A new dimeric dihydrochalcone and a new prenylated flavone from the bud covers of Artocarpus altilis: potent inhibitors of cathepsin K

Antiviral C-geranylated flavonoids from Artocarpus communis

Ten C-geranylated flavonoids, along with three known analogues, were isolated from the leaves of Artocarpus communis. The chemical structures of these compounds were unambiguously determined via comprehensive spectroscopic analysis, single-crystal X-ray diffraction experiments, and quantum chemical electronic circular dichroism calculations. Structurally, artocarones A-I (1-9) represent a group of unusual, highly modified C-geranylated flavonoids, in which the geranyl chain is cyclised with the ortho-hydroxy group of flavonoids to form various heterocyclic scaffolds. Notably, artocarones E and G-I (5 and 7-9) feature a 6H-benzo[c]chromene core that is hitherto undescribed in C-geranylated flavonoids. Artocarone J (10) is the first example of C-9-C-16 connected C-geranylated aurone. Meanwhile, the plausible biosynthetic pathways for these rare C-geranylated flavonoids were also proposed. Notably, compounds 1, 2, 4, 8, 11, and 12 exhibited promising in vitro inhibitory activities against respiratory syncytial virus and herpes simplex virus type 1.

Prenylated dihydroflavones from the root barks of Morus alba

Three new prenylated dihydroflavones, moralbaflavones A-C (1-3), together with four known ones (4a/4b, 5, and 6) were isolated from the root barks of Morus alba L. Their structures including the absolute configurations were determined by the analysis of HRMS, NMR, and ECD data. The neuroprotective properties of these prenylated dihydroflavones were screened at the concentration of 10 µM in the sodium nitroprusside-induced rat pheochromocytoma PC-12 cells, and the results showed moralbaflavone C (3) possessed significant neuroprotective activity, being more potent than the positive control edaravone.

Isoprenylated Flavonoids and 2-Arylbenzofurans from the Root Bark of Morus alba L. and Their Cytotoxic Activity against HGC27 Cancer Cells

Three new compounds (1, 11, and 12), together with 32 known ones, were isolated from the root bark of Morus alba L. using various chromatographic methods. The structures of the undescribed compounds were elucidated based on 1D, 2D NMR, and HRESIMS dataanalysis, while the known ones were identified by comparison of their spectroscopic data with those reported in the literature. All the isolates were evaluated for their cytotoxic activities against human gastric cancer HGC27 cells by CCK-8 assay. Among them, compounds 5, 8, 10, and 30 exhibited cytotoxic activities on HGC27 cells with IC50 values of 33.76 ± 2.64 μM, 28.94 ± 0.72 μM, 6.08 ± 0.34 μM, and 10.24 ± 0.89 μM, respectively. Furthermore, compound 10 was confirmed to reduce proliferation ability, increase apoptosis rate, and inhibit cell migration pathway by annexin V/PI double staining experiment, transwell experiment, and Western blot analysis.

Anti-cancer bioprospecting on medicinal plants from Indonesia: A review

The Indonesian archipelago is home to the second largest biodiversity in the world and is inhabited by more than 300 ethnic groups with a total population of more than 270 million. The indigenous population still rely on traditional medicine practices, especially the use of plant-based remedies. Although modern science-based exploration on Indonesian medicinal plants started with the European settlement in the archipelago in the 16th century, it was not until the 1970's that the phytochemistry of Indonesian medicinal plants was recognized for its potency. The need for new cancer cures to increase the quality of human life has led to the bioprospecting of medicinal plants including those of Indonesian origin. Despite published reports on the anticancer potency of Indonesian medicinal plants, to date there has been no comprehensive review on this topic. In this manuscript, we review the phytochemical and pharmacological studies on medicinal plants from Indonesia related to cancer therapy. Established databases (GARUDA, SciFinder, and PubMed) were used to collate data from 1990 to 2022, resulting in the description of 134 medicinal plants and their phytochemical and pharmacological properties including examples containing potent agents against breast, leukaemia, cervix, lung, and colon cancer cell lines based on in vitro bioassays and in vivo evaluation. These findings provide valuable insights into the bioprospecting of Indonesian medicinal plant providing directions for future studies, including the development of new therapeutics, both as botanicals or by using conventional dosage.

