Immunomodulatory Effect of Plant Extracts and Iridoid Glucosides from Nyctanthes arbortristis Against Systemic Candidiasis in Mice

Quantification of Arbortristoside-A isolated from Nyctanthes arbor-tristis using HPLC: Method development and pharmaceutical applications

Arbortristoside-A (Arbor-A) is a naturally occurring iridoid glycoside and herbal-based lead molecule with proven medicinal potential. Aiming at the development of an efficient analytical tool for the quantification of Arbor-A in pharmaceutical dosage forms, in the presented work, we developed an economical, fast, and sensitive RP-HPLC-UV method and validated the procedure as per the ICH guidelines, Q2(R1). The chromatographic separation was accomplished under the optimised experimental conditions using an HPLC system with an LC-2010 autosampler, a PDA detector, and a Phenomenex C18 column with the mobile phase composed of a 70:30 (v/v) water-acetonitrile mixture eluting isocratically at a flow rate of 1 mL/min at ambient temperature, and UV detection at 310 nm. Arbor-A showed a sharp peak at the retention time of 5.60 min and exhibited linearity (R2 = 0.9988) with LOD and LOQ of 0.50 μg/mL and 1.50 μg/mL, respectively. The accuracy of the method was 98.33-101.36 % with acceptable intra-day and inter-day precisions as well as robustness (<2% RSD). To ratify the applicability of the presented approach in emerging pharmaceuticals, a nanoformulation loaded with Arbor-A was designed and analysed utilising the provided methodology. The method has also enabled to determine the degradation kinetics of Arbor-A under stress conditions, etcetera, employing forced degradation and short term stability studies.

Isolation of Arbortristoside-A from Nyctanthes arbor-tristis seeds and its structural validation by X-ray crystallographic analysis

Aiming at confirming the chemical structure, herein, we report the crystal structure of Arbortristoside-A, isolated from the seeds of Nyctanthes arbor-tristis Linn. and investigated by single crystal X-ray crystallographic analysis. The unambiguously established structure of Arbortristoside-A not only addresses previously reported structural flaws but also encourages its chemical, computational, and physiological studies as a lead drug candidate of pharmaceutical significance.

Revisiting nature: a review of iridoids as a potential antileishmanial class

Leishmaniasis still stands as one of the most prevalent neglected tropical diseases in the least developed and emerging countries. The recommended therapeutic arsenal to treat leishmaniasis is characterized by several shortcomings, and resistance has already been reported. Hence, this dramatic background highlights the pressing need to develop novel, affordable, and safe antileishmanial drugs. Multiple classes of natural compounds have been reported to possess antileishmanial activity. Among these classes, iridoids stand out as a special type of monoterpenoids with diverse biological properties-including their antileishmanial potential. This review aims to discuss the available literature between 1991 and 2020 related to the antileishmanial activity of the iridoid class. Throughout the past decades, various investigations attributed antileishmanial action to assorted iridoid types, including inhibitory potential towards validated drug targets and immunomodulatory activity. The latter deserves special attention due to the ability of some iridoids to improve the host's immune response against parasites. It opens the possibility of iridoids become adjuncts in leishmaniasis treatments by improving the efficacy of currently employed drugs. Furthermore, the present study intends to provide a convenient visual representation of which iridoids and Leishmania spp. species have been most investigated as a guide for further researches.

Anti-rheumatoid arthritis effects of iridoid glucosides from Lamiophlomis rotata (Benth.) kudo on adjuvant-induced arthritis in rats by OPG/RANKL/NF-κB signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Lamiophlomisrotata (Benth.) Kudo. has been used to treat trauma bleeding, rheumatism, yellow water disease in traditional Chinese medicine.

AIM

The aim of this work was to evaluate the anti-rheumatoid arthritis (RA) activities and underlying mechanisms of the total iridoid glucosides (TIG) from Lamiophlomisrotata (Benth.) Kudo.

