Flavanols and Flavanes from Crinum asiaticum and Their Effects on LPS Signaling Pathway Through the Inhibition of NF-κB Activation.

Three new flavanols, (2R,3S)-7-methoxy-flavan-3-ol (1: ), (2R,3S)-7-hydroxy-flavan-3-ol (2: ), and (2R,3S)-2'-hydroxy-7-methoxy-flavan-3-ol (3: ), together with two known flavans (4: and 5: ), were isolated from the chloroform extract of Crinum asiaticum. Their structures were elucidated by various spectroscopic methods, including 1D and 2D NMR, HR-ESI-MS, and CD data. The isolated compounds 1: and 3: -5: showed inhibitory activity toward LPS-induced nitric oxide (NO) production. Further investigation of the NF-κB pathway mechanisms indicated that 1: and 3: -5: inhibited the LPS-induced IL-6 production and p65 subunit phosphorylation of NF-κB in RAW264.7 cells, with an effective dose of 10 µM.

Bioactive Compounds from Medicinal Plants in Myanmar.

Myanmar is a country with rich natural resources and of these, medicinal plants play a vital role in the primary health care of its population. The people of Myanmar have used their own system of traditional medicine inclusive of the use of medicinal plants for 2000 years. However, systematic and scientific studies have only recently begun to be reported. Researchers from Japan, Germany, and Korea have collaborated with researchers in Myanmar on medicinal plants since 2000. During the past two decades, over 50 publications have been published in peer-reviewed journals. Altogether, 433 phytoconstituents, including 147 new and 286 known compounds from 26 plant species consisting of 29 samples native to Myanmar, have been collated. In this contribution, phytochemical and biological investigations of these plants, including information on traditional knowledge are compiled and discussed.

Anti-metastatic effects of ergosterol peroxide from the entomopathogenic fungus Ophiocordyceps gracilioides on 4T1 breast cancer cells.

Ophiocordyceps gracilioides is an entomoparasitic ascomycetes whose bioactivity has not been examined in detail. In this study, we identified the bioactive compounds ergosterol peroxide (EPO) and ergosterol (ERG) from the MeOH extract of O. gracilioides mycelia related to its anti-cancer effects by targeting the Nuclear Factor kappa B (NF-ĸB)/Signal Transducer and Activator of Transcription 3 (STAT3) inflammatory pathways. Using gene-reporter assays, we demonstrated that EPO markedly inhibits both NF-ĸB and STAT3 activity in 4T1 cells, whereas ERG had limited effect. Consistent with their effects on NF-ĸB and STAT3 activity, EPO, but not ERG, exerted anti-proliferative effects on 4T1 cells. Furthermore, EPO significant inhibited both the migration and invasion of 4T1 cells in vitro, and pre-treatment of 4T1 cells with EPO significantly inhibited the formation of experimental lung metastases in vivo. Collectively, we demonstrated that ERG and EPO can be isolated from O. gracilioides mycelia, and further identified EPO as an active constituent of its anti-metastatic effects through the inhibition of NF-ĸB and STAT3 inflammatory pathways in 4T1 breast cancer cells.

Shanpanootols A-F, diterpenoids from Kaempferia pulchra rhizomes collected in Myanmar and their Vpr inhibitory activities.

Six new isopimarane diterpenoids, shanpanootols A-F (1-6), along with two known analogues, were isolated from the ethyl acetate-soluble extract of Kaempferia pulchra rhizomes collected in Myanmar. The structures of these compounds were elucidated by extensive spectroscopic techniques such as 1D and 2D NMR and HRESIMS. The absolute configuration of 1 was determined by the modified Mosher method. The new isolates (1-6) were tested for their Vpr inhibitory activities against TREx-HeLa-Vpr cells. Shanpanootols C (3) and E (5) inhibited Vpr at doses of 2.5 and 5 µM, respectively.

Antimelanogenic Activity of Ocotillol-Type Saponins from Panax vietnamensis.

