A review of the chemical composition and biological activity of Leonotis nepetifolia (Linn.) R. Br. (lion's ear)

Artículo de revisión

 

A review of the chemical composition and biological activity of Leonotis nepetifolia (Linn.) R. Br. (lion's ear)

Una revisión de la actividad biológica y de los compuestos químicos de Leonotis nepetifolia (Linn.) R. Br. (bastón de San Francisco)

 

Jackson de Menezes Barbosa1
Noelly Bastos Cavalcante1
David Marrero Delange2
Jackson Roberto Guedes da Silva Almeida1*

 

1 Center for Studies and Research of Medicinal Plants, Federal University of the San Francisco Valley, Petrolina, Pernambuco, Brazil.
2 Institute of Marine Science, Department of Chemistry. La Habana, Cuba.

* Corresponding author. E-mail: jackson.guedes@univasf.edu.br

 

 


ABSTRACT

Introduction: For centuries, medicinal plants have been used to treat a variety of diseases. Leonotis nepetifolia (Linn.) R. Br. is a species native to tropical regions of Africa and southern India which is widely used for medicinal purposes.
Objective: Review the main publications about L. nepetifolia with a chemical and pharmacological approach, and describe the most relevant papers found in the databases.
Methods: Specialized databases were reviewed (LiLacs, PubMed, SciELO, ScienceDirect and Scopus) using the search terms Leonotis nepetifolia, phytochemistry, biological activity and Lamiaceae. Papers were selected whose titles and abstracts were related to the phytochemical characteristics and biological activity of the species, and their full text was analyzed.
Results: Several studies have been conducted of the species L. nepetifolia, verifying its potential use for the treatment of various diseases. In the review, 32 papers were selected which evaluated the biological activity of extracts from the species, and 11 which dealt with the isolation of compounds produced by the secondary metabolism of the plant, showing the anti-inflammatory and antioxidant activity of some of them. Antibacterial, antiviral, antifungal, anticonvulsant, anxiolytic, anticarcinogenic, analgesic, antidiarrheal, antidiabetic, antiplasmodial and anthelmintic activities were the most carefully evaluated, whereas the diterpenes labdane and bis-spirolabdane, flavonoids, fatty acids and esters, iridoids, and phenylethanoid glycosides and coumarins were the most common chemical compounds.
Conclusions: The presence of certain chemical substances accounts for the various potential biological applications of the extracts and compounds isolated from L. nepetifolia for the production of new drugs and phytomedicines.

Key words: Leonotis nepetifolia, medicinal plant, phytochemical, biological activity.


RESUMEN

Introducción: Las plantas medicinales han sido utilizadas durante siglos por la humanidad como base para el tratamiento de diversas enfermedades. Leonotis nepetifolia (Linn.) R. Br. es una especie nativa de las regiones tropicales de África y del sur de la India, ampliamente utilizada por la población con fines medicinales.
Objetivo: Revisar las principales publicaciones sobre L. nepetifolia centradas en los enfoques farmacológico y químico, y describir los artículos más relevantes encontrados en las bases de datos.
Métodos: El análisis se realizó mediante bases de datos especializadas (LiLacs, PubMed, sciELO, ScienceDirect y Scopus) con diferentes combinaciones de palabras: Leonotis nepetifolia, fitoquímica, actividad biológica y Lamiaceae. Se seleccionaron los artículos con títulos y resúmenes relacionados con la fitoquímica y con la actividad biológica de la especie y posteriormente el texto completo.
Resultados: Se han llevado a cabo varios estudios con la especie L. nepetifolia para comprobar su potencial terapéutico en el tratamiento de varias enfermedades. Para esta revisión se seleccionaron 28 artículos que evaluaron la actividad biológica de los extractos de la especie y 11 artículos relacionados con el aislamiento de los compuestos producidos por el metabolismo secundario de la planta, y se comprobó las actividades antiinflamatoria y antioxidante de algunos compuestos. Las actividades antibacterianas, antivirales, antifúngicas, anticonvulsivantes, ansiolíticas, anticancerígenas, analgésicas, antidiarreicas, antidiabéticas, antiplasmódicas y antihelmínticas fueron las más evaluadas, mientras que los diterpenos labdano y bis-spirolabdano, los flavonoides, los ácidos grasos y los ésteres, los iridoides y los glucósidos feniletanoides, así como las cumarinas fueron los compuestos químicos más comunes.
Conclusiones: La presencia de diferentes sustancias químicas es la responsable de la diversidad de aplicaciones biológicas de los extractos y los compuestos aislados con potencial para la producción de nuevos fármacos y fitoterápicos de L. nepetifolia.