Chemical constituents from Morus alba with proprotein convertase subtilisin/kexin type 9 expression and secretion inhibitory activity

Six new flavanones, including sanggenol W (1), morusalnol D-F (2-4) and neovanone A and B (5 and6), and fourteen known compounds were isolated from the methanol extract of the dried root bark of Morus alba using various column chromatographic methods. Their structures were elucidated using spectroscopic methods. The isolated compounds were tested in vitro for LDLR, PCSK9 and IDOL mRNA regulatory activity, and it was found that betulinic acid (13) showed the most potent effect on downregulation of PCSK9 and upregulation of LDLR at both mRNA and protein levels, showing comparable results to berberine, the positive control. In addition, betulinic acid (13) inhibited PCSK9 secretion, indicating its role as a future PCSK9 synthesis inhibitor.

Effect of geranylated dihydrochalcone from Artocarpus altilis leaves extract on Plasmodium falciparum ultrastructural changes and mitochondrial malate: Quinone oxidoreductase

Nearly half of the world's population is at risk of being infected by Plasmodium falciparum, the pathogen of malaria. Increasing resistance to common antimalarial drugs has encouraged investigations to find compounds with different scaffolds. Extracts of Artocarpus altilis leaves have previously been reported to exhibit in vitro antimalarial activity against P. falciparum and in vivo activity against P. berghei. Despite these initial promising results, the active compound from A. altilis is yet to be identified. Here, we have identified 2-geranyl-2', 4', 3, 4-tetrahydroxy-dihydrochalcone (1) from A. altilis leaves as the active constituent of its antimalarial activity. Since natural chalcones have been reported to inhibit food vacuole and mitochondrial electron transport chain (ETC), the morphological changes in food vacuole and biochemical inhibition of ETC enzymes of (1) were investigated. In the presence of (1), intraerythrocytic asexual development was impaired, and according to the TEM analysis, this clearly affected the ultrastructure of food vacuoles. Amongst the ETC enzymes, (1) inhibited the mitochondrial malate: quinone oxidoreductase (PfMQO), and no inhibition could be observed on dihydroorotate dehydrogenase (DHODH) as well as bc₁ complex activities. Our study suggests that (1) has a dual mechanism of action affecting the food vacuole and inhibition of PfMQO-related pathways in mitochondria.

Chalcone Scaffolds, Bioprecursors of Flavonoids: Chemistry, Bioactivities, and Pharmacokinetics

Chalcones are secondary metabolites belonging to the flavonoid (C6-C3-C6 system) family that are ubiquitous in edible and medicinal plants, and they are bioprecursors of plant flavonoids. Chalcones and their natural derivatives are important intermediates of the flavonoid biosynthetic pathway. Plants containing chalcones have been used in traditional medicines since antiquity. Chalcones are basically α,β-unsaturated ketones that exert great diversity in pharmacological activities such as antioxidant, anticancer, antimicrobial, antiviral, antitubercular, antiplasmodial, antileishmanial, immunosuppressive, anti-inflammatory, and so on. This review provides an insight into the chemistry, biosynthesis, and occurrence of chalcones from natural sources, particularly dietary and medicinal plants. Furthermore, the pharmacological, pharmacokinetics, and toxicological aspects of naturally occurring chalcone derivatives are also discussed herein. In view of having tremendous pharmacological potential, chalcone scaffolds/chalcone derivatives and bioflavonoids after subtle chemical modification could serve as a reliable platform for natural products-based drug discovery toward promising drug lead molecules/drug candidates.

Characterization and Identification of Prenylated Flavonoids from Artocarpus heterophyllus Lam. Roots by Quadrupole Time-Of-Flight and Linear Trap Quadrupole Orbitrap Mass Spectrometry

