Cytotoxic labdane-type diterpenes from Hedychium longipetalum inhibiting production of nitric oxide

Volatile profiling coupled with multivariate analysis, antiproliferative and anti-inflammatory activities of rhizome essential oil of four Hedychium species from India

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Hedychium of family Zingiberaceae comprises several perennial rhizomatous species widely used in perfumery and traditional folk medicine to treat diseases related to asthma, diarrhoea, nausea, stomach disorders, inflammation and tumours. Several species of Hedychium have remained under-explored with respect to their chemical composition and biological activities.

AIM OF THE STUDY

The current research aimed to explore the chemical composition and evaluate the antiproliferative and anti-inflammatory activities of rhizome essential oil from four Hedychium species (H. coccineum, H. gardnerianum, H. greenii and H. griffithianum).

MATERIALS AND METHODS

Compound identification was accomplished using a Clarus 580 gas chromatography system in conjunction with mass spectrometry (GC-MS). The multivariate data statistics using chemometrics (PCA, PLS-DA, sPLS-DA) and cluster analysis (Dendrogram, Heat maps, K-means) were used to compare the similarity and relationship among Hedychium metabolomes. MTT assay was employed to visualize the antiproliferative property against MCF7, HepG2 and PC3 cancerous cell lines. The toxicity of essential oils was determined using 3T3-L1 non-tumorigenic/normal cells. Lipopolysaccharide (LPS)-induced RAW 264.7 cells were used to investigate the anti-inflammatory properties of Hedychium essential oils by measuring the production of nitric oxide (NO) using the Griess reagent method. Furthermore, the levels of prostaglandin (PGE2) and pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) was assessed using the ELISA technique.

RESULTS

In total, 82 compounds were identified in four targeted species of Hedychium from which 1,8-cineole (52.71%), β-pinene (32.83%), α-pinene (19.62%), humulene epoxide II (19.86%) and humulene epoxide I (19.10%) were the major constituents. Monoterpenes (8.5-59.9%) and sesquiterpenes (2.87-54.11%) were the two class of compounds, found as the most prevalent in the extracted essential oils. The multivariate analysis classified the four Hedychium species into three different clusters. Hedychium essential oils exhibited potent antiproliferative activity against MCF7, HepG2 and PC3 cancer cell lines with IC50 values less than 150 μg/mL where H. gardnerianum exhibited the highest selective cytotoxicity against human breast and prostate adenocarcinoma cells with an IC50 value of 44.04 ± 1.07 μg/mL and 56.11 ± 1.44 μg/mL, respectively. The essential oils on normal (3T3-L1) cells displayed no toxicity with higher IC50 values thereby concluding as safe to use for normal human health without causing any side effects. Besides, the essential oils at 100 μg/mL concentration revealed remarkable anti-inflammatory activity in LPS-activated RAW 264.7 murine macrophages by inhibiting the production of inflammatory mediators, with H. greenii exhibiting the maximum anti-inflammation response by significantly suppressing the levels of NO (84%), PGE2 (87%), TNF-α (94.3%), IL-6 (95%) and IL-1β (85%) as compared to LPS treated group.

CONCLUSION

The present findings revealed that the Hedychium species traditionally used in therapeutics could be a potential source of active compounds with antiproliferative and anti-inflammatory properties.

A Comprehensive Review on Pharmacologically Active Phyto-Constituents from Hedychium species

In this review, we describe and discuss the phytoconstituents present in Hedychium species and emphasize their potential as drug candidates. Though they are widely validated in vitro and in vivo models, to date, no efforts have been made to compile in a single review all the pharmacologically active phytoconstituents from Hedychium species, and their pharmacological and toxicity profile. In this study, we present a reinvestigation of the chemical constituents present in Hedychium species obtained from the essential oil and solvent extraction of the flowers, leaves and rhizomes under consideration. Key databases such as PubMed, Science Direct, Scopus, and Google Scholar amongst others were probed for a systematic search using keywords to retrieve relevant publications on this plant. An exhaustive electronic survey of the related literature on Hedychium species resulted in around 200 articles. Articles published between the years 1975-2021 were included. The studies conducted on either crude extracts, solvent fractions or isolated pure compounds from Hedychium species reported with a varied range of biological effects such as anti-inflammatory, analgesic, antidiabetic, potentially anti-asthmatic, and cytotoxic, among other related activities of the chemical constituents present in its essential oil and solvent extract deployed in this review. Traditional and herbal medication around the world that uses different parts of Hedychium species were considered for anti-inflammatory, skincare, analgesic, anti-asthmatic, anti-diabetic, antidotal uses, among others. These uses support the idea that chemical constituents obtained from solvent extraction may also exert the same action individually or in a synergistic manner. The review concluded that there is scope for computation and biological study to find out possible new targets for strengthening the potency and selectivity of the relevant compounds, and to find a commercial method for extraction of active pharmaceutical ingredients.

Cytotoxic Labdane Diterpenes, Norlabdane Diterpenes and Bis-Labdanic Diterpenes from the Zingiberaceae: A Systematic Review

Over the years, labdane diterpenes, norlabdane diterpenes, and bis-labdanic diterpenes with cytotoxic activities have been identified across various families in the plant kingdom including the Zingiberaceae. The present review discusses the distribution of these labdane-type diterpenes within the Zingiberaceae; their extraction, isolation, and characterization from the respective Zingiberaceae species; the structural similarities and differences within each group and between the different groups of the labdane-type diterpenes; and their cytotoxic activities against breast, cervical, liver, colorectal, pancreatic, lung and prostate cancer cell lines. The review will also provide insight into how the cytotoxic activities of the labdane-type diterpenes are influenced by their structural features.

