Discovery of a Nur77-mediated cytoplasmic vacuolation and paraptosis inducer (4-PQBH) for the treatment of hepatocellular carcinoma.

Nur77, an orphan nuclear receptor, has antitumor activity in hepatocellular carcinoma (HCC). However, its antitumor mechanisms of action in HCC are complicated and rarely reported. Our recent work demonstrated that certain quinoline-Schiff-base derivatives were good Nur77 mediators that exerted excellent anti-HCC activities in vitro and in vivo. Interestingly, these compounds shared similar chemical structures, but they displayed different Nur77-targeted anticancer mechanisms of action. As a continuous work, we synthesized a series of 4-(quinoline-4-amino) benzoylhydrazide derivatives and evaluated their anti-HCC activity and binding affinity to Nur77 in vitro. Compound 4-PQBH emerged as the best Nur77 binder (KD = 1.17 µM) and has potentially selective cytotoxicity to HCC cells. Mechanistically, 4-PQBH extensively induced caspase-independent cytoplasmic vacuolization and paraptosis through Nur77-mediated ER stress and autophagy. Moreover, 4-PQBH exhibited an effective xenograft tumor inhibition by modulating Nur77-dependent cytoplasmic vacuolation and paraptosis. This paper is the first to disclose that chemotherapeutic agents targeting Nur77-mediated cytoplasmic vacuolization and paraptosis may provide a promising strategy to combat HCC that frequently evade the apoptosis program.

New Sorbicillinoids with Tea Pathogenic Fungus Inhibitory Effect from Marine-Derived Fungus Hypocrea jecorina H8.

Four new dimeric sorbicillinoids (1-3 and 5) and a new monomeric sorbicillinoid (4) as well as six known analogs (6-11) were purified from the fungal strain Hypocrea jecorina H8, which was obtained from mangrove sediment, and showed potent inhibitory activity against the tea pathogenic fungus Pestalotiopsis theae (P. theae). The planar structures of 1-5 were assigned by analyses of their UV, IR, HR-ESI-MS, and NMR spectroscopic data. All the compounds were evaluated for growth inhibition of tea pathogenic fungus P. theae. Compounds 5, 6, 8, 9, and 10 exhibited more potent inhibitory activities compared with the positive control hexaconazole with an ED50 of 24.25 ± 1.57 µg/mL. The ED50 values of compounds 5, 6, 8, 9, and 10 were 9.13 ± 1.25, 2.04 ± 1.24, 18.22 ± 1.29, 1.83 ± 1.37, and 4.68 ± 1.44 µg/mL, respectively. Additionally, the effects of these compounds on zebrafish embryo development were also evaluated. Except for compounds 5 and 8, which imparted toxic effects on zebrafish even at 0.625 µM, the other isolated compounds did not exhibit significant toxicity to zebrafish eggs, embryos, or larvae. Taken together, sorbicillinoid derivatives (6, 9, and 10) from H. jecorina H8 displayed low toxicity and high anti-tea pathogenic fungus potential.

Synthesis, SAR study, and bioactivity evaluation of a series of Quinoline-Indole-Schiff base derivatives: Compound 10E as a new Nur77 exporter and autophagic death inducer.

We previously reported 5-((8-methoxy-2-methylquinolin-4-yl)amino)-1H-indole- 2-carbohydrazide derivatives as new Nur77 modulators. In this study, we explored whether the 8-methoxy-2-methylquinoline moiety and bicyclic aromatic rings at the N'-methylene position were critical for their antitumor activity against hepatocellular carcinoma (HCC). For this purpose, a small library of 5-substituted 1H-indole-2-carbohydrazide derivatives was designed and synthesized. We found that the 8-methoxy-2-methylquinoline moiety was a fundamental structure for its biological function, while the introduction of the bicyclic aromatic ring into the N'-methylene greatly improved its anti-tumor effect. We found that the representative compound 10E had a high affinity to Nur77. The KD values were in the low micromolar (2.25-4.10 µM), which were coincident with its IC50 values against the tumor cell lines (IC50 < 3.78 µM). Compound 10E could induce autophagic cell death of liver cancer cells by targeting Nur77 to mitochondria while knocking down Nur77 greatly impaired anti-tumor effect. These findings provide an insight into the structure-activity relation of Quinoline-Indole-Schiff base derivatives and further demonstrate that antitumor agents targeting Nur77 may be considered as a promising strategy for HCC therapy.

Two New Cytotoxic Compounds from a Deep-Sea Penicillum citreonigrum XT20-134.