In this study, a combination of quadrupole time-of-flight mass spectrometry (Q-TOF-MS) and linear trap quadrupole orbitrap mass spectrometry (LTQ-Orbitrap-MS) was performed to investigate the fragmentation behaviors of prenylated flavonoids (PFs) from Artocarpus plants. Fifteen PFs were selected as the model molecules and divided into five types (groups A–E) according to their structural characteristics in terms of the position and existing form of prenyl substitution in the flavone skeleton. The LTQ-Orbitrap-MSⁿ spectra of the [M − H]⁻ ions for these compounds provided a wealth of structural information on the five different types of compounds. The main fragmentation pathways of group A were the ortho effect and retro Diels–Alder (RDA), and common losses of C₄H₁₀, CO, and CO₂. The compounds in group B easily lose C₆H₁₂, forming a stable structure of a 1,4-dienyl group, unlike those in group A. The fragmentation pathway for group C is characterized by obvious ^1,4A⁻, ^1,4B⁻ cracking of the C ring. The diagnostic fragmentation for group D is obvious RDA cracking of the C ring and the successive loss of CH₃ and H₂O in the LTQ-Orbitrap-MSⁿ spectra. Fragmentation with successive loss of CO or CO₂, ·CH₃, and CH₄ in the LTQ-Orbitrap-MSⁿ spectra formed the characteristics of group E. The summarized fragmentation rules were successfully exploited to identify PFs from Artocarpusheterophyllus, a well-known Artocarpus plant, which led to the identification of a total of 47 PFs in this plant.

Advances in the discovery of cathepsin K inhibitors on bone resorption

Cathepsin K (Cat K), highly expressed in osteoclasts, is a cysteine protease member of the cathepsin lysosomal protease family and has been of increasing interest as a target of medicinal chemistry efforts for its role in bone matrix degradation. Inhibition of the Cat K enzyme reduces bone resorption and thus, has rendered the enzyme as an attractive target for anti-resorptive osteoporosis therapy. Over the past decades, considerable efforts have been made to design and develop highly potent, excellently selective and orally applicable Cat K inhibitors. These inhibitors are derived from synthetic compounds or natural products, some of which have passed preclinical studies and are presently in clinical trials at different stages of advancement. In this review, we briefly summarised the historic development of Cat K inhibitors and discussed the relationship between structures of inhibitors and active sites in Cat K for the purpose of guiding future development of inhibitors.

Discovery of a New Class of Cathepsin K Inhibitors in Rhizoma Drynariae as Potential Candidates for the Treatment of Osteoporosis

Rhizoma Drynariae (RD), as one of the most common clinically used folk medicines, has been reported to exert potent anti-osteoporotic activity. The bioactive ingredients and mechanisms that account for its bone protective effects are under active investigation. Here we adopt a novel in silico target fishing method to reveal the target profile of RD. Cathepsin K (Ctsk) is one of the cysteine proteases that is over-expressed in osteoclasts and accounts for the increase in bone resorption in metabolic bone disorders such as postmenopausal osteoporosis. It has been the focus of target based drug discovery in recent years. We have identified two components in RD, Kushennol F and Sophoraflavanone G, that can potentially interact with Ctsk. Biological studies were performed to verify the effects of these compounds on Ctsk and its related bone resorption process, which include the use of in vitro fluorescence-based Ctsk enzyme assay, bone resorption pit formation assay, as well as Receptor Activator of Nuclear factor κB (NF-κB) ligand (RANKL)-induced osteoclastogenesis using murine RAW264.7 cells. Finally, the binding mode and stability of these two compounds that interact with Ctsk were determined by molecular docking and dynamics methods. The results showed that the in silico target fishing method could successfully identify two components from RD that show inhibitory effects on the bone resorption process related to protease Ctsk.

Isoprenylated Flavonoids from Roots of Artocarpus styracifolius

Seven isoprenylated flavonoids were isolated from Artocarpus styracifolius, including one new triisoprenylated flavone, styracifolin D (1), and six known ones, artocarpone B (2), kuwanon C (3), 6-C-prenyl luteolin (4), albanin A (5), 2,4,2′,4′-tetrahydroxy-3′-(3-methyl-2-butenyl)-chalcone (6), and 3′-[γ-hydroxymethyl-( E)-γ-methylallyl]-2,4,2′,4′-tetrahydroxychalcone 11′- O-coumarate (7). The structures of these compounds were determined by analysis of their spectroscopic and mass spectrometric data. Of them, 3 and 5 exhibited inhibitory effects on cathepsin K with IC50 values of 114.6 and 7.4 μM, respectively.

Natural Products as Cathepsin Inhibitors

Cathepsins are proteases found in all animals as well as other organisms. There are approximately a dozen members of this family, which are distinguished by their structure, their catalytic mechanism, and which proteins they cleave. Most of the members become activated at the low pH found in lysosomes. Cathepsins have been identified as therapeutic targets in the search for new drugs against a number of human pathologies, including cancer, Alzheimer's, and osteoporosis.

