This is a second part of a review 1) and is mainly a compilation of new secoiridoids reported in the literature during 1994-2005 as well as a high-light of biological and pharmacological activity of iridoids and secoiridoids published during 1998--2005. The earlier first part of review 1) included new naturally occurring iridoids (glycosides, aglycones, derivatives and dimers) reported during 1994-2005. Secoiridoids are monoterpenoids based on the 7,8-secocyclopenta[c]-pyranoid skeleton and represented by 1a. They are possibly derived in plants from iridoid, loganin 1b by oxidative cleavage with redox enzyme to 1c and then undergo various secondary modifications of the basic skeleton namely, epoxidation, oxidation, hydroxylation and esterification of the generated hydroxyl groups leading a group of compounds which constitute the class. The main aim of this review is for rapid identification of isolated secoiridoids by comparison of spectral data as well as to draw attention of the natural product chemists for evaluation of biological and pharmacological activity of the isolated iridoids and secoiridoids in order to justify the use of medicinal plants containing these metabolites in folk medicines. In certain plants, the isolated metabolites showed biological activities other than the use of the concerned plants in traditional system of medicine. The high-light of pharmacological activity may possibly draw the attention of the synthetic chemists for design of new drugs using known iridoids as raw materials.A number of review articles on plant secoiridoids are available. Listings of naturally occurring secoiridoids together with spectroscopic data and plant source (review of El-Naggar and Beal covering the literature through January, 1980 2) and of Boros and Stermitz covering the literature through December, 1989 3) ), and without spectroscopic data (review of Hazimi and Alkhathlan covering through December, 1993 4) ) are available. The reviews on biological activity of plant iridoids, namely of Sticher, covering the works reported up to 1976, 5) of Ghisalberti and of Mandal et al. covering the literature up to a part of 1997 6,7) are also available. Secoiridoids are listed in Table 1 in a fashion similar to that of the Boros and Stermitz review.3) All the new secoiridoids are arranged in four groups. Group 1 contains simple secoiridoids; whereas group 2 contains terpene-conjugated secoiridoids; group 3 contains aromatic conjugated secoiridoids and group 4 contains bis-, tris-and tetrakis-secoiridoids. The oxidation state of C-10 and C-11 guides the arrangement of compounds in each group except group 4. The available data for each compound were listed in the following order: name; structure; molecular formula; calculated molecular weight as per atomic weight of most abundant isotopic atoms of C, H, O, etc.; melting point (°C); optical rotation, [a] D (with concentration and solvent); UV (solvent, l max in nm, log e); IR (medium, n max in cm C-NMR data to the first decimal point. Assignments with the s...

A compilation of new naturally occurring iridoid glycosides, iridoid aglycones, iridoid derivatives and bis-iridoids reported during 1994-2005 is provided with available physical and spectral data: mp, [alpha]D, UV, IR, 1H- and 13C-NMR as well as natural source with family and references. 418 compounds with 202 references are cited.

Naturally occurring new triterpenoid saponins reported from mid-1996 to March, 2007 are reviewed including their physical constants and plant sources, and are compiled in Table 1. New saponins are arranged in Table 1 on the basis of the skeletal structures of their aglycones, e.g., oleanane type, ursane type, lupane type, hopane type, taraxastane type, cycloartane type, lanostane type, tirucallane type, dammarane type, cucurbitane type, and holostane type. The known triterpenoid saponins and prosapogenins of the new saponins, the biological and pharmacological activities of which were published during 1996-2007, are also reviewed together with their plant sources listed in Table 2 according to the skeletal structures of their aglycones in the same fashion as in Table 1. The plant and animal sources of both new and known bioactive triterpenoid saponins are collected in Table 3 in alphabetical order. The biological and pharmacological activities such as antiallergic, antiatherosclerosis and antiplatelet, antibacterial, anticomplementary, antidiabetic, contraceptive, antifungal, anti-inflammatory, antileishmanial, antimalarial/antiplasmodial, anti-obesity, anti-proliferative, antipsoriatic, antispasmodic, antisweet, antiviral, cytotoxic/antitumor, detoxication, gastroprotective, haemolytic, hepatoprotective, immunomodulatory, anti-enzyme, anti-osteoporotic, insecticidal, insulin-like, membrane-porosity, molluscicidal, neuropharmacological, anti-endothelial dysfunction, snake venom antidote, and sweet activities of these saponins or derived prosapogenins are discussed briefly after Table 3.

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