidant activity among M. calabura leaves subjected to different drying methods and extracted with different ethanol ratios using proton nuclear magnetic resonance (¹ H-NMR)-based metabolomics. Methodology The antioxidant activity of M. calabura leaves dried with three different drying methods and extracted with three different ethanol ratios was determined by using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and nitric oxide (NO) scavenging assays. The metabolites variation among the extracts and correlation with antioxidant activity were analysed by ¹ H-NMR-based metabolomics.

RESULTS

Muntingia calabura leaves extracted with 50% and 100% ethanol from air-drying and freeze-drying methods had the highest total phenolic content and the lowest IC₅₀ value for the DPPH scavenging activity. Meanwhile, oven-dried leaves extracted with 100% ethanol had the lowest IC₅₀ value for the NO scavenging activity. A total of 43 metabolites, including sugars, organic acids, amino acids, phytosterols, phenolics and terpene glycoside were tentatively identified. A noticeable discrimination was observed in the different ethanol ratios by the principal component analysis. The partial least-squares analysis suggested that 32 compounds out of 43 compounds identified were the contributors to the bioactivities.

CONCLUSION

The results established set the preliminary steps towards developing this plant into a high value product for phytomedicinal preparations.

Scientific investigation of crude alkaloids from medicinal plants for the management of pain

BACKGROUND

Tissue damage is associated with pain, which is an alarming sign. Aspirin and morphine have been widely used in recent decades for management of pain. Medicinal herbs have been in use for treatment of different diseases for centuries. Many of these herbs possess analgesic activity with relatively less incidences of adverse effects. The strong positive correlation of alkaloids in medicinal plants for analgesic activity persuades an intention to determine possible analgesic activity of total alkaloids extracted from the selected medicinal plants using animal models to answer its possible mechanisms.

METHODS

Crude alkaloids from selected medicinal plants (Woodfordia fruticosa, Adhatoda vasica, Chenopodium ambrosioides, Vitex negundo, Peganum harmala and Broussonetia papyrifera) were extracted as per reported literature. The test crude alkaloids were screened foracute toxicity study. Writhings induced by acetic acid, tail immersion method and formalin-induced nociception assay procedures were used for possible analgesic effects of the crude alkaloids.

RESULTS

Crude alkaloids were safe up to dose of 1250 mg/kg body weight in mice. The alkaloids significantly reduced the abdominal constrictions, and increased the time for paw licking response in both phases with a significant raise in latency time in nociception models (P ≤ 0.05). Moreover, the antinociceptive response was significantly attenuated by pretreatment with naloxone suggesting involvement of the opioid receptors for possible antinociceptive action.

CONCLUSIONS

Crude alkaloids of Woodfordia fruticosa and Peganum harmala showed prominent analgesic potentials through inhibition of peripheral as well as central nervous system mechanisms. Further work is required for isolation of the pharmacologically active constituents.

Methanolic Extract of Clinacanthus nutans Exerts Antinociceptive Activity via the Opioid/Nitric Oxide-Mediated, but cGMP-Independent, Pathways

The objectives of the present study were to determine the mechanisms of antinociceptive effect of methanol extract of Clinacanthus nutans (Acanthaceae) leaves (MECN) using various animal nociceptive models. The antinociceptive activity of orally administered 10% DMSO, 100 mg/kg acetylsalicylic acid (ASA), 5 mg/kg morphine, or MECN (100, 250, and 500 mg/kg) was determined using the acetic acid-induced abdominal constriction (ACT), formalin-induced paw licking (FT), and hot plate tests (HPT). The role of opioid and nitric oxide/cyclic guanosine monophosphate (NO/cGMP) systems was also investigated. The results showed that MECN produced a significant (p < 0.05) antinociceptive response in all nociceptive models with the recorded ED₅₀ value of 279.3 mg/kg for the ACT, while, for the early and late phases of the FT, the value was >500 mg/kg or 227.7 mg/kg, respectively. This antinociceptive activity was fully antagonized by naloxone (a nonselective opioid antagonist) but was partially reversed by l-arginine (l-arg; a nitric oxide [NO] precursor), Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME; an NO synthase inhibitor), or their combinations thereof. In contrast, 1H-[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ; a soluble guanylyl cyclase inhibitor) enhanced the extract's antinociception. UHPLC analysis revealed the presence of several flavonoid-based compounds with antinociceptive action. In conclusion, MECN exerted the peripherally and centrally mediated antinociceptive activity via the modulation of the opioid/NO-mediated, but cGMP-independent, systems.

Antioxidant and anti-inflammatory activities contribute to the prophylactic effect of semi-purified fractions obtained from the crude methanol extract of Muntingia calabura leaves against gastric ulceration in rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional medicine, the leaves, flowers, barks and roots of Muntingia calabura L. (Muntingiaceae) have been employed as a treatment for various ailments including dyspepsia and to relieve pain caused by gastritis and peptic ulcer disease. The methanolic extract of Muntingia calabura leaves (MEMC) has been proven in the previous study to possess significant antiulcer activity. In this study, we attempted to determine the prophylactic effect of the fractions obtained from MEMC against ethanol-induced gastric lesion in rats and the involvement of antioxidants and anti-inflammatory mediators.