Palabras clave: Leonotis nepetifolia; planta medicinal; fitoquímico; actividad biológica.


 

 

Recibido: 12/09/2017
Aprobado: 23/07/2018

 

 

INTRODUCTION

Medicinal plants have been used for centuries by mankind as a basis for the treatment of several diseases. In recent years, several studies have focused on bioprospecting of biologically active plant compounds. Studies showed that many ethnobotanical information correlates with biological activities verified in vivo and in vitro assays. Medicinal plants are rich in secondary metabolites, widely used in traditional medicine to fight and cure various diseases. The exploration of these pharmacological properties, biological activities and identification of bioactive molecules encompasses an investigation of these active ingredients using appropriate extraction, purification, separation, crystallization and identification techniques.1

 

Leonotis is a genus of flowering plants in the Lamiaceae family. The name of the genus is derived from a combination of the Greek (λέων) "leon" meaning lion and "otis" meaning ear, as suggested by the likeness of the flower petals to a lion's ear.2 One species, Leonotis nepetifolia (Linn.), R. Br is native to tropical regions of Africa and southern India. The other species are endemic to southern and eastern Africa. In the Brazil, L. nepetifolia is found in the phytogeographic domains of the Amazon, Cerrado, Atlantic Forest, Caatinga and Pantanal, and is therefore found in all parts of the country. 3 Some researches were carried out to verify the diversity of biological activity of the different types of extracts (hexane, methanolic, ethanolic and etc.) and the elucidation of the chemical constituents present in this species.

The aim of this study was to review the main publications about the species L. nepetifolia, focusing on the pharmacological and chemical approaches, and to describe the most relevant articles found in the databases.

 

 

METHODS

The research was carried out in the year 2016 with the aim of searching the scientific productions that investigated the phytochemical and biological activity of extracts and isolated compounds produced by the L. nepetifolia species. The analysis were conducted using specialized databases (LiLacs, PubMed, SciELO, ScienceDirect and Scopus), with different combinations of key words: Leonotis nepetifolia, phytochemical, biological activity and Lamiaceae. The first criterion for selection of the articles for the review was to consider those who presented the title and the summary related to the phytochemistry and biological activity of the species. In the second and last stage the whole text was evaluated, selecting articles that mentioned the isolation of compounds produced by L. nepetifolia and those that evaluated the pharmacological potential of the extracts of the plant. Review articles, ethnobotanical studies, abstracts, meta-analyzes, and editorials were discarded from our study. The information extracted from the articles that inestimated the extract of the species were: origin and used part of the species, activity and extract. In the articles that deal with the isolation of compounds and activities, the following information was extracted: type of compound, substance, biological activity and used part. At the end of the study, 28 articles were selected that report the biological activity of extracts and 11 that deals with the isolation and biological activity of the compounds.

ANALYSIS AND INTEGRATION OF INFORMATION

Biological activities of L. nepetifolia extracts

Several researchers from different countries have focused their studies on the evaluation of the pharmacological, antibacterial, antiviral, fungicidal, anti-inflammatory, antinociceptive, pesticides, anticancer, antidiarrheal, anticonvulsant, antiplasmodial and antidiabetic activities of the extract of the different parts of L. nepetifolia with solvents (Table 1). In this perspective this species has presented promising biological activities in the discovery of new phytotherapics and drugs based on vegetal biota.

