A novel 15-spiro diterpenoid dimer from Andrographis paniculata with inhibitory potential against human carboxylesterase 2

Tight-Binding Small-Molecule Carboxylesterase 2 Inhibitors Reduce Intracellular Irinotecan Activation

As the primary enzyme responsible for the activatable conversion of Irinotecan (CPT-11) to SN-38, carboxylesterase 2 (CES2) is a significant predictive biomarker toward CPT-11-based treatments for pancreatic ductal adenocarcinoma (PDAC). High SN-38 levels from high CES2 activity lead to harmful effects, including life-threatening diarrhea. While alternate strategies have been explored, CES2 inhibition presents an effective strategy to directly alter the pharmacokinetics of CPT-11 conversion, ultimately controlling the amount of SN-38 produced. To address this, we conducted a high-throughput screening to discover 18 small-molecule CES2 inhibitors. The inhibitors are validated by dose-response and counter-screening and 16 of these inhibitors demonstrate selectivity for CES2. These 16 inhibitors inhibit CES2 in cells, indicating cell permeability, and they show inhibition of CPT-11 conversion with the purified enzyme. The top five inhibitors prohibited cell death mediated by CPT-11 when preincubated in PDAC cells. Three of these inhibitors displayed a tight-binding mechanism of action with a strong binding affinity.

An improved strategy for identification and annotation of easily in-sourced dissociation diterpene lactones from plant natural products: Taking Andrographis paniculata (Burm. f.) as an example

RATIONALE

Diterpene lactones (DL) in Andrographis paniculata (AP) are known as "natural antibiotics" for their excellent antibacterial activity. During mass spectrometry (MS) analysis, the hydroxyl groups in the AP DL skeleton are prone to neutral loss of H₂ O, producing high in-source fragment peaks and affecting the characterization of these components.

METHODS

Mass tags were applied during the MS data acquisition step, and special adduct ion form was used to guide the data processing and characterization steps. Besides, the total number of characterized AP DLs significantly increased when combining the number of neutrally lost H₂ O from AP DLs, incorporating information on the diagnostic ions, and adopting molecular networks generated with the Global Natural Products Social Molecular Networking database.

RESULTS

Ninety-nine DLs, comprising 6 monohydroxyl groups, 20 dihydroxyl groups, 27 trihydroxy groups, and 46 DLs with more than 3 hydroxyl groups, were characterized from AP. In addition, based on the characteristic fragments in the product ions (C₃ H₄ , Δm/z = 40.03 Da), it could be assumed that 90 DLs had the C19-OH structure among the identified DLs. The current study provides a new approach for collecting, processing, and characterizing MS analysis of natural DLs prone to in-source fragmentation.

CONCLUSIONS

MS characterization of AP DLs was significantly improved, and many potential new compounds were identified in AP. This characterization provides new methods for the purification and identification of AP DLs.

Biogenetic and biomimetic synthesis of natural bisditerpenoids: hypothesis and practices

Covering: up to March 2022Bisditerpenoids, or diterpenoid dimers, are a group of natural products with high structural variance, deriving from homo- or hetero-dimeric coupling of two diterpenoid units. They usually possess complex architectures resulting from the diversity of monomeric diterpenoids as building blocks and the dimerization processes. These compounds have attracted the attention of synthetic and biological scientists owing to the rarity of their natural origin and their significant biological activities. Herein, we provide a review highlighting some of the interesting bisditerpenoids reported since 1961 and showcase the chemical diversity in both their structures and biosynthesis, as well as their biological functions. This review focuses on the biosynthetic dimerization pathways of interesting molecules and their biomimetic synthesis, which may act as useful inspiration for the discovery and synthesis of more bisditerpenoids and further pharmacological investigations.

A Comprehensive Review of Andrographis paniculata (Burm. f.) Nees and Its Constituents as Potential Lead Compounds for COVID-19 Drug Discovery

The COVID-19 pandemic has intensively disrupted global health, economics, and well-being. Andrographis paniculata (Burm. f.) Nees has been used as a complementary treatment for COVID-19 in several Asian countries. This review aimed to summarize the information available regarding A. paniculata and its constituents, to provide critical points relating to its pharmacological properties, safety, and efficacy, revealing its potential to serve as a source of lead compounds for COVID-19 drug discovery. A. paniculata and its active compounds possess favorable antiviral, anti-inflammatory, immunomodulatory, and antipyretic activities that could be beneficial for COVID-19 treatment. Interestingly, recent in silico and in vitro studies have revealed that the active ingredients in A. paniculata showed promising activities against 3CLpro and its virus-specific target protein, human hACE2 protein; they also inhibit infectious virion production. Moreover, existing publications regarding randomized controlled trials demonstrated that the use of A. paniculata alone or in combination was superior to the placebo in reducing the severity of upper respiratory tract infection (URTI) manifestations, especially as part of early treatment, without serious side effects. Taken together, its chemical and biological properties, especially its antiviral activities against SARS-CoV-2, clinical trials on URTI, and the safety of A. paniculata, as discussed in this review, support the argument that A. paniculata is a promising natural source for drug discovery regarding COVID-19 post-infectious treatment, rather than prophylaxis.

