Abstract: Quassinoids were initially isolated as bitter principles of plants of the Simaroubaceae family. These natural products are formed by oxidative degradation of triterpene derivatives. Since the 1970s, these molecules have attracted attention because of their promising biological activities, especially in the context of research regarding active anticancer and antimalarial principles. In this chapter, the structural diversity of quassinoids and their botanical and geographical occurrence are described, combining a historical perspective from the literature references regarding these two major biological activities and focusing on the results obtained in vivo with the most promising compounds; in vitro studies are less relevant and have already been extensively reviewed in the literature. The biological activities with respect to the uses of the corresponding Simaroubaceae in traditional medicine are also analyzed.

Abstract: French Guiana records high malaria incidence rates. The traditional antimalarial remedy most widespread and still very much in use there is a tea made out from Quassia amara mature leaves. The antimalarial activity of this preparation was assessed [1] and in order to optimize the in vitro activity, different types of preparation have been realized and tested. The most active in vitro preparation is an infusion of fresh young leaves. It demonstrated a very good activity, in vitro as well as in vivo [2]. A known quassinoid, simalikalactone D (SkD), was identified as the active compound, with an IC50 value of 10 nM against FcB1 Plasmodium falciparum chloroquine resistant strain in vitro [3]. Our next objective was to assess whether it could be contemplated to recommend this young leaves tea for treatment against malaria, since it seemed from literature precedent that SkD was also cytotoxic to a number of cellular lineages [4,5]. We then characterized and quantified the antiparasitic and cytotoxic activities of all the constituents. Several quassinoids were isolated and characterized in the tea: SkD, quassin, neoquassin, and picrasins B, H, I (new) and J (new), SkD being responsible of both antiplasmodial activity and cytotoxicity. In addition, in the context of an antimalarial treatment, it appeared that the dose necessary for obtaining a curative antimalarial effect is close to the toxic dose of an SkD analogue, bruceantin. Prior to emitting a definitive conclusion, a clinical study in humans similar to the one done with bruceantin [6] should be performed.

Abstract: In effort to explain wood durability of Moraceae plants family, a phytochemical study was undertaken on Bagassa guianensis. The phytochemical investigation of the ethyl acetate extract obtained from the heartwood led to the isolation of 18 secondary metabolites, including 6 moracins [the new 6-O-methyl-moracin M (3), 6-O-methyl -moracin N (4) and moracin Z (5); the known moracin M (1), moracin N (2) and moracin P (6)], 8 phenolic derivatives [the new (-)-epialboctalol (12), arachidin 4 (10) and the known alboctalol (11), trans-resveratrol (7), arachidin 2 (9), trans-oxyresveratrol (8) and artogomezianol (13)], the 3 known flavonoids steppogenin (14), katuranin (15), dihydromorin (16), the β-sitosterol (17) and the resorcinol (18). Comparison with literature data indicates that stilbenoids are presumably responsible for the natural resistance of the wood against fungi degradation. In addition, chemical composition points out that B. guianensis is closely related to Morus sp. in the phylogeny and should be placed within the Moreae s. s. tribe in the Moraceae family, accordingly to the latest Weiblen genoma-based classifications [1,2].

Abstract: Plant natural products have been perfected through evolution with respect to their specific biological roles (defense, elicitor, and so on) and are, therefore, an excellent starting point in the search for new biologically active chemicals. Hence, despite the progressive abandonment of the exploration of naturally sourced bioactive substances by the pharmaceutical industry, more than half of the drugs approved in the United States between 2005 and 2007 are natural products or natural product-derived drugs, five of which constituted the first members of new drug classes [1]. Clearly, chemical research into natural substances still has an important role to play in improving quality of life, and can play an important role by inventing innovative strategies to discover new bioactive compounds [1,2].
In the present work, we demonstrated that a bio-inspired approach for the identification of novel bioactive natural products represents a promising biotechnological tool for the development of new drugs. We have studied how natural defenses within decay-resistant wood can generate a large number of positive hits in the search for antimycotic agents. In addition, it was found from bioguided fractionation that ethyl acetate extracts of Sextonia rubra wood contain a relatively large proportion of antifungal metabolites rubrenolide (1) and rubrynolide (2), 1 being slightly more active than 2. The therapeutic potential of the above compounds will be discussed through the evaluation of their antifungal activities against 16 pathogenic fungi strains and their cytotoxicities towards KB cells.

Abstract: Control of metal corrosion is of technical, economical, environmental, and aesthetical importance. The use of corrosion inhibitors is one of the best options to protect metals and alloys from corrosion. The environmental toxicity of synthetic inhibitors has prompted the search for green compounds. Plant extracts have become important as an environmentally acceptable, readily available and renewable source for a wide range of biodegradable, heavy metals-free inhibitors. Among natural compounds, alkaloids have very high corrosion inhibition efficiency. An alkaloidic extract of Geissospermum laeve (Apocynaceae) has been fractionated by centrifugal partition chromatography using the pH-zone refining mode in order to investigate the effect of isolated alkaloids on C38 steel corrosion in HCl 1M. Indole alkaloids were identified by LC-MS, 1H and 13C NMR.