Penicillum citreonigrum XT20-134 (MCCC 3A00956) is a fungus with cytotoxic activity, derived from deep-sea sediment. Five new compounds, adeninylpyrenocine (1), 2-hydroxyl-3-pyrenocine-thio propanoic acid (2), ozazino-cyclo-(2,3-dihydroxyl-trp-tyr) (3), 5,5-dichloro-1-(3,5-dimethoxyphenyl)-1,4-dihydroxypentan-2-one (4), and 2,3,4-trihydroxybutyl cinnamate (5), together with 19 known compounds (6-24), were isolated from an ethyl acetate (EtOAc) extract of its fermentation. The structures of the new compounds were comprehensively characterized by high-resolution electrospray ionization-mass spectrometry (HR-ESI-MS), 1D and 2D nuclear magnetic resonance (NMR). All isolates were evaluated for their cytotoxic activities. The heteroatom-containing new compounds 2 and 4 showed potent cytotoxicity to the human hepatoma tumor cell Bel7402 with IC50 values of 7.63 ± 1.46, 13.14 ± 1.41 µM and the human fibrosarcoma tumor cell HT1080 with IC50 values of 10.22 ± 1.32, 16.53 ± 1.67 µM, respectively.

New Bis-Alkenoic Acid Derivatives from a Marine-Derived Fungus Fusarium solani H915.

Fusarium solani H915 is a fungus derived from mangrove sediments. From its ethyl acetate extract, a new alkenoic acid, fusaridioic acid A (1), three new bis-alkenoic acid esters, namely, fusariumester A1 (2), A2 (3) and B (4), together with three known compounds (5⁻7), were isolated. The structures of the new compounds were comprehensively characterized by high resolution electrospray ionization-mass spectrometry (HR-ESI-MS), 1D and 2D nuclear magnetic resonance (NMR). Additionally, the antifungal activities against tea pathogenic fungi Pestalotiopsis theae and Colletotrichum gloeosporioides were studied. The new compound, 4, containing a ß-lactone ring, exhibited moderate inhibitory activity against P. theae, with an MIC of 50 µg/disc. Hymeglusin (6), a typical ß-lactone antibiotic and a terpenoid alkaloid, equisetin (7), exhibited potent inhibitory activities against both fungal species. The isolated compounds were evaluated for their effects on zebrafish embryo development. Equisetin clearly imparted toxic effect on zebrafish even at low concentrations. However, none of the alkenoic acid derivatives exhibited significant toxicity to zebrafish eggs, embryos, or larvae. Thus, the ß-lactone containing alkenoic acid derivatives from F. solani H915 are low in toxicity and are potent antifungal agents against tea pathogenic fungi.

Compounds from Agathis dammara exert hypoglycaemic activity by enhancing glucose uptake: lignans, terpenes and others.

In this study, two new kaurane diterpenes (16, 17), together with 12 lignans (1-12), a triterpene (15), and two other compounds (13, 14) were isolated from the woods of Agathis dammara. The structure of the new compound was determined by HR ESIMS and 1D/2D NMR spectroscopy, and its absolute configuration was determined by electronic circular dichroism (ECD) exciton chirality method. Compounds 5, 11, 14 exhibit significant hypoglycaemic activity in zebrafish, and their mechanism of action is to enhance glucose uptake in zebrafish.

Hinokione: an abietene diterpene with pancreatic ß cells regeneration and hypoglycemic activity, and other derivatives with novel structures from the woods of Agathis dammara.

In this study, 14 abietene and pimarene diterpenoids were isolated from the woods of Agathis dammara. Among them, 4 new compounds, dammarone A-C and dammaric acid A (1-4), were firstly reported, respectively. The structure of the new compounds was determined by HR ESI-MS and 1D/2D NMR spectroscopy, and their absolute configuration was determined by electronic circular dichroism (ECD) exciton chirality method. The hypoglycemic effect of all compounds was evaluated by transgenic zebrafish model, and the structure-activity relationship was discussed. Hinokione (7, HO) has low toxicity and significant hypoglycemic effects on zebrafish, the mechanism is mainly by promoting the differentiation of zebrafish pancreatic endocrine precursor cells (PEP cells) into ß cells, thereby promoting the regeneration of pancreatic ß cells.

Three new compounds from Anoectochilus roxburghii (Wall.) Lindl.

