Suppression of inflammation-induced lung cancer cells proliferation and metastasis by exiguaflavanone A and exiguaflavanone B from Sophora exigua root extract through NLRP3 inflammasome pathway inhibition.

Objective: Non-small cell lung cancer (NSCLC) is recognized for its aggressive nature and propensity for high rates of metastasis. The NLRP3 inflammasome pathway plays a vital role in the progression of NSCLC. This study aimed to investigate the effects of S. exigua extract and its active compounds on NLRP3 regulation in NSCLC using an in vitro model. Methods: S. exigua was extracted using hexane, ethyl acetate and ethanol to obtain S. exigua hexane fraction (SE-Hex), S. exigua ethyl acetate fraction (SE-EA), and S. exigua ethanol fraction (SE-EtOH) respectively. The active compounds were identified using column chromatography and NMR analysis. A549 cells were primed with lipopolysaccharide (LPS) and adenosine triphosphate (ATP) for activated NLRP3 inflammasome. The anti-inflammatory properties were determined using ELISA assay. The anti-proliferation and anti-metastasis properties against LPS-ATP-induced A549 cells were determined by colony formation, cell cycle, wound healing, and trans-well migration and invasion assays. The inflammatory gene expressions and molecular mechanism were determined using RT-qPCR and Western blot analysis, respectively. Results: SE-EA exhibited the greatest anti-inflammation properties compared with other two fractions as evidenced by the significant inhibition of IL-1ß, IL-18, and IL-6, cytokine productions from LPS-ATP-induced A549 cells in a dose-dependent manner (p < 0.05). The analysis of active compounds revealed exiguaflavanone A (EGF-A) and exiguaflavanone B (EGF-B) as the major compounds present in SE-EA. Then, SE-EA and its major compound were investigated for the anti-proliferation and anti-metastasis properties. It was found that SE-EA, EGF-A, and EGF-B could inhibit the proliferation of LPS-ATP-induced A549 cells through cell cycle arrest induction at the G0/G1 phase and reducing the expression of cell cycle regulator proteins. Furthermore, SE-EA and its major compounds dose-dependently suppressed migration and invasion of LPS-ATP-induced A549 cells. At the molecular level, SE-EA, EGF-A, and EGF-B significantly downregulated the mRNA expression of IL-1ß, IL-18, IL-6, and NLRP3 in LPS-ATP-induced A549 cells. Regarding the mechanistic study, SE-EA, EGF-A, and EGF-B inhibited NLRP3 inflammasome activation through suppressing NLRP3, ASC, pro-caspase-1(p50 form), and cleaved-caspase-1(p20 form) expressions. Conclusion: Targeting NLRP3 inflammasome pathway holds promise as a therapeutic approach to counteract pro-tumorigenic inflammation and develop novel treatments for NSCLC.

Protective Effects of Proanthocyanidin-Rich Fraction from Red Rice Germ and Bran on Lung Cell Inflammation via Inhibition of NF-κB/NLRP3 Inflammasome Pathway.

The activation of the NLRP3 inflammasome pathway during infectious pathogen-induced immunopathology can lead to chronic inflammation and various adverse health outcomes. Identification of functional foods with anti-inflammatory properties is crucial for preventing inflammation triggered by NLRP3 inflammasome activation. This study aimed to investigate the anti-inflammatory properties of a proanthocyanidin-rich fraction obtained from red rice germ and bran against lipopolysaccharide (LPS) and adenosine triphosphate (ATP)-induced condition in A549 lung cells. The proanthocyanidin-rich fraction from Yamuechaebia 3 red rice extract (YM3-PRF) was obtained using column chromatography with Sephadex LH20, and its total proanthocyanidin content was determined to be 351.43 ± 1.18 mg/g extract using the vanillin assay. A549 lung cells were pretreated with YM3-PRF at concentrations of 5-20 µg/mL prior to exposure to LPS (1 µg/mL) and ATP (5 nM). The results showed that YM3-PRF significantly inhibited the expression of inflammatory mRNAs (NLRP3, IL-6, IL-1ß, and IL-18) and the secretion of cytokines (IL-6, IL-1ß, and IL-18) in a dose-dependent manner (p < 0.05). Mechanistically, YM3-PRF exerted its anti-inflammatory effects by inhibiting NF-κB translocation and downregulating proteins associated with the NLRP3 inflammasome pathway (NLRP3, ASC, pro-caspase-1, and cleaved-caspase-1). These findings suggest that the proanthocyanidin-rich fraction from red rice germ and bran has protective effects and may serve as a potential therapeutic option for chronic inflammatory diseases associated with NLRP3 inflammasome activation.