Bisfischoids A and B, dimeric ent-abietane-type diterpenoids with anti-inflammatory potential from Euphorbia fischeriana Steud

Two undescribed ent-abietane-type diterpenoid dimers with nonacyclic backbone formed by intermolecular [4 + 2] cycloaddition into a spirocyclic skeleton, bisfischoids A (1) and B (2), along with a known one fischdiabietane A (3), were identified from Euphorbia fischeriana Steud. Their structures were elucidated by extensive spectroscopic analysis, ECD and NMR calculation combined with DP4+ probability analysis, as well as X-ray diffraction. The anti-inflammatory potential of dimers 1-3 were examined using their inhibitory effects on soluble epoxide hydrolase (sEH), which revealed that 1 and 2 exhibited promising activities with inhibition constant (Ki) of 3.20 and 1.95 μM, respectively. Further studies of molecular docking and molecular dynamics indicated that amino acid residue Tyr343 in the catalytic cavity of sEH was the key site for their inhibitory function.

Andrographis paniculata (Burm.f.) Nees: Traditional uses, phytochemistry, pharmacological properties and quality control/quality assurance

ETHNOPHARMACOLOGICAL RELEVANCE

Andrographis paniculata (Burm.f.) Nees is a medicinal herb of the Asian countries used in many traditional medicinal systems for the treatment of diarrhea, flu, leprosy, leptospirosis, malaria, rabies, upper respiratory infections, sinusitis, syphilis, tuberculosis and HIV/AIDS etc. AIM OF THE STUDY: This review aims to provide the comprehensive, accurate and authentic information on traditional uses, phytochemistry and pharmacological properties of various extracts/fractions as well as phytocostituents of A. paniculata. In addition, this review also aims to provide advance and sensitive analytical methods along with chemical markers used in the standardization of herbal products for quality control (QC)/quality assurance (QA).

MATERIALS AND METHODS

All relevant publications were considered within the years 1983-2020. The publications were searched from Google Scholar, PubChem, Chemspider, PubMed, Elsevier, Wiley, Web of Science, China Knowledge Resource Integrated databases and ResearchGate using a combination of various relevant keywords. Besides, relevant published books and chapters were also considered those providing an overview of extant secondary literature related to traditional knowledge, phytochemistry, pharmacology and toxicity of the plant.

RESULTS AND DISCUSSION

In this review, 344 compounds, including, terpenoid lactones, flavonoids, phenolic acids, triterpenes and volatile compounds were summarized out of which more than half of the compounds have no reported pharmacological activities yet. Terpenoid lactones and flavonoids are the major bioactive classes of compounds of A. paniculata which are responsible for pharmacological activities such as anticancer and antioxidant activities, respectively. Biosynthetic pathways and active sites for target proteins of both terpenoid lactones and flavonoids were considered. Analgesic, anticancer, antidiabetic, antifertility, antiinflammatory, antimalarial, antimicrobial, antioxidant, antipyretic, antiviral, antiretroviral, antivenom, cardioprotective, hepatoprotective, immunomodulatory and neuroprotective activities have been also reported. Andrographolide is a major characteristic active principle and responsible for most of the pharmacological activities. Therefore, andrographolide has been selected as a marker for the standardization of raw and marketed herbal products by TLC, HPTLC, HPLC, GC-MS, HPLC-MS and HPLC-MS/MS methods for QC/QA.

CONCLUSIONS

Conclusive evidence showed that the pharmacological activities reported in crude extracts and chemical markers are supporting and provides confidence in the traditional use of A. paniculata as a herbal medicine. The andrographolide could be used as a chemical marker for the QC/QA of raw and A. paniculata derived herbal products. Lactone ring in terpenoid lactone is an active site for targeted proteins. More efforts should be focused on the identification of the chemical markers from A. paniculata to provide a practical basis for QC/QA. Several aspects such as the mechanism of therapeutic potential, molecular docking technology and multi-target network pharmacology are very important for drug discovery and needed more investigation and should be considered. This compilation may be helpful in further study and QC/QA.

Ethnobotany, Pharmacological activities and Bioavailability studies of "King of Bitter" (Kalmegh): A Review (2010-2020)

BACKGROUND

Andrographis paniculata, commonly known as "Kalmegh", is an annual herbaceous plant from family Acanthaceae. The whole plant of A. paniculata has explored for multiple pharmacological activities and is scientifically recognized by in-vivo and in-vitro studies. Various biotechnologically engineered techniques have been explored to enhance the bioavailability of this plant.

OBJECTIVE

In this review, we aim to present comprehensive recent advances in the ethnopharmacology, phytochemistry, specific pharmacology, safety and toxicology and bioavailability of A. paniculata and its pure compounds. Possible directions for future research are also outlined in brief, which will encourage advance investigations on this plant.

METHODS

Information on the recent updates of the present review is collected from different electronic scientific databases such as Science Direct, PubMed, Scopus, and Google Scholar. All the composed information is classified into different sections according to the objective of the paper.

RESULTS

More than hundred research and review papers have been studied and incorporated in the present manuscript. After vast literature search of A. paniculata, we present a noteworthy report of various phytoconstituents present in plant, which are accountable for potential therapeutic properties of the plant. Forty-five of studied articles give general information about introduction, ethnobotany and traditional uses of the plant. Twenty-two papers enclosed information about the phytoconstituents present in different parts of A. paniculata and seventy-two papers briefly outlined the pharmacological activities like antioxidant, anti-dengue, anti-ulcerogenic, antifungal, some miscellaneous activities like activity against SARS-CoV-2, antidiarrhoeal. Nineteen studies highlighted the research work conducted by various researchers to increased bioavailability of A. paniculata and two studies reported the safety and toxicology of the plant.

CONCLUSION

This review incorporated the scientifically validated research work encompassing the ethnobotanical description of the subjected plant, phytochemical profile, various pharmacological activities, and recent approaches to enhance the bioavailability of active metabolites.