α-Bulnesene, a novel PAF receptor antagonist isolated from Pogostemon cablin

Active Site Loop Engineering Abolishes Water Capture in Hydroxylating Sesquiterpene Synthases

Terpene synthases (TS) catalyze complex reactions to produce a diverse array of terpene skeletons from linear isoprenyl diphosphates. Patchoulol synthase (PTS) from Pogostemon cablin converts farnesyl diphosphate into patchoulol. Using simulation-guided engineering, we obtained PTS variants that eliminate water capture. Further, we demonstrate that modifying the structurally conserved Hα-1 loop also reduces hydroxylation in PTS, as well as in germacradiene-11-ol synthase (Gd11olS), leading to cyclic neutral intermediates as products, including α-bulnesene (PTS) and isolepidozene (Gd11olS). Hα-1 loop modification could be a general strategy for engineering sesquiterpene synthases to produce complex cyclic hydrocarbons without the need for structure determination or modeling.

SMRT sequencing of full-length transcriptome and gene expression analysis in two chemical types of Pogostemon cablin (Blanco) Benth

BACKGROUND

Pogostemon cablin (Blanco) Benth. also called patchouli, is a traditional medicinal and aromatic plant that grows mainly in Southeast Asia and China. In China, P. cablin is divided into two chemical types: the patchouliol-type and the pogostone-type. Patchouliol-type patchouli usually grow taller, with thicker stems and bigger leaves, and produce more aromatic oil.

METHODS

To better understand the genetic differences between the two chemical types that contribute to their differences in morphology and biosynthetic capabilities, we constructed de novo transcriptomes from both chemical types using the Pacific Biosciences (PacBio) Sequel platform and performed differential expression analysis of multiple tissues using Illumina short reads.

RESULTS

In this study, using single-molecule real-time (SMRT) long-read sequencing, we obtained 22.07 GB of clean data and 134,647 nonredundant transcripts from two chemical types. Additionally, we identified 126,576 open reading frames (ORFs), 100,638 coding sequences (CDSs), 4,106 long noncoding RNAs (lncRNAs) and 6,829 transcription factors (TFs) from two chemical types of P. cablin. We adopted PacBio and Illumina sequencing to identify differentially expressed transcripts (DEGs) in three tissues of the two chemical types. More DEGs were observed in comparisons of different tissues collected from the same chemical type relative to comparisons of the same tissue collected from different chemical types. Furthormore, using KEGG enrichment analysis of DEGs, we found that the most enriched biosynthetic pathways of secondary metabolites of the two chemical types were "terpenoid backbone biosynthesis", "phenylpropanoid biosynthesis", "plant hormone signal transduction", "sesquiterpenoid and triterpenoid biosynthesis", "ubiquinone and other terpenoid-quinone biosynthesis", "flavonoid biosynthesis", and "flavone and flavonol biosynthesis". However, the main pathways of the patchouliol-type also included "diterpene biosynthesis" and "monoterpene biosynthesis". Additionally, by comparing the expression levels of the three tissues verified by qRT-PCR, more DEGs in the roots were upregulated in the mevalonate (MVA) pathway in the cytoplasm, but more DEGs in the leaves were upregulated in the methylerythritol phosphate (MEP) pathway in the plastid, both of which are important pathways for terpenoids biosynthesis. These findings promote the study of further genome annotation and transcriptome research in P. cablin.

Medicinal Properties and In Vitro Biological Activities of Selected Helichrysum Species from South Africa: A Review

The genus Helichrysum Mill comprises hundreds of species that are mostly flowering perennial shrubs. Some of these plants that belong to the Helichrysum species are used in traditional medicine to treat cough, back pain, diabetes, asthma, digestive problems, menstrual pain, chest pain, kidney disorders, skin disorders, wounds, open sores, among other conditions, but, only a few scientific studies are reported in the literature with sufficient information that validates the acclaimed folkloric benefits of these plants. This review, therefore, provides a comprehensive update of the available information on the cytotoxicity, genotoxicity, anti-proliferative, anti-bacterial, anti-fungal, anti-viral, anti-HIV, anti-malarial, anti-ulcerogenic, anti-tyrosinase, anti-inflammatory, and anti-oxidant activities of selected Helichrysum species of interest: H. petiolare, H. cymocum, H. foetidum, and H. pandurifolium Schrank, using scientific databases as well as electronic and print sources. The ethnobotanical and morphological characteristics as well as the phytochemical composition and biological activities of these plants are elucidated. The scientific rationale for their current use is discussed based on the evidence in the literature. This review highlights the putative use of the Helichrysum species as a reliable source of bioactive compounds for the production of standard commercial drugs to treat many ailments, including those reported in folkloric uses. Further research on the many plants in the genus Helichrysum is recommended to explore their economic importance both as edible crops and medicinal botanicals.