METHODS

The chemical constituents of TIG was analyzed by high-performance liquid chromatography (HPLC) with seven reference compounds (penstemonoside, chlorotuberside, shanzhiside methyl ester, phloyoside, 7-epliamalbide, phlorigidoside C and lamalbide). The anti-rheumatoid arthritis effects of TIG were investigated by arthritis indexes and paw swelling degrees, as well as histopathological and Micro-CT analysis in adjuvant-induced arthritis (AIA) rats. The impacts of TIG on the level of inflammatory cytokines (IL-1β, TNF-α, IL-6, IFN-γ, IL-17 and IL-10), and the regulation of OPG/RANKL/NF-κB pathways were determined by the ELISA and western blot, respectively.

RESULTS

TIG significantly reduced the arthritis indexes and paws swelling in AIA rats, attenuated the inflammation and bone destruction in joint tissues, reduced the generation of pro-inflammatory cytokines IL-1β, TNF-α, IL-6, IFN-γ and IL-17, as well as increased the generation of anti-inflammatory cytokine IL-10 in serum. Moreover, TIG markedly inhibited the expression of p-IKK-α, p-IκB and p-p65, and decreased the ratio of OPG/RANKL in the synovial tissues.

CONCLUSION

TIG possessed significant anti-RA activities on adjuvant-induced arthritis, which might be ascribed to the regulation of inflammatory cytokines IL-1β, TNF-α, IL-6, IFN-γ IL-17 and IL-10, as well as inhibition of OPG/RANKL/NF-κB signaling pathways.

Antiparasitic and disease-modifying activity of Nyctanthes arbor-tristis Linn. in malaria: An exploratory clinical study

BACKGROUND

An unceasing threat of drug resistance continuously poses demand for new antimalarial drugs. A scientific assessment of traditionally used antimalarial plants through reverse pharmacology is crucial for a fast track drug discovery. An Ayurvedic plant Nyctanthes arbor-tristis Linn. - (Parijat) is being used in clinical practice and had shown antimalarial activity, with a parasite clearance in 76.6% of 120 patients, in an earlier clinical study.

OBJECTIVE

To further explore antimalarial potential of the plant through additional objective markers.

MATERIALS AND METHODS

An open-labelled observational study was conducted at M.A. Podar Hospital - Ayurveda (MAPH-A) after ethics committee approval. Administration of a paste of 5 fresh leaves, thrice a day for a week was a standard practice for management of malaria at MAPH-A. Clinical activity of N. arbor-tristis was evaluated by monitoring pyrexia, parasitemia and morbidity score (MS) in twenty patients. In addition, immune and biochemical markers and organ functions were monitored for objective markers of response. Student's paired-'t' test was applied to assess statistical significance.

RESULTS

Ten out of 20 patients showed both fever and parasite clearance, which was confirmed by polymerase chain reaction. Remaining ten patients had persistent but decreasing parasitemia. Four of them needed chloroquine as a fail-safe procedure. Irrespective of the degree of parasitemia all the patients showed decrease in MS. There was also an increase in platelet count and normalization of plasma lactic acid. There was a good clinical tolerability and an improvement in organ function. The inflammatory cytokines showed a reduction; particularly in TNF-α within a day.

CONCLUSIONS

At the given dosage, N. arbor-tristis showed disease-modifying activity; early clinical recovery with a decline of TNF-α and a gradual parasite clearance. Further studies with a standardised formulation for dose-searching and optimizing the treatment schedule are needed in a larger sample size.

CLINICAL TRIAL REGISTRATION NO

The process of trial registration had not begun when the study was conducted in 2000.

Exploration of anti-Malassezia potential of Nyctanthes arbor-tristis L. and their application to combat the infection caused by Mala s1 a novel allergen

Background

Malassezia commensal yeasts along with multitude of antigens have been found to be associated with various skin disorders including Pityriasis versicolor (PV). Amongst them Mala s1, a 37 kDa protein has been proved to be a major allergen reacting with a large panel of sera. However, there exists no therapeutic alternative to combat such problems in form of plant based natural compounds. The purpose of this study is in the first place, to determine the anti-Malassezia activity of Nyctanthes arbor-tristis L. (NAT) ethanolic leaf extract through turbidimetric growth curves, disruption of plasma membrane and secondly, it aims to present in silico validation of its active constituents over Mala s1a novel allergen.

