Review on Eurycoma longifolia Pharmacological and Phytochemical Properties

Trends in the Tissue Culture Techniques and the Synthesis of Bioactive Compounds in Eurycoma longifolia Jack-Current Status and Future Perspectives

Over the last two decades, there has been a concerted effort by researchers to mass propagate Eurycoma longifolia and improve the yield of its very important and sought-after anti-cancer and aphrodisiac bioactive compounds. To achieve this, various techniques have been used to mass propagate and improve the yield of these bioactive compounds in tissue cultures. These techniques include the optimization of media conditions and application of various types and combinations of plant growth regulators (PGRs). In addition, some elicitation techniques have been used to improve the synthesis of these bioactive compounds. However, in comparison with other herbal species with similar economic importance, many techniques have not been applied to E. longifolia. Adopting the most recent methodologies would ensure efficiency and sustainability in the in vitro production of bioactive compounds in E. longifolia. Therefore, in this review, we present an up-to-date record on the success stories in the tissue culture techniques and synthesis of bioactive compounds. In addition, we attempted to identify some of the missing links on the road to the effective and sustainable biotechnological utilization of this super important biological resource.

Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical Trials

Background and Objectives: Male hypogonadism is a clinical disorder characterized by reduced serum testosterone in men. Although treatment using herbal medicines, including Eurycoma longifolia, has been investigated, the benefits remain unclear. This study aims to investigate the efficacy of E. longifolia as a sole intervention to increase testosterone levels in males. Materials and Methods: We conducted a systematic review and meta-analysis of randomized clinical trials (RCTs) according to the PRISMA guidelines. Relevant articles were retrieved from the databases PubMed, Scopus, Web of Science, Cochrane, Ovid/Embase, and Google Scholar. Results: After literature screening, a total of nine studies was included in the systematic review. Five RCTs were included in the meta-analysis. A significant improvement in total testosterone levels after E. longifolia treatment was mostly reported in both healthy volunteers and hypogonadal men. The random model effect revealed a significant increase (SMD = 1.352, 95% CI 0.565 to 2.138, p = 0.001) in the total testosterone levels in men receiving E. longifolia supplementation, which was confirmed in the hypogonadism subgroup. Conclusions: This systematic review and meta-analysis of the literature supports the possible use of E. longifolia supplementation for enhancing testosterone production. Although more research is required before its use in clinical practice, this may represent a safe and promising therapeutic option, particularly in hypogonadal men.

A Quassinoid Diterpenoid Eurycomanone from Eurycoma longifolia Jack Exerts Anti-Cancer Effect through Autophagy Inhibition

Eurycomanone (EN) is one of the representative quassinoid diterpenoids from roots of Eurycoma longifolia Jack, a natural medicine that is widely distributed in Southeast Asia. Previous studies showed that EN induces cancer cell apoptosis and exhibits anti-cancer activity, but the molecular mechanism of EN against cancer has still not been elucidated. In this study, we examined the regulatory effect of EN on autophagy to reveal the mechanism of EN-mediated colon cancer growth inhibition. First, we found that EN is able to inhibit colon cancer cell proliferation and colony formation. The angiogenesis level in cancer cells was inhibited as well. Next, the treatment of EN led to the suppression of autophagy, which was characterized by the downregulation of the LC3-II level and the formation of GFP-LC3 puncta under EN treatment in colon cancer. Moreover, we revealed that the mTOR signaling pathway was activated by EN in a time- and concentration-dependent manner. Finally, autophagy induction protected colon cancer cells from EN treatment, suggesting that autophagy improves cell survival. Taken together, our findings revealed the mechanism of EN against colon cancer through inhibiting autophagy and angiogenesis in colon cancer, supporting that the autophagy inhibitor EN could be developed to be a novel anti-cancer agent.

