Cuc Phuong National Park
Cuc Phuong National Park
Zhang H.-J.,Hong Kong Baptist University |
Rumschlag-Booms E.,University of Illinois at Chicago |
Guan Y.-F.,Hong Kong Baptist University |
Wang D.-Y.,Hong Kong Baptist University |
And 7 more authors.
Journal of Natural Products | Year: 2017
Justicia gendarussa, a medicinal plant collected in Vietnam, was identified as a potent anti-HIV-1 active lead from the evaluation of over 4500 plant extracts. Bioassay-guided separation of the extracts of the stems and roots of this plant led to the isolation of an anti-HIV arylnaphthalene lignan (ANL) glycoside, patentiflorin A (1). Evaluation of the compound against both the M-and T-Tropic HIV-1 isolates showed it to possess a significantly higher inhibition effect than the clinically used anti-HIV drug AZT. Patentiflorin A and two congeners were synthesized, de novo, as an efficient strategy for resupply as well as for further structural modification of the anti-HIV ANL glycosides in the search for drug leads. Subsequently, it was determined that the presence of a quinovopyranosyloxy group in the structure is likely essential to retain the high degree of anti-HIV activity of this type of compounds. Patentiflorin A was further investigated against the HIV-1 gene expression of the R/U5 and U5/gag transcripts, and the data showed that the compound acts as a potential inhibitor of HIV-1 reverse transcription. Importantly, the compound displayed potent inhibitory activity against drug-resistant HIV-1 isolates of both the nucleotide analogue (AZT) and non-nucleotide analogue (nevaripine). Thus, the ANL glycosides have the potential to be developed as novel anti-HIV drugs. © 2017 The American Chemical Society and American Society of Pharmacognosy.
Gyllenhaal C.,University of Illinois at Chicago |
Kadushin M.R.,University of Illinois at Chicago |
Southavong B.,Institute of Traditional Medicine |
Sydara K.,Institute of Traditional Medicine |
And 22 more authors.
Pharmaceutical Biology | Year: 2012
Context: Whether natural product drug discovery programs should rely on wild plants collected "randomly" from the natural environment, or whether they should also include plants collected on the basis of use in traditional medicine remains an open question. Objective: This study analyzes whether plants with ethnomedical uses from Vietnam and Laos have a higher hit rate in bioassay testing than plants collected from a national park in Vietnam with the goal of maximizing taxonomic diversity ("random" collection). Materials and Methods: All plants were extracted and subjected to bioassay in the same laboratories. Results of assays of plant collections and plant parts (samples) were scored as active or inactive based on whether any extracts had a positive result in a bioassay. Contingency tables were analyzed using χ 2 statistics. Results: Random collections had a higher hit rate than ethnomedical collections, but for samples, ethnomedical plants were more likely to be active. Ethnomedical collections and samples had higher hit rates for tuberculosis, while samples, but not collections, had a higher hit rate for malaria. Little evidence was found to support an advantage for ethnomedical plants in HIV, chemoprevention and cancer bioassays. Plants whose ethnomedical uses directly correlated to a bioassay did not have a significantly higher hit rate than random plants. Discussion: Plants with ethnomedical uses generally had a higher rate of activity in some drug discovery bioassays, but the assays did not directly confirm specific uses. Conclusions: Ethnomedical uses may contribute to a higher rate of activity in drug discovery screening.
Guan Y.-F.,Hong Kong Baptist University |
Guan Y.-F.,HKBU Institute of Research and Continuing Education |
Song X.,Hong Kong Baptist University |
Song X.,Shenzhen University |
And 11 more authors.