MATERIALS AND METHODS

The MEMC was fractionated with petroleum ether (PEF), ethyl acetate (EAF) and distilled water (AQF). These fractions were investigated for possible antiulcer property using ethanol-induced gastric ulcer rat model. The rats were administered orally once daily with 8% Tween 80 (control), 100mg/kg ranitidine, or the fractions, in the doses of 100, 250, and 500 mg/kg, for 7 days, followed by ulcer induction using absolute ethanol. The rats were euthanized; macroscopic and histological observations of the stomach were done. The ulcer area (UA) was determined and the percentage protection afforded by the fractions was calculated. The fractions were subjected to antioxidant studies including the superoxide and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, oxygen radical absorbance capacity (ORAC) and total phenolic content (TPC) assay. Involvement of nitric oxide (NO) and inflammatory mediators such as lipoxygenase (LOX) and xanthine oxidase (XO) were evaluated. Phytochemical screening and HPLC analysis of the fractions were also conducted.

RESULTS

Pre-treatment of PEF and EAF significantly (p<0.001) attenuated the gastric lesions as compared to the control group in a dose-dependent manner. On the other hand, 100 and 250 mg/kg of AQF significantly (p<0.001) prevented the ulcer formation but at the highest dose (500 mg/kg), AQF failed to significantly reduce the ulcer formation, showing a dose-independent antiulcerative effect of AQF. The histological evaluation supported the observed gastroprotective activity of PEF, EAF and AQF. All the fractions showed high superoxide and DPPH scavenging activity, meanwhile the EAF showed highest TPC followed by PEF and AQF. These fractions also significantly (p<0.05) inhibited the NO while maintaining the viability of the cells. EAF exhibited high inhibition towards both the LOX and XO enzymes, meanwhile PEF and AQF exerted high LOX inhibition but low XO inhibition. Phytochemical screening and HPLC profiling suggested the presence of flavonoid- and tannin based compounds in PEF and EAF.

CONCLUSION

It can be concluded that the prophylactic effect of the fractions on gastric ulceration in rats is associated with its high antioxidant activity and its ability to effectively inhibit the inflammation mediators. Presence of several flavonoids and gallic acid explains the effectiveness of the fractions in affording protection against gastric damages.

Effect of acacia honey on cultured rabbit corneal keratocytes

BACKGROUND

Acacia honey is a natural product which has proven to have therapeutic effects on skin wound healing, but its potential healing effects in corneal wound healing have not been studied. This study aimed to explore the effects of Acacia honey (AH) on corneal keratocytes morphology, proliferative capacity, cell cycle, gene and protein analyses. Keratocytes from the corneal stroma of six New Zealand white rabbits were isolated and cultured until passage 1. The optimal dose of AH in the basal medium (FD) and medium containing serum (FDS) for keratocytes proliferation was identified using MTT assay. The morphological changes, gene and protein expressions of aldehyde dehydrogenase (ALDH), marker for quiescent keratocytes and vimentin, marker for fibroblasts were detected using q-RTPCR and immunocytochemistry respectively. Flowcytometry was performed to evaluate the cell cycle analysis of corneal keratocytes.

RESULTS

Cultured keratocytes supplemented with AH showed no morphological changes compared to control. Keratocytes cultured in FD and FDS media supplemented with 0.025% AH showed optimal proliferative potential compared with FD and FDS media, respectively. Gene expressions of ADLH and vimentin were increased in keratocytes cultured with AH enriched media. All proteins were expressed in keratocytes cultured in all media in accordance to the gene expression findings. No chromosomal changes were detected in keratocytes in AH enriched media.

CONCLUSION

Corneal keratocytes cultured in media supplemented with 0.025% AH showed an increase in proliferative capacity while retaining their morphology, gene and protein expressions with normal cell cycle. The results of the present study show promising role of AH role in accelerating the initial stage of corneal wound healing.

A preliminary evaluation of antihyperglycemic and analgesic activity of Alternanthera sessilis aerial parts

Background

Alternanthera sessilis is used by folk medicinal practitioners of Bangladesh for alleviation of severe pain. The objective of this study was to scientifically analyze the analgesic (non-narcotic) property of aerial parts of the plant along with antihyperglycemic activity.

Methods

Antihyperglycemic activity was measured by oral glucose tolerance tests. Analgesic (non-narcotic) activity was determined by observed decreases in abdominal writhings in intraperitoneally administered acetic acid-induced pain model in mice.