A number of natural products have been reported as selective inhibitors of some cathepsins. Chemical structure of natural products as inhibitors of cathepsins can be very diverse. Some peptidic natural products are inhibitors of the cysteine protease cathepsins such as E-64 isolated from Aspergillus, which is a cathepsin B inhibitor, or more recently the marine cyanobacterial metabolite gallinamide A which is a selective inhibitor of human cathepsin L. Also amino acid derivatives have been reported as inhibitors of cathepsin A.

Other natural products include chalcone natural products possessing cytotoxic activities against prostate cancer cells and inhibiting cysteine cathepsins in vitro, antipain and its analogues isolated from Streptomyces as inhibitors of cathepsin K, and natural biflavones as novel inhibitors of cathepsins B and K.

In this review we will report the most representative examples of natural products as inhibitors of cathepsins, especially the ones reported during the last decade.

Dipeptidyl peptidase-IV inhibitory activity of dimeric dihydrochalcone glycosides from flowers of Helichrysum arenarium

A methanol extract of everlasting flowers of Helichrysum arenarium L. Moench (Asteraceae) was found to inhibit the increase in blood glucose elevation in sucrose-loaded mice at 500 mg/kg p.o. The methanol extract also inhibited the enzymatic activity against dipeptidyl peptidase-IV (DPP-IV, IC50 = 41.2 μg/ml), but did not show intestinal α-glucosidase inhibitory activities. From the extract, three new dimeric dihydrochalcone glycosides, arenariumosides V-VII (2-4), were isolated, and the stereostructures were elucidated based on their spectroscopic properties and chemical evidence. Of the constituents, several flavonoid constituents, including 2-4, were isolated, and these isolated constituents were investigated for their DPP-IV inhibitory effects. Among them, chalconaringenin 2'-O-β-D-glucopyranoside (16, IC50 = 23.1 μM) and aureusidin 6-O-β-D-glucopyranoside (35, 24.3 μM) showed relatively strong inhibitory activities.

Structures and bioactivities of dihydrochalcones from Metrodorea stipularis

Metrodorea stipularis stem extracts were studied in the search for possible antichagastic, antimalarial, and antitumoral compounds using cruzain from Trypanosoma cruzi, Plasmodium falciparum, and cathepsins B and L, as molecular targets, respectively. Dihydrochalcones 1, 2, 3, and 4 showed significant inhibitory activity against all the targets. Compounds 1-4 displayed IC50 values ranging from 7.7 to 21.6 μM against cruzain; dihydrochalcones 2 and 4 inhibited the growth of three different strains of P. falciparum in low micromolar concentrations; and against cathepsins B and L these compounds presented good inhibitory activity with IC50 values ranging from 1.0 to 14.9 μM. The dihydrochalcones showed good selectivity in their inhibitory activities against the cysteine proteases.

Safety Evaluation of Artocarpus altilis as Pharmaceutical Agent in Wistar Rats

This study was designed to elucidate the acute toxicity of Artocarpus altilis leaf and bark extracts. In acute toxicity study, no mortality or any toxic reaction was recorded in any group after 14 days of administering the extracts (2000 mg Kg⁻¹ BW). The extracts (ALA, ABA, ALM, and ABM) did not cause any behavioural or physical changes in experimental rats. There was no significant (P ≤ 0.05) difference in the biochemical parameters analysed between the groups. Slight elevation in activities of AST and ALT in extract treated groups was observed, but this did not exert any deleterious effect on the normal metabolism which was supported by the histopathology of liver. Histopathological studies showed no remarkable changes after 14 days of oral administration of ALA, ABA, ALM, and ABM extracts. The study contributes to establishing the nontoxic quality parameters of Artocarpus altilis leaf and bark parts and the results suggest the safety of the extracts in therapeutic uses.

