A Validated HPLC Method for Simultaneous Determination of 2-Hydroxy-4-methoxybenzaldehyde and 2-Hydroxy-4-methoxybenzoic Acid in Root Organs of Hemidesmus indicus

Box-Behnken design avenue for development and validation of high-performance thin-layer chromatography method for estimation of rutin in Hemidesmus indicus

The aim of this study was to determine the content of rutin in Hemidesmus indicus and to optimize the high-performance thin-layer chromatography method. The method was validated in compliance with the International Council for Harmonisation guidelines Q2 (R1) for parameters such as linearity, accuracy, precision, robustness, limit of detection, and limit of quantitation. A Box-Behnken design and response surface methodology has been used to investigate the impact of independent variables on the response. Three independent variables, mobile phase composition (% v/v), mobile phase volume (mL), and duration of saturation (min), were studied. Rutin was verified, and its content was determined using a validated high-performance thin-layer chromatography method with good linearity within the range of 200-1000 ng spot^-1 with r²  = 0.9998 and correlation coefficient with calibration curve equation y = 0.0297x + 0.0001. The average percentage recovery values varied from 99.03 to 101.15 and 98.88 to 100.12%, respectively, for in-house and marketed mother tincture). The peak area determination at three different concentration levels shows low values of percentage relative standard deviation (<2%) for inter-day (0.04-0.06) and intra-day (0.04-0.05) precision of rutin. The average content of rutin in extract and marketed mother tincture was 229 ± 0.57 and 210 ± 0.57 μg g^-1 . The proposed method was simple, precise, and accurate for the determination of rutin with frequent quality control assessment of H. indicus.

Indian Sarsaparilla (Hemidesmus indicus): Recent progress in research on ethnobotany, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Hemidesmus indicus (L.) R. Br. ex Schult. (Apocynaceae) is widely used in traditional medicine in the different parts of the Indian subcontinent due to the various biological activities attributed to its different parts, especially the roots. It has traditionally been used for treating snakebites, scorpion stings, diabetes, urinary diseases, dyspnea, menorrhagia, oligospermia, anorexia, fever, abdominal colic and pain, dysentery, diarrhea, cough, rheumatism, headache, inflammation, pyrosis, skin diseases, leprosy, sexually transmitted diseases and cancer. In Ayurveda, the plant is used in the treatment of bone-loss, low body weight, fever, stress, topical wound and psoriasis. Besides, Ayurvedic literature also depicts its use as anti-atherogenic, anti-spasmodic, memory enhancing, immunopotentiating and anti-inflammatory agents.

AIM OF THE STUDY

In this review, we aim to present a comprehensive update on the ethnopharmacology, phytochemistry, specific pharmacology, and toxicology of H. indicus and its bioactive metabolites. Possible directions for future research are also outlined in brief.

MATERIALS AND METHODS

Popular and widely used international databases such as PubMed, Scopus, Science Direct, Google Scholar and JSTOR were searched and traditional literature were consulted using the various search strings to retrieve a number of citations related to the ethnopharmacology, biological activity, toxicology, quality control and phytochemistry of H. indicus. All studies on the ethnobotany, phtochemistry, pharmacology, and toxicology of the plant up to 2019 were included in this review.

RESULTS

H. indicus has played an important role in traditional Indian medicine (including Ayurveda) and also in European medicine. The main pharmacological properties of H. indicus include hepatoprotective, anti-cancer, anti-diabetic, antioxidant, neuroprotective, anti-ophidian, cardioprotective, nephroprotective, anti-ulcerogenic, anti-inflammatory, and antimicrobial properties. Phytochemical evaluations of the root have revealed the presence of aromatic aldehydes and their derivatives, phenolics, triterpenoids and many other compounds, some of which were attributed to its bioactivity. This review also compiles a list of Ayurvedic formulations and commercial preparations where H. indicus has been used as an active ingredient. We have included the critical assessment of all the papers cited in this manuscript based on experimental observation and other important points which reflect the loop-holes of research strategy and ambiguity in the papers reviewed in this manuscript.

CONCLUSIONS

The study presents an exhaustive and updated review on the traditional, pharmacological and phytochemical aspects of H. indicus with notes on its quality control and toxicological information. Although the crude extracts of H. indicus exhibit an array of pharmacological activities, it is high time to identify more active phyto-constituents by bioactivity-guided isolation besides elucidating their structure-activity relationship. More designed investigations are needed to comprehend the multi-target network pharmacology, to clarify the molecular mode of action and to ascertain the efficacious doses of H. indicus. Moreover, H. indicus is not fully assessed on the basis of its safety and efficacy on human. We hope this review will compile and improve the existing knowledge on the potential utilization of H. indicus in complementary and alternative medicine.

