Protostane triterpenes belong to a group of tetracyclic triterpene that exhibit unique structural characteristics. Their natural distribution is primarily limited to the genus Alisma of the Alismataceae family, but they have also been occasionally found in other plant genera such as Lobelia, Garcinia, and Leucas. To date, there are 59 known structures of protostane. Many of them have been reported to possess biological properties such as improving lipotropism, hepato-protection, anti-viral activity against hepatitis B and HIV-I virus, anti-cancer activity, as well as reversal of multidrug resistance in cancer cells. On the other hand, fusidanes are fungal products characterized by the 29-nor protostane structures. They possess antibiotic properties against staphylococci, including the methicillin-resistant staphylococcus aureus (MRSA). Fusidic acid is a representative member which has found clinical applications. This review covers plant sources of the protostanes, their structure elucidation, characteristic structural and spectral properties, as well as biological activities. The fungal sources, structural features, structure-activity relationship and biological activities of fusidanes are also covered in this review. Additionally, the biogenesis of these two types of triterpene is discussed and a refined pathway is proposed.

Four new prenylated anthranols, harunganols C-F (1-4), along with kenganthranol A (5), harunganin (6), and ferruginin A (7), were identified from the leaves of Harungana madagascariensis. The structures of compounds 2, 5, and 7 were confirmed by single-crystal X-ray diffraction analysis. Compound 1 is a unique symmetrical anthranol dimer connected via a CH2 group. Compound 4 possesses a unique C-10 hemiketal group. All anthranols were evaluated for their α-glucosidase inhibitory activities. They displayed a higher potency compared to acarbose except for 3 and 4. In particular, harunganol C (1) showed an IC50 value of 1.2 μM.

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Protostane and Fusidane Triterpenes -[91 refs.]. -(ZHAO, M.; GODECKE, T.; GUNN, J.; DUAN, J.-A.; CHE, C.-T.; Molecules 18 (2013) 4054-4080, http://dx.doi.org/10.3390/molecules18044054 ; Dep. Med. Chem. Pharmacogn., Coll. Pharm., Univ. Ill., Chicago, IL 60612, USA; Eng.) -Lindner 33-259