In this study, three new compounds, roxburic acid A (1) and two flavone glycosides isorhamnetin-3-O-α-L-rhamnosyl-(1→6)-ß-D-glucopyranose-(1→3)-ß-D-glucopyranoside (2), and kaempferol-7-O-ß-D-glucopyranosyl-(1→3)-ß-D-glucopyranoside (3) were isolated from an ethanol extract of the fresh Anoectochilus roxburghii (Wall.) Lindl., together with 10 known compounds (4-13). The structures of these compounds were comprehensively characterized by HR-ESI-MS, 1H NMR, 13C NMR, and 2 D-NMR. The DPPH free radical scavenging activity of the isolated compounds was evaluated, and the results showed that kaempferol-7-O-ß-D-glucopyranosyl- (1→3) -ß-D-glucopyranoside (3) and rutin (11) has the potential antioxidant activity with IC50 values of 139 µg/mL and 22.5 µg/mL respectively.

Identification of potential ATP-competitive cyclin-dependent kinase 1 inhibitors: De novo drug generation, molecular docking, and molecular dynamics simulation.

Cyclin-dependent kinases 1 (CDK1) has been identified as a potential target for the search for new antitumor drugs. However, no clinically effective CDK1 inhibitors are now available for cancer treatment. Therefore, this study aimed to offer potential CDK1 inhibitors using de novo drug generation, molecular docking, and molecular dynamics (MD) simulation studies. We first utilized the BREED algorithm (a de novo drug generation approach) to produce a novel library of small molecules targeting CDK1. To initially obtain novel potential CDK1 inhibitors with favorable physicochemical properties and excellent druggability, we performed a virtual rule-based rational drug screening on our generated library and found ten initial hits. Then, the molecular interactions and dynamic stability of these ten initial hits and CDK1 complexes during their all-atom MD simulations (total 18 µs) and binding pose metadynamics simulations were investigated, resulting in five final hits. Furthermore, another MD simulation (total 2.1 µs) with different force fields demonstrated the binding ability of the five hits to CDK1. It was found that these five hits, CBMA001 (ΔG = -29.88 kcal/mol), CBMA002 (ΔG = -34.89 kcal/mol), CBMA004 (ΔG = -32.47 kcal/mol), CBMA007 (ΔG = -31.16 kcal/mol), and CBMA008 (ΔG = -34.78 kcal/mol) possessed much greater binding affinity to CDK1 than positive compound Flavopiridol (FLP, ΔG = -25.38 kcal/mol). Finally, CBMA002 and CBMA004 were identified as excellent selective CDK1 inhibitors in silico. Together, this study provides a workflow for rational drug design and two promising selective CDK1 inhibitors that deserve further investigation.

Artemether and aspterric acid induce pancreatic alpha cells to transdifferentiate into beta cells in zebrafish.

BACKGROUND AND PURPOSE: Recently, the antimalarial drug, artemether and the neurotransmitter GABA were identified to convert alpha cells into beta-like cells in vivo. However, some of these observations were challenged by other studies. To help address the controversy, we took advantage of zebrafish as a model to perform this study. EXPERIMENTAL APPROACH: First, we performed a small-molecule screening for artemether and its skeleton analogues. Second, we used the Cre-LoxP system for lineage tracing to indicate the conversion of alpha cells into beta cells in vivo. The stable transgenic ins2:eGFP αTC1-6-cell line was used for evaluation of alpha-cell transdifferentiation in vitro. We further used multiple zebrafish transgenic and mutation lines to demonstrate beta-cell differentiation, beta-cell ablation and alpha-cell hyperplasia in this study. KEY RESULTS: We showed that artemether and another sesquiterpene, aspterric acid, induced alpha-cell transdifferentiation into beta cells, both in zebrafish as well as using αTC1-6 cells. Furthermore, these two compounds also converted alpha cells into beta cells when beta cells were lost or alpha cells were hyperplastic in zebrafish. Unlike the previous report, the conversion of alpha cells to beta cells was mediated by increasing Pax4 expression, but not suppression of Arx expression. CONCLUSION AND IMPLICATIONS: Our data suggest that in zebrafish and αTC1-6 cells, both artemether and aspterric acid induce alpha-cell transdifferentiation. Our data, along with those of Li et al. (2017), suggested that artemether and aspterric acid were able to induce alpha-cell transdifferentiation, at least in zebrafish and αTC1-6 cells.

Inonotus obliquus and its bioactive compounds alleviate non-alcoholic fatty liver disease via regulating FXR/SHP/SREBP-1c axis.