Comparative analysis of bioactive-phytochemical characteristics, antioxidants activities, and anti-inflammatory properties of selected black rice germ and bran (Oryza sativa L.) varieties.

Black rice has numerous health benefits and one of the well-known functional foods throughout the world. To encourage the increasing trend of the consumer interest in health-promoting functional foods, special varieties of rice have been developed offering greater nutrient values and exhibiting biological activities that are beneficial to the consumer. In this study, we aimed to evaluate the associations of the phytochemical contents, antioxidants, and anti-inflammatory properties among eight selected black rice germ and bran extracts (BR extracts) from 4 non-glutinous and 4 glutinous rice varieties. Accordingly, glutinous BR extracts possessed higher degree of Cyanidin-3-O-glucoside (C3G), Peonidin-3-O-glucoside (P3G) contents, antioxidant and anti-inflammatory properties than the non-glutinous BR extracts. Pearson's correlation indicated that the amount of C3G in the BR extracts had a strong positive association with the antioxidant properties (DPPH; r = 0.846, ABTS; r = 0.923, and FRAP; r = 0.958, p < 0.01). While P3G exhibited a strong positive association with the anti-inflammatory properties (r value = 0.717 and 0.797 for IL-6 and TNF-α inhibition, respectively, p < 0.05). Lastly, the principal component analysis (PCA) categorized the black rice varieties into three groups: Group A with high C3G content and superior antioxidant properties, Groups B with a high amount of P3G and potent anti-inflammatory properties, and Group C with a lower amount of phytochemical contents and less potent bioactivities. Overall, the outcomes of this study could provide vital information to food industries in selecting the variety of black rice for the functional food based on the anthocyanin contents that could benefit to consumers for new normal healthy lifestyle.

Hesperetin from Root Extract of Clerodendrum petasites S. Moore Inhibits SARS-CoV-2 Spike Protein S1 Subunit-Induced NLRP3 Inflammasome in A549 Lung Cells via Modulation of the Akt/MAPK/AP-1 Pathway.

Inhibition of inflammatory responses from the spike glycoprotein of SARS-CoV-2 (Spike) by targeting NLRP3 inflammasome has recently been developed as an alternative form of supportive therapy besides the traditional anti-viral approaches. Clerodendrum petasites S. Moore (C. petasites) is a Thai traditional medicinal plant possessing antipyretic and anti-inflammatory activities. In this study, C. petasites ethanolic root extract (CpEE) underwent solvent-partitioned extraction to obtain the ethyl acetate fraction of C. petasites (CpEA). Subsequently, C. petasites extracts were determined for the flavonoid contents and anti-inflammatory properties against spike induction in the A549 lung cells. According to the HPLC results, CpEA significantly contained higher amounts of hesperidin and hesperetin flavonoids than CpEE (p < 0.05). A549 cells were then pre-treated with either C. petasites extracts or its active flavonoids and were primed with 100 ng/mL of spike S1 subunit (Spike S1) and determined for the anti-inflammatory properties. The results indicate that CpEA (compared with CpEE) and hesperetin (compared with hesperidin) exhibited greater anti-inflammatory properties upon Spike S1 induction through a significant reduction in IL-6, IL-1ß, and IL-18 cytokine releases in A549 cells culture supernatant (p < 0.05). Additionally, CpEA and hesperetin significantly inhibited the Spike S1-induced inflammatory gene expressions (NLRP3, IL-1ß, and IL-18, p < 0.05). Mechanistically, CpEA and hesperetin attenuated inflammasome machinery protein expressions (NLRP3, ASC, and Caspase-1), as well as inactivated the Akt/MAPK/AP-1 pathway. Overall, our findings could provide scientific-based evidence to support the use of C. petasites and hesperetin in the development of supportive therapies for the prevention of COVID-19-related chronic inflammation.

Cyanidin-3-O-glucoside and Peonidin-3-O-glucoside-Rich Fraction of Black Rice Germ and Bran Suppresses Inflammatory Responses from SARS-CoV-2 Spike Glycoprotein S1-Induction In Vitro in A549 Lung Cells and THP-1 Macrophages via Inhibition of the NLRP3 Inflammasome Pathway.

