Rational design of transaminases based on comparative analysis of catalytically active and distance-free modes of the high-energy intermediate state.

Bioproduction of chiral amines is limited by low transaminase (TA) activity on nonnatural substrates, leading to the need for protein engineering. To address the challenge of quickly and precisely identifying the engineering targets, a strategy was proposed based on analyzing the mode changes in the high-energy intermediate state (H-state) of the substrate-enzyme complex during catalysis. By substituting the residues with minimal structural changes in catalytically active mode (A-mode) and distance-free mode (F-mode) of the H-state complex with more conserved ones to stabilize it, a TA mutant M5(T295C/L387A/V436A) with 121.9-fold higher activity for synthesizing the (S)-Rivastigmine precursor (S)-1-(3-methoxyphenyl)ethylamine was created. The applicability of this strategy was also validated by engineering another TA for 1.52-fold higher activity and >99% selectivity toward (R)-3-amino-1-butanol biopreparation. The much higher stereoselectivity of the mutant compared with the wild type (28.3%) demonstrated that this strategy is not only advantageous in engineering enzyme activity but also applicable for modulating stereoselectivity.

Novel dual-mode nanobubbles as potential targeted contrast agents for female tumors exploration.

The purpose of this study was to prepare tumor-specific dual-mode nanobubbles as both ultrasound contrast agents (UCAs) and near-infrared fluorescence (NIRF) imaging agents for female tumors. Recent studies have demonstrated the conjugation of anti-tumor ligands on the surface of nanobubbles for use as molecule-targeting ultrasound contrast agents for tumor visualization. However, this complicated procedure has also posed a challenge to nanobubble stability. Thus, in the present study, we combined the fluorescent dye, NIRF IR-780 iodide, which has lipid solubility and tumor-targeting characteristics, with the phospholipid film of nanobubbles that we constructed. We then characterized the physical features of the IR-780-nanobubbles, observed their tumor-targeting capacity in multiple female tumor cell types in vitro, and verified their capability for use in tumor-specific ultrasound contrast imaging and NIRF imaging in vivo. The results showed that the new IR-780-nanobubbles had a uniform nano-size (442.5 ± 48.6 nm) and stability and that they were safe and effective at NIRF imaging and ultrasound imaging in vitro. The IR-780-nanobubbles were found to automatically accumulate on different female tumor cells in vitro with a considerable targeting rate (close to 40 %) but did not accumulate on cardiac muscle cells used as a negative control. Importantly, the IR-780-nanobubbles can detect female tumors precisely via dual-mode imaging in vivo. In conclusion, the new dual-mode IR-780-nanobubbles are stable and have potential advantages in non-invasive tumor-specific detection for female tumors via contrast-enhanced ultrasound and NIRF imaging.

IR-780 dye for near-infrared fluorescence imaging in prostate cancer.

BACKGROUND: The aim of this study was to investigate near-infrared fluorescence (NIRF) imaging as a novel imaging modality that allows for early detection of cancer and real-time monitoring to acquire related information. IR-780 iodide, a lipophilic dye, accumulates selectively in breast cancer cells and drug-resistant human lung cancer cells, with a peak emission at 780 nm that can be easily detected by the NIRF imaging system. The application of IR-780 for prostate cancer imaging was thoroughly investigated to further expand its clinical value. MATERIAL AND METHODS: The impact of IR-780 on the survival of prostate cancer cells PC-3 and LNCaP as well as normal prostate epithelial cells RWPE-1 was determined. Duration of IR-780 dye staining was optimized in PC-3 cells. The involvement of specific OATP1B3 inhibitor in the selective accumulation of IR-780 was investigated. IR-780 for prostate cancer imaging was carried out in athymic nude mouse models and, acute toxicity of IR-780 was evaluated. RESULTS: IR-780 incubation resulted in a dose-dependent inhibition to cell proliferation. Mean fluorescence intensity of prostate cancer cells peaked at 20-min IR-780 incubation. Specific uptake of IR-780 dye in prostate cancer cells was mainly through the function of OATP1B3. We also demonstrated that NIRF dye effectively identified the subcutaneous prostate cancer xenografts, subsequently confirmed by histological examination. There was no significant impact on the physical activity, weight, and tissue histology of BABL/C mice with 10-fold imaging dose of 1-month IR-780 dye administration. CONCLUSIONS: NIRF imaging using IR-780 dye is a feasible and practicable method for prostate cancer detection, with potential tumor-killing ability, although more investigations are needed before clinical translation.

