In Vitro Anticoagulant Activity of Mikania laevigata: Deepening the Study of the Possible Interaction Between Guaco and Anticoagulants

Safety evaluation of Mikania glomerata and Mikania laevigata in healthy volunteers: A randomized, open label and multiple dose phase I clinical trial

ETHNOPHARMACOLOGICAL RELEVANCE

Mikania glomerata (MG) and Mikania laevigata (ML) leaves are used interchangeably in Brazilian ethno-medicine, mainly for the treatment of respiratory diseases, but there is no clinical trial for the safety evaluation of these species at different doses.

AIM OF THE STUDY

To evaluate the safety of two oral solutions from each species, across two weeks of use and two doses.

MATERIALS AND METHODS

A randomized, open-label, multiple dose, two-arm trial. Participants (n = 19) were randomly allocated to one of the arms of the trial. Group 1 received 15 mL of MG oral solution twice daily for 7 days and then 30 mL twice daily for 7 days. Group 2 received ML oral solution in the same manner. After 14 days, the participants went through a washout period of 7 days before cross-over to the other group. Adverse events (AEs), clinical parameters and blood markers were monitored at the beginning (T0) and at the end of each week of the study, which was concluded after six weeks. AEs were classified as mild, moderate or severe, and according to their correlation with the medicine intake, the measured parameters were compared to T0 by generalized estimating equations (GEE) to determine those affected by the use of the oral solutions (p < 0.05).

RESULTS

MG was not correlated to any of the reported AEs; its use affected three of the evaluated parameters: total protein, diastolic blood pressure and urea, although all the changes were within the normal range for healthy individuals. ML was correlated to one moderate AE of pyrosis and the alteration of 12 parameters: erythrocytes, hemoglobin, hematocrit, monocytes, time of prothrombin, time of thromboplastin, albumin, alkaline phosphatase, total protein, urea, potassium and sodium. All changes were within the normal range for healthy individuals.

CONCLUSION

ML and MG are considered safe for humans under the dose regimen tested.

Antithrombotic potential of Lippia alba: A mechanistic approach

ETHNOPHARMACOLOGICAL RELEVANCE

Lippia alba (Mill.) N.E.Br. ex Britton & P. Wilson is traditionally used in Brazil as an adjunct in the relief of mild anxiety, as an antispasmodic, and as an antidyspeptic. This medicinal species was included in the Phytotherapeutic Form of the Brazilian Pharmacopeia 2nd edition (2021) and has already been described as the most used medicinal plant in a study with patients from an Anticoagulation Clinic in Brazil. Meanwhile, no studies were found that support the safety of the use of L. alba in patients using anticoagulants, a drug with several safety limitations.

AIM OF THE STUDY

Provide scientific evidence to ensure the safety of the concomitant use of L. alba and warfarin and support the management of these patients by evaluating its in vitro anticoagulant effect and chemical composition. And, as a timely complementation, evaluate the potential of this medicinal species in the development of new antithrombotics.

METHODS

The chemical profile of L. alba derivatives was analyzed by chromatographic methods such as Ultra-Performance Liquid Chromatography (UPLC) coupled with electrospray ionization mass spectrometry (ESI-MS), qualitative UPLC using Diode-Array Detection, and Thin Layer Chromatography. The anticoagulant activity was evaluated by the innovative Thrombin Generation Assay by Calibrated Automated Thrombogram method and using traditional coagulometric tests: prothrombin time, activated partial thromboplastin time, and plasma fibrinogen measurement.

RESULTS

Extracts and fractions prolonged the coagulation time in all the tests and reduced thrombin formation in thrombin generation assay. Coagulation times with the addition of ethanloic extract (2.26 mg/mL) was 17.78s, 46.43s and 14.25s respectively in prothrombin time, activated partial thromboplastin time and fibrinogren plasma measurement. In thrombin generation test, this same extract showed ETP as 323 nM/min compared to control (815 nM/min) with high tissue factor and 582 nM/min compared to control (1147 nM/min) using low tissue factor. Presence of flavonoids, phenylpropanoids, and triterpenes were confirmed by chromatographic methods and 13 compounds were identified by UPLC-ESI-MS. Based on these results and on the scientific literature, it is possible to propose that phenylpropanoids and flavonoids are related to the anticoagulant activity observed.

CONCLUSION

The results demonstrate the in vitro anticoagulant activity of L. alba, probably due to the activation of intrinsic and extrinsic pathways. It is concluded, then, that there is a potential for interaction, which needs to be further studied, between L. alba and warfarin. Also, this medicinal species shows a great potential for use in the development of new antithrombotics.

Anticoagulant and antiplatelet activity of aqueous extracts of Citrus sinensis and Lippia alba : interactions and potential for the development of antithrombotics

Citrus sinensis and Lippia alba are herbal medicines widely used in the form of tea (infusion, decoction), which ethanolic extracts have already shown great anticoagulant activity in vitro . For this reason, they seem to be excellent candidates for the development of new antithrombotics and also have the potential to interact with them. The aim of this study was to evaluate the activity of aqueous extracts in blood coagulation and platelet aggregation, in addition to analysing the micromolecular composition of these species. Thrombin generation test (TGT) by the Calibrated Automated Thrombogram method and Platelet Aggregation Test by turbidimetry were performed to evaluate the biological activities, while the chemical composition was qualitatively evaluated using high-performance liquid chromatography. Aqueous extracts were elaborated according to the folk use. All extracts were effective in reducing thrombin formation in TGT. Infusion of L. alba and infusion and decoction of C. sinensis at a concentration of 0.6 mg/ml significantly reduced platelet aggregation induced by ADP, and only the decoction of L. alba at the same concentration was able to significantly reduce collagen-induced platelet aggregation. The presence of phenylpropanoids and flavonoids in C. sinensis and L. alba extracts was verified. Furthermore, hesperidin was identified in C. sinensis through coinjection. C. sinensis and L. alba are rich in phenolics and demonstrated an in-vitro effect on important processes of haemostasis (blood coagulation, platelet agreggation), corroborating the potential of C. sinensis and L. alba for the development of antithrombotics and interact with them.