Probing antioxidant activity of 2'-hydroxychalcones: crystal and molecular structures, in vitro antiproliferative studies and in vivo effects on glucose regulation

In order to better understand the antioxidant behavior of a series of polyphenolic 2'-hydroxychalcones, we describe the results of several chemical and biological studies, in vitro and in vivo. Single crystal X-ray methods elucidated their molecular structures and important intermolecular interactions such as H-bonding and molecular stacking in the crystal structures that contribute to our knowledge in explaining antioxidant activity. The results of experiments using the 1,1-diphenyl-2-dipicrylhydrazyl (DPPH) UV-vis spectroscopic method indicate that a hydroxyl group in position 5' induces the highest antioxidant activity. Consequently, 2,2',5'-trihydroxychalcone was selected for further study in vitro towards ROS scavenging in L-6 myoblasts and THP-1 human monocytes, where it shows an excellent antioxidant activity in a concentration range lower than that reported by most studies of related molecules. In addition, this chalcone shows a very selective activity: it inhibits the proliferation of leukemic cells, but it does not affect the normal L-6 myoblasts and human fibroblasts. In studying 2,2',5'-trihydroxychalcone's effect on weight gain and serum glucose and insulin levels in Zucker fatty (fa(-)/fa(-)) rats we found that supplementing the diet with a 10 mg/kg dose of this chalcone (3 times weekly) blunted the increase in glucose that co-occurs with weight gain over the 6-week treatment period. It is concluded that 2,2',5'-trihydroxychalcone has the potential to serve as a protective agent for some debilitating diseases.

Minor C-geranylated flavanones from Paulownia tomentosa fruits with MRSA antibacterial activity

Exhaustive chromatographic separation of the chloroform portion of the ethanolic extract obtained from Paulownia tomentosa (Thunb). Steud. (Paulowniaceae) fruits has led to isolation of ten C-6 geranylated flavanones tomentodiplacone C-I and mimulone C-E, featured by 3'-methoxy and 4'-hydroxy or 4'-hydroxy substitution of the B-ring of the flavonoid, respectively. The structures of these compounds were determined by using mass spectrometry (including HRMS) and 1D and 2D NMR spectroscopy. The absolute configurations of the compounds at C-2 were determined using circular dichroism. The obtained compounds showed the presence of a geranyl moiety functionalized by a carbonyl, hydroxyl or methoxyl group, or by formation of tetrahydrofuran or fused-pyrane ring, respectively. All of the flavanones described were isolated for the first time from a natural source. The antibacterial activities of selected compounds isolated along with the previously isolated geranylated flavanones were evaluated against a common panel of microbes and MRSA strains. The selected isolated compounds were tested for their ability to affect eukaryotic translation initiation via dual-luciferase reporter assay (firefly and renilla).

Characterization of tyrosinase inhibitors in the twigs of Cudrania tricuspidata and their structure-activity relationship study

The twigs of Cudrania tricuspidata were found to show strong tyrosinase inhibitory activity, and further detailed component analysis resulted in the isolation of a new flavanol glucoside, (2S,3S)-2,3-trans-dihydromorin-7-O-β-d-glucoside (1), plus twenty-seven known compounds (2-28). Their structures were elucidated on the basis of ESI-MS and NMR spectral data. Among the isolated compounds, trans-dihydromorin (8), oxyresveratrol (9), and steppogenin (12) were found to exhibit significant tyrosinase inhibition activities. Moreover, the structure-activity relationship of these isolated compounds was also discussed.

A new prenylated aurone from Artocarpus altilis

Phytochemical study of the methanol extract of Artocarpus altilis resulted in the isolation of a new prenylated aurone, artocarpaurone (1), together with eight known compounds including two prenylated chalcones (2 and 3), three prenylated flavanones (4-6), and three triterpenes (7-9). The structure of 1 was elucidated as 6-hydroxy-2-[8-hydroxy-2-methyl-2-(4-methyl-3-pentenyl)-2H-1-benzopyran-5-ylmethylene]-3(2H)-benzofuranone by spectroscopic methods including 1D and 2D NMR spectra and FT-ICR-MS. Compound 1 showed moderate nitric oxide radical scavenging activity, whereas 2 and 3 had moderate 2,2-diphenyl-1-picrylhydrazyl radical scavenging effect, compared with the positive control (+)-catechin.

Antioxidant, antimicrobial and tyrosinase inhibitory activities of xanthones isolated from Artocarpus obtusus F.M. Jarrett

One of the most promising plants in biological screening test results of thirteen Artocarpus species was Artocarpus obtusus FM Jarrett and detailed phytochemical investigation of powdered dried bark of the plant has led to the isolation and identification of three xanthones; pyranocycloartobiloxanthone A (1), dihydroartoindonesianin C (2) and pyranocycloartobiloxanthone B (3). These compounds were screened for antioxidant, antimicrobial and tyrosinase inhibitory activities. Pyranocycloartobiloxanthone A (1) exhibited a strong free radical scavenger towards DPPH free radicals with IC₅₀ value of 2 µg/mL with prominent discoloration observed in comparison with standard ascorbic acid, α-tocopherol and quercetin, The compound also exhibited antibacterial activity against methicillin resistant Staphylococcus aureus (ATCC3359) and Bacillus subtilis (clinically isolated) with inhibition zone of 20 and 12 mm, respectively. However the other two xanthones were found to be inactive. For the tyrosinase inhibitory activity, again compound (1) displayed strong activity comparable with the standard kojic acid.