The ocotillol (OCT)-type saponins have been known as a tetracyclic triterpenoid, possessing five- or six-membered epoxy ring in the side chain. Interestingly, this type saponin was mostly found in Panax vietnamensis Ha et Grushv., Araliaceae (VG), hence making VG unique from the other Panax spp. Five OCT-type saponins, majonoside R2, vina-ginsenoside R2, majonoside R1, pseudoginsenoside RT4, vina-ginsenoside R11, together with three protopanaxadiol (PPD)-type saponins and four protopanaxatriol (PPT)-type saponins from VG were evaluated for their antimelanogenic activity. All of isolates were found to be active. More importantly, the five OCT-type saponins inhibited melanin production in B16-F10 mouse melanoma cells, without showing any cytotoxicity. Besides ginsenoside Rd and ginsenoside Rg3 in PPD and notoginsenoside R1 in PPT-type saponins, majonoside R2 was the most potent melanogenesis inhibitory activity in OCT-type saponins. In this article, we highlighted antimelanogenic activity of OCT-type saponins and potential structure-activity relationship (SAR) of ginsenosides. Our results suggested that OCT-type saponins could be used as a depigmentation agent.

Anti-inflammatory activities of isopimara-8(9),15-diene diterpenoids and mode of action of kaempulchraols B-D from Kaempferia pulchra rhizomes.

Kaempulchraols B-D (2-4), isopimara-8(9),15-diene diterpenoids isolated from Kaempferia pulchra rhizomes collected in Myanmar, were identified as potent NF-κB inhibitors. These compounds were also effective as NO inhibitory agents, with IC50 values of 47.69, 44.97, and 38.17 µM, respectively, without showing any cytotoxicity against LPS-induced RAW264.7 cells. Investigations of the mechanisms of action of 2-4 revealed that they inhibit the NF-κB-mediated transactivation of a luciferase reporter gene, IL-6 production, and COX-2 expression, with an effective dose of 25 µM. Thus, isopimarane diterpenoids are suggested to be potent inhibitors of NF-κB pathways and could be further explored as potential anti-inflammatory lead compounds.

Anti-melanin deposition activity and active constituents of Jatropha multifida stems.

Jatropha multifida is a medicinal plant that belongs to the Euphorbiaceae family. Our investigation revealed that the chloroform extract of J. multifida stems showed anti-melanin deposition activity against α-melanocyte stimulating hormone (α-MSH)- and 3-isobutyl-1-methylxanthine (IBMX)-induced melanogenesis in the mouse melanoma cell line (B16-F10). Further fractionation and purification of the major constituents led to the isolation of two coumarins (1 and 2) and seven known lignoids (3-9). All isolated compounds exhibited anti-melanin deposition activities against the mouse melanoma cell line (B16-F10) with IC50 values ranging from 37.5 to 560.1 µM, without any cytotoxicity even at high concentrations, except for 8. Further mechanistic studies suggested that 9 downregulated tyrosinase mRNA expression, while the anti-melanin deposition activities of 4 and 8 appeared to be unrelated to tyrosinase inhibition and the downregulated expression of the key melanogenesis-associated mRNAs. These results suggested that J. multifida could possess potent skin whitening ingredients.

Two new quassinoids and other constituents from Picrasma javanica wood, and their biological activities.

Picrasma javanica Blume (Simaroubaceae) is a medium-sized tree that is distributed widely in tropical Asia. In our previous study, we isolated quassinoids from P. javanica bark collected in Myanmar, and reported their antiproliferative activities. In our ongoing research for the discovery of bioactive compounds from Myanmar medicinal plants, two new quassinoids, (16R)-methoxyjavanicin B (1) and (16S)-methoxyjavanicin B (2), along with seven known compounds (3-9), were isolated during the phytochemical investigation of the CHCl3 soluble portion of the MeOH extract of P. javanica wood. The structures of the new compounds were elucidated by analyses of their spectroscopic data (1D- and 2D-NMR, HRESIMS, and CD). A cytotoxicity assay revealed that compound 8 showed moderate activities against all tested cancer cell lines, the human lung (A549), breast (MCF7), and cervical (HeLa), and the normal fibroblast cell line, with IC50 values ranging from 48.6 to 65.9 µM. Furthermore, the antibacterial assay demonstrated that 1 and 2 had the highest activities (MIC value of 1.6 µM each), followed by 5 and 3 (MIC values of 3.1 and 6.3 µM, respectively) against the Gram-positive bacterium B. subtilis.

Bis-iridoid and iridoid glycosides: Viral protein R inhibitors from Picrorhiza kurroa collected in Myanmar.