MTDH mediates trastuzumab resistance in HER2 positive breast cancer by decreasing PTEN expression through an NFκB-dependent pathway.

BACKGROUND: Trastuzumab resistance is almost inevitable in the management of human epidermal growth factor receptor (HER) 2 positive breast cancer, in which phosphatase and tensin homolog deleted from chromosome 10 (PTEN) loss is implicated. Since metadherin (MTDH) promotes malignant phenotype of breast cancer, we sought to define whether MTDH promotes trastuzumab resistance by decreasing PTEN expression through an NFκB-dependent pathway. METHODS: The correlations between MTDH and PTEN expressions were analyzed both in HER2 positive breast cancer tissues and trastuzumab resistant SK-BR-3 (SK-BR-3/R) cells. Gene manipulations of MTDH and PTEN levels by knockdown or overexpression were utilized to elucidate molecular mechanisms of MTDH and PTEN implication in trastuzumab resistance. For in vivo studies, SK-BR-3 and SK-BR-3/R cells and modified derivatives were inoculated into nude mice alone or under trastuzumab exposure. Tumor volumes, histological examinations as well as Ki67 and PTEN expressions were revealed. RESULTS: Elevated MTDH expression indicated poor clinical benefit, shortened progression free survival time, and was negatively correlated with PTEN level both in HER2 positive breast cancer patients and SK-BR-3/R cells. MTDH knockdown restored PTEN expression and trastuzumab sensitivity in SK-BR-3/R cells, while MTDH overexpression prevented SK-BR-3 cell death under trastuzumab exposure, probably through IκBα inhibition and nuclear translocation of p65 which subsequently decreased PTEN expression. Synergized effect of PTEN regulation were observed upon MTDH and p65 co-transfection. Forced PTEN expression in SK-BR-3/R cells restored trastuzumab sensitivity. Furthermore, decreased tumor volume and Ki67 level as well as increased PTEN expression were observed after MTDH knockdown in subcutaneous breast cancer xenografts from SK-BR-3/R cells, while the opposite effect were found in grafts from MTDH overexpressing SK-BR-3 cells. CONCLUSIONS: MTDH overexpression confers trastuzumab resistance in HER2 positive breast cancer. MTDH mediates trastuzumab resistance, at least in part, by PTEN inhibition through an NFκB-dependent pathway, which may be utilized as a promising therapeutic target for HER2 positive breast cancer.

Urethral reconstruction with tissue-engineered human amniotic scaffold in rabbit urethral injury models.

BACKGROUND: Mitigating urethral injury remains a great challenge for urologists due to lack of ideal biomaterials for urethroplasty. The application of amniotic membranes (AM) over other synthetic materials make it a better potential source for urethral reconstruction. We separated the basement layer of AM to obtain denuded human amniotic scaffold (dHAS) and then inoculated primary rabbit urethral epithelial cells on the surface of dHAS to define whether this strategy minimize potential rejection and maximize the biocompatibility of human AM. MATERIAL/METHODS: After the successful acquisition of dHAS from AM, cell-seeded dHAS were prepared and characterized. Both cell-seeded dHAS and acellular dHAS were subcutaneously implanted. Immune responses were compared by histological evaluation and CD4 cell and CD8 cell infiltrations. Then they were applied as urethroplastic materials in the rabbit models of urethral injury to fully explore the feasibility and efficacy of tissue-engineered dHAS xenografts in urethral substitution application. RESULTS: Mild inflammatory infiltration was observed in cell-seeded dHAS grafts, as revealed by fewer accumulations of CD4 cells and CD8 cells (or neutrophils or other immune cells). Urethral defects of rabbits in the urethroplastic group with dHAS implantation (n=6) were completely resolved in one month, while there were one infection and one fistula in the control group with acellular dHAS patches (n=6). Histopathological analysis revealed mild immune response in cell-seeded dHAS group (P<0.05). CONCLUSIONS: Tissue-engineered dHAS minimize potential rejection and maximize the biocompatibility of AM, which makes it a potential ideal xenograft for urethral reconstruction.

Capsular Polysaccharide From Bacteroides fragilis Protects Against Ulcerative Colitis in an Undegraded Form.