Non-alcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease worldwide. However, there is still lack of specific drugs for treating NAFLD in clinic. Inonotus obliquus (IO), a folk medicinal fungus, has long been used to prevent against metabolic syndrome related diseases, such as hypertension and diabetes, etc. However, the study of IO anti-NAFLD effect has been reported rarely. This study aimed to investigate whether IO has an inhibitory effect on NAFLD, identify the active compounds in IO and clarify the underlying mechanisms of its anti-NAFLD effects. The results of Oil Red O(ORO) and Hematoxylin-Eosin (HE) staining, lipid extraction and determination showed that IO and its extracts, including inotodiol (Ino), lanosterol (Lan) and trametenolic acid (TA), could remarkably ameliorate lipid accumulation in MCD diet-induced mouse livers or OA-induced LO2 hepatocytes. Moreover, qPCR analysis revealed that IO and its compounds significantly downregulated the mRNA levels of lipogenic genes, such as SREBP-1c, ACC1 and FASN, and upregulated the mRNA levels of FXR and SHP. We found that the administration of guggulsterone (GS), a FXR inhibitor, abolished the inhibitory effect of Ino on lipid deposition in OA-induced LO2 cells. In conclusion, IO and its compounds attenuate hepatic lipid accumulation in NAFLD by inhibiting liver lipogenesis. The anti-NAFLD effects of Ino, a bioactive compound in IO, are through regulating FXR/SHP/SREBP-1c pathway. Our results suggested that IO and its bioactive compound Ino may become promising drugs to treat NAFLD.

Two new compounds from a mangrove sediment-derived fungus Penicillium polonicum H175.

Two new compounds, 6-acetyl-4-methoxy-3,5-dimethyl-2H-pyran-2-one (1) and (2E,4E)-5-((2S,3S,4R,5R)-3,4-dihydroxy-2,4,5-trimethyltetrahydrofuran-2-yl)-2,4-dimethylpenta-2,4-dienal (2), and 22 known compounds were identified from the mangrove-forest-derived fungus Penicillium polonicum H175. The structures of these compounds were elucidated by analysis of the high-resolution electrospray ionisation mass spectroscopy (HR-ESI-MS), 1 D and 2 D nuclear magnetic resonance (NMR) data. The hypoglycaemic effect of compounds was evaluated by the Tg (Ins: htBidTE-ON; LR) zebrafish model. Compound 3 (aspterric acid) exhibited a significant hypoglycaemic effect equivalent to the positive drug rosiglitazone (RSG) at 10 µmol/L.

Anti-inflammatory sesquiterpenoids from the heartwood of Juniperus formosana Hayata.

Juniperus formosana Hayata (J. formosana) is a commom needlebush cultivar growing in China. Six new compounds (1-6), including four cadinene sesquiterpenoids (1-4), one abietane diterpenoid (5), and one ß-naphthol derivative (6), along with 18 known compounds (7-24) were isolated and identified through phytochemical investigation on the heartwood of J. formosana. The structures of these compounds were fully elucidated by their 1D and 2D NMR, HR-ESI-MS, UV, and IR spectral data analyses. The absolute configurations of compounds 1, 3, and 5 were confirmed by experimental and calculated electronic circular dichroism (ECD) data. Moreover, X-ray crystallographic analysis was carried out to characterize the structure of compound 4. The inhibitory effects on the nitric oxide (NO) production of all the isolated compounds were initially examined in RAW264.7 macrophages induced by lipopolysaccharide (LPS). The results showed that compounds 3 and 12 possessed significant inhibitory potency on NO generation with IC50 values of 3.41 µM and 6.15 µM among the new and known compounds, respectively. The expressions of IL-1ß, IL-6, and TNF-α were measured in LPS-stimulated RAW264.7 cells to evaluate the anti-inflammatory effects of compounds 1-24. Compounds 1-6 and 9-12 exhibited potent anti-inflammatory effects. Additionally, the expressions of p38, Erk, and IκBα proteins were further determined to explore the anti-inflammatory mechanism of the most potent compounds 3 and 12. Overall, our findings indicate the potential of J. formosana for developing medicine candidates as the treatments of inflammation.

Analysis of correlation between blood biochemical indicators and bone mineral density of post-menopausal women.