A Review on Platelet Activating Factor Inhibitors: Could a New Class of Potent Metal-Based Anti-Inflammatory Drugs Induce Anticancer Properties?

In this minireview, we refer to recent results as far as the Platelet Activating Factor (PAF) inhibitors are concerned. At first, results of organic compounds (natural and synthetic ones and specific and nonspecific) as inhibitors of PAF are reported. Emphasis is given on recent results about a new class of the so-called metal-based inhibitors of PAF. A small library of 30 metal complexes has been thus created; their anti-inflammatory activity has been further evaluated owing to their inhibitory effect against PAF in washed rabbit platelets (WRPs). In addition, emphasis has also been placed on the identification of preliminary structure-activity relationships for the different classes of metal-based inhibitors.

Chemical composition, antioxidant, antitumor, anticancer and cytotoxic effects of Psidium guajava leaf extracts

Context Psidium guajava L. (Myrtaceae) leaves are used in traditional medicines for the treatment of cancer, inflammation and other ailments. Objective The current study explores scientific validation for this traditional medication. Materials and methods We used ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picryl hydrazil (DPPH) assays to estimate antioxidant activity of P. guajava leaf extracts (methanol, hexane and chloroform). Antitumour and in vivo cytotoxic activities were determined using potato disc assay (PDA) and brine shrimp lethality assay, respectively. Three human carcinoma cell lines (KBM5, SCC4 and U266) were incubated with different doses (10-100 μg/mL) of extracts and the anticancer activity was estimated by MTT assay. NF-κB suppressing activity was determined using electrophoretic mobility shift assay (EMSA). Chemical composition of the three extracts was identified by GC-MS. Total phenolic and flavonoid contents were measured by colorimetric assays. Results and discussions The order of antioxidant activity of three extracts was methanol > chloroform > hexane. The IC50 values ranged from 22.73 to 51.65 μg/mL for KBM5; 22.82 to 70.25 μg/mL for SCC4 and 20.97 to 89.55 μg/mL for U266 cells. The hexane extract exhibited potent antitumour (IC50  value = 65.02 μg/mL) and cytotoxic (LC50  value = 32.18 μg/mL) activities. This extract also completely inhibited the TNF-α induced NF-κB activation in KBM5 cells. GC-MS results showed that pyrogallol, palmitic acid and vitamin E were the major components of methanol, chloroform and hexane extracts. We observed significant (p < 0.05) difference in total phenolic and flavonoid contents of different solvent extracts. Conclusion The present study demonstrates that P. guajava leaf extracts play a substantial role against cancer and down-modulate inflammatory nuclear factor kB.

The Complete Chloroplast Genome Sequences of the Medicinal Plant Pogostemon cablin

Pogostemon cablin, the natural source of patchouli alcohol, is an important herb in the Lamiaceae family. Here, we present the entire chloroplast genome of P. cablin. This genome, with 38.24% GC content, is 152,460 bp in length. The genome presents a typical quadripartite structure with two inverted repeats (each 25,417 bp in length), separated by one small and one large single-copy region (17,652 and 83,974 bp in length, respectively). The chloroplast genome encodes 127 genes, of which 107 genes are single-copy, including 79 protein-coding genes, four rRNA genes, and 24 tRNA genes. The genome structure, GC content, and codon usage of this chloroplast genome are similar to those of other species in the family, except that it encodes less protein-coding genes and tRNA genes. Phylogenetic analysis reveals that P. cablin diverged from the Scutellarioideae clade about 29.45 million years ago (Mya). Furthermore, most of the simple sequence repeats (SSRs) are short polyadenine or polythymine repeats that contribute to high AT content in the chloroplast genome. Complete sequences and annotation of P. cablin chloroplast genome will facilitate phylogenic, population and genetic engineering research investigations involving this particular species.