The prominent human symbiont Bacteroides fragilis protects animals from intestinal diseases, such as ulcerative colitis, and its capsular polysaccharide plays a key role in reducing inflammation. B. fragilis strain ZY-312 was isolated from the feces of a healthy breast-fed infant, and the zwitterionic capsular polysaccharide zwitterionic polysaccharide, TP2, was extracted. In rats with 2,4-dinitrobenzenesulfonic acid (DNBS)-induced enteritis, TP2 at an optimal dose of 2.5 mg/kg could significantly alleviate enteritis and reduced the degree of intestinal adhesions, the intestinal ulcer area, and the incidence of ulcers in rats. To understand the underlying mechanism, TP2 was labeled with Fluorescein isothiocyanate and orally administered at a dose of 2.5 mg/kg in rats. TP2 was mainly distributed in the cecum and colorectum, but it was not detected in the blood and other organs except that a compound with a molecular weight greater than that of TP2-FITC was found in liver tissue. During the absorption, distribution, metabolism, and excretion, TP2 was indigestible. These results were further confirmed by investigation in the simulated gastric, intestinal fluid, and colonic fluid with fecal microbiota in vitro, where TP2 remained unaltered at different time points. Furthermore, flora composition was analyzed in simulated colonic fluid with TP2 added and it was found that TP2 increased the abundance of Faecalibacterium, Enterococcus romboutsia, and Ruminococcaceae, whereas the abundance of the phylum Proteobacteria represented by Sutterella, Desulfovibrio, and Enterobacteriaceae was decreased. However, the amount of short-chain fatty acids in the simulated colonic fluid was not changed by intestinal flora post-TP2 addition. In conclusion, these findings confirmed that TP2, a capsular polysaccharide of B. fragilis, protects against ulcerative colitis in an undegraded form.

Steroidal alkaloid glycosides and phenolics from the immature fruits of Solanum nigrum.

Solanum nigrum L. (also called as European black nightshade) has been traditionally used as folk medicine and food in some regions. Phytochemical investigations of the immature fruits of S. nigrum yielded five steroidal alkaloid glycosides (1-5), including an unprecedented nor-spirosolane type steroidal alkaloid with a five-membered ring A (1) and two novel spirosolane type steroidal alkaloid glycosides (2, 3), together with eight known phenolic compounds (6-13). Their structures were elucidated on the basis of spectroscopic and chemical methods, including IR, NMR, HR-ESI-MS, and GC analyses. Five steroidal alkaloid glycosides were tested for their potential antiproliferative effects against HL-60, U-937, Jurkat, K562, and HepG2 cell lines and inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in a macrophage cell line RAW 264.7. Compound 1 exhibited significant inhibition on NO production with an IC50 value of 23.4 ±â€¯2.0 µM, compared to positive control indomethacin (IC50, 47.40 ±â€¯4.50 µM). Compound 4 exhibited significant cytotoxicity against all tested cell lines.

Furostanol saponins from Chinese onion induce G2/M cell-cycle arrest and apoptosis through mitochondria-mediate pathway in HepG2 cells.

Phytochemical investigations on the bulbs of Chinese onion led to the isolation of three new furostanol saponins (1, 2, 5) together with seven known furostanol saponins (3, 4, 6-10). Their chemical structures were elucidated on the basis of spectroscopic and chemical methods, including IR, MS, NMR, and GC analyses. The anti-proliferative and anti-inflammatory activities of the isolates were evaluated. Compounds 7-10 showed potential anti-proliferative activities against human cancer cell lines (HepG2, A549, SPC-A-1, MGC80-3, MDA-MB-231, SW620 and CNE-1) with IC50 values below 30 µM. Compounds 4 and 7 could induce G2/M cell-cycle arrest and apoptosis through mitochondria-mediate pathway in HepG2 cells. Compounds 7 and 10 showed strong inhibitory effects against LPS induced NO production in RAW264.7 cells with IC50 values of 2.01 ±â€¯1.40 µM and 2.49 ±â€¯1.54 µM, respectively.

Anti-inflammatory steroidal glycosides from the berries of Solanum nigrum L. (European black nightshade).

Seven previously undescribed steroidal glycosides, along with three known congeners were isolated from the unripe berries of Solanum nigrum L. (Solanaceae). Their structures were elucidated on basis of 1D and 2D NMR, HR-ESI-MS spectroscopic data and GC analysis after acid hydrolysis. The potential inhibitory effects on nitric oxide (NO) production induced by lipopolysaccharide in RAW 264.7 cell line and the anti-proliferative activities against five cancer cell lines (HL-60, U-937, Jurkat, K562 and HepG2) were evaluated. Seven compounds exhibited inhibition activities on NO production with IC50 values ranging from 11.33 to 49.35 µM. Structure-activity relationships of the isolated compounds were also discussed.

