Athar Ata

Oleanolic acid and related derivatives as medicinally important compounds

Oleanolic acid has been isolated from chloroform extract of Olea ferruginea Royle after removal of organic bases and free acids. The literature survey revealed it to be biologically very important. In this review the biological significance of oleanolic acid and its derivatives has been discussed. The aim of this review is to update current knowledge on oleanolic acid and its natural and semisynthetic analogs, focussing on its cytotoxic, antitumer, antioxidant, anti-inflamatory, anti-HIV, acetyl cholinesterase, alpha-glucosidase, antimicrobial, hepatoprotective, anti-inflammatory, antipruritic, spasmolytic activity, anti-angiogenic, antiallergic, antiviral and immunomodulatory activities. We present in this review, for the first time, a compilation of the most relevant scientific papers and technical reports of the chemical, pre-clinical and clinical research on the properties of oleanolic acid and its derivatives.

Synthesis of Hydroxyquinoline Derivatives, Aminohydroxychromene, Aminocoumarin and Their Antibacterial Activities

Some new diaminochromenes (3a-f, 7a-c, and 10), 7-amino-4-aryl-coumarins (8a,b), 7-hydroxy-4-aryl-1,2-dihydroquinolines (9a-c) and 2-amino-7-hydroxy-4-(4-chlorophenyl)-4H-chromenes (16a-d) were synthesized viu Michael addition of different substituted aminonaphthol (1), aminophenol (6), resorcinol derivatives (15a-d), chloronaphthol (17) and 4-hydroxycoumarin (19) with a-cyanocinnamonitriles (2a-c) and ethyl α-cyanocinnamate (2d-f). 2-Acetylamino-7-amino-4-(4-chlorophenyl)-4H-chromene-2-carbonitrile (14) was obtained as a unique product via hydrazinolysis of ethoxymethyleneamino derivative (13). The formation of coumarins (8a,b) and quinolines (9a-c) were anomalous case. Structures of the titled compounds cited in this article were elucidated by spectrometric data (IR, 1 H NMR, 1 3 C NMR (APT) and EMS). All of the newly synthesized compounds were evaluated for antimicrobial activities, where 16b and 16c exhibited activity against staphylococcus aureus (ATCC 25923).

Anti-acetylcholinesterase, anti-α-glucosidase, anti-leishmanial and anti-fungal activities of chemical constituents of Beilschmiedia species

Phytochemical investigation of Beilschmiedia alloiophylla has resulted in the isolation of one new alkaloid, 2-hydroxy-9-methoxyaporphine (1), and ten known natural products, laurotetanine (2), liriodenine (3), boldine (4), secoboldine (5), isoboldine (6), asimilobine (7), oreobeiline (8), 6-epioreobeiline (9), β-amyrone (10), and (S)-3-methoxynordomesticine (11). Chemical studies on the bark of B. kunstleri afforded compounds 2 and 4 along with one bisbenzylisoquinoline alkaloid, N-dimethylphyllocryptine (12). Structures of compounds 1-12 were elucidated on the basis of spectroscopic methods. All of these isolates were evaluated for their anti-acetylcholinesterase (AChE), anti-α-glucosidase, anti-leishmanial and anti-fungal activities. Compounds 1-12 exhibited strong to moderate bioactivities in aforementioned bioassays.

New bioactive steroidal alkaloids from Buxus hyrcana.

Phytochemical studies on the crude methanolic extract of Buxus hyrcana, collected from Iran, resulted in the isolation of two new steroidal alkaloids, (+)-O6-buxafurandiene (1) and (+)-7-deoxy-O6-buxafurandiene (2) along with four known steroidal bases, (+)-benzoylbuxidienine (3), (+)-buxapapillinine (4), (+)-buxaquamarine (5) and (+)-irehine (6). The structures of these new and known compounds were established with the aid of extensive NMR spectroscopic studies. Compounds 1 and 2 belong to the rarely occurring class of Buxus alkaloids having a tetrahydrofuran ring incorporated in their structures. Compounds 1-6 exhibited acetylcholinesterase enzyme inhibitory activity.

Synthesis of novel indenoquinoxaline derivatives as potent α-glucosidase inhibitors.

A series of new N-(11H-Indeno[1,2-b]quinoxalin-11-ylidene)benzohydrazide derivatives (3a-3p) were synthesized and evaluated for their α-glucosidase inhibitory activity. The synthesized compounds 3d, 3f, 3g, 3k, 3n, 3p and 4 showed significant α-glucosidase inhibitory activity as compared to acrabose, a standard drug used to treat type II diabetes. Structures of the synthesized compounds were determined by using FT-IR, (1)H NMR, (13)C NMR, mass spectrometry and elemental analysis techniques.