Black rice is a functional food that is high in anthocyanin content, primarily C3G and P3G. It possesses nutraceutical properties that exhibit a range of beneficial effects on human health. Currently, the spike glycoprotein S1 subunit of SARS-CoV-2 (SP) has been reported for its contribution to pathological inflammatory responses in targeting lung tissue and innate immune cells during COVID-19 infection and in the long-COVID phenomenon. Our objectives focused on the health benefits of the C3G and P3G-rich fraction of black rice germ and bran (BR extract) on the inhibition of inflammatory responses induced by SP, as well as the inhibition of NF-kB activation and the NLRP3 inflammasome pathway in an in vitro model. In this study, BR extract was identified for its active anthocyanins, C3G and P3G, using the HPLC technique. A549-lung cells and differentiated THP-1 macrophages were treated with BR extract, C3G, or P3G prior to exposure to 100 ng/mL of SP. Their anti-inflammatory properties were then determined. BR extract at concentrations of 12.5−100 µg/mL exhibited anti-inflammation activity for both A549 and THP-1 cells through the significant suppression of NLRP3, IL-1ß, and IL-18 inflammatory gene expressions and IL-6, IL-1ß, and IL-18 cytokine secretions in a dose-dependent manner (p < 0.05). It was determined that both cell lines, C3G and P3G (at 1.25−10 µg/mL), were compatibly responsible for the significant inhibition of SP-induced inflammatory responses for both gene and protein levels (p < 0.05). With regard to the anti-inflammation mechanism, BR extract, C3G, and P3G could attenuate SP-induced inflammation via counteraction with NF-kB activation and downregulation of the inflammasome-dependent inflammatory pathway proteins (NLRP3, ASC, and capase-1). Overall, the protective effects of anthocyanins obtained from black rice germ and bran can be employed in potentially preventive strategies that use pigmented rice against the long-term sequelae of COVID-19 infection.

Luteolin-rich fraction from Perilla frutescens seed meal inhibits spike glycoprotein S1 of SARS-CoV-2-induced NLRP3 inflammasome lung cell inflammation via regulation of JAK1/STAT3 pathway: A potential anti-inflammatory compound against inflammation-induced long-COVID.

Objective: The multi-systemic inflammation as a result of COVID-19 can persevere long after the initial symptoms of the illness have subsided. These effects are referred to as Long-COVID. Our research focused on the contribution of the Spike protein S1 subunit of SARS-CoV-2 (Spike S1) on the lung inflammation mediated by NLRP3 inflammasome machinery and the cytokine releases, interleukin 6 (IL-6), IL-1beta, and IL-18, in lung epithelial cells. This study has attempted to identify the naturally- occurring agents that act against inflammation-related long-COVID. The seed meal of Perilla frutescens (P. frutescens), which contains two major dietary polyphenols (rosmarinic acid and luteolin), has been reported to exhibit anti-inflammation activities. Therefore, we have established the ethyl acetate fraction of P. frutescens seed meal (PFEA) and determined its anti-inflammatory effects on Spike S1 exposure in A549 lung cells. Methods: PFEA was established using solvent-partitioned extraction. Rosmarinic acid (Ra) and luteolin (Lu) in PFEA were identified using the HPLC technique. The inhibitory effects of PFEA and its active compounds against Spike S1-induced inflammatory response in A549 cells were determined by RT-PCR and ELISA. The mechanistic study of anti-inflammatory properties of PFEA and Lu were determined using western blot technique. Results: PFEA was found to contain Ra (388.70 ± 11.12 mg/g extract) and Lu (248.82 ± 12.34 mg/g extract) as its major polyphenols. Accordingly, A549 lung cells were pre-treated with PFEA (12.5-100 µg/mL) and its two major compounds (2.5-20 µg/mL) prior to the Spike S1 exposure at 100 ng/mL. PFEA dose-dependently exhibited anti-inflammatory properties upon Spike S1-exposed A549 cells through IL-6, IL-1ß, IL-18, and NLRP3 gene suppressions, as well as IL-6, IL-1ß, and IL-18 cytokine releases with statistical significance (p < 0.05). Importantly, Lu possesses superior anti-inflammatory properties when compared with Ra (p < 0.01). Mechanistically, PFEA and Lu effectively attenuated a Spike S1-induced inflammatory response through downregulation of the JAK1/STAT3-inflammasome-dependent inflammatory pathway as evidenced by the downregulation of NLRP3, ASC, and cleaved-caspase-1 of the NLRP3 inflammasome components and by modulating the phosphorylation of JAK1 and STAT3 proteins (p < 0.05). Conclusion: The findings suggested that luteolin and PFEA can modulate the signaling cascades that regulate Spike S1-induced lung inflammation during the incidence of Long-COVID. Consequently, luteolin and P. frutescens may be introduced as potential candidates in the preventive therapeutic strategy for inflammation-related post-acute sequelae of COVID-19.