Novel triterpenoids and glycosides from durian exert pronounced anti-inflammatory activities.

Durian, known for its abundant nutrition, is a delicious fruit from Southeast Asia with increasing popularity worldwide. In this study, a series of chromatographic methods and bioactivity assays were applied to identify major compounds from durian shells. Two new triterpenoids, two new phenolics, and seven new glycoside esters, as well as sixteen known compounds, were isolated and identified. Anti-inflammatory activities were assayed and evaluated for the isolated compounds. Most of the isolated compounds exhibited pronounced inhibitory activities on lipopolysaccharides-induced NO production in RAW 264.7 cells. The results indicated that durian shells could serve as anti-inflammatory agents for functional food or medicinal use. This study additionally provided motivation for the ecological protection of durian shells.

Apoptosis and pro-death autophagy induced by a spirostanol saponin isolated from Rohdea chinensis (Baker) N. Tanaka (synonym Tupistra chinensis Baker) on HL-60 cells.

BACKGROUND: Our previous study has revealed that the spirostanol saponins isolated from the rhizomes of Rohdea chinensis (Baker) N. Tanaka (synonym Tupistra chinensis Baker) (Convallariaceae) (a reputed folk medicine) exhibited potent antiproliferative activity. However, the underlying mechanism of purified saponins remains unclear. More studies are necessary to assess the apoptosis and autophagy activities of the saponins from R. chinensis and clarify their antiproliferative mechanisms. PURPOSE: The present study certificated the potential antiproliferative activity and mechanism of 5ß-spirost-25(27)-en-1ß,3ß-diol-1-O-α-L-rhamnopyranosyl-(1→2)- ß-D-xylopyranosyl-3-O-α-L-rhamnopyranoside (SPD), a spirostanol saponin from R. chinensis, against human acute promyelocytic leukemia cells (HL-60). METHODS: The antiproliferative activity of SPD in vitro was evaluated by MTT assay compared with cis-dichlorodiammineplatinum (II). The autophagic activity was assessed using MDC staining and western blot, cell apoptosis inspection was detected by Annexin V-FITC/PI double staining and the mitochondrial membrane potential was detected by JC-1 fluorescence dye combined with flow cytometry. The potential mechanisms for protein levels of apoptosis and autophagy were evaluated by western blot. RESULTS: Treatment of HL-60 cells with SPD resulted in growth inhibition (IC50 value of 2.0 ± 0.2 µM, after 48 h treatment) and induction of apoptosis and autophagy. Results from Annexin V-FITC/PI double-staining assay and mitochondrial membrane potential detection showed that apoptosis was happened after SPD treatment. The regulation of caspase-3, Bax, Bcl-2, PARP following SPD treatment contributed to the induction of mitochondria-dependent apoptosis. Meanwhile, SPD induced autophagy related with Akt/mTOR/p70S6K signaling and activated of AMPK signaling pathway. Furthermore, blocking autophagy with bafilomycin A1 reduced the cytotoxicity of SPD in HL-60 cells. CONCLUSION: The antiproliferative, apoptosis and pro-death autophagy activities of SPD suggested that spirostanol saponins from R. chinensis would be a potential cytotoxic candidate against acute promyelocytic leukemia.

Potential Anti-inflammatory Steroidal Saponins from the Berries of Solanum nigrum L. (European Black Nightshade).

Solanum nigrum L. or European black nightshade (Solanum genus) is a common weed of crops and gardens. The berries and leaves of S. nigrum L. are consumed as food or vegetable in some regions and reported to possess a range of biological activities. In this study, nine new steroidal saponins, solanigrosides Y1-Y9 (1-6, 10-12), together with seven known congeners, were isolated from the berries of S. nigrum. Their potential inhibitory effects on nitric oxide (NO) and IL-6 and IL-1ß production induced by lipopolysaccharide (LPS) in macrophages cell line RAW 264.7 were evaluated. Compound 1 exhibited significant inhibition on NO production with an IC50 value of 9.7 µM, and some compounds exhibited significant inhibition effects on the LPS-induced IL-6 and IL-1ß production. These results suggest that the steroidal saponins from berries of S. nigrum demonstrated pronounced anti-inflammatory activity and might be explored as a healthy benefit agent.

Piperidine alkaloids from Alocasia macrorrhiza.