Four new bis-iridoid glycosides, saungmaygaosides A-D (1-4), and six known iridoid glycosides (5-10) were isolated from the n-butanol extract of the stems of Picrorhiza kurroa collected in Myanmar. Their structures were elucidated by extensive spectroscopic techniques. All of the isolates were assayed for anti-Vpr activity, using TREx-HeLa-Vpr cells. Among the isolates, saungmaygaoside D (4), sylvestroside IV dimethyl acetal (7), and sweroside (8) were the most potent inhibitors with effective doses of 5 and 10 µM, respectively, without showing any notable cytotoxicities.

Dinorcassane Diterpenoid from Boesenbergia rotunda Rhizomes Collected in Lower Myanmar.

A new dinorcassane diterpenoid, seikphoochinal A (1), and four known compounds, pinostrobin (2), 4',7-dimethylkaempferol (3), and galanals A (4) and B (5), were isolated from the chloroform-soluble crude extract of wild type Boesenbergia rotunda rhizomes collected in Lower Myanmar. The chemical structures of these compounds were identified, using a combination of spectroscopic methods. The presence of the diterpenoids 1, 4, and 5 demonstrated the structural diversity of wild type B. rotunda. Among the isolates, compounds 4 and 5 exhibited significant antiproliferative activities against a small panel of human cancer cell lines, including lung (LK-2, A549), stomach (ECC4), breast (MCF7), cervix (HeLa), and prostate (DU145).

Lignans with melanogenesis effects from Premna serratifolia wood.

Three new lignoids, premnan A (1), premnan B (2), and tauntangyiol C (3), were isolated from Premna serratifolia wood, a traditional cosmetic plant in Myanmar, together with a new lignoid, premnan C (4) assumed to be an artifact, one natural new lignoid (5), and three known lignoids (6-8). The structures of the new compounds 1-4 were elucidated based on 1D and 2D NMR, IR spectroscopy, and HRESIMS. The absolute configurations of 1-4 were also determined by optical rotation, circular dichroism (CD) data analyses, and comparisons with the reported literature. All isolated compounds were tested for their melanogenesis activities against the B16-F10 mouse melanoma cell line. Compounds 1 and 4 showed melanogenesis enhancing activities of 31% and 50%, respectively, at a 50 µM concentration. Compounds 2, 3, and 6 increased melanin production by 67%, 30%, and 45%, respectively, at a 100 µM concentration, without any cytotoxicity.

Tetrahydrofuran lignans: Melanogenesis inhibitors from Premna integrifolia wood collected in Myanmar.

Two new tetrahydrofuran lignans, taungtangyiols A (1) and B (2), and eight known furofuran lignans (3-10), were isolated from the chloroform extract of Premna integrifolia wood collected in Myanmar. Their structures were elucidated by extensive spectroscopic techniques. The X-ray crystal structure of 1 clearly indicated its relative configuration. Taungtangyiols A (1) and B (2) inhibited the deposition of melanin in B16F10 mouse melanoma cells, with IC50 values of 50.7 and 40.9 µM, respectively, without notable cytotoxicity. An SAR study demonstrated that the furofuran and dioxymethylene moieties of the lignans play a vital role in inhibiting melanogenesis.

Two new pyrrolo-2-aminoimidazoles from a Myanmarese marine sponge, Clathria prolifera.

Marine organisms such as marine sponges and soft corals are valuable sources of pharmacologically active secondary metabolites. In our ongoing research on the discovery of new secondary metabolites from marine organisms, two new pyrrolo-2-aminoimidazoles, clathriroles A (1) and B (2), were isolated from the water-soluble portion prepared from the methanol and acetone (2:1) extract of the marine sponge, Clathria prolifera, collected in Myanmar. The chemical structures of the isolated compounds were determined using extensive spectroscopic techniques, including NMR, HRESIMS, IR, and optical rotation, and comparisons with the reported literature. The spectroscopic analyses of 1 and 2 suggested that 1 is an enantiomer of antifungal N-methylmanzacidin C isolated from the marine sponge Axinella brevistyla, whereas 2 is a diastereomer of manzacidin D at C-11 isolated from the marine sponge Astrosclera willeyana. To the best of our knowledge, this is the first report of the isolation of the pyrrolo-2-aminoimidazole compounds from C. prolifera. Furthermore, in contrast to the potency of N-methylmanzacidin C against Saccharomyces cerevisiae, the antifungal assay revealed that 1 and 2 lack any activity against this strain. Thus, these observations may suggest that the absolute configurations at both C-9 and C-11 play an important role in controlling the antifungal activity of this type of compound.

Three new sesquiterpene aminoquinones from a Vietnamese Spongia sp. and their biological activities.