LC-PDA-MS/MS-Based Characterization of Key Phytochemicals in Eurycoma Longifolia Roots

The objective of the study was to fractionate the crude extract of Eurycoma longifolia (E. longifolia) roots and identify the intense peaks using HPLC-PDA-MS/MS, UPLC-MS/MS and H-NMR. Column chromatography was used to fractionate the crude extract into individual fractions using six solvent systems ranged from ethyl acetate, methanol and water in increasing polarity. Two fractions with nearly pure and intense peaks were selected for compound identification. Chromenone (coumarin) and chromone derivatives were putatively identified, besides several previously reported quassinoid glycosides (eurycomanone derived glycoside, 2,3-dehydro-4α-hydroxylongilactone glucoside, eurycomanol glycoside and eurycomanol trimer) in the fraction 11 of 100% methanol. A newly reported compound, namely hydroxyl glyyunanprosapogenin D (838 g/mol) was proposed to be the compound detected in the fraction 11 of 50% ethyl acetate and 50% methanol. This is also the first study to report the identification of chromenones and chromones in E. longifolia extract.

A review on extraction techniques and therapeutic value of polar bioactives from Asian medicinal herbs: Case study on Orthosiphon aristatus, Eurycoma longifolia and Andrographis paniculata

Medicinal plants have gained much interest in the prevention and treatment of common human disease such as cold and fever, hypertension and postpartum. Bioactive compounds from medicinal plants were synthesised using effective extraction methods which have important roles in the pharmaceutical product development. Orthosiphon aristatus (OA), Eurycoma longifolia (EL) and Andrographis paniculata (AP) are among popular medicinal herbs in Southeast Asia. The major compounds for these medicinal plants are polar bioactive compounds (rosmarinic acid, eurycomanone and andrographolide) which have multiple benefits to human health. The bioactive compounds are used as a drug to function against a variety of diseases with the support of scientific evidence. This paper was intended to prepare a complete review about the extraction techniques (e.g. OA, EL and AP) of these medicinal plants based on existing studies and scientific works. Suitable solvents and techniques to obtain their major bioactive compounds and their therapeutic potentials were discussed.

Medicinal plants as a potential source of Phosphodiesterase-5 inhibitors: A review

ETHNOPHARMACOLOGICAL RELEVANCE

The prevalence and distress caused by erectile dysfunction (ED) to both male and female partners are increasing at a steady rate. ED has now become the most treated sexual disorder for men among young and old age groups due to varying physical and psychological factors. The treatment with synthetic Phosphodiesterase-5 (PDE5) inhibitors are cost-effective but due to adverse effects such as priapism, loss of vision, heart attack and syncope, the daily life patterns of these patients are distressed and hence the need for alternative medicaments or sources are of utmost important. Therefore, the exploration of medicinal plants as PDE5 inhibitors will be worthwhile in tackling the problems as many plant extracts and fractions have been long used as aphrodisiacs and sexual stimulants which may be found to be active against PDE5 enzyme.

AIM OF THE STUDY

To provide a review on the different medicinal herbs traditionally used as natural aphrodisiacs, libido or sexual enhancers which are proven for their PDE5 inhibitory effect.

MATERIALS AND METHODS

Ethnobotanical and scientific information was procured, reviewed and compiled from the literature search of electronic databases and search engines.

RESULTS

A total of 97 medicinal plants exhibiting PDE5 inhibitory effect are reviewed in this paper which is supported by preclinical experimental evidence. Among them, 77 plants have been selected according to their traditional and ethnobotanical uses as aphrodisiacs and the rest are screened according to their effectiveness against predisposing factors responsible for ED and sexual dysfunction such as diabetes and hypertension or due to the presence of phytochemicals having structural similarity towards the identified natural PDE5 inhibitors. In addition, sixteen alkaloids, sixty-one phenolics and eight polycyclic aromatic hydrocarbons have been isolated or identified from active extracts or fractions that are exhibiting PDE5 inhibitory activity. Among them, isoflavones and biflavones are the major active constituents responsible for action, where the presence of prenyl group for isoflavones; and the methoxy group at C-5 position of flavones are considered essential for the inhibitory effect. However, the prenylated flavonol glycoside, Icariin and Icariside II isolated from Epimedium brevicornum Maxim (hory goat weed) are the most effective inhibitor, till date from natural sources. Traditional medicines or formulations containing extracts of Ginkgo biloba L., Kaempferia parviflora Wall. ex Baker, Clerodendrum colebrookianum Walp., Eurycoma longifolia Jack and Vitis vinifera L. are also found to be inhibitors of PDE5 enzyme.