Table 1. Biological activities of extracts obtained from L. nepetifolia

Origin (Part used)

Activity

Extract

Result

References

India (Leaves)

Antibacterial

MeOH

Active

[6]

Kenya (Leaves)

Antifungal

Hexane/CH2Cl2/EtOAc/ EtOH 96 %

Active

[17]

Kenya (Leaves, stalk and fruits)

Antifungal

MeOH

Active

[21]

Kenya (Leaves)

Antibacterial

Hexane/CH2Cl2/EtOAc/ EtOH 96 %

Active

[16]

India (Leaves)

Antioxidant/ anti-cancer

CHCl3/EtOAc/Me OH

Active

[13]

India (Leaves)

Antihelmintic

Aqueous extract/MeOH/EtOAc

Active

[9]

India (Leaves, root and stem)

Antibacterial/Antioxidant/Larvicidal/Pesticidal

Acetone/CHCl3/EtOH/EtOAc

Active

[8]

Brazil (leaves, flowers, stems)

Antimicrobial/ cytotoxic activities

Ethanolic extract

Inactive

[3]

India (Leaves)

Antibacterial/ antifungal

Essential oil

Active

[11]

Uganda (Leaves)

Antiplasmodial/ cytotoxic

AcOEt/MeOH

Active

[22]

Ruanda (Leaves)

Antibacterial

EtOH 80 %

Inactive

[20]

Kenya (Root)

Anti-giardial

MeOH

Inactive

[18]

India (Flowers)

Antifungal

Aqueous extract

Active

[12]

Ruanda (Leaves)

Antibacterial/ antiviral

EtOH 80 %

Inactive

[19]

Congo (Whole plant)

Analgesic

EtOH/Aqueous

Active

[24]

Tanzanian (Leaves)

Antibacterial/antifungal/ Antiviral

n -Hexane/MeOH

Active

[25]

India (Leaves)

Healing

EtOH

Active

[14]

India (Leaves, stem and flowers)

Antibacterial

MeOH

Active

[7]

Nigeria (Non specified)

Anticonvulsant

MeOH

Active

[26]

India (Whole plant)

Antidiabetic

EtOH

Active

[15]

Uganda (Leaves)

Antidiarrheal

EtOH 70 %

Active

[23]

México (Leaves, flowers and stems)

Anti-inflammatory

n -Hexane/AcOEt/MeOH

Active

[28]

India (Leaf, stem, inflorescence and root)

Antimicrobial

Petroleum ether/AcOEt/MeOH

Active

[10]

Brazil (Aerial parts)

Antibacterial/ cytotoxic

MeOH/Acetone

Inactive and Active

[29]

Nigéria (Stem)

Anxiolytic

MeOH

Active

[27]

India (No specified)

Antioxidant

MeOH

Active

[4]

India (Whole plant)

Antihelmintic

EtOH/Aqueous

Active

[5]

 

In India, different researchers investigated the therapeutic potential of L. nepetifolia against several pathogens and microorganisms that cause human diseases in addition to anticancer, antihelminticand antioxidant activity.4,5 From the methanolic extract (MeOH) of the leaves, stem and flowers of L. nepetifolia was verified the antibacterial activity.6,7

It was also verified that different extracts obtained from some parts ofL. nepetifolia exhibit strong activity against the bacteria,Pseudomonas aeruginosa, Bacillus subtilis, Klebsiella pneumoniae, Escherichia coli andStaphylococcus aureus, besides the antioxidant, larvicidal
(Artemia salina) and pesticide (Sitophilus oryzae) activities.8 Studies of Gnaneswari et al.,9 with different extracts of L. nepetifolia showed potential against helminthic parasites that cause disease in people living in underdeveloped countries. Thus, the use of extracts produced by the flora appears as a promising alternative in the treatment of diseases caused by these worms.

Gnaneswari & Raju10 have shown that L. nepetifolia extracts were efficient against different strains of bacteria and could be used to treat diseases caused by pathogenic microorganisms.