Evaluation of Biological Activity of Natural Compounds: Current Trends and Methods

Natural compounds have diverse structures and are present in different forms of life. Metabolites such as tannins, anthocyanins, and alkaloids, among others, serve as a defense mechanism in live organisms and are undoubtedly compounds of interest for the food, cosmetic, and pharmaceutical industries. Plants, bacteria, and insects represent sources of biomolecules with diverse activities, which are in many cases poorly studied. To use these molecules for different applications, it is essential to know their structure, concentrations, and biological activity potential. In vitro techniques that evaluate the biological activity of the molecules of interest have been developed since the 1950s. Currently, different methodologies have emerged to overcome some of the limitations of these traditional techniques, mainly via reductions in time and costs. These emerging technologies continue to appear due to the urgent need to expand the analysis capacity of a growing number of reported biomolecules. This review presents an updated summary of the conventional and relevant methods to evaluate the natural compounds' biological activity in vitro.

Mechanisms and interactions in concomitant use of herbs and warfarin therapy: An updated review

This review is an updated and expanded version published in this journal in 2016. Warfarin pharmacotherapy is extremely complex, since in addition to being a low therapeutic index drug, it does not follow the dose-response pattern and has characteristics that predispose the occurrence of interactions, such as high binding rate to plasma proteins, metabolization by cytochrome P450 enzymes, further to acting in the complex process of blood coagulation, platelet activation, and inflammation. For these reasons, warfarin has great potential for interaction with drugs, foods, and herbal medicines. Herb-warfarin interactions, however, are still not very well studied; thus, the objective of this update is to present new information on the subject aiming to provide a scientific basis to help health professionals in the clinical management of these interactions. A literature review was performed from May to June 2021 in multiple databases and articles published in 2016 to 2021 were included. A total of 59 articles describing 114 herbal medicines were reported to interact with warfarin. Of the plants mentioned, 84% had the potential to increase warfarin effect and the risk of bleeding. Targets possibly involved in these interactions include the processes of blood coagulation, platelet activation, and inflammation, in addition to the pharmacokinetics and pharmacodynamics of warfarin. Despite these alarming numbers, however, the clinical management of interactions is known to be effective. Thus, it is important that the use of these herbal medicines be done with caution in anticoagulated patients and that studies of herb-drug interactions be encouraged in order to generate information to support the clinical management of patients.

In vitro anticoagulant activity of selected medicinal plants: potential interactions with warfarin and development of new anticoagulants

OBJECTIVES

Warfarin is the most widely used anticoagulant in the world, but it has several limitations including its narrow therapeutic range, need for dose adjustment and high potential for interactions. The simultaneous use of other drugs or even medicinal plants and certain foods could interfere with its therapeutic activity. In this context, this study aims to investigate the in vitro anticoagulant potential and phytochemical constitution of 17 plants selected from a previous clinical cross-sectional study (2014), that investigated the habits of plant utilization among patients taking warfarin.

METHODS

Ethanol extracts and essential oils were evaluated, in vitro, as to their effect in the prothrombin time (PT) and activated partial thromboplastin time (aPTT) tests. Four species that presented aPTT >50 s were selected for phytochemical evaluation.

RESULTS

Thirteen of the 17 plants selected demonstrated a significant anticoagulant effect in at least one of the evaluated parameters. Citrus sinensis (PT=14.75 and aPTT=53.15), Mentha crispa (aPTT=51.25), Mikania laevigata (PT=14.90 and aPTT=52.10), and Nasturtium officinale (aPTT=50.55) showed greater anticoagulant potential compared to normal plasma pool (PT=12.25 and aPTT=37.73). Chemical profiles of these four species were obtained, and certain compounds were identified: rosmarinic acid from M. crispa and isoorientin from N. officinale.

CONCLUSIONS

Thus, the results of this study could be a useful indicator for clinical practice towards the possibility of interaction between these plants and anticoagulants, although further clinical research is needed taking into consideration the limitations of in vitro studies. These findings also suggest that further research into the action of these plants could be of real clinical value in identifying potential alternative anticoagulant therapies.

Thrombin generation test with the calibrated automated thrombogram and anticoagulant activity of Mentha crispa

: Evaluate the in-vitro effect of Mentha crispa extract on blood coagulation, compare the conventional coagulometric tests with thrombin generation test (TGT), and study the qualitative micromolecular composition of M. crispa. Extract of M. crispa was incubated with plasma and used in the coagulometric tests: prothrombin and activated partial thromboplastin times, fibrinogen, and TGT. A phytochemical prospection was performed to evaluate the chemical composition of this extract. The extract was efficient in prolonging prothrombin time and activated partial thromboplastin time, and reducing fibrinogen levels and TGT parameters, indicating that the extract of M. crispa inhibited the intrinsic and extrinsic pathways of blood coagulation. The results obtained in TGT are in agreement with the results of conventional coagulometric tests and the in-vitro anticoagulant activity of M. crispa suggests that its use by patients using oral anticoagulants deserves caution.