Indonesia mempunyai keanekaragaman hayati terbesar di dunia, memiliki potensi sebagai sumber bahan baku obat alami yang sangat besar. Potensi hutannya belum dimanfaatkan secara optimal, sala h satunya di Kalimantan Barat. Tanaman Laban (Vitex pubescens Vahl.) merupakan salah satu tanaman asli daerah ini, digunakan sebagai obat tradisional oleh penduduk setempat dan dimanfaatkan sebagai tanaman penahan kebakaran di areal hutan serta penghasil charcoal. Melihat potensi dan kelimpahannya maka perlu upaya eksplorasi lebih lanjut baik pemanfaatan maupun pengembangannya melalui penelitian tentang isolasi, identifikasi struktur serta potensi bioaktif tanaman Laban tersebut. Ekstrak kloroform dipartisi dengan n-heksana diperoleh fraksi larut nheksana aktif. Fraksi tersebut dipartisi menggunakan n-heksana:etanol:air (15:7,5:2 v/v) didapatkan fraksi lapisan atas dan bawah. Fraksi lapisan bawah yang aktif difraksinasi menggunakan Vacuum Liquid Chromatography (VLC) diperoleh 10 fraksi dan didapatkan 6 fraksi gabungan (A-F) berdasarkan kesamaan profil KLTnya. Fraksi gabungan tersebut diuji dengan metode BST dan fraksi C paling aktif. Fraksinasi lanjut menghasilkan 11 fraksi dan digabung menjadi 3 fraksi gabungan (CI-CIII). Fraksi CII lebih aktif (10 mg/mL, 97% kematian). Hasil KLT preparatif fraksi CII diperoleh tiga bercak (CIIa -CIIc). Bercak CIIb sebagai bercak teraktif (10mg/mL 97% kematian) selanjutnya diisolasi didapatkan isolat CIIb-1 dan CIIb-2. Kedua isolat diuji efek sitotoksiknya terhadap tiga cell line yaitu sel HeLa, Mieloma, dan SiHa. Nilai IC50 isolat CIIb-1 terhadap sel HeLa, Mieloma dan Siha berturut turut 238,26; 329,68; 131,58mg/mL dan isolat CIIb-2 berturut-turut 32,70; 12,73; dan 96,82mg/mL. Isolat CIIb-2 ternyata memberikan nilai IC50 terkecil pada sel Mieloma (12,73mg/mL) sehingga dikatakan mempunyai efek sitotoksik terbesar pada sel Mieloma in vitro. Identifikasi struktur kimia isolat CIIb-2 berdasarkan data spektra UV, IR, 1H-NMR, 13C-NMR dan hasil studi literatur menunjukkan bahwa is olat CIIb-2 mempunyai kerangka kumarin dengan substitusi metoksi pada C-3, asetil pada C-7 dan adanya gugus X serta gugus OH.

Indonesia is reported to have number one biodiversity in the world, and considered to be best resource of natural product. So far, the potency of the forest is not explored yet. Laban (Vitex pubescens Vahl.) is native plant in West Kalimantan used as herbal medicine by people, and used as fire resistor in many areas of forest, to produce charcoal. Based on its potency and abundance, further step of exploration through isolation, identification of bioactive compound and potency from Laban is undertaken. Chloroform extract was separated with n-heksana to give soluble fraction that was active. Three funnel-partition of this active fraction using a mixture of n- Hexane:etanol:water (15:7,5:2 v/v) to give lower layer and upper layer fractions. The lower layer was then fractionated by Vacuum Liquid Chromatography (VLC) to give 10 fractions that were combined to 6 combined fractions (A-F) based on TLC picture. Based on BST result fraction C was the most active, as this fraction was still a mixture then this fraction was partitioned to give 11 fractions that were combined to 3 combined fractions (CI-CIII). The combined fraction CII was more active (10 mg/mL ;96% of death) than that of other fractions. The compounds present in fraction CII were separated further by preparative thin layer chromatography (TLCp) to give 3 compounds (CIIa -CIIc). The CIIb fraction was the most active (10 mg/mL, 97% death) and was subjected on TLCp to give isolate CIIb-1 and CIIb-2. Both of them were tested for its cytotoxicity against HeLa, Mieloma, and Siha cell in vitro. IC50 values of isolate CIIb-1 against these cells were 238,26; 329,68; 131,58mg/mL and isolate CIIb-2 were 32,70; 12,73; and 96,82mg/mL. Isolate CIIb-2 was higher cytotoxicity on mieloma cell (12,73mg/mL) in vitro. According to spectroscopy data (UV, IR, H-NMR,13C-NMR) and literature, structure of isolate CIIb-2 was coumarin that substituted metoxy at C-3, acetyl at C-7 and X group also OH group.

Kata Kunci : Tanaman Laban,Senyawa Bioaktif