The essential oil of L. nepetifolia leaves has been shown to be potent inhibitor of several bacteria, except Pseudomonas aeruginosa. It has also been found that essential oil has an inhibitory potential against dermatophyte fungi.11

From the aqueous extract of L. nepetifolia flowers, the activity against the aflatoxin produced by the fungi Aspergillus flavus and Aspergillus parasiticus was verified, being important in the combat of toxins produced by the secondary metabolism of these fungi, which are parasites of food and feed besides having carcinogenic potential.12

Veerabadran et al.,13 in India demonstrated that among the extracts tested, methanolic had a higher antioxidant potency and efficiency against cancer cells of MFC-7 and Hep2, being a relevant result indicating that natural phytotherapy may be a Pathway for the treatment of various diseases that are related to the release of free radicals, such as: cancer, Alzheimer, Parkinson's, atherosclerosis, hypertension and ischemic diseases.

In the analysis performed by Nithya et al.,14 with the crude ethanolic extract of L. nepetifolia, they verified the healing activity of the extract in animal model (rats). The antidiabetic activity was performed at doses of 250 and 500 mg/kg orally also with crude ethanolic extract of L. nepetifolia leaves in rats.15

In the countries of Africa, the species L. nepetifolia is well investigated, due to being part of the traditional medicine exhibiting therapeutic potential. In Kenya, the different extracts (hexane, dichloromethane, ethyl acetate and ethanolic) of L. nepetifolia were investigated and exhibited antibacterial activity against Staphylococcus aureus, Gram-positive bacterium, only the extract dichloromethane and ethanol exhibited activity against the bacteria Escherichia coli.16 In addition, also demonstrated antifungal activity against Candida albicans, and the ethanolic extract showed higher activity.17 However, the MeOH extract of the L. nepetifolia root did not show activity against Giardia.18

However, in studies conducted in Rwanda by Cos et al.,19-20 with the crude ethanolic extract of L. nepetifolia, it did not demonstrate antiviral and antibacterial activities. In studies with the crude ethanolic extract of L. nepetifolia, moderate antiviral activity and low antifungal and antibacterial activities were observed.21

In Uganda, it was found that ethyl acetate and methanolic extracts of L. nepetifolia have moderate antiplasmodial activity with 27 % inhibition against the parasite Plasmodium falciparum and low cytotoxic activity.22 The oral doses of 225, 450 and 900 mg/kg of L. nepetifolia crude ethanolic extract were also tested orally in rats, verifying that they have activity against diarrhea.23

In the Congo, the ethanolic and aqueous extracts were tested in rats to evaluate the analgesic activity. The single dose of 250 mg/kg orally administered caused a decrease in the number of abdominal writhings induced by 0.6 % acetic acid, emphasizing the importance of studies of medicinal plants for the production of new pharmaceutical products.24 In Tanzania, studies conducted by Maregesi et al.,25 evaluated the antibacterial and antifungal potential.

In Nigeria, tests performed on mice with L. nepetifolia methanolic extract at doses of 150, 300 and 600 mg/kg exhibited interesting anticonvulsant activity, being important for the use of the extract in the treatment of seizures in patients with epilepsy.26 Studies with the methanolic extract of L. nepetifolia also presented anxiolytic effect in mice.27

In Mexico, through the model of ear edema induced by (TPA) 12-O -tetradecanoylphorbol-13-acetate in mice, there was a reduction of edema after treatment with L. nepetifolia extracts at the dose of 1 mg per ear. As with the crude extract of ethyl acetate, it had the highest activity, showing the following edema reduction: leaves (65.75 %), flowers (69.06 %) and stem (72.92 %) indicated a strong anti-inflammatory activity.28

In Brazil, studies with L. nepetifolia showed antibacterial activity and low cytotoxicity.3 Another study with the extract of L. nepetifolia found the absence of anti-bacterial activity. In addition, it was demonstrated that the concentration of 200 μg/mL of the L. nepetifolia extract has a great potential against prostate cancer cells, causing 100% cell death after 48 h. 29 It has also been shown that the L. nepetifolia species has antioxidant activity.