Glutathione S-transferase- and acetylcholinesterase-inhibiting natural products from medicinally important plants*

Naturally occurring enzyme inhibitors play an important role in a drug discovery program. Glutathione S-transferases (GSTs) play a significant role in the detoxification and metabolism of many xenobiotic and endobiotic compounds. GSTs are considered to be responsible for decreasing the effectiveness of anticancer/antiparasitic agents used for the treatment of cancer and parasitic diseases. The effectiveness of these biomedical agents may be improved by using GST inhibitors as an adjuvant during chemotherapy. Acetylcholinesterase (AChE) inhibitors have potential applications in curing cardiac problems and Alzheimers disease. This article describes the identification of natural products exhibiting GST and AChE inhibitory activities, from medicinally important plants. Results obtained from the structure-activity relationship (SAR) studies of some of these newly discovered enzyme inhibitors are also discussed.

Bioactive dimeric carbazole alkaloids from Murraya koenigii.

Phytochemical studies on the CHCl3 extract of the fruit pulp of Murraya koenigii afforded three new dimeric carbazole alkaloids, bisgerayafolines A-C (1-3). Bisgerayafolines A-C (1-3) are structurally unique dimeric carbazole alkaloids comprising geranyl moieties incorporated in their structures. Compounds 1-3 exhibited various levels of antioxidant, anti-α-glucosidase, DNA binding, and cytotoxic activities and protein interactions.

Triterpenoidal alkaloids from Buxus hyrcana and their enzyme inhibitory, anti-fungal and anti-leishmanial activities.

From the aerial parts of Buxus hyrcana, three triterpenoidal alkaloids, 17-oxo-3-benzoylbuxadine (1), buxhyrcamine (2), and 31-demethylcyclobuxoviridine (3), along with 16 known compounds, cyclobuxoviridine (4), N(b)-dimethylcyclobuxoviricine (5), E-buxenone (6), Z-buxenone (7), moenjodaramine (8), homomoenjodarmine (9), buxamine A (10), buxamine B (11), 31-hydroxybuxamine B (12), N(20)-formylbuxaminol E (13), papillozine C (14), buxmicrophylline F (15), buxrugulosamine (16), cyclobuxophylline O (17), spirofornabuxine (18) and arbora-1,9(11)-dien-3-one (19) were isolated. Their structures were elucidated by using NMR spectroscopic methods. All of the compounds exhibited moderate to weak acetylcholinesterase, butyrylcholinesterase and glutathione S-transferase inhibitory activities. Compounds 1-19 also exhibited modest anti-fungal activities against Candidaalbicans. Compounds 1, 2, 8, 9 and 18 also exhibited weak anti-leishmanial activity.

Antioxidant and structure–activity relationships of five tetraoxygenated xanthones from Swertia minor (Griscb.) Knobl.

Antioxidant activity-guided fractionations of chloroform extract of Swertia minor yielded five known tetraoxygenated xanthones (1–5), of which compound 3 was isolated for the first time from plant sources. Compounds 1–5 were identified with the aid of extensive NMR spectroscopic studies. A relationship between the structural features of 1–5 and their antioxidant activity was also determined. Among these bioactive isolates (1–5), compound 4 exhibited strong scavenging effect in DPPH (IC50 = 10.31 µg mL−1), FRAP (8536.32 ± 34.1 Mmol Fe (II) g−1) and metal chelating (17.2 ± 0.88 mg EDTA g−1) assays. Compound 5 was potently active in secondary antioxidant assay (i.e. binding to metal ions strongly); however, its primary antioxidant capacity was found to be feeble.

Triterpenoidal alkaloids from Buxus natalensis and their acetylcholinesterase inhibitory activity.

Acetylcholinesterase (AChE) inhibition-directed phytochemical studies on the methanolic extract of Buxus natalensis, collected in South Africa, resulted in the isolation of 12 compounds: O(2)-natafuranamine (1), O(10)-natafuranamine (2), cyclonataminol (3), 31-demethylbuxaminol A (4), buxaminol A (5), buxafuranamide (6), buxalongifolamidine (7), buxamine A (8), cyclobuxophylline K (9), buxaminol C (10), methyl syringate (11), and p-coumaroylputrescine (12). Compounds 1-4 were new alkaloids, and compound 5 was isolated for the first time as a natural product. Their structures were elucidated with the aid of extensive NMR and mass spectroscopic studies. Compounds 1 and 2 are members of a rarely occurring class of Buxus alkaloids, having a tetrahydrofuran ring incorporated in their structures. Compounds 1-12 exhibited strong to moderate AChE inhibitory activity.