Population Genetics Coupled Chemical Profiling for Conservation Implications of Decalepis salicifolia (Bedd. ex Hook.f.) Venter, an Endemic and Critically Endangered Species of Western Ghats, India

Information on the genetic diversity and population structure is essential for developing conservational management programs, especially for threatened species. Decalepis salicifolia (Bedd. ex Hook.f.) Venter is a steno-endemic and critically endangered species of the south Western Ghats of India. The present study used ISSR markers as well as essential oil profiling to reveal the extent and distribution of genetic as well as the chemical diversity of all the twelve known populations of D. salicifolia. A total of 84 amplicons generated using 17 ISSR primers represented an overall 72.34% polymorphism. The highest percentage of polymorphic loci was recorded in the population of Theemalai (40.48%) and lowest in Kokanmalai (4.76%) with an average of 20.04% across all the studied populations. At the species level, the Nei's genetic diversity observed was 0.255 ± 0.186, while Shannon's information index observed was 0.385 ± 0.260. The genetic similarity-based unweighted pair-group method with arithmetic average dendrogram grouped the populations according to their geographic locations, which was corroborated by principal component analysis and Bayesian clustering. Distribution of genetic variance through analysis of molecular variance indicated that 38% variance resides within the population, and 62% variance resides among the populations (P < 0.001). Gas chromatography analyses of root volatiles showed significant variation in the percent content of 2-hydroxy-4-methoxybenzaldehyde. The Mantel test analyses showed a positive correlation between the genetic versus geographic distances. Based on the results, both ex situ and in situ conservation strategies are suggested to maximally preserve the genetic resources of this endangered species.

Profiling of volatile and non-volatile metabolites in Polianthes tuberosa L. flowers reveals intraspecific variation among cultivars

Polianthes tuberosa L. (tuberose) is a widely cultivated ornamental crop in Asian countries. Different cultivars of tuberose have been developed through breeding programs in India. However, no reports on floral fragrance and metabolite contents of these cultivars are available. In this study, an attempt has been made to evaluate the levels of both volatile and non-volatile metabolites from seven different cultivars of P. tuberosa. Presence of benzenoids, phenylpropanoids, terpenoids, and few fatty acid derivatives as emitted, endogenous and glycosylated forms were revealed from the studied cultivars. Further, chemometric analyses in both supervised and unsupervised manner led to identification of patterns among the cultivars. Among the seven cultivars, four distinct clusters were obtained linking to their volatiles, flavonoids and primary metabolite levels. Metabolic variations obtained from the cultivars also suggest cross-talks between phenylpropanoid, benzenoid, and flavonoid pathways. Thus metabolite profiling reported here may help in characterization of tuberose cultivars for perfumery utility and future breeding programme.

Redirection of metabolite biosynthesis from hydroxybenzoates to volatile terpenoids in green hairy roots of Daucus carota

A metabolic shift in green hairy root cultures of carrot from phenylpropanoid/benzenoid biosynthesis toward volatile isoprenoids was observed when compared with the metabolite profile of normal hairy root cultures. Hairy roots cultures of Daucus carota turned green under continuous illumination, while the content of the major phenolic compound p-hydroxybenzoic acid (p-HBA) was reduced to half as compared to normal hairy roots cultured in darkness. p-Hydroxybenzaldehyde dehydrogenase (HBD) activity was suppressed in the green hairy roots. However, comparative volatile analysis of 14-day-old green hairy roots revealed higher monoterpene and sesquiterpene contents than found in normal hairy roots. Methyl salicylate content was higher in normal hairy roots than in green ones. Application of clomazone, an inhibitor of 1-deoxy-D-xylulose 5-phosphate synthase (DXS), reduced the amount of total monoterpenes and sesquiterpenes in green hairy roots compared to normal hairy roots. However, methyl salicylate content was enhanced in both green and normal hairy roots treated with clomazone as compared to their respective controls. Because methyl-erythritol 4-phosphate (MEP) and phenylpropanoid pathways, respectively, contribute to the formation of monoterpenes and phenolic acids biosynthesis, the activities of enzymes regulating those pathways were measured in terms of their in vitro activities, in both green and normal hairy root cultures. These key enzymes were 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), an early regulatory enzyme of the MEP pathway, pyruvate kinase (PK), an enzyme of primary metabolism related to the MEP pathway, shikimate dehydrogenase (SKDH) which is involved in biosynthesis of aromatic amino acids, and phenylalanine ammonia-lyase (PAL) that catalyzes the first step of phenylpropanoid biosynthesis. Activities of DXR and PK were higher in green hairy roots as compared to normal ones, whereas the opposite trend was observed for SKDH and PAL activities. Gene expression analysis of DXR and PAL showed trends similar to those for the respective enzyme activities. Based on these observations, we suggest a possible redirection of metabolites from the primary metabolism toward isoprenoid biosynthesis, limiting the phenolic biosynthetic pathway in green hairy roots grown under continuous light.