CONCLUSION

The review suggests and supports the rational use of traditional medicines that can be further studied for the development of potential PDE5 inhibitors. Many traditional medicines are still used in various regions of Africa, Asia and South America that are poorly characterized and experimented. Despite the availability of a vast majority of traditional formulations as aphrodisiacs or sexual stimulants, there exists a need for systemic evaluation on the efficacy as well as the mechanism of action of the herbal constituents for the identification of novel chemical moieties that can be further developed for maximum efficacy.

Unfermented Freeze-Dried Leaf Extract of Tongkat Ali (Eurycoma longifolia Jack.) Induced Cytotoxicity and Apoptosis in MDA-MB-231 and MCF-7 Breast Cancer Cell Lines

The present study was conducted to determine the cytotoxicity effect of Eurycoma longifolia (Jack.) leaf extracts and also its possible anticancer mechanism of action against breast cancer cell lines: non-hormone-dependent MDA-MB-231 and hormone-dependent MCF-7. The leaves of E. longifolia were processed into unfermented and fermented batches before drying using freeze and microwave-oven drying techniques. Obtained extracts were tested for cytotoxicity effect using MTT assay and phenolic determination using HPLC-DAD technique. The most toxic sample was analyzed for its apoptotic cell quantification, cell cycle distribution, and the expression of caspases and apoptotic protein using flow cytometry technique. Fragmentation of DNA was tested using an agarose gel electrophoresis system. The results determined that the unfermented freeze-dried leaf extract was the most toxic towards MDA-MB-231 and MCF-7 cells, in a dose-dependent manner. This extract contains the highest phenolics of gallic acid, chlorogenic acid, ECG, and EGCG. The DNA fragmentation was observed in both cell lines, where cell cycle was arrested at the G 2/M phase in MCF-7 cells and S phase in MDA-MB-231 cells. The number of apoptotic cells for MDA-MB-231 was increased when the treatment was prolonged from 24 h to 48 h but slightly decreased at 72 h, whereas apoptosis in MCF-7 cells occurred in a time-dependent manner. There were significant activities of cytochrome c, caspase-3, Bax, and Bcl-2 apoptotic protein in MDA-MB-231 cells, whereas MCF-7 cells showed significant activities for caspase-8, cytochrome c, Bax, p53, and Bcl-2 apoptotic protein. These results indicate the ability of unfermented freeze-dried leaf extract of E. longifolia to induce apoptosis cell death on MDA-MB-231 and MCF-7, as well as real evidence on sample preparation effect towards its cytotoxicity level.

Differentially expressed genes on the growth of mouse Leydig cells treated with standardised Eurycoma longifolia extract

Eurycoma (E.) longifolia Jack (Tongkat Ali) is a widely applied medicine that has been reported to boost serum testosterone and increase muscle mass. However, its actual biological targets and effects on an in vitro level remain poorly understood. Therefore, the present study aimed to investigate the effects of a standardised E. longifolia extract (F2) on the growth and its associated gene expression profile in mouse Leydig cells. F2, even at lower doses, was found to induce a high level of testosterone by ELISA. The level was as high as the levels induced by eurycomanone and formestane in Leydig cells. However, Leydig cells treated with F2 demonstrated reduced viability, which was likely due to the diminished cell population at the G0/G1 phase and increased cell population arrested at the S phase in the cell cycle, as assessed by MTT assay and flow cytometry, respectively. Cell viability was revived when the treatment time‑point was prolonged to 96 h. Genome‑wide gene analysis by reverse transcription‑quantitative PCR of F2‑treated Leydig cells at 72 h, when the cell growth was not revived, and 96 h, when the cell growth had started to revive, revealed cyclin‑dependent kinase‑like 2 (CDKL2) to be a potential target in regulating the viability of F2‑treated Leydig cells. Functional analysis, as analysed using GeneMANIA Cytoscape program v.3.6.0 (https://genemania.org/), further suggested that CDKL2 could act in concert with Casitas B‑lineage lymphoma and sphingosine kinase 1 interactor‑A‑kinase anchoring protein domain‑containing genes to regulate the viability of F2‑treated Leydig cells. The findings of the present study provide new insights regarding the potential molecular targets associated with the biological effect of E. longifolia extract on cell growth, particularly on the cell cycle, which could aid in enhancing the bioefficacy and reducing the toxicity of this natural product in the future.