Anti-allergic and anti-inflammatory effects of aqueous extract of Pogostemon cablin

Allergic disease is caused by exposure to normally innocuous substances that activate mast cells. Mast cell-mediated allergic inflammation is closely related to a number of allergic disorders, such as anaphylaxis, allergic rhinitis, asthma and atopic dermatitis. The discovery of drugs for treating allergic disease is an interesting subject and important to human health. The aim of the present study was to investigate the anti‑allergic and anti-inflammatory effects of the aqueous extract of Pogostemon cablin (Blanco) Benth (AEPC) (a member of the Labiatae family) using mast cells, and also to determine its possible mechanisms of action. An intraperitoneal injection of compound 48/80 or a serial injection of immunoglobulin E and antigen was used to induce anaphylaxis in mice. We found that AEPC inhibited compound 48/80‑induced systemic and immunoglobulin E-mediated cutaneous anaphylaxis in a dose-dependent manner. The release of histamine from mast cells was reduced by AEPC, and this suppressive effect was associated with the regulation of calcium influx. In addition, AEPC attenuated the phorbol 12-myristate 13-acetate plus calcium ionophore A23187 (PMACI)-stimulated expression of pro-inflammatory cytokines in mast cells. The inhibitory effects of AEPC on pro-inflammatory cytokines were dependent on the activation of nuclear factor (NF)-κB and p38 mitogen-activated protein kinase (MAPK). AEPC blocked the PMACI-induced translocation of NF-κB into the nucleus by hindering the degradation of IκBα and the phosphorylation of p38 MAPK. Our results thus indicate that AEPC inhibits mast cell‑mediated allergic inflammation by suppressing mast cell degranulation and the expression of pro-inflammatory cytokines caused by reduced intracellular calcium levels and the activation of NF-κB and p38 MAPK.

A Comprehensive Review on the Phytochemical Constituents and Pharmacological Activities of Pogostemon cablin Benth.: An Aromatic Medicinal Plant of Industrial Importance

Pogostemon cablin Benth. (patchouli) is an important herb which possesses many therapeutic properties and is widely used in the fragrance industries. In traditional medicinal practices, it is used to treat colds, headaches, fever, nausea, vomiting, diarrhea, abdominal pain, insect and snake bites. In aromatherapy, patchouli oil is used to relieve depression, stress, calm nerves, control appetite and to improve sexual interest. Till now more than 140 compounds, including terpenoids, phytosterols, flavonoids, organic acids, lignins, alkaloids, glycosides, alcohols, aldehydes have been isolated and identified from patchouli. The main phytochemical compounds are patchouli alcohol, α-patchoulene, β-patchoulene, α-bulnesene, seychellene, norpatchoulenol, pogostone, eugenol and pogostol. Modern studies have revealed several biological activities such as antioxidant, analgesic, anti-inflammatory, antiplatelet, antithrombotic, aphrodisiac, antidepressant, antimutagenic, antiemetic, fibrinolytic and cytotoxic activities. However, some of the traditional uses need to be verified and may require standardizing and authenticating the bioactivity of purified compounds through scientific methods. The aim of the present review is to provide comprehensive knowledge on the phytochemistry and pharmacological activities of essential oil and different plant extracts of patchouli based on the available scientific literature. This information will provide a potential guide in exploring the use of main active compounds of patchouli in various medical fields.

Lignans from the aerial parts of Saururus chinensis: isolation, structural characterization, and their effects on platelet aggregation

Five new diaryldimethylbutane lignans, saurulignans A-E (1-5), four new tetrahydrofuran lignans, saurufurins A-D (6-9), and one arylnaphthalene lignan, saurunarin (10), were isolated from Saururus chinensis, along with 18 known compounds. Lignan 5 showed significant inhibition of ADP-induced aggregation with an IC50 value of 9.8 μM and AA-induced aggregation with an IC50 value of 14.0 μM. Compound 19 showed significant activity to inhibit PAF-induced aggregation with an IC50 value of 9.1 μM. In addition, five isolated compounds could induce platelet aggregation. These results suggest that secondary metabolites in S. chinensis have bidirectional regulation on blood clotting and anticlotting effects.

Four new sesquiterpenes from the stems of Pogostemon cablin

Four new sesquiterpenes (1-4), together with four known compounds (5-8), were isolated from the stems of Pogostemon cablin (Blanco.) Benth. Their chemical structures were elucidated by means of spectroscopic methods, including 1D and 2D NMR, HRESIMS, IR, and UV. Hepatoprotective activities of these compounds were investigated, by studying the protective effect on HL-7702 cellular injury induced by dl-galactosamine.