Results

Administration of methanol extract of aerial parts led to dose-dependent and significant reductions in blood glucose levels in glucose-loaded mice. At doses of 50, 100, 200 and 400 mg per kg body weight, the extract reduced blood sugar levels by 22.9, 30.7, 45.4 and 46.1%, respectively compared to control animals. By comparison, a standard antihyperglycemic drug, glibenclamide, when administered at a dose of 10 mg per kg body weight, reduced blood glucose level by 48.9%. In analgesic activity tests, the extract at the above four doses reduced the number of abdominal writhings by 27.6, 37.9, 41.4, and 44.8%, respectively. A standard analgesic drug, aspirin, reduced the number of writhings by 31.0 and 51.7%, respectively, when administered at doses of 200 and 400 mg per kg body weight.

Conclusion

The results validate the folk medicinal use of the plant to alleviate pain. At the same time, the antihyperglycemic activity result suggests that the plant may be a potential source for blood sugar lowering drug(s).

Amelioration of paracetamol-induced hepatotoxicity in rat by the administration of methanol extract of Muntingia calabura L. leaves

Muntingia calabura L. is a tropical plant species that belongs to the Elaeocarpaceae family. The present study is aimed at determining the hepatoprotective activity of methanol extract of M. calabura leaves (MEMC) using two models of liver injury in rats. Rats were divided into five groups (n=6) and received 10% DMSO (negative control), 50 mg/kg N-acetylcysteine (NAC; positive control), or MEMC (50, 250, and 500 mg/kg) orally once daily for 7 days and on the 8th day were subjected to the hepatotoxic induction using paracetamol (PCM). The blood and liver tissues were collected and subjected to biochemical and microscopical analysis. The extract was also subjected to antioxidant study using the 2,2-diphenyl-1-picrylhydrazyl-(DPPH) and superoxide anion-radical scavenging assays. At the same time, oxygen radical antioxidant capacity (ORAC) and total phenolic content were also determined. From the histological observation, lymphocyte infiltration and marked necrosis were observed in PCM-treated groups (negative control), whereas maintenance of hepatic structure was observed in group pretreated with N-acetylcysteine and MEMC. Hepatotoxic rats pretreated with NAC or MEMC exhibited significant decrease (P<0.05) in ALT and AST enzymes level. Moreover, the extract also exhibited good antioxidant activity. In conclusion, MEMC exerts potential hepatoprotective activity that could be partly attributed to its antioxidant activity and, thus warrants further investigations.

Antinociceptive activity of methanolic extract of Muntingia calabura leaves: further elucidation of the possible mechanisms

Background

Muntingia calabura (Elaecoparceae) is a medicinal plant traditionally used, particularly, by the Peruvian people to alleviate headache and cold, pain associated with gastric ulcers or to reduce the prostate gland swelling. Following the recent establishment of antinociceptive activity of M. calabura leaf, the present study was performed to further elucidate on the possible mechanisms of antinociception involved.

Methods

The methanol extract of M. calabura (MEMC) was prepared in the doses of 100, 250 and 500 mg/kg. The role of bradykinin, protein kinase C, pottasium channels, and various opioid and non-opioid receptors in modulating the extract’s antinociceptive activity was determined using several antinociceptive assays. Results are presented as Mean ± standard error of mean (SEM). The one-way ANOVA test with Dunnett's multiple comparison was used to analyze and compare the data, with P < 0.05 as the limit of significance.

Results

The MEMC, at all doses, demonstrated a significant (p < 0.05) dose-dependent antinociceptive activity in both the bradykinin- and phorbol 12-myristate 13-acetate (PMA)-induced nociception. Pretreatment of the 500 mg/kg MEMC with 10 mg/kg glibenclamide (an ATP-sensitive K⁺ channel inhibitor), the antagonist of μ-, δ- and κ-opioid receptors (namely 10 mg/kg β-funaltrexamine, 1 mg/kg naltrindole and 1 mg/kg nor-binaltorphimine), and the non-opioid receptor antagonists (namely 3 mg/kg caffeine (a non-selective adenosinergic receptor antagonist), 0.15 mg/kg yohimbine (an α₂-noradrenergic antagonist), and 1 mg/kg pindolol (a β-adrenoceptor antagonist)) significantly (p < 0.05) reversed the MEMC antinociception. However, 10 mg/kg atropine (a non-selective cholinergic receptor antagonist), 0.15 mg/kg prazosin (an α₁-noradrenergic antagonist) and 20 mg/kg haloperidol (a non-selective dopaminergic antagonist) did not affect the extract's antinociception. The phytochemicals screening revealed the presence of saponins, flavonoids, tannins and triterpenes while the HPLC analysis showed the presence of flavonoid-based compounds.

Conclusions

The antinociceptive activity of MEMC involved activation of the non-selective opioid (particularly the μ-, δ- and κ-opioid) and non-opioid (particularly adenosinergic, α₂-noradrenergic, and β-adrenergic) receptors, modulation of the ATP-sensitive K⁺ channel, and inhibition of bradikinin and protein kinase C actions. The discrepancies in MEMC antinociception could be due to the presence of various phytochemicals.