A Pharmacological Strategy Using Stemofoline for more Efficacious Chemotherapeutic Treatments Against Human Multidrug Resistant Leukemic Cells

Our previous study reported that stemofoline (STF) exhibited a synergistic effect with chemotherapeutic drugs in human multidrug-resistant (MDR) leukemic cells (K526/Adr) by inhibiting the function of P-glycoprotein, which is a membrane transporter that is overexpressed in several types of MDR cancers. This study further investigated the effects of a combination treatment of STF and doxorubicin (DOX) in vitro and in vivo. The combination treatment of 50 mg/kg of STF strongly enhanced the anti-tumor activity of DOX in SCID-beige mice bearing K562/Adr xenografts without additional toxicity when compared to the single treatment groups. Additionally, an examination of the proliferation markers (Ki67) and the apoptotic marker (TUNEL) in tumor tissues in each group revealed that the combination therapy significantly reduced Ki67 positive cells and increased apoptotic cells. From the in vitro experiments we also found that this combination treatment dramatically induced G1 and G2M arrest in K562/Adr when compared to a single treatment of DOX. STF treatment alone did not show any cytotoxic effect to the cells. These results suggest that the accumulation of DOX enhanced by STF was sufficient to induce cell cycle arrest in K562/Adr. These findings support our previous in vitro data and indicate the possibility of developing STF as an adjuvant therapy in cancer treatments.

Relationships of Ex-Vivo Drug Resistance Assay and Cytokine Production with Clinicopathological Features in the Primary Cell Culture of Thai Ovarian and Fallopian Tube Cancer Patients

Objective: Our goal was to determine the ex-vivo drug resistance assay, as well as the cytokine production, in response to platinum-based chemotherapy treatment in primary culture cells established from the tumor tissue of ovarian or fallopian tube carcinoma patients, and to predict the clinical responses to chemotherapy. Methods: Sensitivity to the platinum-based drug was analyzed in two ovarian cancer cell lines and 19 tumor samples using the primary cell culture obtained from 19 patients having ovarian or fallopian tube cancer that had undergone surgery from 2014 to 2017. Results: Our findings in the ovarian cancer cell lines showed that SKOV3 cells displayed 10-fold greater resistance to cisplatin and 5.8 times more resistance to carboplatin than A2780 cells. SKOV3 cells displayed platinum-induced IL-6 and IL-8 overproduction whereas wild type A2780 displayed no detectable cytokine production. Regarding the primary cell culture obtained from patients, ex-vivo drug resistance assay results revealed that although extreme drug resistance was correlated with late stage ovarian cancer (P= 0.031), it could not independently predict or alter the outcomes of patients with ovarian or fallopian tube cancer. No relationship was found between basal cytokine secretion and the clinical parameters. However, carboplatin-induced IL-6 and IL-8 production had a significant association with the clinical response to chemotherapy (P=0.016 and P=0.038 respectively). Carboplatin-induced IL-8 overproduction was correlated with FIGO staging III-IV (P=0.026), but no correlation between carboplatin-induced IL-6 and FIGO staging (P= 0.061) was noted. Conclusion: These results suggest that cytokine production in response to platinum-based chemotherapy in primary culture cells may be useful as a predictive marker for the therapeutic outcomes among ovarian or fallopian tube cancer patients.

Modulation of P-glycoprotein by Stemona alkaloids in human multidrug resistance leukemic cells and structural relationships.