Platelet-activating factor (PAF)-antagonists of natural origin

Presently herbal medicines are being used by about 80% of the world population for primary health care as they stood the test of time for their safety, efficacy, cultural acceptability and lesser side effects. The discovery of platelet activating factor antagonists (PAF antagonists) during these decades are going on with different framework, but the researchers led their efficiency in studying in vitro test models. Since it is assumed that PAF play a central role in etiology of many diseases in humans such as asthma, neuronal damage, migraine, cardiac diseases, inflammatory, headache etc. Present days instinctively occurring PAF antagonist exists as a specific grade of therapeutic agents for the humans against these and different diseases either laid hold of immunological or non-immunological types. Ginkgolide, cedrol and many other natural PAF antagonists such as andrographolide, α-bulnesene, cinchonine, piperine, kadsurenone, different Piper species' natural products and marine origin plants extracts or even crude drugs having PAF antagonist properties are being used currently against different inflammatory pathologies. This review is an attempt to summarize the data on PAF and action of natural PAF antagonists on it, which were evaluated by in vivo and in vitro assays.

Analgesic and Anti-Inflammatory Activities of the Methanol Extract from Pogostemon cablin

Pogostemon cablin (PC) is a herbal medicine traditionally applied to treat not only common cold, nausea and diarrhea but also headache and fever. The aim of this study was to investigate the analgesic and anti-inflammatory properties of standardized PC methanol extract (PCMeOH) in vivo. Investigations were performed in mice with two analgesic models. One was acetic acid-induced writhing response and the other formalin-induced paw licking. The anti-inflammatory effect was tested by λ-carrageenan (Carr)-induced mice paw edema. These analgesic experimental results indicated that PCMeOH (1.0 g/kg) decreased the acetic acid-induced writhing responses and PCMeOH (0.5 and 1.0 g/kg) decreased the licking time in the second phase of the formalin test. Moreover, Carr-induced paw edema inflammation was significantly reduced in a dose-dependent manner when PCMeOH (0.5 and 1.0 g/kg) was administered 3 and 4 h after the Carr injection. Mechanistic studies showed that PCMeOH decreased the levels of malondialdehyde in the edema paw by increasing the activities of anti-oxidant enzymes, such as superoxide dismutase, glutathione peroxidase and glutathione reductase, in the liver and decreasing the cyclooxygenase 2 and tumor necrosis factor-α activities in the edema paw. This study has demonstrated the analgesic and anti-inflammatory effects of PCMeOH, thus verifying its popular use in traditional medicine.

Pogostemon cablin as ROS Scavenger in Oxidant-induced Cell Death of Human Neuroglioma Cells

Reactive oxygen species (ROS) have been implicated in the pathogenesis of a wide range of acute and long-term neurodegenerative diseases. This study was undertaken to examine the efficacy of Pogostemon cablin, a well-known herb in Korean traditional medicine, on ROS-induced brain cell injury. Pogostemon cablin effectively protected human neuroglioma cell line A172 against both the necrotic and apoptotic cell death induced by hydrogen peroxide (H₂O₂). The effect of Pogostemon cablin was dose dependent at concentrations ranging from 0.2 to 5 mg ml⁻¹. Pogostemon cablin significantly prevented depletion of cellular ATP and activation of poly ADP-ribose polymerase induced by H₂O₂. The preservation of functional integrity of mitochondria upon the treatment of Pogostemon cablin was also confirmed by 3-(4,5-dimethyl-2-thiazyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Furthermore, Pogostemon cablin significantly prevented H₂O₂-induced release of cytochrome c into cytosol. Determination of intracellular ROS showed that Pogostemon cablin might exert its role as a powerful scavenger of intracellular ROS. The present study suggests the beneficial effect of Pogostemon cablin on ROS-induced neuroglial cell injury. The action of Pogostemon cablin as a ROS-scavenger might underlie the mechanism.

Isolation and identification of antiplatelet aggregatory principles from the leaves of Piper lolot

The methanolic extract of Piper lolot, having shown potent inhibitory activity on platelet aggregation induced by arachidonic acid (AA) and platelet activating factor (PAF), was subjected to activity-guided isolation to yield twelve new amide alkaloids, piperlotine A-L (1-12), along with twenty-nine known compounds. Their structures were elucidated on the basis of spectroscopic analysis. The isolated compounds were tested for their inhibitory activity on the rabbit platelet aggregation. The compounds piperlotine A (1), piperlotine C (3), piperlotine D (4), piperlotine E (5), 3-phenyl-1-(2,4,6-trihydroxyphenyl)propan-1-one (21), 3-(4-methoxyphenyl)-1-(2,4,6-trihydroxyphenyl)propan-1-one (22), 1-trans-cinnamoylpyrrolidine (24), sarmentine (26), pellitorine (27), methyl 3-phenylpropionate (32), and (10S)-10-hydroxypheophorbide a methyl ester (40) showed potent antiplatelet aggregation activity.