Osteoporosis is a degenerative disease of the skeletal system, and its major complication is fracture that severely influences the living quality of the middle-aged and the aged. The purpose of this study was to investigate the significance of sex hormones and some biochemical indicators related to bone metabolism in the genesis and development of osteoporosis. The plasma samples were collected from 244 post-menopausal women of Xi'an urban area, and their plasma contents of testosterone, estradiol, calcitonin, osteocalcin and N-terminal propeptide of type I procollagen were detected by ELISA. The activity of tartrate-resistant acid phosphatase was determined by spectrophotometric method, and the content of nitric oxide was measured by Griess method. Bone mineral density (BMD) in lumbar vertebrae (L1-L4) and hips was measured by QDR-2000 dual energy X-ray absorptiometry. The concentrations of the biochemical indicators were compared among the three groups (normal bone mass group, osteopenia group and osteoporosis group), and Pearson correlation analysis was used to verify the correlations between the indicators and BMD. The comparison results of blood biochemical indicators of BMD-based groups showed that the plasma contents of estradiol (P = 0.006), testosterone (P = 0.038) and calcitonin (P = 0.042) decreased more significantly in the osteoporosis group, but the content of osteocalcin (P = 0.008) increased significantly in osteoporosis group than those in the other groups. The correlation analysis between BMD of different parts and the blood biochemical indicators showed that there was a significant positive correlation between estradiol and the BMD of lumber vertebra (r = 0.200, P = 0.002), femoral neck (r = 0.160, P = 0.013), and great trochanter (r = 0.204, P = 0.001). Significant positive correlations between calcitonin and BMD of lumber vertebra (r = 0.166, P = 0.018) and femoral great trochanter (r = 0.152, P = 0.041), and between testosterone and BMD of femoral great trochanter (r = 0.158, P = 0.014) were also observed. In addition, there existed significant negative correlations between osteocalcin and BMD of lumber vertebra (r = -0.220, P = 0.001), femoral neck (r = -0.259, P < 0.000), and great trochanter (r = -0.221, P = 0.001), and between the activity of tartrate-resistant acid phosphatase and BMD of femoral great trochanter (r = -0.135, P = 0.037). The partial correlation analysis also showed that there were significant correlations between estradiol (r = 0.160, P = 0.014), calcitonin (r = 0.240, P = 0.013), osteocalcin (r = -0.226, P = 0.023) and BMD when the influence of age was excluded. The Pearson correlation analysis of biochemical indicators showed there were positive correlations between the contents of testosterone and calcitonin, testosterone and osteocalcin, calcitonin and osteocalcin, calcitonin and PINP, calcitonin and NO, osteocalcin and NO, and PINP and NO, but negative correlations between the contents of testosterone and PINP, estradiol and calcitonin, estradiol and osteocalcin, and estradiol and NO. The blood contents of sex hormones and calcitonin significantly influence BMD and osteoporosis development, and the increase of osteocalcin contents could be used as a biomarker to indicate the degree of osteoporosis in post-menopausal women.

Two new troponoides with anti-inflammatory activity from the stems of Juniperus formosana Hayata.

Two new troponoides (1-2) were isolated from a 95% ethanol extract of the stems of Juniperus formosana (Cupressaceae), together with six known compounds (3-8). The structures of the new compounds were comprehensively characterized by high resolution electrospray ionization-mass spectrometry (HR-ESI-MS), 1D and 2D nuclear magnetic resonance (NMR). Compounds 1-7 were evaluated for their anti-inflammatory against the expression of IL-1ß, IL-6 and TNF-α in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. The new compounds showed moderate anti-inflammatory effect, while other compounds did show no activity.

Bioactive compounds derived from the marine-derived fungus MCCC3A00951 and their influenza neuraminidase inhibition activity in vitro and in silico.

Penicillium polonicum MCCC3A00951 is a fungus with influenza neuraminidase (NA) inhibition activity derived from a sediment of the mangrove forest of Zhangjiangkou in Fujian province, China. Chemical investigation on an ethyl acetate extract of its fermentation led to the isolation of a new compound, 7-hydroxy-3,10-dehydrocyclopeptine (1), and 13 known compounds (2-14). The new compound was comprehensively characterised by high-resolution electrospray ionisation-mass spectrometry, and 1D, 2D nuclear magnetic resonance (NMR) spectra. The anti-influenza NA assay was performed to evaluate the potential biological activity. Surprisingly, Cyclopenin (2) showed potent influenza NA inhibition with an IC50 value of 5.02 µM. Besides, molecular docking simulation was performed to investigate the binding model of cyclopenin (2) with influenza NA. Consequently, cyclopenin (2) could be further optimised to be a potential anti-influenza NA candidate.

New cyclopentenoneacrylic acid derivatives from a marine-derived fungus Trichoderma atroviride H548.