BACKGROUND: Multidrug resistance (MDR) is a major reason for the failure of chemotherapy in the treatment of cancer patients. P-gp over-expression in MDR cancer cells is a multifactorial phenomenon with biochemical resistance mechanisms. Stemofoline (STF), isolated from Stemona bukillii, has been reported to be an MDR reversing compound. PURPOSE: This study investigated whether other Stemona alkaloids that had been purified from Stemonaceae plants exerted MDR modulation activity. METHODS: MTT assay was performed to determine the MDR reversing property of the alkaloids. Modulation of P-gp function by these compounds was investigated using cell cycle analysis and P-gp fluorescent substrate accumulation assays. P-gp expression was determined by Western blot analysis. We preliminarily examined the safety of these compounds in normal human fibroblasts and human peripheral blood mononuclear cells (PBMCs) using the MTT assay, and in red blood cells (human and rat) through in vitro hemolysis assays. RESULTS: Three of the eight alkaloids tested, isostemofoline (ISTF), 11Z -didehydrostemofoline (11Z-DSTF) and 11E-didehydrostemofoline (11E-DSTF), enhanced the chemotherapeutic sensitivity of MDR leukemic K562/Adr cells, which overexpressed P-gp. The P-gp functional studies showed that these three alkaloids increased the accumulation of P-gp substrates, calcein-AM (C-AM) and rhodamine123 (Rho 123) in K562/Adr cells, while this effect was not seen in drug sensitive parental K562 cells. Whereas, the alkaloids did not alter P-gp expression as was determined by Western blotting analysis. CONCLUSION: The alkaloids reversed MDR via the inhibition of P-gp function. For pharmaceutical safety testing, the alkaloids were found to be not toxic to normal human fibroblasts and PBMCs. Moreover, the effective compounds did not induce hemolysis in either human or rat erythrocytes. These compounds may be introduced as potential candidate molecules for treating cancers exhibiting P-gp-mediated MDR.

Kuguacin J isolated from bitter melon leaves modulates paclitaxel sensitivity in drug-resistant human ovarian cancer cells.

We previously reported the multidrug resistance-reversing ability of kuguacin J (KJ) in cervical cancer cells via the inhibition of P-glycoprotein (P-gp) function. This study investigated whether KJ could promote cisplatin- and paclitaxel (PTX)-induced cancer cell death in drug-resistance human ovarian cancer cells (SKOV3). Cytotoxicity testing showed that SKOV3 was more resistant to cisplatin and PTX compared to drug-sensitive human ovarian cancer cells (A2780). The cytotoxicity of PTX was significantly increased in SKOV3 cells when co-treated with KJ. We found that enhancement of PTX toxicity in the cells was not related to P-gp inhibition. To elucidate the mechanism by which KJ increases PTX sensitivity, the expression of cell death involving proteins was analyzed by Western blot analysis. The results showed that PTX treatment increased the level of an anti-apoptotic protein, survivin, which may be involved in drug resistance in SKOV3. The co-treatment with PTX and KJ dramatically decreased the level of survivin and markedly induced cleavage of PARP and caspase-3, which are apoptotic-induced molecules. These findings may support the use of KJ as an effective chemosensitizer in combination with conventional chemotherapy to promote PTX sensitization in ovarian cancer patients.

Phorbol esters in seed oil of Jatropha curcas L. (saboodam in Thai) and their association with cancer prevention: from the initial investigation to the present topics.

PURPOSE: In 1988, we first reported the complete chemical structure of a new type of phorbol ester, abbreviated to DHPB, found in seed oil of Jatropha curcas L. (Saboodam in Thai) and its tumor-promoting activity on mouse skin. Although this seed oil contains toxic phorbol ester, it was planned to use it as a feasible renewable oil and the extracted seed cake as fertilizer. This utilization value opened a new science of Jatropha curcas. METHODS: The main experimental results are cited from our publications, and the relevant literature screened from journals and PubMed. RESULTS AND DISCUSSION: This paper begins with our original work on the structural elucidation of a new phorbol ester, 12-deoxy-16-hydroxyphorbol (DHPB): its tumor-promoting activity was compared with that of TPA. We think that it is timely to review the following research advances with Jatropha curcas, so numerous topics are classified as follows: (1) historical development of phorbol esters in seed oil; (2) toxicity of phorbol ester based on various bioassays; (3) degradation of phorbol ester; (4) a new pharmaceutical compound in seed; and (5) tumor promotion and progression with endogeneous tumor promoters in human carcinogenesis. The discovery of phorbol ester in seed oil raised awareness of the danger of public use of seed oil and seed cake in Thailand, and also indicated the necessity of discussing the concept of primary and tertiary cancer preventions. CONCLUSION: It is worthwhile to study the future benefits and cancer risks of globally distributed Jatropha curcas L.