Advances on Natural Abietane, Labdane and Clerodane Diterpenes as Anti-Cancer Agents: Sources and Mechanisms of Action

Extensive research over the past decades has identified numerous phytochemicals that could represent an important source of anti-cancer compounds. There is an immediate need for less toxic and more effective preventive and therapeutic strategies for the treatment of cancer. Natural compounds are considered suitable candidates for the development of new anti-cancer drugs due to their pleiotropic actions on target events with multiple manners. This comprehensive review highlighted the most relevant findings achieved in the screening of phytochemicals for anticancer drug development, particularly focused on a promising class of phytochemicals such as diterpenes with abietane, clerodane, and labdane skeleton. The chemical structure of these compounds, their main natural sources, and mechanisms of action were critically discussed.

Penitholabene, a rare 19-nor labdane-type diterpenoid from the deep-sea-derived fungus Penicillium thomii YPGA3

Chemical examination of the fermented material of the deep-sea-derived fungus Penicillium thomii YPGA3 led to the identification of a rare 19-nor labdane-type diterpenoid, named penitholabene (1). The structure was elucidated based on extensive analyses of the spectroscopic data and quantum chemical calculations of the ¹³C NMR and ECD data. A synthetic compound from commercial sources with the same planar structure is recorded in SciFinder (CAS number: 1217878-75-5), but there is no related reference and the configurations of chiral centers and double bond are not depicted. Penitholabene was reported as a new compound in the current study. To our knowledge, Penitholabene represents the first 19-nor labdane-type diterpenoid found in nature. It showed inhibitory effect against α-glucosidase with an IC₅₀ value of 282 μM, being more active than the positive control acarbose (1.33 mM).

Uncharted Source of Medicinal Products: The Case of the Hedychium Genus

A current research topic of great interest is the study of the therapeutic properties of plants and of their bioactive secondary metabolites. Plants have been used to treat all types of health problems from allergies to cancer, in addition to their use in the perfumery industry and as food. Hedychium species are among those plants used in folk medicine in several countries and several works have been reported to verify if and how effectively these plants exert the effects reported in folk medicine, studying their essential oils, extracts and pure secondary metabolites. Hedychium coronarium and Hedychium spicatum are the most studied species. Interesting compounds have been identified like coronarin D, which possesses antibacterial, antifungal and antitumor activities, as well as isocoronarin D, linalool and villosin that exhibit better cytotoxicity towards tumor cell lines than the reference compounds used, with villosin not affecting the non-tumor cell line. Linalool and α-pinene are the most active compounds found in Hedychium essential oils, while β-pinene is identified as the most widespread compound, being reported in 12 different Hedychium species. Since only some Hedychium species have been investigated, this review hopes to shed some light on the uncharted territory that is the Hedychium genus.

Diterpenes and Their Derivatives as Potential Anticancer Agents

As therapeutic tools, diterpenes and their derivatives have gained much attention of the medicinal scientists nowadays. It is due to their pledging and important biological activities. This review congregates the anticancer diterpenes. For this, a search was made with selected keywords in PubMed, Science Direct, Web of Science, Scopus, The American Chemical Society and miscellaneous databases from January 2012 to January 2017 for the published articles. A total 28, 789 published articles were seen. Among them, 240 were included in this study. More than 250 important anticancer diterpenes and their derivatives were seen in the databases, acting in the different pathways. Some of them are already under clinical trials, while others are in the nonclinical and/or pre-clinical trials. In conclusion, diterpenes may be one of the lead molecules in the treatment of cancer. Copyright © 2017 John Wiley & Sons, Ltd.

Therapeutic Potential of Essential Oils Focusing on Diterpenes

Among all plant derivates, essential oils (EOs) have gained the attention of many scientists. Diterpenes, a family of components present in some EO, are becoming a milestone in the EOs world. The goal of this review is to describe a scenario of diterpenes taking into health-consumption deportment. Previous studies revealed that diterpenes have antioxidant, antimicrobial, antiviral, antiprotozoal, cytotoxic, anticancer, antigenotoxic, antimutagenic, chemopreventive, antiinflammatory, antinociceptive, immunostimulatory, organoprotective, antidiabetic, lipid-lowering, antiallergic, antiplatelet, antithrombotic, and antitoxin activities. In conclusion, diterpenes may be an immense featuring concern in pharmaceutical consumption from a drug discovery point of view. Copyright © 2016 John Wiley & Sons, Ltd.

Cytotoxic Labdane Diterpenes from Hedychium ellipticum Buch.-Ham. ex Sm

In order to reveal the constituents and their biological activities, we carried out a phytochemical study on Hedychium ellipticum Buch.-Ham. ex Sm. (Zingiberaceae). Ten labdane diterpenoids (1–10) were isolated from the rhizomes of H. ellipticum for the first time. Their structures were identified on the basis of spectroscopic analyses including two-dimensional NMR and comparison with literature data. All of these compounds were evaluated for their antimycobacterial activity against Mycobacterium tuberculosis and cytotoxicity against KB, MCF7, NCI-H187 and Vero cells. The result showed that compounds 1 and 7 exhibited moderate activity against Mycobacterium tuberculosis and compounds 4, 6 and 7 displayed remarkable cytotoxic activity. This is the first report on the presence of all compounds in H. ellipticum and the first time that their structure activity relationship has been discussed.

Diterpenoids of terrestrial origin

This review covers the isolation and chemistry of diterpenoids from terrestrial as opposed to marine sources and includes labdanes, clerodanes, pimaranes, abietanes, kauranes, cembranes and their cyclization products. The literature from January to December, 2015 is reviewed.