Chemical constituents and synergistic anti-gout studies on Eurycoma longifolia and potential mechanisms evaluation based on systemic analysis approach

37 compounds mainly including triterpenoids with the quassinoid skeleton and β-carboline alkaloids have been isolated from the roots of Eurycoma longifolia Jack (EL), which has been used as traditional medicine for a long history. It has been demonstrated that the total extracts from EL could significantly inhibit the joint swelling in MSU-induced acute gout arthritis rat model at middle and high doses (P < 0.05, P < 0.01), as meanwhile, better performance than that of positive control (P < 0.05, P < 0.01) has been observed at the dose of 10 g/kg. Aiming to search potential compounds and probable mechanisms, network pharmacology, molecular docking and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis were adopted, leading to the hypothesis of 17 targets related to different pathogenesis of gout and 5 potential compounds (C36, C107, C124, C125 and C130) among 156 selected compounds, playing synergetic role with multiple targets. Instead of the guiding ideology of "a gene, a drug, a disease", varieties of compounds but not a single one from EL display holistic performance through multiple pathways with multi-targets. It was noteworthy that Xanthine dehydrogenase/oxidase (XDH), Prostaglandin G/H synthase 2 (PTGS2), Fatty acid-binding protein, liver (FABP1), Purine nucleoside phosphorylase (PNP), and Peroxisome proliferator activated receptor alpha (PPARA) were the key targets with intensely interaction. Furthermore, the functional enrichment analysis indicated that EL probably produced the gout protection effects by synergistic regulation in multiple biological pathways, including Toll-like receptor signaling pathway, MAPK signaling pathway, and NOD-like receptor signaling pathway, etc.

Development of a selective HPLC-DAD/ELSD method for the qualitative and quantitative assessment of commercially available Eurycoma longifolia products and plant extracts

Aqueous extracts of the roots of Eurycoma longifolia are traditionally used to improve sexual performance, to treat infertility and other sexual dysfunctions but also to increase muscle strength. Nowadays, many different products are commercially available which are promoted as E. longifolia extracts and claim to possess beneficial aphrodisiac effects. Since such herbal aphrodisiac preparations have been recently the target of fraudulent product counterfeiting and because eurycomanone, one of the main quassinoids of E. longifolia, is suspected to possess toxic effects at higher concentrations, a highly selective HPLC-DAD/ELSD method has been established to analyze commercially available products and extracts of plant material. The presented method was established by the use of a mixture of 27 reference compounds for qualitative issues and fully validated according to the ICH guidelines for the quantification of three quassinoides: laurycolactone A, longilactone, and eurycomanone. The calibration curves of these showed a linearity over a range of 0.05 to 1.0mg/ml, with a regression coefficient not lower than R²=0.9969. The inter-day and intra-day precision (indicated as relative standard deviation) of the developed method was <2.9%. The recovery ranged from -3.3% to +6.0%. Eight randomly purchased products have been analyzed with this method, but only five of them contained E. longifolia compounds in detectable amounts. The concentration of eurycomanone in these products varied from 0.22±0.002mg eurycomanone per capsule to 1.84±0.08mg corresponding to a maximal recommended daily intake of 0.76±0.02 to 31.90±0.21mg.

Review: DNA Barcoding and Chromatography Fingerprints for the Authentication of Botanicals in Herbal Medicinal Products

In the last two decades, there has been a tremendous increase in the global use of herbal medicinal products (HMPs) due to their claimed health benefits. This has led to increase in their demand and consequently, also, resulted in massive adulteration. This is due to the fact that most of the traditional methods cannot identify closely related species in a process product form. Therefore the urgent need for simple and rapid identification methods resulted in the discovery of a novel technique. DNA barcoding is a process that uses short DNA sequence from the standard genome for species identification. This technique is reliable and is not affected by external factors such as climates, age, or plant part. The difficulties in isolation of DNA of high quality in addition to other factors are among the challenges encountered using the DNA barcoding in the authentication of HMP. These limitations indicated that using DNA barcoding alone may ineffectively authenticate the HMP. Therefore, the combination of DNA barcoding with chromatographic fingerprint, a popular and generally accepted technique for the assessment and quality control of HMP, will offer an efficient solution to effectively evaluate the authenticity and quality consistency of HMP. Detailed and quality information about the main composition of the HMPs will help to ascertain their efficacy and safety as these are very important for quality control.