Genus Barleria L. (Acanthaceae): a review of its taxonomy, cytogenetics, phytochemistry and pharmacological potential

OBJECTIVES

Barleria, a large genus of the Acanthaceae family, comprises more than 300 species with diverse taxonomy, cytogenetics, phytochemistry and pharmacological potential. Therefore, the aim of this review is to critically assess the research on Barleria and provide guidance for future investigations.

METHODS

The data were obtained from different sources, such as books, theses, journals and some of the websites and internet-based searches, published from 1901 to 2020. Data obtained from PubMed, Google Scholar, ScienceDirect, online electronic journals, SpringerLink, Wiley, etc. have also been used.

KEY FINDINGS

The species of this genus exhibit considerable medicinal properties. Cytogenetical data are scantily available with chromosome counts available for only 24 species. The most common chromosome number is 2n = 2x = 40. So far, 187 compounds are reported from Barleria species. The active principles, their uses, toxicity and pharmacological effects are discussed. Essential oils, flavones, flavonoids, glycosides, terpenes and terpenoids form the major compounds.

SUMMARY

It is highly recommended that the pharmacological and economic potential of Barleria species should be exploited and more detailed studies and attention be geared towards its utilization and conservation. In addition, to ensure maximum pharmacological benefits and sustainable use, it is necessary to have empirical information explaining its ethnobotanical values as well as commercial potential.

Inhibition of the pro-inflammatory mediators in rat neutrophils by shanzhiside methyl ester and its acetyl derivative isolated from Barleria prionitis

ETHNOPHARMACOLOGICAL RELEVANCE

The aerial parts of Barleria prionitis Linn. (BP) (Acanthaceae) plant has long been used to treat inflammatory disorders such as toothache, swellings, arthritis and gout.

AIM OF THE STUDY

The purpose of this study was to evaluate the effects of shanzhiside methyl ester (SME), 8-O-acetyl shanzhiside methyl ester (ASME) and iridoid glycosides rich monoterpenoidal fraction (IFBp), isolated from the aerial part of BP, on the pro-inflammatory mediators in stimulated rat neutrophils.

MATERIALS AND METHODS

Rat neutrophils were incubated with or without test drugs. The influence of laboratory isolated and identified SME, ASME and IFBp on the production and release of pro-inflammatory mediators i.e. myeloperoxidase (MPO), elastase, matrix metalloproteinase-9 (MMP-9), interleukin 8 (IL-8), tumor necrosis factor alpha (TNF-α) and leukotriene B4 (LTB4) was evaluated in the formyl-met-leu-phenylalanine (f-MLP) and lipopolysaccharide (LPS) stimulated rat neutrophils using enzyme-linked immunosorbent assay (ELISA) methods. IFBp was also standardized with the high performance thin layer chromatography by simultaneous determination of SME and ASME marker compounds.

RESULTS

SME, ASME and IFBp displayed concentration-dependent inhibitory effects on the MPO, elastase and MMP-9 enzymes release, and IL-8, TNF-α and LTB4 cytokines production in the f-MLP and LPS stimulated rat neutrophils. The content of SME and ASME was found to be 17.32 ± 1.98 and 11.30 ± 1.06% w/w, respectively, in IFBp by HPTLC method.

CONCLUSION

Altogether, the present results suggest that the iridoidal glycosides of BP may be considered as therapeutic strategy against neutrophil-mediated inflammatory diseases. Developed and validated HPTLC method for the standardization of IFBp of BP can be used as a quality control tool for the routine qualitative and quantitative analysis of Barleria species containing SME and/or ASME.

Biochemical fingerprint and pharmacological applications of Barleria noctiflora L.f. leaves

Background Antioxidant and antihistamine agents from Barleria noctiflora L.f. as natural source due to the existing modern medicine give various adverse effects to overcome these problems with natural products. MethodsB. noctiflora leaves extract was fractionated with column chromatography; the homogenized fractions were monitored with thin layer chromatography (TLC) and characterized by using UV-visible, FT-IR, 1H NMR, 13C NMR and mass spectrometry spectral studies. The volatile phytoconstituents of B. noctiflora extract were analysed by gas chromatography-mass spectrometry. Phytoconstituents from B. noctiflora leaves extract were screened for their antioxidant and antihistamine potential in vitro (2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, 2,2'-azinobis-3-ethylbenzothiozoline-6-sulfonic acid radical decolouration assay, nitric oxide radical scavenging activity, superoxide radical scavenging activity and hydrogen peroxide radical scavenging activity) and in silico (molecular docking), respectively. Results Antioxidant and antihistamine barlerinoside has been isolated and characterized from the leaves of B. noctiflora L.f. Barlerinoside revealed their free-radical scavenging ability on OH-, OH•, NO-, O2- and H2O2 radicals and found high percentage inhibition against OH- radical at the IC50 value of 50.45±2.52  µg. The methanol (MeOH) extract of B. noctiflora leaves contains cyclotene; N,N-dimethylglycine; tetrahydrocyclopenta [1,3] dioxin-4-one; phenol, 2-methoxy-; benzofuran, 2-methyl-; 1,4:3,6-dianhydro-α-d-glucopyranose; 2-methoxy-4-vinylphenol; 1,3;2,5-dimethylene-l-rhamnitol; levoglucosan and bicyclo[2.2.2]oct-7-ene-2,5-dione as being the major compounds. Among phytoconstituents present in the extract, the hexestrol; 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester; 1-(3,6,6-trimethyl-1,6,7,7a-tetrahydrocyclopenta[c]pyran-1-yl) ethanone; megastigmatrienone; furan interacted with histamine H1 receptor and bind at GLU-177 and ASP-178 with high binding energy score -13.95, -13.41, -12.56, -12.03, and -11.72 kcal/mol, respectively, and the expected hydrolysed products of compound-1a and compound-1b from barlerinoside showed -8.91 and -8.68 kcal/mol binding energy against the histamine H1 receptor. This showed that the active ligands exactly bind with active binding site of the protein. ConclusionsWe can conclude that isolated barlerinoside from B. noctflora L.f. has potent antioxidant activity against synthetic free radicals and antihistamine activity against histamine H1 receptor.