Three new cyclopentenoneacrylic acid derivatives, trichodermacid A (1), trichodermester A (2), and trichodermester B (3), together with thirteen known compounds, were isolated from an ethyl acetate extract of Trichoderma atroviride H548, a fungus derived from mangrove sediment. The structures of the new compounds were elucidated by spectroscopic methods including HR ESI-MS, 1H NMR, 13C NMR, and 2D-NMR techniques. The antifungal activity of the isolated compounds was evaluated against tea pathogenic fungus Pestalotiopsis theae. Trichodermester A (2) showed potent anti P. theae activity with MIC of 125 µg/disc, while the other compounds were inactive.

Design, synthesis, and biological evaluation of 5-((8-methoxy-2-methylquinolin-4-yl)amino)-1H-indole-2-carbohydrazide derivatives as novel Nur77 modulators.

Nur77 is a potential target for the treatment of cancer such as HCC. Herein, we detailed the discovery of a novel series of 5-((8-methoxy-2-methylquinolin-4-yl)amino)-1H-indole-2-carbohydrazide derivatives as potential Nur77 modulators. The studies of antiproliferative activity and Nur77-binding affinity of target compounds resulted in the discovery of a lead candidate (10g), which was a good Nur77 binder (KD = 3.58 ± 0.16 µM) with a broad-spectrum antiproliferative activity against all tested hepatoma cells (IC50 < 2.0 µM) and was low toxic to normal LO2 cells. 10g could up-regulate Nur77 expression and mediate sub-cellular localization of Nur77 to induce apoptosis in hepatocellular carcinoma cell lines, which relied on 10g inducing Nur77-dependent autophagy and endoplasmic reticulum stress as the upstream of apoptosis. Moreover, the in vivo assays verified that 10g significantly inhibited xenograft tumor growth. These results indicate that 10g has the potential to be developed as a novel Nur77-targeting anti-hepatoma drug.

Population genetics for Y-chromosomal STRs haplotypes of Chinese Tibetan ethnic minority group in Tibet.

Y-chromosomal STRs loci were analyzed from a sample of 119 healthy unrelated autochthonous male individuals of Chinese Tibetan ethnic minority group using a multiplex PCR system. Allele and haplotype frequencies for DYS19, DYS389 I, DYS389 II, DYS390, DYS391, DYS392, DYS393, DYS385a,b, DYS438, and DYS439 were determined by the Y-PLEXtrade mark 12 kit. The gene diversity values for the Y-STRs loci ranged from 0.3347 (DYS438) to 0.9547 (DYS385a,b). A total of 110 haplotypes were identified in the Y-STR loci, among which 104 were unique, while six occurred more than once. The overall haplotype diversity for the Y-STRs loci was 0.9981, and the discrimination capacity was 0.9897. The results in the present study can be used for routine forensic application in the region, and enrich Chinese ethnical genetic informational resources.

Distributions of HLA-A and -B alleles and haplotypes in the Yi ethnic minority of Yunnan, China: relationship to other populations.

OBJECTIVE: To investigate the distributions of human leukocyte antigen (HLA)-A and -B alleles and HLA-A-B haplotypes in the Yi ethnic minority of the Yunnan Province, situated in southwestern China. METHODS: DNA typing for HLA-A and -B loci was performed using the polymerase chain reaction-sequence-based typing (PCR-SBT) method on 114 randomly selected healthy individuals of the Yi population. The allelic frequencies of HLA-A and -B loci were calculated by direct counting and HLA-A-B haplotypes were estimated using the expectation maximization algorithm. RESULTS: A total of 17 HLA-A and 38 HLA-B alleles were found in the Yi population. The most frequent alleles were A*2402 (32.46%), A*1101 (26.32%), and A*0203 (10.09%) at the HLA-A locus and B*4601 (12.28%), B*1525 (10.09%), B*4001 (8.77%), and B*3802 (7.89%) at the HLA-B locus. The predominant HLA-A-B haplotypes were A*2402-B*1525 (7.86%) and A*0203-B*3802 (5.64%), followed by A*1101-B*4001 (4.69%). Phylogenetic analysis indicates that the Yi population in the Honghe, Yunnan Province of China basically belongs to groups of southeastern Asian origin, but shares some characteristics with northeastern Asian groups. CONCLUSION: The present study may add to the understanding of HLA polymorphism in the Yi ethnic group that was poorly defined previously, and provide useful information for bone marrow transplantation, anthropological research, and forensic sciences as well as for disease-association studies.