Sesquiterpenoid quinones with remarkable properties, such as anti-inflammatory, antibacterial, antiviral, antitumor, antiangiogenic, and differentiation-inducing activities, have reportedly been isolated from the marine sponge genera Dysidea, Spongia, and Dactylospongia. In our continuing search for bioactive compounds from marine sponges, three new sesquiterpenoid quinones, langcoquinones D-F (1-3), were isolated from the ethyl acetate extract of Spongia sp. collected from Vietnam. Their chemical structures were elucidated on the basis of extensive spectroscopic analyses. The newly isolated compounds 1-3 were assessed for their antibacterial activities against Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, and Gram-negative bacteria, Klebsiella pneumoniae and Escherichia coli, as well as their cytotoxic activities against three human cancer cell lines (A549, lung cancer; MCF7, breast cancer; HeLa, cervical cancer) and a human normal cell line (WI-38 fibroblast). All compounds were inactive against the Gram-negative bacteria. Furthermore, langcoquinones E (2) and F (3) lacked antibacterial activities against the Gram-positive bacteria and cytotoxic activities against the tested cell lines. However, langcoquinone D (1) exhibited good antibacterial activities against Bacillus subtilis and Staphylococcus aureus, with MIC values of 12.5 and 25.0 µM, respectively. Furthermore, 1 exhibited significant cytotoxic activities against three human cancer cell lines (A549, lung cancer; MCF7, breast cancer; HeLa, cervical cancer) and a human normal cell line (WI-38 fibroblast).

Labdane diterpenoids from Curcuma amada rhizomes collected in Myanmar and their antiproliferative activities.

Four new labdane diterpenoids, 12ß-hydroxy-15-norlabda-8(17),13(14)-dien-16-oic acid (1), (E)-15-ethoxy-15-methoxylabda-8(17),12-dien-16-al (2), (E)-15α-ethoxy-14α-hydroxylabda-8(17),12-dien-16-olide (3), and 15-ethoxy-12ß-hydroxylabda-8(17),13(14)-dien-16,15-olide (4) were isolated from the methanol extract of Curcuma amada rhizomes collected in Myanmar, together with 13 known analogs. Their structures were elucidated by extensive spectroscopic techniques. All of the isolates were evaluated for their antiproliferative activities against a small panel of five different human cancer cell lines (A549, human lung cancer; HeLa, human cervical cancer; MCF7, human breast cancer; PANC-1 and PSN-1, human pancreatic cancer). Among the isolates, compounds 2-4, 7, 8, 12, and 17 showed mild antiproliferative activities with IC50 values ranging from 19.7 to 96.1µM. (E)-14-Hydroxy-15-norlabda-8(17),12-dien-16-al (11) exhibited strong antiproliferative activities selectively against HeLa, PANC-1, and PSN-1 cells, with IC50 values of 5.88, 1.00, and 3.98µM, respectively. These potencies were comparable to those of the positive control, 5-fluorouracil.

Naturally occurring Vpr inhibitors from medicinal plants of Myanmar.

Human immunodeficiency virus type-1 (HIV-1) is a lentiviral family member that encodes the retroviral Gag, Pol, and Env proteins, along with six additional accessory proteins, Tat, Rev, Vpu, Vif, Nef, and Vpr. The currently approved anti-HIV drugs target the Pol and Env encoded proteins. However, these drugs are only effective in reducing viral replication. Furthermore, the drugs' toxicities and the emergence of drug-resistant strains have become serious worldwide problems. Resistance eventually arises to all of the approved anti-HIV drugs, including the newly approved drugs that target HIV integrase (IN). Drug resistance likely emerges because of spontaneous mutations that occur during viral replication. Therefore, new drugs that effectively block other viral components must be developed to reduce the rate of resistance and suppress viral replication with little or no long-term toxicity. The accessory proteins may expand treatment options. Viral protein R (Vpr) is one of the promising drug targets among the HIV accessory proteins. However, the search for inhibitors continues in anti-HIV drug discovery. In this review, we summarize the naturally occurring compounds discovered from two Myanmar medicinal plants as well as their structure-activity relationships. A total of 49 secondary metabolites were isolated from Kaempferia pulchra rhizomes and Picrasama javanica bark, and the types of compounds were identified as isopimarane diterpenoids and picrasane quassinoids, respectively. Among the isolates, 7 diterpenoids and 15 quassinoids were found to be Vpr inhibitors lacking detectable toxicity, and their potencies varied according to their respective functionalities.