Chemical Biology and Drug Design | Year: 2016
Tuberculosis (TB) is a highly contagious disease mainly caused by Mycobacterium tuberculosis H37RV. Antitubercular (anti-TB) bioassay-guided isolation of the CHCl3 extract of the leaves and stems of the medicinal plant Ardisia gigantifolia led to the isolation of two anti-TB 5-alkylresorcinols, 5-(8Z-heptadecenyl) resorcinol (1) and 5-(8Z-pentadecenyl) resorcinol (2). We further synthesized 15 derivatives based on these two natural products. These compounds (natural and synthetic) were evaluated for their anti-TB activity against Mycobacterium tuberculosis H37RV. Resorcinols 1 and 2 exhibited anti-TB activity with MIC values at 34.4 and 79.2 μm in MABA assay, respectively, and 91.7 and 168.3 μm in LORA assay, respectively. Among these derivatives, compound 8 was found to show improved anti-TB activity than its synthetic precursor (2) with MIC values at 42.0 μm in MABA assay and 100.2 μm in LORA assay. The active compounds should be regarded as new hits for further study as a novel class of anti-TB agents. The distinct structure–activity correlations of the parent compound were elucidated based on these derivatives. © 2016 John Wiley & Sons A/S
News Article | November 15, 2016
The rest of his body is marked by red lacerations, and he will probably never regain enough strength to return to the wild. But he is among the lucky ones. Rescued from poachers, Mi Bo and dozens of other pangolins are being nursed back to health by Vietnamese conservationists fighting to save the scale-covered creatures from extinction. The reclusive pangolin has become the most trafficked mammal on earth due to soaring demand in Asia for their scales for traditional medicine and their flesh, considered a delicacy. An estimated one million of the animals, often called "scaly anteaters", have been plucked from Asian and African forests over the past decade, shunting them onto the list of species at the highest risk of extinction. About the size of a small dog, pangolins are defenceless in the wild, curling up into a ball when they are scared, allowing poachers to easily scoop them up. Their dire predicament will be on the agenda at a major wildlife conference opening in Hanoi on Thursday, which will be attended by Britain's Prince William—a champion of better-known endangered species such as elephants and rhinos. At the rescue centre in Vietnam, a team of staff and volunteers work late into the night to keep the latest batch of nearly 60 pangolins alive. "They have a second life here, they're kind of born again," Nguyen Van Thai, director of Save Vietnam's Wildlife, said from the leafy rehabilitation centre in Cuc Phuong National Park southwest of the capital. A previous group of rescued pangolins arrived barely alive after being stored on ice by poachers who thought it would keep them fresh. Others have been stripped of scales or pumped full of fluids to make them look fatter to prospective buyers. The sorry state of the animals leaves no shortage of work for veterinarian Lam Kim Hai, who treats up to 10 pangolins a day. "I feel at the same time sad and angry," the 24-year-old told AFP after treating Mi Bo for over an hour under a heat lamp. Although the pangolin trade is illegal in Vietnam and they are in the government's "red book" of endangered species, law enforcement remains weak. Authorities have even been caught selling the endangered animals after seizing them from poachers, according to media reports. With a booming traditional medicine industry, Vietnam remains both a destination and source country for illegally poached wildlife. Like in China, their meat is steamed, boiled or grilled. It is eaten on special occasions or to grease business wheels, mostly among members of Vietnam's growing wealthy class willing to spend as much as $1,000 for each creature. "I don't care if it's name is mentioned in the red book. Whenever I have guests or partners who want it, I absolutely have to obtain it for them," Vu Trong Phat, a 45-year-old real estate and construction boss, told AFP at a local pub. At that price, nothing goes to waste. Customers often drink their blood, and their scales are used in special elixirs believed to cure anything from impotence to menstrual cramps to asthma and even cancer. The scales have also been used as guitar plectrums. "Pangolin meat is very delicious and nutritious and very good for your health," said government employee Nguyen Van Thinh, 56. "Pangolin scales are... very good for heart and blood circulation diseases. Any woman who has no milk for her child can be cured just with a small quantity of the medicine," he told AFP at the pub. He shares that belief with many others across Vietnam and China, though there is no scientific evidence for any of the supposed medical benefits of pangolin products. Scientists don't know how many pangolins are left in the wild, since the nocturnal and notoriously shy animals are difficult to track. But experts say the size of illegal pangolin hauls in Asia has grown in recent years—in 2015, two tonnes of dead pangolins from Nigeria were found in a single seizure in Hong Kong. With wild populations plummeting, some fear that traders may be seeking to set up breeding farms—which conservationists fear are just a cover for black-market trafficking. Pangolins are also difficult to keep alive in captivity and breeding farms would not necessarily boost their numbers. "That is not a conservation solution, it's nothing we would support. It seems to be just kind of a way to aid and abet the (illegal) trade," John Baker, managing director of WildAid, told AFP from California. The Hanoi conference follows a decision at a Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) summit in September to include pangolins on its "Appendix 1"—the highest level of protection that outlaws all trade in animals facing possible extinction. Thai, the 34-year-old director of Save Vietnam's Wildlife, said he has watched in dismay as pangolin numbers have fallen through the floor. "It's really sad, it's like over 20 years later and there are no pangolins in this area. We need to take action," he said. Explore further: Shy pangolins need world spotlight to survive
Pan W.,Hong Kong Baptist University |
Liu K.,Hong Kong Baptist University |
Guan Y.,Hong Kong Baptist University |
Tan G.T.,University of Hawaii at Hilo |
And 6 more authors.