Down-regulation of histone deacetylase 4, -5 and -6 as a mechanism of synergistic enhancement of apoptosis in human lung cancer cells treated with the combination of a synthetic retinoid, Am80 and green tea catechin.

(-)-Epigallocatechin gallate (EGCG), a green tea catechin, acts as a synergist with various anticancer drugs, including retinoids. Am80 is a synthetic retinoid with a different structure from all-trans-retinoic acid: Am80 is now clinically utilized as a new drug for relapsed and intractable acute promyelocytic leukemia patients. Our experiments showed that the combination of EGCG and Am80 synergistically induced both apoptosis in human lung cancer cell line PC-9 and up-regulated expressions of growth arrest and DNA damage-inducible gene 153 (GADD153), death receptor 5, and p21waf1 genes in the cells. To understand the mechanisms of synergistic anticancer activity of the combination, we gave special attention to the lysine acetylation of proteins. Proteomic analysis using nanoLC-ESI-MS/MS revealed that PC-9 cells treated with the combination contained 331 acetylated proteins, while nontreated cells contained 553 acetylated proteins, and 59 acetylated proteins were found in both groups. Among them, the combination increased acetylated-p53 and acetylated-α-tubulin through reduction of histone deacetylase (HDAC) activity in cytosol fraction, although the levels of acetylation in histones H3 or H4 did not change, and the combination reduced protein levels of HDAC4, -5 and -6 by 20% to 80%. Moreover, we found that a specific inhibitor of HDAC4 and -5 strongly induced p21waf1 gene expression, and that of HDAC6 induced both GADD153 and p21waf1 gene expression, which resulted in apoptosis. All results demonstrate that EGCG in combination with Am80 changes levels of acetylation in nonhistone proteins via down-regulation of HDAC4, -5 and -6 and stimulates apoptotic induction.

Reversal of human multi-drug resistance leukaemic cells by stemofoline derivatives via inhibition of P-glycoprotein function.

Our previous study reported multi-drug resistance (MDR) reversing properties of synthetic stemofoline derivatives (STFD), OH-A1, NH-B6 and NH-D6 on P-glycoprotein (P-gp) overexpressing leukaemic cells (K562/Adr); however, the mechanism was unclear. In this study, we further investigated whether the STFD reverse MDR through either the inhibition of P-gp function or expression in K562/Adr cells, or both. The P-gp functional studies showed that the STFD increased the accumulation of calcein-AM, rhodamine 123 and [(14) C]-doxorubicin in K562/Adr cells, while the effects have not been seen in their parental sensitive cancer cell line (K562). Further, the STFD did not alter the P-gp expression as determined by Western blotting. This study concludes that the STFD reverse MDR via the inhibition of P-gp function. The efficacy of the STFD to inhibit P-gp function followed the order: NH-B6 > OH-A1 > NH-D6. These compounds could be introduced as candidate molecules for treating cancers exhibiting P-gp-mediated MDR.

Inhibition of P-glycoprotein mediated multidrug resistance by stemofoline derivatives.

Resistance to chemotherapy in cancer patients has been correlated to the overexpression of the ATP-binding cassette (ABC) drug transporters including P-glycoprotein (P-gp) that actively efflux chemotherapeutic drugs from cancer cells. We examined the multidrug resistance reversing property of stemofoline derivatives in drug-resistance human cervical carcinoma (KB-V1) and human leukemic (K562/Adr) cell lines that overexpress P-gp. Didehydrostemofoline and eleven of its derivatives were synthesized and the cytotoxicity and their effect on doxorubicin, vinblastine and paclitaxel sensitivity in drug resistant (KB-V1 and K562/Adr) and drug sensitive (KB-3-1 and K562) cell lines by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay were determined. We found that three out of the twelve stemofoline derivatives including OH-A1, NH-B6 and NH-D6 showed commitment efficiency to increase sensitivity to doxorubicin, vinblastine and paclitaxel in KB-V1 cells and increase sensitivity to doxorubicin, and paclitaxel in K562/Adr cells whereas the effects have not been seen in their parental sensitive cancer cell lines (KB-3-1 and K562). These results indicate that stemofoline derivatives reversed P-gp-mediated multidrug resistance in vitro, and thus could be developed as effective chemosensitizers to treat multidrug-resistant cancers. The molecular mechanism of modulation of P-gp would be further determined.