Six previously undescribed piperidine alkaloids were isolated from the rhizomes of Alocasia macrorrhiza (L.) Schott. Their structures were elucidated based on 1D and 2D NMR, IR, HR-ESI-MS spectroscopic analysis and the application of a modified Mosher method. All isolated alkaloids were evaluated for cytotoxicity against five human cancer cell lines (CNE-1, Detroit 562, Fadu, MGC-803, and MCF-7) using the MTT method. Only one compound exhibited cytotoxic effects against Detroit 562, Fadu, and MCF-7 cell lines with IC50 values less than 10 µM.

Anti-inflammatory phenylpropanoids and phenolics from Ficus hirta Vahl.

Four new phenylpropanoids (1-4) along with ten known phenolics were isolated and purified from the roots of hairy fig (Ficus hirta Vahl.). Their structures were elucidated by the extensive spectroscopic analysis and chemical degradation. The anti-inflammatory activities of the purified compounds were evaluated. Results indicated that the extracts and some purified compounds exhibited pronounced inhibitory effects on the lipopolysaccharides (LPS) induced nitric oxide (NO) production in murine macrophage RAW 264.7 compared to indomethacin, which suggested that hairy fig could be served as an anti-inflammatory agent for health products.

Anti-inflammatory lignanamides and monoindoles from Alocasia macrorrhiza.

Five new lignanamides (1-5), and one new monoindole alkaloid (6), along with eight known compounds (7-14) were isolated and identified from the rhizomes of Alocasia macrorrhiza (giant taro). All purified compounds were evaluated for their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 cells, and the antiproliferative activities against human nasopharyngeal carcinoma epithelial (CNE-1), human gastric carcinoma (MGC-803), and human breast cancer (MCF-7) cell lines by MTT method. Compounds 2, 4, 7 and 8 exhibited significant inhibitory effects on NO production with the IC50 values of 2.35±0.38, 9.20±0.94, 3.45±0.39 and 7.96±0.56µM, respectively. The results suggested the lignanamides and monoindoles might be responsible for the anti-inflammatory activity of giant taro and might be potential anti-inflammatory candidates.

Anticancer activities of harmine by inducing a pro-death autophagy and apoptosis in human gastric cancer cells.

BACKGROUND: Harmine, a ß-carboline alkaloid from Peganum harmala, has multiple anti-tumor activities, especially for its folk therapy for digestive system neoplasm. However, the underlying mechanism of harmine on gastric cancer remains unclear. PURPOSE: To illuminate the potential anti-tumor activity and mechanism of harmine against gastric cancer cells. METHODS/STUDY DESIGNS: The anti-proliferative activity of harmine in vitro was evaluated by MTT assay. The autophagic activity induced by harmine was assessed using GFP-LC3 transfection. FITC/PI double staining was applied for the apoptosis inspection. The mitochondrial membrane potential was detected by JC-1 fluorescence probe. The potential mechanisms for proteins level in autophagy and apoptosis were analyzed by Western blot. RESULTS: Harmine exhibited potent effects on both autophagy and apoptosis. Treatment with harmine could enhance dots of GFP-LC3 in cells. Meanwhile, the process had connection with Beclin-1, LC3-II, and p62 by the inhibition of Akt/mTOR/p70S6K signaling. However, high concentration of harmine led to apoptosis characterized by the propidium/Annexin V-positive cell pollution, cell shrunk and the collapse of mitochondrial membrane potential. The regulation of Bcl-2, Bax and the gathering of cleaved-PARP, cleaved-caspase 3 and cleaved-caspase 9 contributed to the induction of apoptosis. In addition, 10µM LY294002 (a specific inhibitor of PI3K/Akt) combination with 40µM harmine significantly increased the cytotoxicity to the gastric cancer cells and up-regulated both the apoptosis-related protein (cleaved-PARP, cleaved-caspase-3) and autophagy-related protein (Beclin-1, LC3-II, and p62). Adding the inhibitor of autophagy, 3-MA or BafA1, increased the viability of harmine-exposured gastric cancer cells, which confirmed the role of autophagy played in the gastric cancer cell death induced by harmine. CONCLUSION: Harmine might be a potent inducer of apoptosis and autophagy, which offered evidences to therapy of harmine in gastric carcinoma in the folk medicine.

Antiproliferative and anti-inflammatory furostanol saponins from the rhizomes of Tupistra chinensis.