Journal of Natural Products | Year: 2014
A new lignan, vitexkarinol (1), as well as a known lignan, neopaulownin (2), a known chalcone, 3-(4-hydroxyphenyl)-1-(2,4,6-trimethoxyphenyl)-2-propen- 1-one (3), two known dehydroflavones, tsugafolin (4) and alpinetin (5), two known dipeptides, aurantiamide and aurantiamide acetate, a known sesquiterpene, vemopolyanthofuran, and five known carotenoid metabolites, vomifoliol, dihydrovomifoliol, dehydrovomifoliol, loliolide, and isololiolide, were isolated from the leaves and twigs of Vitex leptobotrys through bioassay-guided fractionation. The chalcone (3) was found to inhibit HIV-1 replication by 77% at 15.9 μM, and the two dehydroflavones (4 and 5) showed weak anti-HIV activity with IC50 values of 118 and 130 μM, respectively, while being devoid of cytotoxicity at 150 μM. A chlorophyll-enriched fraction of V. leptobotrys, containing pheophorbide a, was found to inhibit the replication of HIV-1 by 80% at a concentration of 10 μg/mL. Compounds 1 and 3 were further selected to be evaluated against 21 viral targets available at NIAID (National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA). © 2014 The American Chemical Society and American Society of Pharmacognosy.
Guan Y.,Hong Kong Baptist University |
Guan Y.,Institute of Integrated Bioinfomedicine and Translational Science |
Wang D.,Hong Kong Baptist University |
Wang D.,Institute of Integrated Bioinfomedicine and Translational Science |
And 8 more authors.
American Journal of Chinese Medicine | Year: 2016
Litsea verticillata Hance (Lauraceae), a Chinese medicine used to treat swelling caused by injury or by snake bites, was the first plant identified by our National Institutes of Health (NIH)-funded International Cooperative Biodiversity Group (ICBG) project to exhibit anti-HIV activities. From this plant, we discovered a class of 8 novel litseane compounds, prototypic sesquite rpenes, all of which demonstrated anti-HIV activities. In subsequent studies, 26 additional compounds of different structural types were identified. During our continuing investigation of this plant species, we identified two new litseanes, litseaverticillols L and M, and a new sesquiterpene butenolide, litseasesquibutenolide. Litseaverticillols L and M were found to inhibit HIV-1 replication, with an IC50 value of 49.6μM. To further determine the antiviral properties of this plant, several relatively abundant isolates, including a litseane compound, two eudesmane sesquiterpenes and three lignans, were evaluated against an additional 21 viral targets. Lignans 8 and 9 were shown to be active against the Epstein-Barr Virus (EBV), with EC50 values of 22.0μM (SI=3.8) and 16.2μM (SI>6.2), respectively. Since many antiviral compounds have been discovered in L. verticillata, we further prepared 38 plant extracts made from the different plant parts of 9 additional Litsea species. These extracts were evaluated for their anti-HIV and cytotoxic activities, and four of the extracts, which ranged across three different species, displayed 97-100% inhibitory effects against HIV replication without showing cytotoxicity to a panel of human cell lines at a concentration of 20μg/mL. © 2016 World Scientific Publishing Company.
PubMed | Shenzhen University, Vietnam Academy of Science and Technology, CAS Kunming Institute of Botany, Hong Kong Baptist University and 2 more.
Type: Journal Article | Journal: Chemical biology & drug design | Year: 2016
Tuberculosis (TB) is a highly contagious disease mainly caused by Mycobacterium tuberculosis H37 RV . Antitubercular (anti-TB) bioassay-guided isolation of the CHCl3 extract of the leaves and stems of the medicinal plant Ardisia gigantifolia led to the isolation of two anti-TB 5-alkylresorcinols, 5-(8Z-heptadecenyl) resorcinol (1) and 5-(8Z-pentadecenyl) resorcinol (2). We further synthesized 15 derivatives based on these two natural products. These compounds (natural and synthetic) were evaluated for their anti-TB activity against Mycobacterium tuberculosis H37 RV . Resorcinols 1 and 2 exhibited anti-TB activity with MIC values at 34.4 and 79.2 m in MABA assay, respectively, and 91.7 and 168.3 m in LORA assay, respectively. Among these derivatives, compound 8 was found to show improved anti-TB activity than its synthetic precursor (2) with MIC values at 42.0 m in MABA assay and 100.2 m in LORA assay. The active compounds should be regarded as new hits for further study as a novel class of anti-TB agents. The distinct structure-activity correlations of the parent compound were elucidated based on these derivatives.