Antiproliferative activity of xanthones isolated from Artocarpus obtusus

An investigation of the chemical constituents in Artocarpus obtusus species led to the isolation of three new xanthones, pyranocycloartobiloxanthone A (1), dihydroartoindonesianin C (2), and pyranocycloartobiloxanthone B (3). The compounds were subjected to antiproliferative assay against human promyelocytic leukemia (HL60), human chronic myeloid leukemia (K562), and human estrogen receptor (ER+) positive breast cancer (MCF7) cell lines. Pyranocycloartobiloxanthone A (1) consistently showed strong cytotoxic activity against the three cell lines compared to the other two with IC₅₀ values of 0.5, 2.0 and 5.0 μg/mL, respectively. Compound (1) was also observed to exert antiproliferative activity and apoptotic promoter towards HL60 and MCF7 cell lines at respective IC₅₀ values. The compound (1) was not toxic towards normal cell lines human nontumorigenic breast cell line (MCF10A) and human peripheral blood mononuclear cells (PBMCs) with IC₅₀ values of more than 30 μg/mL.

12-Acetyl-6-hy-droxy-3,3,9,9-tetra-methyl-furo[3,4-b]pyrano[3,2-h]xanthene-7,11(3H,9H)-dione

The title compound, Artonol B, C(24)H(20)O(7), isolated from the stem bark of Artocarpus kemando, consists of four six-membered rings and one five-membered ring. The tricyclic xanthone ring system is almost planar [maximum deviation 0.115 (5) Å], whereas the pyran-oid ring is in a distorted boat conformation·The furan ring is almost coplanar with the fused aromatic ring, making a dihedral angle of 3.76 (9)°. The phenol ring serves as a intra-molecular hydrogen-bond donor to the adjacent carbonyl group and also acts as an inter-molecular hydrogen-bond acceptor for the methyl groups of adjacent mol-ecules, forming a three-dimensional network in the crystal.

Two-dimensional counter-current chromatography for the preparative separation of prenylflavonoids from Artocarpus altilis

A two-dimensional counter-current chromatographic system (2D-CCC) for preparative isolation and purification of three prenylflavonoids from Artocarpus altilis is presented. An upright CCC instrument (CCC1, total capacity: 1600 ml) was used as the first dimension. Effluent of interest from CCC1 was collected on-line into a 30 ml sample loop by a laboratory-prepared column-switching interface and introduced into a high-speed CCC instrument (CCC2, total capacity: 210 ml) for the second dimension separation. With this 2D-CCC system and a pair of two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water (5:5:7:3 and 5:5:6.5:3.5, v/v/v/v), which had been selected by high-speed CCC, about a 500 mg amount of the crude extract was separated, yielding 9 mg of compound 1, 28 mg of compound 2 and 78 mg of compound 3. The purities of the three prenylflavonoids were 98.7 (1), 98.3 (2) and 97.2% (3), respectively, as determined by HPLC analysis. Their chemical structures were identified by electrospray ionization MS, (1)H NMR and (13)C NMR.

Bioassay-guided isolation of antiatherosclerotic phytochemicals fromArtocarpus altilis

The cytoprotective effects of various solvent extracts of Artocarpus altilis (Parkinson) Fosberg were evaluated. The cytoprotective effects were determined in human U937 cells incubated with oxidized LDL (OxLDL) using the 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1, 3-benzene disulfonate (WST-1) assay. The results demonstrated that the ethyl acetate extract showed cytoprotective activities. To identify the main cytoprotective components, a bioassay guided isolation of the ethyl acetate extract afforded b-sitosterol (1) and six flavonoids (2-7). Their chemical structures were established on the basis of spectroscopic evidence and comparison with literature data. Of these compounds, compound 6 was obtained from A. altilis for the first time. The cytoprotective effect offers good prospects for the medicinal applications of A. altilis.