Anti-influenza virus activity of extracts from the stems of Jatropha multifida Linn. collected in Myanmar.

BACKGROUND: To contribute to the development of novel anti-influenza drugs, we investigated the anti-influenza activity of crude extracts from 118 medicinal plants collected in Myanmar. We discovered that extract from the stems of Jatropha multifida Linn. showed anti-influenza activity. J. multifida has been used in traditional medicine for the treatment of various diseases, and the stem has been reported to possess antimicrobial, antimalarial, and antitumor activities. However, the anti-influenza activity of this extract has not yet been investigated. METHODS: We prepared water (H2O), ethyl acetate (EtOAc), n-hexane (Hex), and chloroform (CHCl3) extracts from the stems of J. multifida collected in Myanmar, and examined the survival of Madin-Darby canine kidney (MDCK) cells infected with the influenza A (H1N1) virus, and the inhibitory effects of these crude extracts on influenza A viral infection and growth in MDCK cells. RESULTS: The H2O extracts from the stems of J. multifida promoted the survival of MDCK cells infected with the influenza A H1N1 virus. The EtOAc and CHCl3 extracts resulted in similar, but weaker, effects. The H2O, EtOAc, and CHCl3 extracts from the stems of J. multifida inhibited influenza A virus H1N1 infection; the H2O extract possessed the strongest inhibitory effect on influenza infection in MDCK cells. The EtOAc, Hex, and CHCl3 extracts all inhibited the growth of influenza A H1N1 virus, and the CHCl3 extract demonstrated the strongest activity in MDCK cells. CONCLUSION: The H2O or CHCl3 extracts from the stems of J. multifida collected in Myanmar demonstrated the strongest inhibition of influenza A H1N1 viral infection or growth in MDCK cells, respectively. These results indicated that the stems of J. multifida could be regarded as an anti-influenza herbal medicine as well as a potential crude drug source for the development of anti-influenza compounds.

Isopimarane diterpenoids from Kaempferia pulchra rhizomes collected in Myanmar and their Vpr inhibitory activity.

Viral protein R (Vpr), an accessory gene of HIV-1, plays important roles in viral pathogenesis. Screening of Myanmar medicinal plants that are popular as primary treatments for HIV/AIDS and for HIV-related problems revealed the potent anti-Vpr activity of the CHCl3-soluble extract of Kaempferia pulchra rhizomes, in comparison with that of the positive control, damnacanthal. Fractionation of the active CHCl3-soluble extract led to the identification of 30 isopimarane diterpenoids, including kaempulchraols A-W (1-23). All isolates were assayed for anti-Vpr activity against TREx-HeLa-Vpr cells, in which Vpr expression is tightly regulated by tetracycline. Kaempulchraols B (2), D (4), G (7), Q (17), T (20), U (21), and W (23) exhibited potent anti-Vpr activity, at concentrations ranging from 1.56 to 6.25µM. The structure-activity relationships of the active kaempulchraols suggested that the presence of a hydroxy group at C-14 in an isopimara-8(9),15-diene skeleton and the presence of an acetoxy group at C-1 or C-7 in an isopimara-8(14),15-diene skeleton are the critical factors for the inhibitory effects against TREx-HeLa-Vpr cells.

Novel anticancer agents, kayeassamins C-I from the flower of Kayea assamica of Myanmar.

A CHCl3-soluble fraction of 70% EtOH extract of the flower of Kayea assamica from Myanmar exhibited 100% preferential cytotoxicity (PC(100)) against human pancreatic cancer PANC-1 cells under nutrient-deprived conditions at 1 microg/mL. Bioassay-guided fractionation and isolation afforded nine new coumarins, kayeassamins A (8), B (9), and C-I (1-7), together with nine known coumarins (10-18). The structures of these compounds were identified by extensive spectroscopic techniques as well as by comparison with published data. Absolute configuration at C-1' of 1 was established as S-configuration by the modified Mosher method. All the isolates were evaluated for their in vitro preferential cytotoxicity using novel anti-austerity strategy. Among them, the novel coumarins, kayeassamins A (8), B (9), D (2), E (3), and G (5) exhibited the most potent preferential cytotoxicity (PC(100) 1 microM) in a concentration- and time-dependent manner and induced apoptosis-like morphological changes of PANC-1 cells within 24 h of treatment. Based on the observed cytotoxicity, structure-activity relationships have been established.