Chemical compounds of L. nepetifolia

Researchers are investigating the phytochemistry of L. nepetifolia , and several important studies describe its chemical composition (Table 2). Investigations have shown extracts from L. nepetifolia consists mainly of diterpenes, of the labdane diterpenes type (Manchand;30 Von Dreele et al.;31 Blount and Marchant; 32Li et al.;33 Ueda et al.34) and bis-spirolabdane diterpenes type.32

 

Table 2 Compounds in L. nepetifolia

Compound type

Substance (structure)

Biological activity

Place (part used)

References

Labdane diterpenes

Methoxynepetaefolin

Not evaluated

United States (no specified)/ (no specified)/(leaves)

[30], [32], [33]

Nepetaefolin

Not evaluated

United States (no specified)/ (leaves)

[31], [33]

Nepetaefolinol

Not evaluated

United States (no specified)

[32]

Nepetaefuran

Not evaluated/
Anti-inflammatory

United States (leaves)/
Japan (aerial parts)

[33]

[34]

Dubiin

Not evaluated

United States (leaves)

[33]

Compound 15 (without denomination)

Not evaluated

United States (leaves)

[33]

Leonotinin

Not evaluated/ Anti-inflammatory

United States (leaves)/
Japan (aerial parts)

[33]

[34]

Leonotin

Not evaluated/ Anti-inflammatory

United States (leaves)/
Japan (aerial parts)

[33]

[34]

LS-1

Not evaluated

United States (leaves)

[33]

Bis -spirolabdane diterpenes

Leonepetaefolin A

Not evaluated

United States (leaves)

[33]

Leonepetaefolin B

Not evaluated

United States (leaves)

[33]

Leonepetaefolin C

Not evaluated

United States (leaves)

[33]

Leonepetaefolin D

Not evaluated

United States (leaves)

[33]

Leonepetaefolin E

Not evaluated

United States (leaves)

[33]

15-epi-leonepetaefolin A

Not evaluated

United States (leaves)

[33]

15-epi-leonepetaefolin B

Not evaluated

United States (leaves)

[33]

15-epi-leonepetaefolin C

Not evaluated

United States (leaves)

[33]

15-epi-leonepetaefolin D

Not evaluated

United States (leaves)

[33]

15-epi-leonepetaefolin E

Not evaluated

United States (leaves)

[33]

Diterpenes

Hydroxy-dialactone nepetaefolinol

Not evaluated

India (no specified)

[38]

9,13-epoxylabd-5-ene-16,15:19,20-diolactone

Not evaluated

India (no specified)

[38]

15,16-epoxy-labda-13(16),14-diene-6b, 9,17,19-tetrol

Not evaluated

India (no specified)

[38]

Flavonoids

Apigenin

Not evaluated

United States (leaves)

[31]

Cirsiliol

Not evaluated

United States (leaves)/
Brazil (leaves, flowers, stems)

[33]

[41]

Fatty esters

Methyl tetradeca-2,3-dienoate

Not evaluated

China (seed oil)

[40]

Methyl tetradeca-3,4-dienoate

Not evaluated

China (seed oil)

[40]

Methyl tetradeca-4,5-dienoate

Not evaluated

China (seed oil)

[40]

Methyl octadeca-7,8-dienoate

Not evaluated

China (seed oil)

[40]

Methyl tetradeca-12,13-dienoate

Not evaluated

China (seed oil)

[40]

Labalenic acid

Not evaluated

China (seed oil)

[40]

Iridoids

Geniposidic acid

Not evaluated

Japan (stems)

[37]

Mussaenoside

Not evaluated

Japan (stems)

[37]

Ixoside

Not evaluated

Japan (stems)

[37]

Iridoid glycosides

10-O-(trans-3,4-dimethoxycinnamoyl) geniposidic acid

Not evaluated

Japan (stems)

[37]

10-O-(p-hydroxybenzoyl)- geniposidic acid

Not evaluated

Japan (stems)

[37]

Phenylethanoid glycosides

Acteoside

Antioxidant activity

Japan (stems)

[37]

Martinoside

Antioxidant activity

Japan (stems)

[37]

Lavandulifolioside

Antioxidant activity

Japan (stems)