Chemical composition of root aroma of Decalepis arayalpathra (J. Joseph and V. Chandras.) Venter, an endemic and endangered ethnomedicinal plant from Western Ghats, India

Decalepis arayalpathra (J. Joseph and V. Chandras.) Venter, which belongs to the family Apocynaceae, is a perennial under shrub, endemic to southern Western Ghats, India. The highly aromatic tuberous roots of the D. arayalpathra are used as an effective remedy for peptic ulcer, cancer-like afflictions and as rejuvenating tonic by native tribes. The objective of this study was to characterise the root aroma of D. arayalpathra for possible industrial applications. Hydrodistilled volatile oil of the roots was analysed by gas chromatography-flame ionisation detector and gas chromatography-mass spectrometry. The volatile oil was characterised by the presence of higher amount of an industrially important flavour molecule, 2-hydroxy-4-methoxybenzaldehyde (96.8%) along with some other minor or trace constituents. Owing to characteristic vanillin-like flavour, the root oil of the D. arayalpathra can be explored as a potential substitute of vanillin-aroma in the flavour industry.

Flavoring extracts of Hemidesmus indicus roots and Vanilla planifolia pods exhibit in vitro acetylcholinesterase inhibitory activities

Acetylcholinesterase inhibitors (AChEIs) are important for treatment of Alzheimer's disease and other neurological disorders. Search for potent and safe AChEIs from plant sources still continues. In the present work, we explored fragrant plant extracts that are traditionally used in flavoring foods, namely, Hemidesmus indicus and Vanilla planifolia, as possible sources for AChEI. Root and pod extracts of H. indicus and V. planifolia, respectively, produce fragrant phenolic compounds, 2-hydroxy-4-methoxybenzaldehyde (MBALD) and 4-hydroxy-3-methoxybenzaldehyde (vanillin). These methoxybenzaldehydes were shown to have inhibitory potential against acetylcholinesterase (AChE). Vanillin (IC50 = 0.037 mM) was detected as more efficient inhibitor than MBALD (IC50 = 0.047 mM). This finding was supported by kinetic analysis. Thus, plant-based food flavoring agents showed capacity in curing Alzheimer's disease and other neurological dysfunctions.

Hemidesmus indicus induces apoptosis as well as differentiation in a human promyelocytic leukemic cell line

ETHNOPHARMACOLOGICAL RELEVANCE

The decoction of the roots of Hemidesmus indicus is widely used in the Indian traditional medicine for the treatment of blood diseases, dyspepsia, loss of taste, dyspnea, cough, poison, menorrhagia, fever, and diarrhea. Poly-herbal preparations containing Hemidesmus are often used by traditional medical practitioners for the treatment of cancer. The aim of this study was to investigate the cytodifferentiative, cytostatic and cytotoxic potential of a decoction of Hemidesmus indicus's roots (0.31-3 mg/mL) on a human promyelocytic leukemia cell line (HL-60).

MATERIALS AND METHODS

The decoction of Hemidesmus indicus was characterized by HPLC to quantify its main phytomarkers. Induction of apoptosis, cell-cycle analysis, levels of specific membrane differentiation markers were evaluated by flow cytometry. The analysis of cell differentiation by nitroblue tetrazolium (NBT) reducing activity, adherence to the plastic substrate, α-napthyl acetate esterase activity and morphological analysis was performed through light microscopy (LM) and transmission electron microscopy (TEM).

RESULTS

Starting from the concentration of 0.31 mg/ml, Hemidesmus indicus induced cytotoxicity and altered cell-cycle progression, through a block in the G0/G1 phase. The decoction caused differentiation of HL-60 cells as shown by NBT reducing activity, adherence to the plastic substrate, α-naphtyl acetate esterase activity, and increasing expression of CD14 and CD15. The morphological analysis by LM and TEM clearly showed the presence of granulocytes and macrophages after Hemidesmus indicus treatment.

CONCLUSIONS

The cytodifferentiating, cytotoxic and cytostatic activities of Hemidesmus indicus offers a scientific basis for its use in traditional medicine. Its potent antileukemic activity provides a pre-clinical evidence for its traditional use in anticancer pharmacology. Further experiments are worthwhile to determine the in vivo anticancer potential of this plant decoction and its components.