Methods

The antifungal susceptibility 50 % ethanolic extract of NAT was determined by broth microdilution method according to CLSI guidelines. Further MICs and IC₅₀ were determined spectrophotometrically using the software SoftMax® Pro-5 (Molecular Devices, USA). Active constituents mediated disruption of plasma membrane was studied through flowcytometry by permeabilization of fluorescent dye Propidium Iodide (PI). Antioxidant activity of the extract was determined using the DPPH stable radical. Molecular validation of fungal DNA from the extract was observed using PCR amplification. In silico analysis of its active constituents over Mala s1 was performed using HEX software and visualized through Pymol.

Results

The anti-Malassezia potential of NAT leaf extracts reflected moderate MIC 1.05 μg/μl against M. globosa, while least effective against M. restricta with MIC 1.47 μg/μl. A linear correlation coefficient R² = 0.866 was obtained in case of M. globosa while minimum was observed in M. restricta with R² = 0.732. The flow cytometric data reveal ~ 75 % cell death when treated with active constituents β-Sitosterol and Calceolarioside A. The docking confirmations and the interaction energies between Mala s1 and the active constituents (β-Sitosterol and Calceolarioside A) from extracts showed an effective binding which suggests Mala s1 as efficient allergen for site specific targeting.

Conclusions

This study revealed that Nyctanthes arbor-tristis L. (NAT) extracts possess high anti-Malassezia potential which is driven mainly by disruption of plasma membrane. Also in silico validation and molecular modeling studies establishes Mala s1 as a novel allergen that could be a potential target in disease treatment. Our results would also provide a foundation for the development of new therapeutic approach using NAT extract as lead compound with high antioxidant property as an added trait for skin care.

Nyctanthes arbor-tristis Linn--a critical ethnopharmacological review

ETHNOPHARMACOLOGICAL RELEVANCE

Nyctanthes arbor-tristis (Oleaceae) is a mythological plant; has high medicinal values in Ayurveda. The popular medicinal use of this plant are anti-helminthic and anti-pyretic besides its use as a laxative, in rheumatism, skin ailments and as a sedative. Vitally, the natives plant it in their home gardens to pass on its medicinal usage to oncoming generations.

AIM OF THE REVIEW

The present review encompasses an ethnopharmacological evaluation focusing on information on the chemical constituents, pharmacological actions and toxicology in order to reveal the therapeutic potential and gaps requiring research involvement.

MATERIALS AND METHODS

The present review is based on searches in Scifinder(®), Pubmed (National Library of Medicine) and books published on the subject during the period 1933 to 2012.

RESULTS

Nyctanthes arbor-tristis is most important in local and traditional medicines especially in India for treating intermittent fevers, arthritis and obstinate sciatica. Crude extracts and isolated compounds from the plant were shown to be pharmacologically active against inflammation, malaria, viral infection, leishmanisis and as an immunostimulant. The major class of biologically active compounds are the iridoid glucosides incl., Arbortristoside A, B and C from the seeds active as anticancer, anti-leishmania, anti-inflammatory, anti-allergic, immunomodulatory and antiviral. Other molecules; calceolarioside A, 4-hydroxyhexahydrobenzofuran-7one and β-sitosterol from leaves have been reported to be active as anti-leishmanial, anticancer and anti-inflammatory, respectively. The crude extracts have been found to be safe with an LD50 of 16gm/kg, while the LD50 of arbortristoside-A isolated from the seeds was found to be 0.5g/kg.

CONCLUSION

Mostly in-vitro or in some cases in-vivo models provide some evidence especially in the treatment of inflammatory conditions like arthritis, fevers related to malaria and protozoan diseases especially leishmaniasis. The only clinical study found, is for treating malaria, but with crude extract only. Further, more detailed safety data pertaining to the acute and sub-acute toxicity, cardio and immunotoxicity also needs to be generated for crude extracts or pure compounds.

Modified iridoid glycosides as anti-implantation agents: inhibition of cell adhesion as an approach for developing pregnancy interceptive agents

Structural modifications in iridoid glycosides and evaluation of their efficacy on adhering capability (in vitro) of immature hamster uterine epithelial cells to the substratum have been studied. Out of 31, eight compounds in vitro, five compounds in utero and two in vivo showed adhesion/implantation preventing activity, respectively. The results provide an indication for further exploration in the line of development of anti-adhesive agents.