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Yuliansyah. Haqiqi MT, Setiawan KA, Setiawan A, Saputra PD, Romadlon HSI, Mukhdlor A, Ramadhan R, Amirta R. 2022. Fast-growing native tree species to the secondary forest of East Kalimantan, Indonesia: Physicochemical properties of woody materials for bioelectricity feedstocks. Biodiversitas 23: 3379-3386. The conversion of woody biomass into electricity through a thermochemical process has recently attracted significant attention worldwide to promote green energy production. It provides a low-cost and straightforward operation promising for developing rural areas, especially with limited transportation access. In East Kalimantan Province, almost all remote areas are surrounded by forests with high tree species diversity, which is the potential to be utilized for sustainable feedstocks in electric power plants. This study pointed out the energy potential produced from woody biomass of selected fast-growing tree species native to East Kalimantan secondary tropical forest: Elaeocarpus ferrugineus (Jacq.) Steud., Ficus aurata (Miq.) Miq., Fordia splendidissima (Blume ex Miq.) Buijsen, Lindera lucida (Blume) Boerl., Mallotus paniculatus (Lam.) Mull. Arg. and Schima wallichii (DC). Their wood physicochemical properties were firstly investigated. Furthermore, each species' wood quality for solid energy purposes was presented as the fuel value index (FVI). The results revealed that the change from greenwood into wood chip effectively removed the moisture content, thus improving efficiency to achieve higher energy potency. Our findings showed that the highest energy potency was obtained from the wood chip of F. splendidissima (3.61 MWh/ton), followed by S. wallichii (2.98 MWh/ton). A similar pattern was also found in FVI determination showing that the wood chip of S. Splendidissima had the greatest value (8970). Therefore, we observed that the high quality of S. splendidissima compared to other selected fast-growing species indicates its high suitability for further large-scale crop plantation to supply wood chips for biomass-based electricity generation.

Abstract. Ramadhan R, Phuwapraisirisan P, Amirta R, Darmawan MFB, Ul-Haq K, Kusuma IW, Suwito H, Abdulgani N, Mukhdlor A, Saparwadi. 2022. The potency of selected ethnomedicinal plants from East Kalimantan, Indonesia as antidiabetic agents and free-radical scavengers. Biodiversitas 23: 2225-2231. Ten ethnomedicinal plant extracts from East Kalimantan flora, traditionally used to treat blood sugar levels and other diabetes-related diseases, were examined in vitro for their antidiabetic and free radical scavenging activities by inhibiting rat alpha-glucosidase and several free radicals such as DPPH, ABTS, and Nitric oxide respectively. Out of the ten plant species investigated for their antidiabetic activity against maltase and sucrase rat alpha-glucosidase, three exhibited the strongest ?-glucosidaseinhibitory activity with maltose as a substrate, namely extracts of Garcinia nervosa, Syzygium caudatilimbum, and Shorea balangeran with IC50 values of 0.046; 0.037; 0.045 mg/mL. Meanwhile, quercetin as a positive control appeared to have a comparable IC50value. Furthermore, among the ten extracts, Syzygium caudatilimbum, Shorea balangeran, and Ixora javanica showed good inhibition against sucrase rat alpha-glucosidase. Moreover, the antioxidant test showed that the ten methanol extracts of plants from East Kalimantan have an antioxidant activity indicated by IC50values. The present study confirms that the ethnopharmacological use of selected plants from East Kalimantan might have potential as an antidiabetic and natural antioxidant.

Amirta R, Mukhdlor A, Mujiasih D, Septia E, Supriadi, Susanto D. 2016. Suitability and availability analysis of tropical forest wood species for ethanol production: a case study in East Kalimantan. Biodiversitas 17: 544-552. Fifteen species of woody biomass from tropical forest of East Kalimantan, Indonesia and identified as Acacia mangium, Aleurites moluccana, Alstonia scholaris, Anthocephalus cadamba, Artocarpus altilis, Artocarpus elasticus, Cananga odorata, Gmelina arborea, Lagerstroemia speciosa, Leucaena leucocephala, Macaranga gigantea, Macaranga tanarius, Paraserianthes falcataria, Shorea leprosula and Swietenia macrophylla were characterized and studied to find out and discover their potential utilization as suitable feedstocks for biofuel (ethanol) production. Characterization was done by evaluation of lignin, holocellulose and cellulose contents of woody biomass including the yield of reducing sugar (saccharification) after pretreated with alkaline (NaOH) at moderate temperature. Among 15 species of tropical forest wood biomass evaluated, our findings showed that M. gigantea was gave the highest yield of saccharified sugar (42.22%, weight of original wood dry basis) and also yield of theoretical ethanol (± 273 L/ton). We also found growth of M. giganteawas very fast to produce approximately 26,119 kg ha-1 dry biomass within 3 years. In general, the tropical wood biomass such as M. gigantea, A. moluccana, G. arborea, A. cadamba, and P. falcataria are suitable and potentially to be used as feedstocks for ethanol production due to their fast growing ability, availability and attractive chemical composition to produce high saccharified sugar and yield of ethanol.