[37]

Allenic acid

Laballenic acid

Not evaluated

United States (seeds)

[35]

Coumarin

4,6,7-Trimethoxy-5-methylchromen-2-one

Not evaluated

India (whole plant)

[36]

 

The first study related to the chemical composition of L. nepetifolia was conducted by Bagby et al.35 where the seed oil was investigated. A new allenic acid, named laballenic acid, was isolated. The authors report that seed oil from L. nepetifolia contains 16 % of laballenic [(-)-5,6-octadecadienoic] acid. This is the first example of a natural C 18 allene from higher plants. An anomalous result with periodate-permanganate oxidation was found in which glutaric acid, an expected cleavage product, was not detected. Laballenic acid was very stable to alkali.

Manchand 30 carried out the isolation and identification of the first diterpene of the labdane type, denominated methoxynepetaefolin. The compound has the molecular formula C23H3O8 and the NMR spectrum (CDCl3) revealed a close structural similarity to that of nepetaefolin.

In 1976, a study conducted by Purushothaman et al.,36 a new coumarin from L. nepetifolia was isolated. The compound was named 4,6,7-trimethoxy-5-methylchromen-2-one. According to the authors, the NMR spectrum revealed the presence of three methoxy-groups (δ 3.75, 3.91, and 3.94), an aromatic methyl group (δ 2.59), a vinyl proton [δ 5.53 (1 H, s)], and an aromatic proton [δ 6.68 (1 H, s)]. NMR and U.V. [Xmax 225, 275 Inf, 287, 313, 327 Inf] nm (20 000, 8 800, 12 800, 15 000 and 11 000)] are similar to those of siderin (4,7-dimethoxy-5-methylchromen-2-ones).

In study conducted by Takeda et al.,37 three antioxidative phenylethanoid glycosides and two new iridoid glycosides, along with three known iridoids were isolated from the L. nepetifolia. Stems of L. nepetifolia were collected in 1995 in Saitama, in the botanical garden herbarium of Kyoritsu College of Pharmacy, and voucher specimens have been deposited at the herbarium of this College. The new iridoid glycosides were established as 10-O -(trans-3,4-dimethoxycinnamoyl) geniposidic acid and 10-O -(p-hydroxybenzoyl) geniposidic acid. Antioxidant activities of the compounds were measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method, and the three known phenylethanoid glycosides, acteoside, martynoside and lavandulifolioside showed strong antioxidant activity.

Govindasamy et al.,38 described the interesting structural studies on three new diterpenoids, namely, hydroxy-dialactone nepetaefolinol (9,13-epoxy-6β-hydroxy-8α-labdane-16,15:19,20-diolactone), dehydrated nepetaefolinol (9,13-epoxylabd-5-ene-16,15:19,20-diolactone) and isomeric tetrol (15,16-epoxy-labda-13(16),14-diene-6b,9,17,19-tetrol: which is the reduction product of new diterpenoid leonotinin) isolated from Indian herbal plant L. nepetifolia (collected in the flowering season from Guindy area, Madras), and are found to be the major compounds in their extractions, so they are expected to possess interesting pharmacological properties. This work suggests that more in-depth studies on the pharmacological properties of L. nepetifolia.

In the study conducted by Li et al.,33 ten new bis-spirolabdane diterpenoids, leonepetaefolins A-E (1, 3, 5, 7, 9) and 15-epi-leonepetaefolins A-E (2, 4, 6, 8, 10), together with eight known labdane diterpenoids (11-18) as well as two known flavonoids, apigenin and cirsiliol, were isolated from the leaves of L. nepetifolia. The structures of the new compounds were determined on the basis of 1D and 2D NMR experiments including 1 H, 13C, DEPT, 1H-1H COSY, HSQC, HMBC, and NOESY. The absolute configuration of an epimeric mixture of 1 and 2 was determined by X-ray crystallographic analysis. The compounds isolated were evaluated for their binding propensity in several CNS G-protein-coupled receptor assays in vitro, suggested no potential for further evaluation or development.