Phytochemical investigations of the rhizome of Tupistra chinensis led to the isolation of ten new furostanol saponins along with fourteen known spirostanols. Their chemical structures were elucidated on the basis of spectroscopic and chemical methods, including IR, NMR, MS, and GC analyses. The antiproliferative effects against FaDu and Detroit 562 cell lines and inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in a macrophage cell line RAW 264.7 were assayed for all the isolated compounds. Compound 14 exhibited significant antiproliferative effects against FaDu and Detroit 562 cells with IC50 values of 1.1±0.1 and 1.2±0.1µM, respectively. Compounds 1, 2, 6, 13, 16, 19 and 24 exhibited inhibitory effects on NO production with IC50 values ranging from 15.7 to 46.2µM.

Antiproliferative and anti-inflammatory polyhydroxylated spirostanol saponins from Tupistra chinensis.

Tupistra chinensis is widely distributed in southwestern China and its rhizome is a famous folk medicine for the treatment of carbuncles and pharyngitis. Its chemical identity of potent antiproliferative and anti-inflammatory constituents has been carried out in this study. Twenty-three polyhydroxylated spirostanol saponins, including nine novels, were isolated and identified. The new spirostanol saponins were elucidated as spirost-25(27)-en-1ß,2ß,3ß,4ß,5ß-pentol-2-O-ß-D-xylopyranoside (1), spirost-25(27)- en-1ß,2ß,3ß,4ß,5ß-pentol-2-O-α-L-arabinopyranoside (2), spirost-25(27)-en- 1ß,3α,5ß-triol (12), spirost-25(27)-en-1ß,3α,4ß,5ß,6ß-pentol (13), spirost-25(27)-en- 1ß,2ß,3ß,5ß-tetraol-5-O-ß-D-glucopyranoside (16), 5ß-spirost-25(27)-en-1ß,3ß-diol- 3-O-ß-D-glucopyranosyl-(1 → 4)-ß-D-glucopyranoside (17), (25R)-5ß-spirostan- 1ß,3ß-diol-3-O-ß-D-glucopyranosyl-(1 → 6)-ß-D-glucopyranoside (18), (25R)-5ß- spirostan-1ß,3ß-diol-3-O-ß-D-fructofuranosyl-(2 → 6)-ß-D-glucopyranoside (19), 5ß-spirost-25(27)-en-3ß-ol-3-O-ß-D-glucopyranosyl-(1 → 4)-ß-D-glucopyranoside (20). The antiproliferative effects against seven human cancer cell lines and inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in a macrophage cell line RAW 264.7 were assayed for all the isolated compounds. Compounds 17, 19 and 21 exhibited potential antiproliferative activities against all of human cancer cell lines tested. Compounds 21 showed significant inhibition on NO production with IC50 values of 11.5 µM. These results showed that the spirostanol saponins isolated from the dried rhizomes of T. chinensis have potent antiproliferative and anti-inflammatory activities and T. chinensis might be used as anticancer and.anti-inflammatory supplement.

Bioactive spirostanol saponins from the rhizome of Tupistra chinensis.

Phytochemical investigations of the rhizome of Tupistra chinensis led to the isolation of six new spirostanol saponins, one new spirostanol, along with eight known spirostanols. Their chemical structures were elucidated on the basis of spectroscopic and chemical methods, including IR, NMR, MS, and GC analyses. The antiproliferative effects against five human cancer cell lines were assayed for all the isolated compounds. Compounds 8, 12 and 15 showed potent cytotoxic activities against K562 cells. The isolated compounds were evaluated for their inhibitory activities on nitric oxide (NO) production induced by lipopolysaccharide in a macrophage cell line RAW 264.7. Compounds 2 and 12 showed significant inhibition on NO production with IC50 values of 16.1±1.8 and 13.5±1.2 µM, respectively.

Phenolics from Durian Exert Pronounced NO Inhibitory and Antioxidant Activities.

Durian, known as the king of fruits, is native to Southeast Asia and popular in many countries. Bioactivity-guided fractionation of the peel of durian was applied to determine its bioactive constituents. Four novel phenolics, along with 16 known, were purified and identified. Four novel phenolics were elucidated to be durianol A (1), durianol B (2), durianol C (3), and 5'-methoxy-7'-epi-jatrorin A (4), respectively. The antioxidant and NO inhibitory activities were evaluated for the isolated phenolics. Some phenolics showed significant antioxidant activity in the DPPH and superoxide anion radical scavenging capacity assay. Most of the phenolics revealed pronounced inhibitory effects on NO production in murine RAW 264.7 cells induced by LPS, which showed more potent NO inhibitory activity compared to indomethacin. The results strongly demonstrated that the phenolics may be partially responsible for durian's NO inhibitory activity.