Shikimate pathway modulates the elicitor-stimulated accumulation of fragrant 2-hydroxy-4-methoxybenzaldehyde in Hemidesmus indicus roots

Enzymatic route to fragrant 2-hydroxy-4-methoxybenzaldehyde (MBALD) formation in Hemidesmus indicus roots is not known. Earlier studies with H. indicus excised roots suggested a possible origin of MBALD via central phenylpropanoid pathway. Different elicitors (e.g., chitosan, methyl jasmonate, yeast extract) were tested for their relative efficiency in uplifting MBALD accumulation in roots, amongst which, treatment with yeast extract for 18 h showed maximum accumulation in excised roots. As benzoate pathways originate either directly from shikimate or via phenylpropanoid pathway, this study aimed at finding the roles of shikimate pathway in uplifting/enhancing MBALD accumulation in H. indicus roots upon elicitation. In fact, a sharp increase in shikimate dehydrogenase (SKDH; E.C. 1.1.1.25) along with phenylalanine ammonia-lyase (PAL; E.C. 4.3.1.24) activities was noted on a time-course basis in yeast extract-treated roots as compared to the untreated ones. PAL as well as phenylpropanoid C₂ side-chain cleavage activities (leading to p-hydroxybenzaldehyde, the first benzoate product formed in the MBALD pathway) were compared in elicited roots, non-elicited roots and glyphosate-treated elicited roots at different concentrations of glyphosate. It was observed that glyphosate treatment, in addition to 25% suppressions of phenylalanine ammonia-lyase and C₂ chain-cleavage enzyme activities as compared to elicited one, also resulted in around 40% suppression of MBALD accumulation, when used in conjunction with yeast extract treatment; in contrast, shikimic acid content was increased as compared to glyphosate untreated ones. These findings suggest that shikimate pathway plays an important role in modulating MBALD biosynthesis in H. indicus roots.

Mitochondrial pathway mediates the antileukemic effects of Hemidesmus indicus, a promising botanical drug

Background

Although cancers are characterized by the deregulation of multiple signalling pathways, most current anticancer therapies involve the modulation of a single target. Because of the enormous biological diversity of cancer, strategic combination of agents targeted against the most critical of those alterations is needed. Due to their complex nature, plant products interact with numerous targets and influence several biochemical and molecular cascades. The interest in further development of botanical drugs has been increasing steadily and the FDA recently approved the first new botanical prescription drug. The present study is designed to explore the potential antileukemic properties of Hemidesmus indicus with a view to contributing to further development of botanical drugs. Hemidesmus was submitted to an extensive in vitro preclinical evaluation.

Methodology/Principal Findings

A variety of cellular assays and flow cytometry, as well as a phytochemical screening, were performed on different leukemic cell lines. We have demonstrated that Hemidesmus modulated many components of intracellular signaling pathways involved in cell viability and proliferation and altered the protein expression, eventually leading to tumor cell death, mediated by a loss of mitochondrial transmembrane potential and increased Bax/Bcl-2 ratio. ADP, adenine nucleotide translocator and mitochondrial permeability transition pore inhibitors did not reverse Hemidesmus-induced mitochondrial depolarization. Hemidesmus induced a significant [Ca²⁺]_i raise through the mobilization of intracellular Ca²⁺ stores. Moreover, Hemidesmus significantly enhanced the antitumor activity of three commonly used chemotherapeutic drugs (methotrexate, 6-thioguanine, cytarabine). A clinically relevant observation is that its cytotoxic activity was also recorded in primary cells from acute myeloid leukemic patients.

Conclusions/Significance

These results indicate the molecular basis of the antileukemic effects of Hemidesmus and identify the mitochondrial pathways and [Ca²⁺]_i as crucial actors in its anticancer activity. On these bases, we conclude that Hemidesmus can represent a valuable tool in the anticancer pharmacology, and should be considered for further investigations.

Phenylalanine ammonia-lyase-mediated biosynthesis of 2-hydroxy-4-methoxybenzaldehyde in roots of Hemidesmus indicus

The fragrant rootstocks of Hemidesmus indicus are known to accumulate 2-hydroxy-4-methoxybenzaldehyde (MBALD), yet, the enzymatic route to this hydroxybenzoate is not known. Therefore, root organs of H. indicus hold promises to unravel the biosynthesis related to this phenolic fragrance. Chitosan treatment at 200mg/L concentration to the excised roots effectively increased phenolic accumulation in both the cortex and cork tissues reaching a peak after 24h treatment and decreasing thereafter. The activity of phenylalanine ammonia-lyase (PAL) enzyme in excised roots also increased upon chitosan elicitation, and the maximum specific activity was recorded after 12h of elicitation. Suppression of PAL in vivo by using a specific irreversible inhibitor aminooxyacetic acid (AOAA) resulted in the decrease in MBALD content, indicating its formation via phenylpropanoid pathway.