News Article | December 8, 2015
A pygmy slow loris (Nycticebus pygmaeus) in its natural habitat. The picture was taken in the Cuc Phuong National Park in Vietnam. More Hibernation is well-documented in a number of animal species, and is common across the mammal family tree. In primates, however, it's almost unheard of. Until recently, the only primates known to hibernate were Madagascar lemurs. But scientists have found another primate that settles down for a seasonal snooze: the pygmy slow loris, native to Vietnam. Researchers conducted the first-ever study of hibernation in pygmy slow lorises (Nycticebus pygmaeus), working with six adult animals at Vietnam's Endangered Primate Rescue Center. The researchers were looking for evidence such as reduced body temperature for extended periods of time, occurring in otherwise healthy animals. They built nesting boxes to mimic the tree holes that the lorises typically use for hibernating, and implanted the lorises with devices that logged their temperatures every 6 minutes for nearly a year. During the cool, dry winter months, from late October until early April, the lorises exhibited behavior and physical responses consistent with animals that are known hibernators. They would repeatedly retreat to their nesting boxes and lapse into periods of inactivity that lasted up to 63 consecutive hours at a time, the researchers said. While in hibernation, their temperatures would dip to about 52 degrees Fahrenheit (11 degrees Celsius). [In Photos: Cute New Slow Loris Species] The animals' bodies would also be stiff to the touch, said the study's corresponding author, Thomas Ruf, a physiologist with the University of Veterinary Medicine in Vienna. Ruf told Live Science that he had suspected for some time that lorises hibernated, based on accounts dating back to the 1980s. Those reports described lorises curled up in trees, where they remained inactive for days. But without monitoring the animals over time, it was impossible to tell whether this was a sign of hibernation or of illness, Ruf added. The data gathered by Ruf and his colleagues provided the first evidence that the lorises entered a state of inactivity and reduced metabolic rate in response to seasonal changes, the new study reported. Hibernation is an effective survival strategy for animals living in parts of the world where changing seasons mean that food is less available for parts of the year. Pygmy slow lorises eat fruit and insects, and when winter rolls around, the insects become scarce. "That's why we think they hibernate — they have to save energy somehow," Ruf said. Another benefit of hibernation is that the drop in body temperature means that animals' natural body odors are reduced, making the creatures harder for predators to detect, Ruf said. He recalled an experiment from decades ago that "you couldn't do these days," in which hibernating mice were placed in a room with hungry weasels. Because the mice were cold, motionless and stiff, the weasels weren't interested and left the potential prey alone. Likewise, lorises hibernating in trees would be easy prey for snakes, but a cold, stiff, loris doesn't have much appeal to predators looking for a warm, lively dinner. "Hibernation is a very safe time for animals," Ruf told Live Science. "They have a very high survival probability." Small wonder, then, that so many animals hibernate. In mammals, hibernation appears in 11 different orders, which suggests the behavior originated far back in the ancestral time line of mammals. "It's unlikely that it evolved independently among so many genetic branches, " Ruf said. "So it must be really old." It's possible that more hibernating species are yet to be discovered, even in the primate lineage, where hibernation is considered rare. Hibernating lemurs and the pygmy slow loris all belong to the same suborder, Strepsirrhini, and more species in that grouping could be hibernators, too, the researchers said. "I suspect there are more primates that hibernate," Ruf added. "Now we have to go and look." The findings were published online Dec. 3 in the journal Scientific Reports. Follow Mindy Weisberger on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science. Copyright 2015 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Truong B.N.,Vietnam Academy of Science and Technology |
Pham V.C.,Vietnam Academy of Science and Technology |
Mai H.D.T.,Vietnam Academy of Science and Technology |
Nguyen V.H.,Vietnam Academy of Science and Technology |
And 7 more authors.
Phytochemistry Letters | Year: 2011
Two new glucosides, 3-methoxy-4-hydroxyphenylpropane-7,8-(6′-benzoyl- 2′,1′-O-β-glucopyranosyl)-7,8,9-trio (1), and 2-hydroxyphenyl-4-caffeoyl-β-d-glucoside (2), together with seven known compounds were isolated from the stem bark of Xylosma longifolia (Flacourtiaceae). The structures of the isolates were established on the basis of their spectral data, including mass spectrometry and 2D-NMR. The compound 8-hydroxy-6-methoxy-pentylisocoumarin (3) exhibited an MIC value of 40.5 μg/mL against M. tuberculosis. © 2011 Phytochemical Society of Europe.
Truong N.B.,Vietnam Academy of Science and Technology |
Pham C.V.,Vietnam Academy of Science and Technology |
Doan H.T.M.,Vietnam Academy of Science and Technology |
Nguyen H.V.,Vietnam Academy of Science and Technology |
And 7 more authors.
Journal of Natural Products | Year: 2011
Three new triterpenoids, bonianic acids A (1) and B (2) and 3-O-acetyluncaric acid (3), were isolated from the leaves and twigs of Radermachera boniana, together with six known compounds, ursolic acid (4), oleanolic acid (5), 3-epi-oleanolic acid (6), 3α-O-acetyl-α- boswellic acid (7), ergosterol peroxide (8), and β-sitostenone (9). Ergosterol peroxide (8) and bonianic acids A (1) and B (2) exhibited significant activity against Mycobacterium tuberculosis H37Rv strain. (Chemical Equation Presented). © 2011 The American Chemical Society and American Society of Pharmacognosy.