In Japan, researchers isolated three labdane diterpenes capable of inhibiting the LPS signaling pathway by suppressing the transactivation of NF-κB. The compounds were denominated nepetaefuran, leonotinin and leonotin, and were isolated from the aerial parts of L. nepetifolia, on the LPS signaling pathway in order to elucidate the anti-inflammatory mechanism involved. Nepetaefuran more potently inhibited the LPS-induced production of NO and CCl2 than leonotinin by suppressing the expression of iNOS mRNA and CCl2 mRNA. The authors concluded that nepetaefuran and leonotinin could be the components responsible for the anti-inflammatory activity of L. nepetifolia by specifically inhibiting the LPS-induced activation of NF-κB.34

The seeds of L. nepetifolia were investigated in Cuba, and the chemical determination of its fatty acids constituents was performed. To these effects, a number of them were collected, ground and extracted with hexane in an ultrasonic bath. The extracts were filtered and the solvent was evaporated on a rotary evaporator at 60 °C and under vacuum. Organoleptic characteristics and extraction yields were determined. The FA content analyzed as methyl esters was determined by gas chromatography with BPX-70 capillary column and flame ionization detector. A characteristic yellow odor [28.2 % (m/m)] was obtained. The main FA found were oleic (C18:1 n-9, 43.2 %), labalenic (C18:2 n-5,6, 18,4 %), palmitic (C16: 0, 15,0 % (C18:2 n-9.12, 13.4 %), and stearic (C18:0, 5.7 %), while other fatty acids such as C12: 0 to C16: 0, C16: 1 (n- 7 and n-9), C17: 0, C18: 1 (n-7), C18: 3 (n-9,12,15), C20: 0, and C24: 0, were found in proportions <1 %. According to the authors, in general, the FA content of L. nepetifolia coincided with that described in the literature for this species. These results constituted the first study of the chemical composition of this species in Cuba and could contribute to support their possible nutritional and medicinal uses.39

In China, researchers isolated six fatty acids from the seeds of L. nepetifolia. Their chemical structures were determined by nuclear magnetic resonance (NMR) spectroscopy, observing the correlation of the chemical shift signals. The fatty acids identified were: Methyl tetradeca-2,3-dienoate, methyl tetradeca-3,4-dienoate, methyl tetradeca-4,5-dienoate, methyl octadeca-7,8-dienoate, methyl tetradeca-12,13-dienoate and labalenic acid.40

A study conducted by Oliveira et al., in Brazil, was isolated from ethyl acetate extract of L. nepetifolia the flavonoid 3',4',5-trimethoxy-6,7-dihydroxyflavone (cirsiliol). The compound was detected by liquid chromatography of high performance (HPLC-DAD) and its identification obtained through nuclear magnetic resonance (NMR) spectroscopy, using the 1D and 2D methods. To evaluate the bioactive potential of isolate flavonoid, in vitro tests were carried out to determine possible antimicrobial and cytotoxic properties. The authors concluded that the flavonoid cirsiliol showed a strong cytotoxic activity in the in vitro tests due to its chemical structure, which presents substitution by methoxyl groups at position 6, besides the presence of a catechol group (hydroxyls at the 3 'and 4' positions of the ring B). This pattern of substitution that is present in the structure of cirsiliol justifies, according to the authors, the high cytotoxic potential observed in the cited study.41

 

 

CONCLUSIONS

Important studies were conducted with L. nepetifolia, and the research shown in this review justifies its traditional use for the treatment of various diseases. This species presents important active substances, demonstrating the relevance of its medicinal application. The presence of different chemical substances confers the diversity of biological application of extracts and isolated compounds, with potential for the production of new drugs and phytotherapics of this plant.

 

Acknowledgments

The authors thank the collaboration of the Brazilian agencies CAPES and FACEPE for financial support.

 

 

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Conflicto de intereses

Los autores expresan que no tienen conflicto de intereses.





Copyright (c) 2019 Jackson Roberto Guedes da Silva Almeida, Jackson de Menezes Barbosa, Noelly Bastos Cavalcante, David Marrero Delange

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